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Elbow Instability

Elbow ligamentous and bony instability, including dislocation and the terrible-triad pattern.

104 citationsUpdated Sep 2026

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Overview

Complex elbow instability is a challenging clinical entity that requires a precise balance between stability, mobility, and concentric reduction [2]. Although understanding of elbow joint instability has improved in recent years, optimal results have not been consistently achieved [3]. Recognizing all possible lesions is critical to achieving an optimal outcome [1]. Current concepts for injuries leading to elbow instability in children include the recognition and treatment of both traumatic and nontraumatic causes [5]. In select NCAA athletes, elbow instability injuries represent an infrequent but serious source of disability [16]. For simple elbow dislocations, good long-term outcomes have been reported after non-operative management [8]; however, approximately 8% of patients develop persistent instability symptoms and a small proportion (2%) require surgical intervention if treated nonoperatively [8].

Surgical management is indicated for unstable elbows requiring flexion beyond 50 to 60 degrees to remain reduced, as well as for unstable periarticular fractures [73]. Operative repair is indicated for most fracture-dislocations of the elbow to restore sufficient osseoligamentous support to allow safe, early motion and provide a stable functional elbow in the long term [52]. Treatment protocols for terrible triad injuries must restore the integrity of the elbow by repairing all structures, and a standardised surgical protocol gives the best results and prognosis by restoration of elbow stability [53]. An understanding of the relevant anatomy and the factors associated with elbow stability allows the application of a systematic algorithm for treatment of terrible triad injuries, which helps ensure sufficient elbow stability to allow early motion and leads to improved outcomes in most patients [13].

Arthroscopic techniques provide safe and objective means to evaluate and diagnose both medial and lateral elbow instability [6]. Elbow arthroscopy has become a valid and safe option for the diagnosis and treatment of both acute and chronic elbow instability, allowing for the management of soft tissue lesions and associated intra-articular bone or cartilage lesions with minimal disruption [9]. It is a valuable tool in the diagnosis and management of chronic elbow instability [12]. Using a systematic diagnostic pathway including assessment of elbow stability and consecutive individualized, respectively, less invasive surgical procedure acquired high patients satisfaction and good clinical outcome with a low complication rate [29]. Patients with red flags for persistent instability should be considered for a primary surgical approach [81]. Further research, particularly multicenter prospective trials, is needed for complex elbow instability due to the rare nature of these injuries [2].

Anatomy & Pathophysiology

Bony Anatomy

The elbow is a trocho-ginglymoid joint consisting of medial and lateral articulations that provide bony stability [90]. The ulnohumeral joint functions as a hinged or trochoid portion where the trochlea articulates with the ulna within the greater sigmoid notch [90]. This articulation provides highly congruent anatomy through almost 180° of articular contact, with the exception of a bare area in the greater sigmoid notch devoid of cartilage [90]. The humeroulnar joint functions as a ginglymus (hinge) joint with intrinsic stability resulting from the depth of the trochlear fossa [46]. The trochlear groove is stabilized by the olecranon and coronoid processes [46]. The coronoid process has medial and lateral facets that buttress the trochlea anteriorly [90]. The sublime tubercle is located just distal and medial to the coronoid and serves as the attachment site for the anterior bundle of the medial ulnar collateral ligament [90].

The radiocapitellar joint is formed by the articulation of the capitellum and the radial head [90]. The radial head is a concave elliptical structure covered with articular cartilage along the radiocapitellar joint and approximately 270° of the articular margin [90]. The proximal radioulnar joint holds the radius in close approximation to the ulna via the annular ligament [90]. The olecranon provides a broad attachment site for the triceps muscle posteriorly [90].

The distal humeral articulation is angled 30° from the longitudinal axis of the humerus [90]. The axis of rotation of the elbow is angulated 5° to 7° in the coronal plane relative to the epicondylar axis, with the medial side more distal than the lateral side [90]. The articulation to the tip of the coronoid is approximately 30° from the long axis of the ulna in the sagittal plane [90]. The ulnohumeral articulation contributes to elbow stability, and olecranon resection increases valgus angulation and medial collateral ligament strain during valgus stress [26]. In full extension, 60% of axial load is transmitted through the radiocapitellar joint [93].

The normal range of elbow flexion/extension is 0 to 150 degrees [93]. The normal range of forearm pronosupination is 80 to 85 degrees in each direction [93]. The functional range of motion for the elbow is 30 to 130 degrees of flexion/extension and 50 degrees of pronosupination [93]. The normal valgus carrying angle of the elbow is 5 to 10 degrees for men and 10 to 15 degrees for women [93].

Ligamentous Anatomy

The medial collateral ligament complex comprises the anterior oblique, posterior oblique, and transverse ligaments [38]. The anterior oblique ligament is the strongest component of the medial collateral ligament complex and is the primary stabilizer to valgus stress [38]. It is composed of anterior and posterior bands that provide reciprocal function in resisting valgus stress through the range of flexion-extension motion [38]. The anterior band of the medial collateral ligament is taut in extension, while the posterior band is tight in flexion [38]. The anterior oblique ligament originates on the anterior-inferior edge of the medial epicondyle and inserts on the sublime tubercle of the ulna [38]. The posterior bundle of the medial collateral ligament is the primary restraint to valgus stress with the elbow in maximal flexion [93]. Stability in full extension is provided by the medial collateral ligament, joint capsule, and ulnohumeral articulation [93].

The lateral collateral ligament complex includes the radial collateral ligament, annular ligament, and lateral ulnar collateral ligament [133]. The lateral collateral ligament is the primary varus and posterolateral rotational stabilizer of the elbow [133]. The radial collateral ligament arises from the lateral epicondyle and blends with the annular ligament [133]. The lateral ulnar collateral ligament is posterior to the radial collateral ligament and attaches to the crista supinatoris of the proximal ulna, just distal to the annular ligament [133]. The radial head plays a minor role in posterolateral rotatory stability by tensioning the lateral ulnar collateral ligament [131]. Both the lateral ulnar collateral ligament and radial collateral ligament must be compromised for the lateral ligaments to become insufficient [131].

Stability Mechanisms

Elbow stability is conferred by bony articular anatomy, which is highly congruent, and ligamentous structures on the medial and lateral sides [34]. The three primary stabilizers of the elbow are the ulnohumeral articulation, the medial ulnar collateral ligament, and the lateral ulnar collateral ligament complex [34]. Secondary stabilizers of the elbow include the radiocapitellar articulation, common flexor tendon, common extensor tendon, and joint capsule [34]. The elbow consists of static and dynamic stabilizers that function in synchrony to prevent instability [36].

Dynamic constraints are provided by muscles crossing the elbow joint, specifically the anconeus, triceps, and brachialis, which apply compressive force [131]. The dynamic restraints of the elbow include the biceps, brachialis, and triceps, which provide compressive stability due to joint reactive forces [133]. The joint capsule provides the most stabilizing effect when the elbow is extended [131]. The normal joint capsule is thin but contributes to stability with the elbow in full extension and flexion [133]. The radiocapitellar articulation is an important secondary valgus stabilizer [131]. The coronoid process blocks rotational instability and posterior subluxation of the ulna from the posterior pull of the triceps or weight bearing on the hand [131]. 50% of the coronoid height is needed to provide substantial stability to the elbow [131]. Sagittal plane fractures of the coronoid may disrupt the medial collateral ligament insertion or cause substantial articular deformity [131].

The medial collateral ligament becomes the primary constraint to valgus instability when the radial head is resected [131]. Injuries to the medial collateral ligament in isolation are typically well tolerated, except in overhead throwers [131]. The common extensor muscles provide varus stability and the common flexor muscles provide valgus stability [133]. Pronation stabilizes a lateral collateral ligament-deficient elbow, while supination decreases stability in this setting [133]. The lateral ulnar collateral ligament injury is the cause of recurrent instability following simple elbow dislocation [24].

Pathophysiology of Instability

Elbow dislocations occur when loads placed on the structures about the elbow exceed the intrinsic stability provided by the anatomic shape of the joint surfaces and soft-tissue constraints [24]. Posterior dislocation is the most common type of elbow dislocation, accounting for 80% of cases [24]. Posterior dislocations result from an axial force applied to the extended elbow [24]. In posterior elbow dislocations, both collateral ligaments are disrupted, whether the dislocation is posteromedial or posterolateral [24]. Simple elbow dislocations are defined as those without fracture [24]. Elbow instability is a spectrum of injuries ranging from acute traumatic dislocation to chronic ligamentous laxity resulting in transient joint subluxation [45].

The mechanism of elbow dislocation involves a circle of soft tissue disruption starting from the lateral side and progressing to the medial side in three stages [45]. Stage 1 of soft tissue disruption involves the lateral collateral ligament, resulting in subluxation of the joint surfaces [45]. Stage 2 of soft tissue disruption involves the anterior and posterior capsular structures, allowing posterior rotation of the proximal ulna [45]. Stage 3 of soft tissue disruption involves partial or complete disruption of the medial collateral complex, allowing the coronoid process to rest behind the humerus [45]. The classic mechanism for posterolateral dislocation is a combination of axial load, external rotation of the forearm (supination), and valgus force [131]. Posterolateral elbow dislocation may also occur with a combination of axial load, external rotation of the forearm, and varus force [131]. The lateral collateral ligament complex is disrupted in all elbow dislocations [131]. Some authors believe the medial collateral ligament is always disrupted with elbow dislocation, but this is controversial [131].

Simple elbow dislocations are typically the result of a fall on an outstretched hand [122]. O'Driscoll et al. described a valgus, axial, and posterolateral force that results in the typical posterolateral dislocation of the elbow joint [122]. Soft tissue injury in simple dislocation is thought to begin on the lateral side with disruption of the lateral collateral ligament and proceeds through the capsule to the medial side [122]. Magnetic resonance imaging and video studies suggest that complete ligamentous tears are more common on the medial side of the elbow, with lateral ligaments preserved in some cases [122]. These studies suggest the sequence of failure may begin on the medial side with acute valgus instability in an extended elbow [122]. Patients with simple elbow dislocations routinely have disruption of both the medial and lateral collateral ligaments and the elbow capsule [133]. Muscular origins may be disrupted in simple dislocations, with injury to the lateral common extensor origin typically more extensive than the medial common flexor origin [133].

Residual instability after simple dislocation is usually due to incompetence of the lateral collateral ligament in the majority of patients, as most activities of daily living exert a varus force on the elbow [133]. The medial collateral ligament is the most important stabilizer of the elbow joint only in patients who routinely load their elbow in valgus, such as throwing athletes [133]. When the elbow dislocates, the radial head may cause an impression fracture of the posterior capitellum which can contribute to recurrent instability [133]. Residual instability following simple elbow dislocation is uncommon, with posterolateral instability being the best documented form [82]. Posterolateral instability may develop in some patients despite the development of secondary contracture [82].

Complex elbow instability involves injuries to the radial head, coronoid process, and ligaments [18]. The terrible triad of the elbow involves posterolateral elbow dislocation, a radial head or neck fracture, and a coronoid process fracture [143]. Elbow stability arises from a combination of bony congruity, static ligamentous and capsular restraints, and dynamic muscular activation [54]. Elbow trauma can disrupt these static and dynamic stabilizers leading to predictable patterns of instability dependent on the mechanism of injury [54]. There are three main patterns of instability in elbow fracture-dislocation: valgus posterolateral rotatory instability, varus posteromedial rotatory instability, and transolecranon fracture-dislocation [86]. Loads across the elbow joint at the time of injury lead to specific patterns of complex elbow instability [168].

A healthy elbow is reduced, meaning its joint surfaces are well aligned, and stable, meaning joint alignment is maintained throughout its entire range of movement regardless of physiological stresses [14]. Dislocation or subluxation is defined as a static condition characterized by a loss of normal joint relationships [14]. Instability is defined as a dynamic condition where, due to movement or mechanical stress, a reduced joint can lose its congruency [14]. All forms of elbow instability or dislocation can be grouped into three main types: not reduced-unstable, reduced-unstable, and not reduced-not reducible [14]. The "not reduced-unstable" type includes simple elbow dislocation not yet reduced and acute complex elbow instability [14]. The "reduced-unstable" type includes forms of temporary instability after a recent reduction of a simple elbow dislocation and chronic recurrent instability [14]. The "not reduced-not reducible" type includes simple elbow dislocation not reducible and persistent chronic dislocation [14]. Parameters for characterizing elbow instability include the stabilizers involved, timing, extent of dislocation, and direction [14]. Elbow instability is considered a spectrum of injuries from acute traumatic dislocation to chronic ligamentous laxity that results in transient joint subluxation [45]. Classification of elbow instability requires considering timing, direction of displacement, and presence of articular subluxation or associated fractures [45]. The concepts of instability and dislocation are apparently simple but can be confusing in clinical conditions, especially in the elbow [14].

Although understanding of elbow joint instability has improved, optimal results have not been consistently achieved [3]. Recognising the precise pattern of injury is critical in restoring elbow function and preventing chronic instability, pain and weakness [10]. An understanding of the relevant anatomy and factors associated with elbow stability allows the application of a systematic algorithm for treatment [13]. The primary goal of treatment for nonacute elbow fracture with persistent ulnohumeral dislocation or subluxation is stable reduction of the ulnohumeral joint and functional elbow motion [21]. The elbow is a congruent joint with a high degree of inherent stability provided by osseous and soft-tissue constraints [22]. Instability of the elbow occurs when substantial lesions of these stabilising structures happen [22]. Simple dislocations of the elbow are highly congruent joints with inherent stability provided by bony structures and dynamic stabilizers [23]. A simple elbow dislocation that is rotationally unstable can be stabilized by simply repositioning the forearm [11]. Rehabilitation programs for simple elbow dislocation should stress early active range of motion through the stable arc of motion [11]. Approximately 8% of patients with simple elbow dislocation develop persistent instability symptoms if treated nonoperatively [8]. A small proportion (2%) of patients with simple elbow dislocation require surgical intervention [8].

Optimal outcomes for coronoid fractures and traumatic elbow instability are founded upon concentric reduction of the elbow [51]. Operative repair is indicated for most fracture-dislocations to restore sufficient osseoligamentous support to allow safe, early motion and provide a stable functional elbow in the long term [52]. Use of a surgical protocol for terrible triad injuries restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome [33]. An internal joint stabilizer with a standardized treatment protocol could maintain concentric reduction while allowing early functional motion and improve clinical outcomes for patients with complex persistent elbow instability [27]. Biomechanical and clinical outcomes show that an external joint stabilizer via the posterior approach can restore mobility and stability in all patients, serving as a valuable alternative option for the treatment of persistent instability of the elbow [40]. Patients with traumatic elbow instability treated with or without an internal joint stabilizer revealed similar elbow range of motion in the first 6 months [30]. A stiff, congruent elbow is preferable to an unstable elbow [71]. The terrible triad has given way to the subtle triad with persistent microinstability of the elbow [18]. The next challenge for elbow surgeons is to diagnose and fix persistent subclinical instability after surgery in order to prevent the onset of post-traumatic osteoarthritis [18]. Post-traumatic osteoarthritis at long-term follow-up is still an issue for terrible triad injuries regardless of the treatments [18]. No consensual surgical protocol for the treatment of the terrible triad has been widely accepted [18].

Elbow dislocations are the second most common joint dislocation, with an incidence of 5.2 cases per 100,000 person-years [86]. Approximately one-quarter of all elbow dislocations involve a fracture [86]. The sequelae of elbow fracture-dislocations may include recurrent instability, posttraumatic arthritis, contracture, and poor functional results [86]. Early determination and appreciation of the magnitude and scope of injury in elbow fracture-dislocations generally leads to a more favorable result [86]. Complex elbow dislocations are challenging injuries to treat and may result in significant patient morbidity [55]. Chronic instability, posttraumatic arthrosis, and poor functional outcomes are frequent in complex elbow dislocations [55]. Orthopaedic surgeons should strive to optimize elbow function through restoration of articular congruity and stability coupled with early rehabilitation for complex elbow dislocations [55]. Understanding elbow biomechanics and the injury mechanism provides valuable insight into the variations of pathology observed in complex elbow dislocations [55]. Identifying the particular fracture pattern, such as an axial loading, valgus posterolateral rotatory, or varus posteromedial rotatory injury mechanism, helps guide appropriate treatment for complex elbow dislocations [55]. Recent advancements in the understanding of injury patterns have led to improved surgical treatment algorithms and better clinical outcomes in complex elbow injury [136]. By combining an understanding of anatomy and biomechanics with surgical technique, chronically dislocated joints can

Classification

Elbow dislocations are classified according to whether they are simple or complex and the direction of displacement [42]. A simple elbow dislocation is defined as a dislocation without osseous injury, whereas a complex elbow dislocation is defined as a dislocation with osseous injury [42]. Posterior dislocations are the most common direction of displacement and can be further classified as posterior, posterolateral, or posteromedial [42]. Anterior, medial, lateral, and divergent dislocations also occur in the elbow [42].

Terrible Triad: This pattern is characterized by an elbow dislocation with an LCL complex tear, a radial head fracture, and a coronoid fracture [42].

Varus Posteromedial Rotatory Instability: This condition is characterized by an LCL tear with a fracture of the medial facet of the coronoid or a comminuted coronoid fracture [42].

Instability Spectrum: Elbow instability is considered a spectrum of injuries ranging from acute traumatic dislocation to chronic ligamentous laxity resulting in transient joint subluxation [45]. Criteria for classifying this instability include timing (acute, chronic, recurrent), direction of displacement (valgus, varus, posterior, anterior), and the presence of articular subluxation or associated fractures [45].

Three-Type Grouping: Elbow instability can be grouped into three main types: not reduced-unstable, reduced-unstable, and not reduced-not reducible [14]. The "not reduced-unstable" type includes simple elbow dislocation not yet reduced and acute complex elbow instability [14]. The "reduced-unstable" type includes forms of temporary instability after a recent reduction of a simple elbow dislocation and chronic recurrent instability [14]. The "not reduced-not reducible" type includes simple elbow dislocation not reducible and persistent chronic dislocation [14]. Classification of elbow instability should consider the stabilizers involved, distinguishing between simple or complex forms [14]. It should also consider timing, distinguishing between acute, chronic recurrent, or chronic persistent [14], and the extent of dislocation, distinguishing between subluxation or dislocation [14].

Chronic Instability: Chronic instability of the adult elbow without associated fracture can be divided into valgus instability, posterolateral instability, and isolated radial head instability [139].

Wrightington Classification: The Wrightington classification of elbow fracture dislocation is a comprehensive, reliable, and valid classification with treatment algorithms associated with good functional outcomes [124].

Coronoid Fracture Patterns: Specific patterns of traumatic elbow instability have correspondingly specific coronoid fracture patterns [78]. The Regan and Morrey classification for coronoid fractures defines Type I as a fracture of the tip of the coronoid process, Type II as a fracture of 50% or less of the coronoid, and Type III as a fracture of greater than 50% of the coronoid [62].

Radial Head Fractures: The Modified Mason classification system for radial head fractures defines Type I as nondisplaced, Type II as partial articulation with displacement, Type III as comminuted fractures involving the entire head of the radius, and Type IV as fractures associated with ligamentous injury or other associated fractures [62].

Clinical Presentation

General Principles and Classification

Elbow instability represents a spectrum of injuries ranging from acute traumatic dislocation to chronic ligamentous laxity resulting in transient joint subluxation [45]. Dislocation or subluxation is defined as a static condition characterized by a loss of normal joint relationships, whereas instability is a dynamic condition where a reduced joint loses congruency due to movement or mechanical stress [14]. All forms of elbow instability and dislocation are grouped into three main types: not reduced-unstable, reduced-unstable, and not reduced-not reducible [14]. Understanding these patterns is essential for counseling and managing patients [15]. While infrequent, elbow instability is a serious source of disability for select NCAA athletes with associated risk factors [16]. In young active patients, elbow instability due to Ehlers-Danlos Syndrome is a rare but disabling condition [7].

Simple Elbow Dislocation

Posterior dislocations are the most common type, accounting for 80% of elbow dislocations, and result from an axial force applied to the extended elbow [24]. Simple dislocations are defined as those without fracture [24]. The extremity is typically shortened, and the elbow is held slightly flexed [24]. Anterior dislocations are relatively rare and typically involve severe soft-tissue damage [24]. In lateral elbow dislocations, some semblance of joint motion may be present as the ulna may be displaced into the groove between the trochlea and the capitellum [24]. Isolated ulnar dislocations occur when the humerus pivots around the radial head, displacing the coronoid process posterior to the humerus or the olecranon anterior to the humerus [24]. The more common isolated ulnar dislocation is posterior, causing cubitus varus deformity of the forearm [24].

Most simple elbow dislocations are readily managed nonoperatively and are amenable to early mobilization [64]. Closed reduction and early motion are standard, with recurrent instability being uncommon due to intrinsic bony stability [32]. Uncomplicated elbow dislocations have a favorable long-term prognosis, though a loss of extension of 5–10 degrees compared with the contralateral elbow can be expected [24]. Few patients develop complications requiring surgery; those that do most commonly undergo soft-tissue stabilisation or contracture release within 4 years of the injury [19]. A small proportion (2%) of patients require surgical intervention [8]. Posterolateral dislocation has been associated with persistent valgus instability in some patients, which is associated with a worse overall clinical result [24]. In one study, one patient showed signs of valgus instability and three patients had clinical signs of posterolateral rotatory instability while performing stress tests [48].

Complex Elbow Instability and Terrible Triad

The terrible triad of the elbow consists of injuries to the radial head, coronoid process, and lateral ligament complex [24]. An elbow dislocation and associated fracture of the coronoid process increase the risk of recurrent and chronic instability [24]. When there is greater than 50% loss of the coronoid, fixation is mandatory according to cadaver studies [24]. The most common problems after terrible triad lesions are recurrent and chronic instability, stiffness, posttraumatic arthrosis, and pain [24]. Complex elbow fracture dislocations are difficult to manage and associated with poor outcomes [119]. The rate of post-traumatic osteoarthritis at long-term follow-up for terrible triad injuries remains high regardless of the treatments [18].

Despite the complexities of terrible triad injury, an understanding of the relevant anatomy and factors associated with elbow stability allows the application of a systematic algorithm for treatment that can help ensure sufficient elbow stability to allow early motion [13]. Fixation or replacement of injured bony elements, ligamentous repair, and hinged fixation may be used to successfully manage complex elbow instability [17]. The variability in patients' pathoanatomic conditions in chronic complex persistent elbow instability requires customized surgical treatment aimed at elbow stabilizer reconstruction when the ulnohumeral joint is preserved or aimed at joint replacement in case of severe articular degeneration [118].

Posterolateral Rotatory Instability (PLRI)

Posterolateral rotatory instability (PLRI) may occur after elbow dislocation, iatrogenically, or in a delayed fashion after varus malunion of the distal humerus [154]. Insufficiency of the lateral ulnar collateral ligament (LUCL) is the essential lesion in PLRI [154]. Deficiencies in the coronoid, radial head, and medial collateral ligaments can further destabilize the elbow in a rotational manner [154]. PLRI is primarily an instability pattern of the ulnohumeral articulation, with secondary involvement of the radiocapitellar joint, while the radioulnar articulation remains stable [154]. A fall onto an outstretched hand that supinates the forearm with a valgus thrust and axially loads the forearm leads to PLRI [154]. In many cases of PLRI, the common extensor origin is avulsed proximally from the lateral epicondyle [154]. Tardy posterolateral elbow instability is a potential late complication of a varus supracondylar humerus malunion, where the abnormal lateral thrust across the joint line caused by the malunion slowly stretches the LUCL over time [154].

The most common physical examination tests performed to detect PLRI are the PLRI stress test, the posterior drawer test, the table top relocation test, the push-up test, and the chair-rise test [154]. In purely ligamentous PLRI, radiographs will be normal; however, associated lesions of the radial head, capitellum, coronoid, and articular surface may be seen [154]. MRI is unreliable to assess the integrity of the LUCL because of the oblique course of the ligament [154]. Cartilaginous injury can be appreciated on magnetic resonance arthrogram in PLRI [154]. CT markers provide valuable diagnostic information for posterolateral elbow instability, particularly in subtle cases [58]. The literature presents eight surgically proven cases of typical and atypical patterns of injury of the annular ligament in the setting of posterolateral elbow instability [41].

Medial Elbow Instability and UCL Injuries

Chronic medial elbow instability can be a debilitating problem for the throwing athlete [109]. The anterior oblique ligament of the medial collateral ligament complex is the strongest and is the primary stabilizer to valgus stress [26]. Patients with medial collateral ligament injuries report medial elbow pain during the acceleration phase of throwing; pain may occur only when throwing at more than 50% to 75% of maximal effort [26]. Acute medial collateral ligament injuries may present suddenly, with a pop, sharp pain, and inability to continue throwing [38]. Point tenderness can be noted at the medial collateral ligament or toward its insertion sites [38].

Valgus instability is tested with the patient’s elbow flexed between 20° and 30° to unlock the olecranon from its fossa as valgus stress is applied [38]. The milking maneuver is performed by having the patient or the examiner pull on the patient’s thumb to create valgus stress while the patient’s forearm is supinated and the elbow is flexed beyond 90° [38]. A subjective feeling of apprehension, instability, or localized pain at the medial collateral ligament during the milking maneuver indicates injury [38]. The moving valgus stress test is a modification of the milking maneuver where valgus stress is applied while the elbow is moved through an arc of flexion or extension [38]. Valgus stress radiographs with the elbow in 20° to 30° of flexion and the forearm in full supination may be used to measure medial joint line opening; greater than 3 mm has been considered diagnostic for valgus instability [38]. Standardized stress radiographs with comparison to the uninjured side can reveal increased medial joint gapping and aid in the diagnosis of a complete ulnar collateral ligament injury [115].

Conventional MRI can help identify thickening within the ligament from chronic injury or more obvious full-thickness tears [38]. Magnetic resonance arthrography enhanced with intra-articular gadolinium improves the diagnosis of partial undersurface tears of the medial collateral ligament [38]. Dynamic ultrasonography can help detect increased laxity with valgus stress, however, the diagnostic quality of the results is operator dependent [38]. Changes present in the ulnar collateral ligament and detectable on ultrasound may help distinguish elbows at risk for later clinical ulnar collateral ligament insufficiency [68]. An ultrasound can be utilized as a dynamic test to assess the ulnar collateral ligament thickness, integrity, and joint gapping with a valgus stress [115].

Valgus Extension Overload Syndrome

During throwing, the olecranon is repeatedly and forcefully driven into the olecranon fossa, exerting shear forces on the medial aspect of the olecranon tip and the olecranon fossa [26]. This process may cause cartilage injury and the development of osteophytes [26]. Medial ligamentous laxity commonly exacerbates valgus extension overload syndrome [26]. The pathoanatomy of valgus extension overload syndrome includes chondrosis, osteophyte development on the posteromedial olecranon and humerus, and loose bodies [26].

Patients with valgus extension overload report posteromedial elbow pain that occurs during the deceleration phase of throwing as the elbow reaches terminal extension [26]. Pain in valgus extension overload may also occur during acceleration [26]. Loss of terminal elbow extension may occur in valgus extension overload [26]. Crepitus and tenderness over the posteromedial olecranon may be noted in valgus extension overload [26]. Pain is reproduced when the elbow is forced into extension in valgus extension overload [26]. Elbow flexion contracture may be seen in valgus extension overload [26].

AP, lateral, oblique, and axillary views of the elbow may reveal posteromedial olecranon osteophytes and/or loose bodies in valgus extension overload [26]. CT with two-dimensional reconstruction and three-dimensional surface rendering best visualizes the pathology of valgus extension overload [26]. MRI may be most helpful in evaluating associated injuries including partial or complete tears of the medial collateral ligament in valgus extension overload [26].

Most throwing injuries of the elbow occur during the acceleration stage in which high valgus forces are countered by rapid elbow extension [69]. This motion results in three distinct pathologic forces: a tensile force on the medial stabilizing structures, a compression force at the radiocapitellar joint, and a medially directed shear force in the posterior compartment [69]. Valgus extension overload syndrome is the most common diagnosis requiring surgical treatment in baseball players and other overhead throwing athletes [69]. 85% of overhead athletes with valgus extension overload experience symptoms during the acceleration phase of throwing [69]. Athletes with valgus extension overload usually present with chronic medial elbow pain and concomitant changes in performance, including decreased pitch speed and stamina [69]. Some athletes with valgus extension overload report elbow clicking or locking [69].

Key physical examination maneuvers for valgus extension overload include the moving valgus stress test and the milking maneuver [69]. Evaluation for ulnar neuritis or subluxation is critical for future surgical planning in valgus extension overload [69]. The large valgus force exerted on the elbow in overhead throwing is countered by rapid elbow extension [69]. Repetitive, near-failure tensile stresses exerted on the ulnar collateral ligament subject it to microtrauma and subsequent attenuation of the anterior bundle [69]. Damage to the anterior bundle of the ulnar collateral ligament results in valgus instability [69]. Even subtle ulnar collateral ligament laxity results in stretch of other medial structures, including the ulnar nerve and the flexor-pronator mass causing ulnar neuritis and flexor mass tendinitis or tears [69]. In skeletally immature athletes, medial epicondyle apophysitis can occur as a result of ulnar collateral ligament microtrauma [69].

As a result of ulnar collateral ligament incompetency, osseous constraints of the posteromedial elbow become key stabilizers during throwing [69]. Repetitive shear stresses from continued throwing cause posterior compartment impingement [69]. Valgus laxity secondary to ulnar collateral ligament stretching further exacerbates valgus extension overload by altering the contact area between the medial humeral crista and the olecranon [69]. The abnormal ulnohumeral congruency results in increased contact pressures causing posteromedial impingement [69]. With chronic impingement, athletes become susceptible to synovitis, olecranon tip osteophyte formation, olecranon stress fractures, loose bodies, and chondral lesions of the posteromedial trochlea [69]. Because of the high compression forces exerted on the lateral radiocapitellar joint, athletes are at risk for chondromalacia, loose bodies, and lateral osteophyte formation [69].

Pediatric and Athletic Elbow Instability

Current concepts review injuries leading to elbow instability in children, discuss recognition and treatment of instability, and address nontraumatic causes [5]. Little Leaguer’s elbow is an overuse injury in which there is stress at the medial epicondyle apophysis due to valgus overload [44]. It is caused by repetitive throwing, primarily pitching, in the youth baseball player [44]. The maximal valgus moment on the elbow occurs during the late cocking through early acceleration phase [44].

Little Leaguer’s elbow presents primarily as medial elbow pain in the throwing athlete, loss of velocity, tenderness over the medial epicondyle, and pain with valgus stress [44]. A 2015 survey of healthy youth baseball players found that 74% and 80% of them had at least some pain during or after throwing, respectively [44]. MRI studies in symptomatic youth athletes often show edema at the distal humerus or medial epicondyle apophysis [44]. Preseason MRI abnormalities in youth baseball players were associated with year-round play, private coaching, and loss of shoulder internal rotation [44]. Postseason MRI evaluation of dominant elbows revealed abnormalities in 46% of Little League players [44]. Players lost an average of 11.2° of internal rotation of the shoulder during the season [44].

Risk factors for developing elbow pain during a season include recent increase in height, shoulder or elbow pain during the previous season, team training 4 days or more per week, self-training 7 days per week, and being in the starting lineup [44]. Other risk factors for shoulder and elbow pain in the youth baseball player include age, height, higher velocity pitches, playing for multiple teams, and arm fatigue [44].

Investigations

Physical Examination

Physical examination is a critical component in formulating an accurate diagnosis of elbow instability [35]. The examination is directed by the patient's history and the specific location of pain in the anterior, posterior, medial, or lateral aspect of the elbow [34]. Neurovascular status must be documented both before and after elbow reduction [42]. During the physical exam, open injuries and compartment syndrome, which require immediate surgical treatment, should be ruled out [42]. A sonographic ulnohumeral laxity greater than 4 mm should raise suspicion of underlying instability [174]. Preoperative MRI could be used to exclude subtle instability; surgeons should consider checking for subtle instability, especially when patients have a history of multiple corticosteroid injections (≥3) or severe pain [171].

Imaging

Plain radiography: Plain radiographs remain the hallmark and the best screening test for elbow evaluation [34]. Plain AP and lateral radiographs are necessary to document congruent reduction [42]. Oblique views may be useful to identify periarticular fractures [42]. The drop sign and radiographic Warner sign are associated with elbow instability [25]. Oblique and axial views have been proposed to improve measurement accuracy of displacement in medial epicondyle fractures [28].

CT: CT is useful to identify associated osseous injury [42]. With an incongruous reduction, CT should be considered to identify potential incarcerated osteocartilaginous fragments [42]. CT with two-dimensional reconstruction and three-dimensional surface rendering best visualizes the pathology of valgus extension overload syndrome [26]. CT can be helpful in identifying mineralized intra-articular loose bodies or delineating the anatomy of a complex intra-articular fracture [103]. CT evaluation of the dropping sign and radial head subluxation provides valuable diagnostic information for posterolateral elbow instability, particularly in subtle cases [58].

MRI: MRI is the imaging modality best suited for evaluating soft-tissue structures in the elbow, including ligaments, tendons, cartilage, and nerves [103]. MRI may be most helpful in evaluating associated injuries, including partial or complete tears of the medial collateral ligament [26]. Magnetic resonance arthrography (MRA) is particularly beneficial in the evaluation of osteochondral lesions, loose bodies, and ulnar collateral ligament (UCL) injury in a throwing athlete [103]. MRI findings in acute elbow dislocation provide insight into the mechanism of injury [57]. MRI of the elbow and the upper extremity athlete may be employed to identify partial or periosteal sleeve avulsions of the medial epicondyle [28]. Lower MRI grade and humeral location were objectively associated with higher return to throw, higher return to play, lower UCLR, and higher survival compared to higher grade and ulnar or both-sided tears [85].

Ultrasonography: Ultrasonography allows dynamic imaging, which may be useful in evaluating for ulnar nerve subluxation or a snapping triceps [103]. Changes present in the UCL and detectable on ultrasound may help distinguish elbows at risk for later clinical UCL insufficiency [68].

Arthroscopy

Elbow arthroscopy has become a valid and safe option for the diagnosis and treatment of both acute and chronic elbow instability, allowing for the management of soft tissue lesions and associated intra-articular bone or cartilage lesions with minimal disruption [9]. Arthroscopy allows a direct and dynamic approach to the ulnohumeral joint so that the degree and the pattern of instability can be quantified by several arthroscopic tests [43]. Arthroscopic-assisted lateral ulnar collateral ligament reconstruction provides less insult and dissection to the soft tissue at the lateral side of the elbow while being an excellent tool to diagnose any concomitant intraarticular pathologies [178].

Treatment

General Principles and Outcomes

Despite the complexities of terrible triad injuries, a systematic algorithm for treatment can help ensure sufficient elbow stability to allow early motion, leading to improved outcomes in most patients [13]. Surgical treatments for elbow instability can be challenging even for expert surgeons, and the rate of persistent instability, post-traumatic arthritis, stiffness and pain can still be high especially in most demanding cases [22]. Elbow instability due to EDS is a rare but disabling condition, especially in young active patients [7].

Advanced Stabilization Techniques: Bridge plating effectively maintains joint reduction in selected complex elbow instability cases [66]. The IJS represents an effective and reliable option as a temporary stabilization for residual elbow instability [117]. Biomechanical and clinical outcomes show that EJS-E via the posterior approach can restore mobility and stability in all patients, serving as a valuable alternative option for the treatment of persistent instability of the elbow [40]. Ulnohumeral cross-pinning for persistent and recurrent elbow instability results in maintained ulnohumeral joint alignment, functional arcs of elbow range of motion, and acceptable patient-reported outcome measures, particularly in the setting of a primary procedure indicated for persistent intraoperative instability [20]. In the setting of atraumatic, bilateral elbow instability that is refractory to nonoperative management, recurrent instability can be prevented by surgical reconstruction of the LUCL and internal joint stabilization [146]. Three patients have remained stable at their elbow status post bilateral ligament reconstruction for bidirectional elbow instability [50].

Simple Elbow Dislocation

Non-Operative Management: Conservative management remains the gold standard for most simple elbow dislocations [147]. Good long-term outcomes have been reported after non-operative management of simple elbow dislocations; however, a small proportion (2%) of patients require surgical intervention and approximately 8% develop persistent instability symptoms if treated nonoperatively [8]. Simple dislocations of the elbow are highly congruent joints with inherent stability provided by bony structures and dynamic stabilizers, allowing for early active range of motion during rehabilitation [23]. A simple elbow dislocation that is rotationally unstable can be stabilized by simply repositioning the forearm, and rehabilitation programs should stress early active range of motion through the stable arc of motion [11]. Treatment of simple elbow dislocations that are stable throughout an arc of motion following reduction has been shown to benefit from 2 days of immobilization and then early motion to avoid stiffness according to a recent randomized trial [128]. All patients in a series of simple elbow dislocations showed excellent to very good elbow function, with no significant differences concerning elbow flexion and extension compared to the non-affected side [48]. One patient in a series of simple elbow dislocations showed signs of a valgus instability and three patients had clinical signs of a posterolateral rotatory instability while performing stress tests [48].

Operative Indications: Surgery is indicated for unstable elbows requiring flexion beyond 50 to 60 degrees to remain reduced or for unstable periarticular fractures [73]. Surgical management is indicated when the elbow remains unstable, with the lateral ulnar collateral ligament being the most critical structure to repair or reconstruct [79]. Persistent instability within 30 degrees of full extension after simple elbow dislocation is an indication for acute ligamentous repair [125, 126]. Surgical procedures provide similar outcomes regarding MEPS and ROM for patients with slight initial instability, while those with red flags for persistent instability should be considered for a primary surgical approach [81].

Surgical Approach and Technique: The lateral ligamentous complex is always repaired for persistent instability in simple elbow dislocations, followed rarely by MCL if instability persists [125, 126]. The most common complication after closed treatment of simple elbow dislocation is loss of terminal extension [125, 126].

Pathophysiology and Classification: Simple dislocations are those without fracture [24]. Elbow dislocations occur when loads are placed on the structures about the elbow that exceed the intrinsic stability provided by the anatomic shape of the joint surfaces and soft-tissue constraints [24]. Elbow dislocations are potentially limb-threatening, as vascular compromise is a possible sequela [24]. Expeditious reduction of the elbow joint is the goal of treatment for elbow dislocations [24]. Isolated radial head dislocation is rare and is usually accompanied by an ulnar fracture (Monteggia fracture) [24]. When combinations of dislocations with concomitant fractures occur, treatment of the combined injury is usually dictated by the treated fracture [24]. Adequate fracture care will usually cause secondary reduction of the dislocation [24].

Posterior Dislocation Management: Both collateral ligaments are disrupted in posterior elbow dislocations, whether the dislocation is posteromedial or posterolateral [24]. Diagnosis of posterior elbow dislocation is made by clinical examination and verified by radiograph to rule out associated fractures [24]. The extremity is typically shortened and the elbow held slightly flexed in posterior dislocation [24]. Treatment of posterior elbow dislocation is initiated after documenting the neurovascular examination [24]. Anesthesia, either injected locally into the joint or administered intravenously, is necessary for reduction of posterior elbow dislocation [24]. Traction on the extremity with correction of the medial or lateral displacement usually produces reduction with a “clunk” in posterior dislocation [24]. The elbow is put through a range of motion to ensure that reduction has been obtained and that there is no soft-tissue or bony mechanical blockage to motion after reduction [24]. The elbow is generally splinted in flexion and pronation to maintain stability after reduction of posterior dislocation [24]. Postreduction radiographs are necessary to rule out occult fracture after reduction of posterior dislocation [24].

Anterior and Lateral Dislocations: Anterior dislocations are relatively rare [24]. Soft-tissue damage is typically severe in anterior elbow dislocations [24]. Treatment of anterior elbow dislocations is similar to that for posterior dislocations, except that the method of reduction is reversed [24]. The radius and ulna may be displaced medially or laterally in medial and lateral elbow dislocations [24]. Some semblance of joint motion may be present with lateral dislocations, as the ulna may be displaced into the groove between the trochlea and the capitellum [24]. The anteroposterior radiograph is diagnostic for medial or lateral elbow dislocations [24]. Medial or lateral force is used, after attempting to distract the joint surfaces, to reduce medial or lateral dislocations [24]. The more common isolated ulnar dislocation is posterior dislocation, which causes cubitus varus deformity of the forearm [24]. Traction in extension and supination reduces the ulna in isolated ulnar dislocations [24].

Stability Assessment and Immobilization: The elbow is tested for stability to varus and valgus stress and to pronation and supination in early treatment of elbow dislocation [24]. Stable dislocations are splinted for comfort at 90 degrees of flexion, and motion is instituted as soon as possible, generally within a few days [24]. Maintenance of reduction is necessary, and radiographs should be taken periodically if any doubt exists [24]. Immobilization does not guarantee maintenance of reduction [24]. Unstable reductions are rare [24]. Immobilization for longer periods may be necessary in cases of unstable reductions, as a stiff but stable elbow is preferable to an unstable elbow [24]. The lateral ulnar collateral ligament injury is the cause of recurrent instability [24].

Late Reduction and Fracture Management: Late reduction of elbow dislocations can be accomplished with closed techniques for up to several weeks from the time of injury [24]. Dislocations left untreated for longer periods generally require open reduction techniques [24]. Better function with less flexion contracture after open reduction of posterior dislocations is obtained by lengthening the triceps tendon [24]. The size of the coronoid fragment varies from a small marginal fragment (Reagan-Morrey type I) to a larger fragment (Reagan-Morrey type II), or includes the insertion of the anterior bundle of the medial collateral ligament (Reagan-Morrey type III) [24]. The decision to fix a coronoid fracture should be made based on elbow stability [24]. Even small rim fractures may require surgical fixation if instability is present after repair of associated fractures [24]. When there is greater than 50% loss of coronoid, fixation is mandatory according to the cadaver studies [24]. Interfragmentary screws can be used to fix a large coronoid fragment [24]. A pullout technique can be used to fix a coronoid fragment if interfragmentary screws are not used [24].

Terrible Triad Injuries: Denominated the terrible triad of the elbow, injuries involving radial head and coronoid fractures are difficult to treat, and the reported results have been poor [24]. Appropriate treatment for terrible triad injuries should include ORIF of the coronoid fracture and/or repair of the anterior capsule, ORIF or replacement of the radial head, and repair of the lateral ligament complex [24]. Residual instability after treatment of terrible triad injuries represents an indication for further intervention [24].

Acute Dislocation Protocol: Open injuries and compartment syndrome, which require immediate surgical treatment, should be ruled out during physical examination of acute elbow dislocation [42]. CT is useful to identify associated osseous injury in acute elbow dislocation [42]. Simple dislocation is defined as dislocation without osseous injury [42]. Complex dislocation is defined as dislocation with osseous injury [42]. “Terrible triad” is characterized by an elbow dislocation with an LCL complex tear, a radial head fracture, and a coronoid fracture [42]. Posterior dislocations are most common and can be posterior, posterolateral, or posteromedial [42]. Anterior, medial, lateral, and divergent dislocations also occur [42].

Reduction and Post-Reduction Care: Reduction of the joint under adequate analgesia is performed first for nonsurgical treatment of simple elbow dislocations [42]. The reduction maneuver for posterior dislocations involves applying inline traction, progressive elbow flexion, and anterior directed force to the olecranon [42]. Postreduction stability is assessed, and in posterior dislocations, the elbow is typically more unstable in extension [42]. Therefore, the elbow should be immobilized at 90° of flexion after reduction of a posterior dislocation [42]. If the LCL is disrupted and the MCL is intact, the elbow will be more stable with the forearm in pronation [42]. If the LCL and the MCL are disrupted, the forearm should be immobilized in neutral [42]. A posterior splint is applied, typically with the forearm placed in a splint for 5 to 7 days, with the elbow positioned at 90° and with appropriate forearm rotation [42]. Postreduction radiographic assessment (AP and lateral views with the elbow at 90° and appropriate forearm rotation) is performed to confirm concentric reduction [42]. Attention is directed to ensuring a concentric ulnohumeral reduction and alignment of the radial head with the capitellum [42]. Once reduction is confirmed, the arm is immobilized for 5 to 7 days [42]. Depending on stability, the splint can be removed to allow early active range of motion exercises using a brace with or without an extension block [42].

Surgical Indications and Contraindications: Surgical indications for acute elbow dislocation include inability to achieve stability of the elbow with reduction and immobilization [42]. Surgical indications include osteochondral fragment or soft-tissue entrapment preventing concentric reduction [42]. Surgical indications include complex dislocation–associated fractures [42]. Surgical indications include open injuries [42]. Surgical indications include neurovascular injuries requiring surgical care [42]. A relative indication for surgery is a reducible joint that is unstable (dislocates) when the elbow is extended between 90° and 60° [42]. Contraindications for surgery include patients with severe medical comorbidities [42].

Operative Technique: The incision for surgical treatment of acute elbow dislocation can be made in the posterior midline or on the lateral elbow over the Kocher interval (extensor carpi ulnaris and anconeus) with or without a medial approach [42]. Open reduction of the elbow with repair (or reconstruction) of the LCL complex is performed, then stability is assessed [42]. If the elbow is still unstable, the MCL is repaired (or reconstructed); then stability is assessed again [42]. Hinged or static external fixation is required only if the elbow is unstable after other surgical procedures have failed to maintain a concentric, stable reduction [42].

Complications and Pitfalls: Loss of extension is the most common complication of acute elbow dislocation treatment [42]. Early active range of motion exercises can help prevent or minimize the occurrence of loss of extension [42]. Static, progressive splinting may be initiated when the elbow is less inflamed, typically 6 to 8 weeks after injury [42]. Neurovascular injuries are a complication of acute elbow dislocation treatment [42]. Compartment syndrome is a complication of acute elbow dislocation treatment [42]. Articular surface injuries are a complication of acute elbow dislocation treatment [42]. Chronic or recurrent elbow instability is a complication, with residual laxity common with stress radiographs, but recurrent instability seen in less than 10% to 20% of cases [42]. Late osteoarthritis is a complication of acute elbow dislocation treatment [42]. Heterotopic ossification is a complication of acute elbow dislocation treatment [42]. The most common pitfall in treating acute elbow dislocation is failure to attain and maintain a concentric reduction after surgical or nonsurgical treatment [42]. The joint must be reduced concentrically, and treatment does not stop until satisfactory reduction is achieved [42]. Forearm rotation is used to its fullest advantage to attain or maintain concentric reduction [42]. Early active range of motion through a stable arc with the use of splints can help prevent contracture [42].

Complications

Simple Elbow Dislocation

Approximately 8% of patients treated nonoperatively for simple elbow dislocation develop persistent instability symptoms [8]. The etiology of posterolateral instability in this population remains unclear, with no specific predisposing factors identified that pose a particular risk [82]. Posterolateral instability may develop even when secondary contracture is present, suggesting that some ligamentous complexes heal in a contracted manner while others fail to heal entirely [82]. Despite appropriate and timely care, simple elbow dislocations can result in devastating complications, including prolonged rehabilitation, surgical intervention, and loss of function [82].

Complex Elbow Instability and Terrible Triad

Optimal results for elbow joint instability have not been consistently achieved despite improved understanding in recent years [3]. Terrible triad injuries are characterized by historically poor outcomes secondary to persistent instability, stiffness, and arthrosis [163]. Complications associated with the treatment of terrible triad injuries include stiffness, heterotopic bone formation, infection, ulnar neuropathy, persistent instability, nonunion, and malunion [163]. Revision surgery is necessary in 20% to 25% of cases for these injuries [163]. Post-traumatic osteoarthritis remains an issue at long-term follow-up regardless of the treatment modality employed [18]. Surgical treatments for elbow instability can be challenging even for expert surgeons, with high rates of persistent instability, post-traumatic arthritis, stiffness, and pain persisting especially in the most demanding cases [22].

Pediatric Elbow Instability

In a review of 145 elbow dislocations at a single institution, 80% of dislocations presented with a fracture [75]. The presence of multiple fractures, the need for surgical intervention, and prolonged immobilization were correlated with less than excellent functional outcome scores in pediatric elbow dislocations [75]. Complications were found in 20% of the cohort at a minimum 2-year follow-up for medial ulnar collateral ligament reconstruction in skeletally immature athletes [75]. Major complications in this pediatric medial ulnar collateral ligament reconstruction cohort included ulnar nerve injuries, medial epicondyle fractures, and revision surgery for osteophyte formation, accounting for 4% of the cohort [75]. Surgical correction of posterolateral rotatory instability in children is technically difficult, and ligament reconstruction carries the risk of injury to the lateral physes and apophyses [75].

Arthroplasty-Related Instability

Instability is the major complication of unlinked total elbow arthroplasty, often requiring revision [76].

Surgical Technique and Stabilization Complications

The literature demonstrates a distinct difference in complication profile between external fixation and the internal joint stabilizer (IJS) when used as treatment for traumatic elbow instability [160]. Ulnar collateral ligament reconstruction provides excellent patient-reported and clinical outcomes at medium-term follow-up with low complication and revision rates [148]. In contrast, ulnar collateral ligament repair is associated with an increased risk of revision surgery compared to reconstruction [172].

Recovery

Rehabilitation protocol: Rehabilitation for complex elbow instability is divided into three phases: acute (0–6 weeks or until union), sub-acute (6–12 weeks), and functional (after 3 months) [77]. In the acute phase, patients are instructed in rest, limb elevation, precautions, activity modification, and pain management [77]. Passive range of motion exercises begin in the first seven postoperative days [77], followed by active assisted range of motion exercises after the first postoperative week and active range of motion exercises after the second postoperative week [77]. Physiotherapy is performed five times a week for one hour each session [77]. Therapists treat the wrist, hand, and shoulder during rehabilitation to avoid secondary issues [77].

Other Considerations: Few patients with simple elbow dislocations develop complications requiring surgery [19]; those who do most commonly undergo soft-tissue stabilisation or contracture release within 4 years of the injury [19]. Post-traumatic osteoarthritis remains an issue at long-term follow-up for terrible triad injuries regardless of treatment, with high rates persisting [18]. The next challenge for elbow surgeons is to diagnose and fix persistent subclinical instability after surgery to prevent the onset of post-traumatic osteoarthritis [18].

In a series of lateral collateral ligament instability, all patients had resolution of symptoms and regained a near full arc of elbow flexion and forearm rotation [4]. At 43 months mean follow-up, none of the patients with varus posteromedial instability treated with internal brace augmentation had significant postoperative contracture [88]. At 43 months mean follow-up, none of these patients had clinically apparent signs of instability or suffered subluxation or re-dislocation [88]. An internal joint stabilizer with a standardized treatment protocol can maintain concentric reduction while allowing early functional motion for complex persistent elbow instability [27] and improves clinical outcomes for these patients [27]. Biomechanical and clinical outcomes show that the External Joint Stabilizer – Elbow (EJS-E) via the posterior approach can restore mobility and stability in all patients [40], serving as a valuable alternative option for the treatment of persistent instability of the elbow [40].

Use of a standard surgical protocol for elbow dislocations with radial head and coronoid fractures restored sufficient elbow stability to allow early motion postoperatively [33], which enhances the functional outcome [33]. Three patients remained stable at their elbow status post bilateral ligament reconstruction for bidirectional elbow instability [50]. The patient with a greatly delayed complication of medial epicondyle injury had full range of movement at the elbow with no obvious deformity at 6 weeks [87] and no weakness in the limb at 6 weeks [87].

All patients with residual increased valgus stress angulation and posterolateral rotatory translation after simple elbow dislocation showed excellent to very good elbow function [48]. No significant differences concerning elbow flexion and extension were detected compared to the non-affected side in patients with residual instability after simple elbow dislocation [48]. One patient showed signs of valgus instability in a series of patients with residual instability after simple elbow dislocation [48], while three patients had clinical signs of posterolateral rotatory instability [48]. Strut allograft augmentation in revision elbow arthroplasty has a survivorship free of revision with death as competing risk approaching 75% at 10 years [83].

Key Evidence

• [L5] Complex elbow instability is a challenging injury where recognizing all possible lesions is critical to achieve an optimal outcome. [1] (10.1007/s12306-010-0065-8)
• [L5] Complex elbow instability remains a challenging clinical entity requiring a balance between stability, mobility, and concentric reduction; further research, particularly multicenter prospective trials, is needed due to the rare nature of these injuries. [2] (10.1016/j.hcl.2007.11.010)
• [L4] Although our understanding of elbow joint instability has improved in recent years, in reality, optimal results have not been consistently achieved. [3] (10.1007/s00068-012-0205-y)
• [L4] All patients in the series had resolution of their symptoms of instability and regained a near full arc of elbow flexion and forearm rotation. [4] (10.1016/j.hcl.2007.11.001)
• [L5] The article reviews current concepts of injuries leading to elbow instability in children, discusses recognition and treatment of instability, and addresses nontraumatic causes. [5] (10.1016/j.hcl.2007.11.007)
• [Paper] Despite the invasive nature of arthroscopy in comparison to modalities such as ultrasonography and radiography, these described techniques provide safe and objective means to evaluate and diagnose both medial and lateral elbow instability. [6] (10.1016/j.eats.2023.04.029)
• [L5] Elbow instability due to EDS is a rare but disabling condition, especially in young active patients. [7] (10.2106/jbjs.cc.19.00355)
• [L5] Good long-term outcomes have been reported after non-operative management of simple elbow dislocations; however, a small proportion (2%) of patients require surgical intervention and approximately 8% develop persistent instability symptoms if treated nonoperatively. [8] (10.1177/1758573217694163)
• [L5] Elbow arthroscopy has become a valid and safe option for the diagnosis and treatment of both acute and chronic elbow instability, allowing for the management of soft tissue lesions and associated intra-articular bone or cartilage lesions with minimal disruption. [9] (10.1016/j.jseint.2022.12.001)
• [Paper] Recognising the precise pattern of injury is critical in restoring elbow function and preventing chronic instability, pain and weakness. [10] (10.1016/j.injury.2013.09.032)
• [L5] A simple elbow dislocation that is rotationally unstable can be stabilized by simply repositioning the forearm, and rehabilitation programs should stress early active range of motion through the stable arc of motion. [11] (10.1016/j.hcl.2015.06.002)
• [L4] Elbow arthroscopy is a valuable tool in the diagnosis and management of chronic elbow instability. [12] (10.1016/j.arthro.2013.08.016)
• [L5] Despite the complexities of this injury, an understanding of the relevant anatomy and the factors associated with elbow stability allows the application of a systematic algorithm for treatment that can help ensure sufficient elbow stability to allow early motion, thereby leading to improved outcomes in most patients. [13] (10.5435/00124635-200903000-00003)
• [L4] [14] (10.1007/s12306-016-0424-1)
• [L5] Understanding the patterns of traumatic elbow instability helps the surgeon counsel and manage patients with these injuries. [15] (10.1016/j.jhsa.2010.05.002)
• [L4] Elbow instability injuries are an infrequent but serious source of disability for select NCAA athletes, with a number of associated risk factors. [16] (10.1177/2325967117750105)
• [L5] Fixation or replacement of injured bony elements, ligamentous repair, and hinged fixation may be used to successfully manage complex elbow instability. [17] (10.5435/00124635-200605000-00003)
• [L5] [18] (10.1016/j.jseint.2023.03.018)
• [Paper] Few patients with simple elbow dislocations develop complications requiring surgery, but those that do most commonly undergo soft-tissue stabilisation or contracture release within 4 years of the injury. [19] (10.1016/j.injury.2015.02.009)
• [L4] Ulnohumeral cross-pinning for persistent and recurrent elbow instability results in maintained ulnohumeral joint alignment, functional arcs of elbow range of motion, and acceptable patient-reported outcome measures, particularly in the setting of a primary procedure indicated for persistent intraoperative instability. [20] (10.1016/j.jhsa.2024.06.003)
• [L5] The primary goal of treatment is stable reduction of the ulnohumeral joint and functional elbow motion. [21] (10.2106/jbjs.m.00817)
• [L5] [22] (10.1136/jisakos-2019-000316)
• [L5] Simple dislocations of the elbow are highly congruent joints with inherent stability provided by bony structures and dynamic stabilizers, allowing for early active range of motion during rehabilitation. [23] (10.1016/j.hcl.2004.07.002)
• [L4] An internal joint stabilizer with a standardized treatment protocol could maintain concentric reduction while allowing early functional motion and improve clinical outcomes for patients with complex persistent elbow instability. [27] (10.1097/corr.0000000000002159)
• [Paper] Using a systematic diagnostic pathway including assessment of elbow stability and consecutive individualized, respectively, less invasive surgical procedure we acquired high patients satisfaction and good clinical outcome with a low complication rate. [29] (10.1007/s00402-014-2087-4)
• [L3] Patients with traumatic elbow instability treated with or without the IJS revealed similar elbow ROM in the first 6 months. [30] (10.1016/j.jse.2025.03.012)
• [L5] Simple elbow dislocations are usually managed by closed reduction and early motion, with recurrent instability being uncommon due to intrinsic bony stability. [32] (10.1016/j.hcl.2007.11.012)
• [L4] Use of the surgical protocol restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome. [33] (10.2106/jbjs.d.02933)
• [L5] Physical examination of the elbow is a critical component in formulating an accurate diagnosis. [35] (10.5435/jaaos-d-16-00622)
• [L5] The elbow consists of static and dynamic stabilizers that function in synchrony to prevent elbow instability. [36] (10.1016/j.jhsa.2016.11.025)
• [L4] Biomechanical and clinical outcomes show that EJS-E via the posterior approach can restore mobility and stability in all patients, thus serving as a valuable alternative option for the treatment of persistent instability of the elbow. [40] (10.1186/s12891-022-06103-0)
• [L4] The article presents eight surgically proven cases of typical and atypical patterns of injury of the annular ligament in the setting of posterolateral elbow instability. [41] (10.2214/ajr.13.12263)
• [L5] [43] (10.1016/j.eats.2024.103096)
• [L5] [45] (10.1055/s-2005-867103)
• [L5] [46] (10.5435/00124635-200411000-00005)
• [L4] [48] (10.1007/s00167-016-4176-0)
• [L4] A stable, functional elbow can be restored in most patients with persistent instability after fracture-dislocation of the elbow using a treatment protocol incorporating hinged external fixation. [49] (10.1016/j.jhsa.2004.01.005)
• [L4] Three patients have remained stable at their elbow status post bilateral ligament reconstruction. [50] (10.1016/j.jhsg.2026.101040)
• [L5] Optimal outcomes are founded upon concentric reduction of the elbow. [51] (10.1016/j.jseint.2023.03.020)
• [L5] Operative repair is indicated for most of these injuries to restore sufficient osseoligamentous support to allow safe, early motion and provide a stable functional elbow in the long term. [52] (10.1016/j.hcl.2004.06.005)
• [L4] They must restore the integrity of the elbow repairing all structures, using a standardised surgical protocol, which gives the best results and prognosis by restoration of the elbow stability. [53] (10.1016/s0020-1383(15)70004-5)
• [L5] [54] (10.5435/jaaos-d-23-00460)
• [L4] [55] (10.5435/jaaos-d-14-00023)
• [Paper] These markers provide valuable diagnostic information for posterolateral elbow instability, particularly in subtle cases. [58] (10.1016/j.jseint.2025.101602)
• [L5] The most common indications are acute or chronic instability of the elbow after trauma, distraction interposition arthroplasty, or use after contracture release or excision of heterotopic ossification. [59] (10.1016/j.hcl.2010.04.004)
• [L5] Most simple elbow dislocations are readily managed nonoperatively and are amenable to early mobilization. [64] (10.1016/j.hcl.2020.07.013)
• [L4] However, the available current evidence possesses a high degree of fragility, and further studies are needed with objective measurements to determine the optimal elbow flexion angle for graft fixation. [65] (10.1016/j.jse.2018.07.029)
• [L4] Bridge plating effectively maintains joint reduction in selected complex elbow instability cases. [66] (10.1016/j.jse.2024.03.013)
• [L2] Our data suggests that changes present in the UCL and detectable on ultrasound may help distinguish elbows at risk for later clinical UCL insufficiency. [68] (10.1177/2325967115s00162)
• [L5] A stiff, congruent elbow is preferable to an unstable elbow. [71] (10.1016/j.hcl.2017.09.008)
• [L5] Surgery is indicated for unstable elbows requiring flexion beyond 50 to 60 degrees to remain reduced or for unstable periarticular fractures. [73] (10.5435/00124635-199801000-00002)
• [L4] Instability is the major complication of unlinked total elbow arthroplasty, often requiring revision, whereas linked arthroplasty is preferred for patients with posttraumatic articular damage, ligamentous instability, deformity, or bone loss. [76] (10.1016/j.hcl.2007.11.002)
• [L3] [77] (10.1016/j.injury.2013.11.033)
• [L4] Specific patterns of traumatic elbow instability have correspondingly specific coronoid fracture patterns. [78] (10.1016/j.jhsa.2014.06.123)
• [L5] Surgical management is indicated when the elbow remains unstable, with the lateral ulnar collateral ligament being the most critical structure to repair or reconstruct. [79] (10.1016/j.hcl.2016.08.003)
• [L1] Surgical procedures provide similar outcomes regarding MEPS and ROM for patients with slight initial instability, while those with red flags for persistent instability should be considered for a primary surgical approach. [81] (10.1186/s12891-024-07260-0)
• [Paper] [82] (10.1016/j.hcl.2007.11.013)
• [L4] Despite early success of this technique for most elbows within the first two tears, survivorship free of revision with death as competing risk approaches 75% at 10 years. [83] (10.1016/j.jseint.2025.101581)
• [L3] Lower MRI grade and humeral location were objectively associated with higher return to throw, higher return to play, lower UCLR, and higher survival compared to higher grade and ulnar or both-sided tears. [85] (10.1177/2325967119s00311)
• [L5] [86] (10.1016/j.hcl.2020.07.011)
• [L5] The patient had full range of movement at the elbow with no obvious deformity at 6 weeks and no weakness in the limb. [87] (10.1016/s0020-1383(98)00141-7)
• [L4] At 43 months mean follow-up, none of the patients had significant postoperative contracture, and none had any clinically apparent signs of instability or suffered subluxation or re-dislocation. [88] (10.1016/j.jseint.2024.08.043)
• [L5] Chronic medial elbow instability can be a debilitating problem for the throwing athlete. [109] (10.1016/j.ocl.2007.12.003)
• [L5] [115] (10.1016/j.jhsa.2021.11.026)
• [L4] The IJS represents an effective and reliable option as a temporary stabilization for residual elbow instability. [117] (10.1016/j.jseint.2024.08.033)
• [L4] The variability in patients' pathoanatomic conditions requires customized surgical treatment aimed at elbow stabilizer reconstruction when the ulnohumeral joint is preserved or aimed at joint replacement in case of severe articular degeneration. [118] (10.1016/j.jse.2019.11.021)
• [L1] [119] (10.1016/j.jse.2024.02.038)
• [L5] The Wrightington classification of elbow fracture dislocation is a comprehensive, reliable, and valid classification with treatment algorithms that are associated with good functional outcomes. [124] (10.1016/j.jseint.2022.12.002)
• [L4] Recent advancements in the understanding of injury patterns have led to improved surgical treatment algorithms and better clinical outcomes in complex elbow injury. [136] (10.5435/jaaosglobal-d-23-00041)
• [L5] Chronic instability of the adult elbow without associated fracture can be divided into valgus instability, posterolateral instability, and isolated radial head instability. [139] (10.1016/s0030-5898(05)70062-6)
• [Case_report] In the setting of atraumatic, bilateral elbow instability that is refractory to nonoperative management, recurrent instability can be prevented by surgical reconstruction of the LUCL and internal joint stabilization. [146] (10.1016/j.jse.2015.12.020)
• [L4] Conservative management remains the gold standard for most simple elbow dislocations. [147] (10.1016/j.arthro.2014.02.037)
• [L4] UCLR provides excellent patient-reported and clinical outcomes to patients at medium-term follow-up with low complication and revision rates. [148] (10.1136/jisakos-2021-000614)
• [L4] The literature demonstrates a distinct difference in complication profile between external fixation and the IJS when used as treatment for traumatic elbow instability. [160] (10.1016/j.xrrt.2023.12.004)
• [L5] [168] (10.1302/2058-5241.1.000036)
• [L4] Preoperative MRI could be used to exclude subtle instability, and surgeons should consider checking for subtle instability, especially when patients have a history of multiple corticosteroid injections (≥3) or severe pain. [171] (10.1186/s12891-018-2069-8)
• [L3] [172] (10.1016/j.arthro.2024.10.049)
• [L4] A sonographic ulnohumeral laxity greater than 4 mm should raise suspicion of underlying instability. [174] (10.1016/j.pmrj.2016.06.014)
• [L5] It provides less insult and dissection to the soft tissue at the lateral side of the elbow while being an excellent tool to diagnose any concomitant intraarticular pathologies. [178] (10.1016/j.eats.2024.103101)

See Also

• Elbow arthroscopy
• Radial Head Fracture
• Ligament Injuries
• Elbow Arthroplasty

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