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Tendons, Ligaments and Muscles

Hand/wrist tendon, ligament, and muscle injuries: acute repair principles, chronic tendinopathy management, and anatomical considerations.

94 citationsUpdated Sep 2026

Overview

Tendon and ligament pathology management requires precise terminology, as the term 'tendon' may be inappropriate for certain pathologies and can mislead understanding of both the pathology and its management [1]. Clinical assessment of disruption relies on the '50% rule', though this should not be considered an exact rule due to the subjective nature of clinical evaluations and a lack of high intraobserver and interobserver reliability [2]. Surgical intervention is indicated across a spectrum of conditions, including degenerate abductor tendons when MRI confirms separation and clinical findings are consistent with known tendon disruption [10], chronic ulnar collateral ligament injuries managed with tendon graft ligament reconstruction or tendon transfers [15], and symptomatic chronic proximal hamstring tears not amenable to primary repair, which may require allograft augmentation or interposition [18]. For flexor tendon injuries, secondary reconstruction remains an important technique for complicated cases or those that have failed primary repair [21], while primary tendon repair is permissible only when strict criteria are met, including early presentation, minimal contamination, and favorable wound conditions; otherwise, secondary repair via tendon graft is recommended [27]. In more active patients with Achilles tendon ruptures, surgical treatment is the treatment of choice due to significantly better functional results and a lower incidence of reruptures compared to non-surgical treatment [34]. Additionally, tendon lengthening and transfer are indicated for neuromuscular disorders, nerve injuries, and congenital or traumatic lesions [60], with specific late-stage congenital flexion deformities of the long, ring, and little fingers managed via local release and thorough muscle sliding [3].

Outcomes vary by procedure and technique. Both cortical button and interference screw techniques for distal biceps tendon repair provided excellent short- to mid-term clinical and functional outcomes [16]. In rheumatoid hands with extensor tendon ruptures, the time to surgery should be considered, and there is concern over extension lag of the MP joint [14]. Even after clinically successful flexor tendon autograft, tendons may still be at risk of degeneration and rupture a decade or more after reconstruction [20]. Tendon adhesion and joint contracture are the most common complications after flexor tendon repair, managed through prevention, meticulous surgical technique, and thoughtful rehabilitation protocols [35]. Recent repair and motion protocols lead to remarkably more reliable repairs, with over 80% good or excellent outcomes achieved rather consistently after Zone 2 repair along with infrequent need of tenolysis [58]. Published clinical results for the contralateral C7 transfer have demonstrated significant improvements in upper limb function, confirming the procedure's safety and efficacy, with donor site morbidity that is typically mild and transient [51].

Rehabilitation protocols and research methodologies continue to evolve. Relative motion extension plus and relative motion extension only are used interchangeably depending on surgeon preferences and patient/tendon factors for zones V and VI extensor tendon repairs [26]. More stringent criteria, such as Tang's criteria, are necessary as results move toward more ideal functional outcomes, and surgeon expertise should always be considered when comparing outcomes [135]. Tissue engineering approaches hold great promise for improving tendon and ligament repair, but they have not yet succeeded clinically [4]. Although repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, the repair of the flexor digitorum superficialis together with flexor digitorum profundus is not mandatory in acute Zone 2B injuries [62]. Novel flexor tendon repair techniques, including barbed suture, should be tested cyclically in a manner that closely mimics in vivo conditions during postoperative rehabilitation before clinical adoption [63]. There is considerable variability in published protocols for in vitro testing of flexor tendon repairs, with no standardized method currently in place [65].

Anatomy & Pathophysiology

Tendon Structure and Healing

Tendons consist of organized fascicles containing longitudinally oriented type I collagen bundles and tenocytes [72]. Individual fascicles are covered by the endotenon, while groups of fascicles are covered by the epitenon [72]. The visceral and parietal paratenon line the tendon surface and the undersurface of the tendon sheath, respectively [72]. The inflammatory phase of healing lasts from injury to seven days, during which fibroblast and macrophage migration results in phagocytosis of the clot and necrotic tissue [72]. During this phase, repair strength relies entirely on the strength of the suture used [72]. Tendon remodeling begins six to eight weeks after injury, characterized by decreased cellularity, reduced matrix synthesis, a decrease in type III collagen, and an increase in type I collagen synthesis [6]. Type I collagen fibers organize longitudinally along the tendon axis, providing mechanical strength to the regenerate tissue [6]. In later remodeling phases, interactions between collagen structural units lead to higher tendon stiffness and greater tensile strength [6]. Repair tissue never achieves the characteristics of normal tendon [6].

Healing proceeds via extrinsic and intrinsic mechanisms. Extrinsic healing involves fibroblasts and inflammatory cells moving from peripheral or external tissue sources to invade the healing site [6]. This mechanism requires a well-established vascular network for effective healing [6]. Extrinsic healing is mediated by the ingrowth of fibroblasts, inflammatory cells, and other extratendinous cells [12]. It activates earlier than intrinsic healing and is responsible for the initial formation of adhesions [6]. The extrinsic mechanism results in a disorganized collagen matrix with high cellularity and high water content at the injury site [6]. Intrinsic tendon healing occurs through the migration and proliferation of cells from the endotenon and epitenon into the injury site [6]. It involves the establishment of an extracellular matrix and an internal neovascular network [6]. Intrinsic healing occurs within the tendon through the activity of tenocytes and the intratendinous blood supply [12]. The intrinsic mechanism is responsible for the reorganization of collagen [6]. Synovial fluid diffusion limits the production of adhesions during tendon healing [12]. Tendon adhesion and joint contracture are the most common complications after flexor tendon repair [35]. The term 'tendon' in pathology descriptions may mislead understanding of both the pathology and its management [1].

Flexor Tendon Anatomy and Physiology

Flexor tendons are perfused by longitudinal vessels entering the tendon in the palm, segmental vessels from digital arteries supplying the tendon through vincula, and vessels entering at insertions [72]. In relatively avascular watershed areas, particularly over the proximal phalanx, flexor tendon nutrition is accomplished by synovial fluid diffusion via a process called imbibition [72]. In the uninjured finger, flexor tendons have a frictionless excursion within the flexor sheaths [44]. The A1 pulley has a covering of amorphous extracellular matrix including hyaluronan and lubricin [44]. The surface of the A1 pulley is fragmented and partially absent in trigger finger [44].

The extrinsic finger flexors consist of the flexor digitorum profundus and the flexor digitorum superficialis [83]. The flexor digitorum profundus originates from the proximal ulna and the interosseous membrane [83]. It divides into a radial component supplying the index finger and an ulnar component supplying the middle, ring, and little fingers [83]. The flexor digitorum profundus inserts into the proximal palmar base of the distal phalanx [83]. It provides digital flexion at both the proximal and distal interphalangeal joints [83]. The innervation of the flexor digitorum profundus of the index and middle fingers is through the anterior interosseous branch of the median nerve [83]. The innervation of the flexor digitorum profundus of the ring and little fingers is by the ulnar nerve [83]. The flexor digitorum superficialis has a radial head originating from the proximal shaft of the radius and a humeral ulnar head originating from the medial humeral epicondyle and coronoid process of the ulna [83]. The flexor digitorum superficialis tendon bifurcates around the flexor digitorum profundus at the beginning of the A2 pulley [83]. The tendon slips reunite distally at the Camper chiasm, with approximately half of the fibers staying on the ipsilateral side and half crossing to the contralateral side [83]. The flexor digitorum superficialis inserts via radial and ulnar slips into the proximal metaphysis of the middle phalanx [83]. Its primary function is digital flexion at the proximal interphalangeal joint [83]. The entire flexor digitorum superficialis muscle receives innervation from the median nerve [83]. Individual FDS contractions, particularly of the index and middle fingers, contribute most to stabilization against valgus stress [110].

The flexor pollicis longus originates from a radial head on the proximal radius and interosseous membrane, and an accessory head on the coronoid process of the ulna and medial epicondyle of the humerus [83]. It inserts into the proximal base of the thumb distal phalanx [83]. The flexor pollicis longus is innervated by the anterior interosseous branch of the median nerve [83]. It flexes both the interphalangeal and metacarpophalangeal joints of the thumb [83]. The fibroosseous tunnel, or digital flexor sheath, extends distally to the proximal aspect of the distal phalanx [83]. The tendinous sheath consists of annular pulleys that provide mechanical stability and cruciate pulleys that provide flexibility [83]. The A1, A3, and A5 annular pulleys are located over the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints, respectively [83]. The A2 and A4 pulleys are situated over the middle portion of the proximal and middle phalanges [83]. The A2 and A4 pulleys are the most essential in maintaining the mechanical advantage of the flexor tendons [83]. The tenosynovium lining the fibroosseous tunnel supplies nutrition and lubrication to the poorly vascularized flexor tendons [83]. Within the flexor sheath, tendon vascularity is supplied via the vinculum longus and brevis [83]. The tenosynovial sheath of the flexor pollicis longus is continuous with the radial bursa [83]. The tenosynovial sheath to the little finger is continuous with the ulnar digital bursa [83]. In some patients, the radial and ulnar bursae communicate, allowing a horseshoe abscess to spread between the thumb and little finger [83]. The lumbricals originate from the radial side of the index, middle, ring, and little fingers in the palm [83]. The profundus tendon passes through the bifurcation of the flexor digitorum superficialis before inserting into the proximal palmar base of the distal phalanx [83].

Extensor Tendon Anatomy and Physiology

The extrinsic extensors run through six different fibroosseous retinacular compartments at the wrist level [42]. The first extensor compartment contains the abductor pollicis longus and the extensor pollicis brevis [42]. The abductor pollicis longus inserts at the base of the thumb metacarpal and radially abducts the thumb [42]. The extensor pollicis brevis inserts on the dorsum of the proximal aspect of the proximal phalanx of the thumb and actively extends the metacarpophalangeal joint of the thumb [42]. The second extensor compartment contains the extensor carpi radialis longus and the extensor carpi radialis brevis [42]. The extensor carpi radialis longus inserts on the index metacarpal, dorsiflexes and radially deviates the wrist [42]. The extensor carpi radialis brevis inserts into the base of the middle metacarpal and provides balanced wrist dorsiflexion [42]. The third compartment contains the extensor pollicis longus, which turns abruptly radialward about Lister tubercle [42]. The extensor pollicis longus inserts on the distal phalanx and provides forceful extension of the thumb interphalangeal joint [42]. The oblique course of the extensor pollicis longus tendon provides a substantial adduction component to its pull [42]. The fourth extensor compartment contains the extensor indicis proprius lying deep to the four tendons of the extensor digitorum communis [42]. The fifth compartment contains the extensor digiti quinti [42]. The principal bony insertion of the extrinsic digital extensors is on the dorsal proximal aspect of the middle phalanx [42]. Metacarpophalangeal joint extension is provided by extrinsic extensor force transmitted through the sagittal bands [42]. Distal interphalangeal joint extension is achieved through the conjoined lateral bands composed of tendinous slips from the extrinsic and intrinsic tendons [42]. The extensor indicis proprius inserts on the index finger ulnar to the extensor digitorum communis [42]. The extensor digitorum communis inserts on the index, middle, ring, and, in some cases, little fingers [42]. The extensor digiti quinti tendon inserts on the little finger ulnar to the extensor digitorum communis insertion [42]. The extensor carpi ulnaris tendon runs through the sixth compartment and inserts at the base of the little finger metacarpal [42]. The extensor carpi ulnaris provides wrist extension and ulnar deviation [42]. The extensor digitorum communis tendons of the middle, ring, and little fingers are tethered together by juncturae tendinum over the dorsum of the hand proximal to the metacarpophalangeal joint [42]. The extensor indicis proprius tendon possesses the most distal muscle belly of any of the digital extensor tendons at the wrist level [42].

Digital extensor tendons are stabilized over the midline of the metacarpophalangeal joint by their attachment to sagittal band fibers [42]. Sagittal band fibers insert onto the volar proximal phalanx and onto the lateral borders of the volar plate [42]. Sagittal bands form a sling that allows proximal extrinsic extensor tension to be transmitted to the proximal phalanx, permitting metacarpophalangeal joint extension without a tendinous insertion onto the proximal phalanx [42]. Sagittal bands keep the extrinsic extensor as far as possible away from the center of rotation of the metacarpophalangeal joint, giving it the greatest mechanical efficiency [42]. With rupture or attenuation of the sagittal band fibers, the extrinsic extensor tendon can sublux to the ulnar side of the metacarpal head causing ulnar deviation of the finger [42]. At the level of the wrist joint, extensor tendon nutrition is accomplished via diffusion from vessels in the mesotenon, which spans the length of the extensor retinaculum [72]. Distally, extensor tendons are covered by the paratenon [72]. Small segmental vessels from the paratenon supply the tendon distal to the retinaculum [72].

The extensor mechanism at the proximal interphalangeal joint is a trifurcation of the extensor tendon into the central slip and the two lateral bands [69]. The central slip of the extensor tendon inserts into the base of the middle phalanx [69]. The two lateral bands pass on either side of the proximal interphalangeal joint and fuse distally to insert into the distal phalanx [69]. The extensor mechanism at the proximal interphalangeal joint is held centered over the joint by the transverse retinacular ligaments [69]. The extensor mechanism is joined on either side by tendons of the lumbricals and interossei [69]. The central slip extends the middle phalanx, and the two lateral bands bypass the proximal interphalangeal joint to join and extend the distal phalanx [69]. Extension of the proximal interphalangeal and distal interphalangeal joints takes place together when the lengths of the central slip and lateral bands are balanced [69]. Dorsal migration of the lateral bands as the proximal interphalangeal joint extends is generally attributed to the elastic quality of the triangular ligament [69]. The ulnar slip of the extensor digiti minimi tendon is the major contributor to aberrant abduction with active small finger extension, producing almost twice as much abduction as the radial slip [120]. Loss of the abductor pollicis longus and extensor pollicis brevis motor units had no functional effect upon thumb pinch-strength or hand grip, and only a minimal adverse effect upon thumb movement [116].

Intrinsic Muscle Anatomy and Physiology

There are seven interosseous muscles, four dorsal and three volar [77]. The dorsal interossei are abductors [77]. They lie to the radial side of the index and middle fingers and the ulnar side of the middle and ring fingers [77]. The little finger is abducted by the abductor digiti quinti [77]. The volar interossei are adductors and lie to the ulnar side of the index finger and the radial side of the ring and little fingers [77]. The middle finger has two dorsal interossei (abductors) and no volar interossei (adductors) because the central axis of the hand lies within it [77]. Each dorsal interosseous muscle, with the exception of the third, has two muscle heads [77]. The superficial head of the dorsal interosseous arises from the shaft of the contiguous metacarpals and is inserted by a medial tendon onto the lateral tubercle of the base of the proximal phalanx [77]. The superficial head abducts and weakly flexes the proximal phalanx [77]. The deep head of each dorsal interosseous muscle forms a lateral tendon, or lateral band, at the level of the metacarpophalangeal joint [77]. The deep head flexes and weakly abducts the proximal phalanx while extending the middle and distal phalanges [77]. Transverse fibers arch dorsally from each lateral band to join each other over the dorsum of the finger, flexing the proximal phalanx [77]. Oblique fibers (spiral fibers) from the lateral bands sweep over the distal third of the proximal phalanx to insert onto the lateral tubercles at the base of the middle phalanx [77]. The oblique fibers extend the middle phalanx at the proximal interphalangeal joint [77]. The lateral bands are joined by the lateral slips of the extensor tendon to form the conjoined lateral band [77]. The two conjoined lateral bands to each finger unite at the distal third of the middle phalanx to form the terminal tendon [77]. The terminal tendon inserts at the base of the distal phalanx to extend it [77].

The flexor digiti quinti brevis is structurally and functionally similar to the deep head of the dorsal interossei, forming the ulnar lateral band of the little finger [77]. The three volar interossei arise from adjacent surfaces of contiguous metacarpal shafts [77]. Each volar interosseous muscle has only one muscle head and none of them insert onto the proximal phalanx [77]. The volar interossei form the ulnar lateral band of the index finger and the radial lateral band of the ring and little fingers [77]. The abductor digiti quinti and flexor digiti quinti brevis are similar in structure and function to the superficial and deep heads of the dorsal interossei, respectively [77]. The abductor digiti quinti inserts onto the ulnar lateral tubercle at the base of the proximal phalanx of the little finger [77]. The flexor digiti quinti forms the ulnar lateral band [77]. The opponens digiti quinti arises from the pisohamate ligament and the hook of the hamate and inserts onto the ulnar side of the diaphysis of the fifth metacarpal [77]. The opponens digiti quinti flexes and supinates the fifth met

Classification

Extensor Tendon Zones

Tang’s Simplified Classification: This system aligns with current treatment strategies, such as conservative splinting for closed injuries and strong surgical repair for open injuries [59]. It is expected to enhance the accuracy of operative evaluations and provide valuable insights into surgical outcomes for anatomically diverse extensor tendon injuries, though future studies are needed to validate its effectiveness [125].

Retinaculum-Based Classification: A classification of extensor tendon zones based on the presence of the extensor retinaculum is suggested to be preferable to those based on the wrist joint [138]. This approach simplifies treatment discussion and aligns with flexor tendon zoning [138].

Other Considerations: A survey of views in a hand surgery department suggests that a revisit of popular extensor tendon zone classification systems may be necessary for future clinical practice and communication among surgeons [111].

Flexor Tendon Injuries

Zone I Definition: Zone I flexor tendon injuries are defined as the region from the FDP tendon to the insertion of the FDS tendon, involving a laceration or an avulsion [61]. Leddy and Packer classified subtypes of zone I avulsion injuries to help guide management [61].

Type I: These avulsion injuries involve retraction of the proximal stump of the FDP to the palm, disruption of both vincula, and retraction proximal to the synovial sheath, resulting in a tendon devoid of nutrition [61]. Repair should proceed within 7 days to avoid tendon contracture and necrosis [61]. Type I zone I trauma has the worst prognosis of all zone I injuries [61].

Type II: These avulsions involve tendon retraction to the level of the proximal interphalangeal (PIP) joint, sometimes with a small fleck of bone [61]. Correction is less urgent because there is less potential for contracture and necrosis, and the avulsion may be successfully repaired within 6 weeks of injury [61].

Type III: These avulsions are characterized by large bony fragments that prevent the tendon from retracting past the distal edge of the A4 pulley [61]. Direct repair may be possible for up to 6 weeks [61].

Type IV: These injuries involve fracture and avulsion of the FDP tendon from the fracture fragment [61]. Management requires fixation of the fragment followed by repair of the tendon [61]. Advancing the tendon 1 cm for repair can cause a quadriga effect due to the common muscle belly of the FDP [61].

Ligament and Tendon Anatomy Classifications

Scaphotrapezial Ligament: The scaphotrapezial ligament consists of three distinct fascicles, including a deep fascicle that attaches 3.3 mm from the most distal point of the scaphoid [28].

Ulnar Collateral Ligament of the Elbow: The anterior bundle, posterior bundle, and common tendon of the ulnar collateral ligament of the elbow can each be classified into an independent form and an unclear form [141].

Sagittal Band Injuries: A modification to the most prevalent classification system for sagittal band injuries has been described to guide treatment and allow standardization in documenting and describing injuries [143].

Türker Classification: An additional category (Type 3) has been proposed to the Türker classification system to encompass rare findings of two radial-sided accessory extensor tendons in the same individual [109].

General Classification and Terminology

Other Considerations: The term 'tendon' may be inappropriate for certain intramuscular tendon pathologies as it misleads understanding of both the pathology and its management [1]. The '50% rule' for tendon and ligament disruption should not be considered an exact rule in medical science because clinical evaluations are relatively subjective and lack high intraobserver and interobserver reliability [2].

Clinical Presentation

General Tendon and Ligament Pathology

The pathophysiology of tendinosis is characterized by degenerative rather than inflammatory changes, with susceptibility related to activity and age [47]. While fibril morphology is abnormal in tendinopathy, tendon mechanical properties are not [133]. Hormonal factors significantly influence tissue integrity; estrogen improves muscle mass and strength and increases collagen content in connective tissues, but decreases stiffness in tendons and ligaments, which can decrease power and increase the risk of catastrophic ligament injury [54]. Conversely, testosterone replacement therapy in adult males is associated with higher odds of tendon and ligament injuries, with estimates of similar magnitude at one and two years where both were reported [13]. Normal tendons do not rupture except at the musculotendinous junction or tendon insertion, typically due to excessive weight application when the muscle is holding at maximum power [25]. The myotendinous junction is prone to stretching injury because of its microanatomical structure [19]. Clinical evaluations of tendon and ligament disruption are relatively subjective and lack high intraobserver and interobserver reliability [2]. Extensor tendon injuries are common, and early recognition and treatment are key to the management of such injuries [8]. Most closed extensor tendon injuries can be treated conservatively in the acute phase, but chronic injuries often require operative intervention [50].

Specific Clinical Presentations and Diagnostic Findings

The BPT appears to be highly accurate in the clinical diagnosis of distal biceps tendon pathology [46]. Patients with extensor carpi ulnaris tendinitis or stenosing tenosynovitis usually report a gradual, insidious onset of ulnar-sided wrist pain over the course of weeks to months [107]. Pain in extensor carpi ulnaris tendinitis is generally worsened with activity and may be elicited with resisted radial deviation or active ulnar deviation against resistance [107]. The extensor carpi ulnaris synergy test is performed with the patient’s elbow on the examination table, flexed at 90° and in full supination, while the examiner grasps the patient’s thumb and long finger between his or her thumb and index fingers [107]. In this test, the patient is asked to abduct the thumb against the examiner’s provided resistance, which isometrically activates the extensor carpi ulnaris [107]. Pain with the extensor carpi ulnaris synergy test favors extensor carpi ulnaris tendinitis over an intra-articular cause such as a triangular fibrocartilage complex tear [107]. In a series of fifty-four consecutive patients, a positive extensor carpi ulnaris synergy test in the absence of other positive examination maneuvers for intra-articular pathology correctly identified ten of eleven patients with isolated extensor carpi ulnaris tendinitis [107]. In the same series, the extensor carpi ulnaris synergy test correctly ruled out extensor carpi ulnaris tendinitis in all twenty-one patients with a negative test [107].

Proximal hamstring tears can be categorized as complete tendinous avulsions, partial tendinous avulsions, apophyseal avulsions, or degenerative avulsions (tendinosis) [48]. Only 12% of hamstring muscle injuries were proximal ruptures, and 9% were complete [48]. The presentation of proximal hamstring injuries may be more vague and difficult to diagnose [48]. Sitting pain is common in proximal hamstring injuries, but functional pain (stairs, hiking, sprinting) is a more specific finding for hamstring pathology rather than other causes of buttock pain [48]. Patients with a suspected hamstring injury should undergo a radiographic workup with, at minimum, an anterior-posterior view of the pelvis to evaluate for an avulsion off of the ischial tuberosity [48]. Magnetic resonance imaging (MRI) is the gold standard to evaluate for hamstring injury; however, it should be reserved for patients in whom a complete rupture is suspected or who do not respond to conservative management [48].

Surgical reconstruction of degenerate abductor tendons should be considered in the presence of an MRI confirmed separation where clinical findings are consistent with the known tendon disruption [10]. Closed rupture of the flexor tendon should be recognized as a complication in patients with asymptomatic Kienböck disease, and plain radiographs are important in the assessment of patients presenting with closed flexor tendon rupture [31]. The quadriga phenomenon, caused by interconnected flexor digitorum profundus tendons, significantly affects clinical situations including strength testing, movement assessment, and rehabilitation exercise selection [121]. Pulley rupture or insufficiency is a diagnostic and therapeutic dilemma owing to the overall rarity of the injury as well as the lack of comparative clinical studies describing its diagnosis, treatment, and outcome [23].

A 30-year-old right-handed woman presented with fifth-digit pain and a prominent lump on her right wrist, denying any specific injury connected with onset of symptoms and endorsing a 6-month history of pain [49]. Sharp pain occurred with immediate onset following extension of the fifth digit in a patient with anomalous extensor digiti minimi [49]. The patient experienced major swelling which caused considerable discomfort and stated that her small finger felt as though it was snapping over the dorsal aspect of the fifth metacarpal [49]. Magnetic resonance imaging of the right wrist showed prominent thickening of the extensor digiti minimi tendon within the wrist extensor region localized at the level of the distal ulnar styloid [49]. Initial plain films demonstrated a possible marginal osteophyte at the base of the fifth metacarpal on the right wrist when compared to the left wrist [49].

In cases of pronounced pain where the patient is not cooperative for preoperative examination, ultrasonography is conducted to assess the continuity of the tendon [106]. If doubt persists after ultrasonography, an MRI is performed to assess tendon continuity [106]. Patient evaluation for medial gastrocnemius proximal tendon avulsion begins with a thorough clinical examination to check for tenderness to palpation of the MGT and gastrocnemius tubercle, knee range-of-motion differences, strength deficits, and stability of the knee [122]. Radiographic imaging for medial gastrocnemius proximal tendon avulsion should include lower extremity long-standing views to assess alignment bilaterally and magnetic resonance imaging to assess for any MGT or possible meniscal pathology [122]. The authors recommend evaluation of specific clinical and imaging findings to grade lumbrical muscle injuries and determine suitable therapy [11]. Chronic UCL injuries are traditionally managed with tendon graft ligament reconstruction or tendon transfers, though evidence is limited to case reports and retrospective series [15]. Most authors agree that both acute and chronic grade 3 RCL tears should be surgically treated [53].

Investigations

Plain radiography: Plain radiographs are important in the assessment of patients presenting with closed flexor tendon rupture [31]. In shoulder pathology, the radiographic appearance of a bone fragment beneath the humeral head is a valuable sign for avulsion of the subscapularis tendon [159].

MRI: MRI is probably most useful in identifying additional pathology such as flexor tendon bowstringing in Dupuytren's disease [91]. It may provide a quantitative noninvasive measure of cellularity of affected areas in Dupuytren's disease, which serves as an index of biologic activity [91]. However, MR assessment of Dupuytren's disease is hindered by the resolution of current equipment, orientation issues due to multiplanar deformities of the fingers, and lack of intraoperative availability [91]. In revision cases, MRI might be worth considering, as 43% of those cases with clinical signs of olecranon bursitis had previous surgery [153]. Magnetic resonance imaging indicates that the donor site after autologous osteochondral mosaicplasty is resurfaced with fibrous tissue [160].

CT: Fast-field echo sequences resembling computed tomography, specifically FRACTURE VR, provide excellent visualization of both flexor and extensor tendons, enabling 3-dimensional comprehension of all hand and finger tendons [55]. These sequences enable the instantaneous recognition of previously unnoticed anatomical variations or anomalous muscles in the hand [55].

Ultrasound: Ultrasound is superior to MRI for the dynamic evaluation of stenosing synovitis of the extensor pollicis longus tendon [73]. An 8-MHz Doppler tone assessment may be used to identify superficially displaced neurovascular bundles when Dupuytren cords lie beneath soft fleshy prominences [91]. False-negatives are possible when using 8-MHz Doppler tone assessment to identify neurovascular bundles in Dupuytren's disease [91].

Clinical Examination: A careful physical examination is essential to direct care and future testing if indicated, as diagnostic tests such as imaging can be expensive, time consuming, and often nonspecific [40]. Patients often have difficulty accurately describing their symptoms and may incorrectly attribute pathology to a perceived deficit [40]. The Biceps Provocation Test (BPT) appears to be highly accurate in the clinical diagnosis of distal biceps tendon pathology [46].

Other Considerations: Embalmed tendon can give a misleading impression of strength, as its strength is increased to three times that of normal tendon [166].

Treatment

General Principles and Pathology

The "50% rule" for tendon and ligament disruption is not an exact rule due to subjective clinical evaluations and a lack of high intraobserver and interobserver reliability [2]. While tissue engineering approaches hold promise for improving tendon and ligament repair, they have not yet succeeded clinically [4].

Tendon Healing Biology

Remodeling of tendon tissue begins 6–8 weeks after injury [6]. This phase is characterized by a decrease in cellularity, reduced matrix synthesis, a decrease in type III collagen, and an increase in type I collagen synthesis [6]. Healing proceeds via extrinsic and intrinsic mechanisms. Extrinsic healing involves fibroblasts and inflammatory cells moving from peripheral or external tissue sources to invade the healing site [6]. This mechanism is activated earlier than the intrinsic mechanism and is responsible for initial adhesion formation, a disorganized collagen matrix with high cellularity, and high water content at the injury site [6]. The ingrowth of fibroblasts, inflammatory cells, and other extratendinous cells mediates this extrinsic healing [12]. Synovial fluid diffusion is important by limiting the production of adhesions [12]. Intrinsic healing occurs through the migration and proliferation of cells from the endotenon and epitenon into the injury site [6].

Flexor Tendon Injuries

Zone I Management: Zone I is defined as the region from the FDP tendon to the insertion of the FDS tendon [61]. Leddy and Packer Type I injuries involve retraction of the proximal stump of the FDP to the palm with disruption of both vincula [61]. These injuries have the worst prognosis of all zone I injuries and should be repaired within 7 days to avoid tendon contracture and necrosis [61]. Leddy and Packer Type II avulsions involve tendon retraction to the level of the proximal interphalangeal joint, sometimes with a small fleck of bone, and may be successfully repaired within 6 weeks of injury [61]. Leddy and Packer Type III avulsions are characterized by large bony fragments that prevent the tendon from retracting past the distal edge of the A4 pulley; direct repair may be possible for up to 6 weeks [61]. Leddy and Packer Type IV injuries involve fracture and avulsion of the FDP tendon from the fracture fragment [61].

Zone II Management: Recent repair and motion protocols lead to remarkably more reliable repairs, with over 80% good or excellent outcomes achieved rather consistently after Zone 2 repair [58]. These protocols result in an infrequent need for tenolysis after Zone 2 repair [58]. Tendon adhesion and joint contracture are managed through prevention, meticulous surgical technique, and thoughtful rehabilitation protocols [35]. Early active motion leads to a quicker recovery in terms of grip strength and patient-reported outcomes [136]. However, both early active motion and other regimens lead to similar results at 12 months following Zone 2 flexor tendon injury rehabilitation [136].

Surgical Technique and Grafting: Release of the flexor retinaculum permits the tendon to move smoothly in its track, but the prognosis is guarded as the tendon is weakened [5]. Advancing a tendon more than 0.1 cm during repair can cause a quadriga effect due to the common muscle belly of the FDP [61]. The use of a skin hook is a simple and effective technique to retrieve proximal flexor tendons with minimal morbidity and without a palmar incision [137]. Repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, though repair of the FDS together with FDP is not mandatory [62]. Achieving consistent, satisfactory results with single-stage flexor tendon grafting remains an elusive goal [112]. Tendon grafts will tolerate early motion therapy if the proximal and distal tenorrhaphy junctures are strong enough [112]. Both bridge tendon grafts and end-to-side tendon transfers have comparable and satisfactory outcomes after surgical treatment of closed rupture of the flexor tendons in the little finger [134].

Extensor Tendon Injuries

Non-Operative Management: Most closed extensor tendon injuries can be treated conservatively in the acute phase [50]. A simpler classification system for extensor tendon zones has been proposed to align with current treatment strategies, such as conservative splinting for closed injuries and strong surgical repair for open injuries [59].

Operative Management: Chronic extensor tendon injuries often require operative intervention [50]. For zones V and VI extensor tendon repairs, RME plus and RME only are used interchangeably depending on surgeon preferences and patient/tendon factors [26]. A relative motion extension program for zones V and VI extensor tendon repairs is associated with earlier hand function, total active motion, and orthotic satisfaction compared to controlled active motion [67]. Surgical release of the extensor retinaculum of the first dorsal extensor compartment with the presence of anomalous musculature provides successful treatment without recurrence [29]. Patients with chronic sagittal band injuries or those failing nonoperative management may benefit from surgical exploration [149]. Extensor tendon salvage and reconstruction using a tendon from an unsalvageable finger may be a reasonable remedy for reconstruction of tendon loss or gaps in zone I [145].

Stenosing Synovitis: Ultrasound is superior to MRI for dynamic evaluation of stenosing synovitis of the extensor pollicis longus tendon [73]. Surgical release is a viable treatment to prevent tendon rupture in stenosing synovitis of the extensor pollicis longus tendon [73].

Ligament Injuries

Ulnar Collateral Ligament: Chronic ulnar collateral ligament injuries are traditionally managed with tendon graft ligament reconstruction or tendon transfers [15]. Evidence for the management of chronic ulnar collateral ligament injuries is limited to case reports and retrospective series [15]. Completely ruptured collateral ligaments frequently result in prolonged disability when treated non-operatively [36]. Surgical repair of fourteen fingers with complete collateral ligament rupture yielded satisfactory results with restored joint stability and pain relief [36]. Injured ulnar collateral ligaments were naturally stable after reduction and did not need surgical repair [38].

Other Ligament and Tendon Pathology: Fascial lengthening at the time of surgical release for de Quervain’s tenosynovitis theoretically prevents tendon subluxation while providing acceptable relief of tenosynovitis with no increase in recurrence rates over the baseline [140].

Muscle and Other Tendon Injuries

Achilles Tendon: Surgical treatment is the treatment of choice for ruptures of the tendo achillis and should be recommended for more active patients due to significantly better functional results and a lower incidence of reruptures compared to non-surgical treatment [34]. A repair using the tendo achillis itself has been suggested for defects in the tendo achillis [32].

Hamstring and Gluteal Tendons: Acute repair is recommended for patients desiring return to sports following proximal hamstring tendon rupture [66]. Nonoperative management with delayed reconstruction is an option for low-demand patients with proximal hamstring tendon rupture [66]. Both open and endoscopic gluteal tendon tear repair using suture anchors can be used successfully [139].

Other Muscular and Tendon Injuries: For late-stage cases of congenital flexion deformity with aberrant origin of the flexor digitorum profundus, both local release and a thorough muscle sliding were preferred [3]. The authors recommend evaluation of specific clinical and imaging findings to grade lumbrical muscle tears and determine suitable therapy [11]. Published clinical results have demonstrated significant improvements in upper limb function following contralateral C7 transfer, confirming the procedure's safety and efficacy [51]. Donor site morbidity for contralateral C7 transfer is typically mild and transient [51]. The present scoping review shows contradictory results regarding tendon-related outcomes although studies point to increasing tendon function after rehabilitation with blood flow restriction training [33].

Complications

Tendon Healing and Degeneration: Repaired tendon tissue never achieves the histological characteristics of normal tendon [6]. A single traumatic event can induce a degenerative pattern that is microscopically indistinguishable from the degeneration observed in human supraspinatus tendons following partial or complete rupture [37]. Increasing age and mechanical use are significant factors driving this degeneration, which ultimately leads to rupture [37]. Clinical outcomes following rotator cuff repair are compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle [64].

Specific Complications and Pathologies: Closed rupture of the flexor tendon is a recognized complication in patients with asymptomatic Kienböck disease [31]. Proximal hamstring tendon repair carries an overall complication rate of 15.4%, with a major complication rate of 4.6% [114]. In rheumatoid hands undergoing tendon grafting for extensor tendon ruptures, extension lag of the metacarpophalangeal joint is a specific concern [14]. Release of the flexor retinaculum for partial rupture of the flexor hallucis longus tendon permits smooth movement, yet the prognosis remains guarded due to tendon weakening [5]. Non-operative treatment of completely ruptured collateral ligaments of the proximal interphalangeal joint frequently results in prolonged disability [36]. Silicone rod use in flexor tendon reconstruction can lead to infection, scar formation, and dense fibrosis that compromise or prevent successful grafting [142]. Following zone 2 flexor tendon repair with early active mobilization, sixteen of thirty-four patients continued to suffer from cold sensitivity [147].

Risk Factors and Predispositions: Testosterone replacement therapy in adult males is associated with higher odds of tendon and ligament injuries [13]. Estrogen decreases stiffness in tendons and ligaments, which can increase the risk of catastrophic ligament injury [54]. The incidence of an anomalous slip of tendon to the long finger is 25% in cadaveric studies [152].

Management and Outcomes of Complications: Distal release of deltoid muscle contracture yielded a good clinical result in forty-seven (96 per cent) of forty-nine shoulders [74]. Injured ulnar collateral ligaments in the thumb metacarpophalangeal joint were naturally stable after reduction and did not require surgical repair [38]. For late-stage congenital flexion deformity with aberrant flexor digitorum profundus origin, both local release and a thorough muscle sliding were preferred [3].

Recovery

Tendon Healing Biology: The remodeling phase is characterized by a decrease in cellularity and reduced matrix synthesis [6]. During this period, there is a decrease in type III collagen and an increase in type I collagen synthesis [6]. In later phases of remodeling, interactions between collagen structural units lead to higher tendon stiffness and greater tensile strength [6]. Tendon healing is dependent on tendon location, extent of trauma, and postoperative motion [6].

Extrinsic Healing Mechanism: Extrinsic healing involves fibroblasts and inflammatory cells moving from peripheral or external tissue sources to the healing site [6]. This process requires a well-established vascular network for effective tissue healing [6]. The extrinsic mechanism is activated earlier than the intrinsic mechanism and is responsible for initial adhesion formation [6]. In most cases, both extrinsic and intrinsic mechanisms are involved in tendon healing [6]. The ingrowth of fibroblasts, inflammatory cells, and other extratendinous cells mediates extrinsic healing [12]. Different tendons express unique growth-factor profiles after similar, simultaneous injuries [30].

Rehabilitation Protocol: An autonomous patient-controlled mobilization protocol after flexor tendon repair achieves good results in range of motion and early return of function [45]. A scoping review shows contradictory results regarding tendon-related outcomes from blood flow restriction training, although studies point to increasing tendon function after rehabilitation [33].

Other Considerations: Clinical outcome after rotator cuff repair is compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle [64]. In cases of tendon graft for extensor tendon ruptures, there is concern over extension lag of the metacarpophalangeal joint [14]. The time to surgery should be considered in cases of tendon graft for extensor tendon ruptures [14].

Key Evidence

• [L5] Perhaps the most appropriate term for the pathology should not include ‘tendon’ as it misleads our understanding of both the pathology and its management. [1] (10.1136/bjsports-2017-098834)
• [L5] The authors agree that the '50% rule' should not be considered an exact rule in medical science because clinical evaluations of tendon and ligament disruption are relatively subjective and lack high intraobserver and interobserver reliability. [2] (10.1016/j.arthro.2011.10.003)
• [Case_report] For late-stage cases, both local release and a thorough muscle sliding were preferred. [3] (10.1016/j.jhsa.2008.04.013)
• [L4] Release of the flexor retinaculum permits the tendon to move smoothly in its track, but the prognosis is guarded as the tendon is weakened. [5] (10.2106/00004623-197961010-00031)
• [L5] [6] (10.1016/j.jhsa.2007.09.007)
• [L5] Extensor tendon injuries are common and early recognition and treatment are key to the management of such injuries. [8] (10.1016/j.hcl.2014.12.006)
• [L4] Surgical reconstruction of degenerate abductor tendons should be considered in the presence of an MRI confirmed separation where clinical findings are consistent with the known tendon disruption. [10] (10.1016/j.arth.2019.11.012)
• [L4] The authors recommend evaluation of specific clinical and imaging findings to grade the injuries and determine suitable therapy. [11] (10.1177/1753193418765716)
• [L4] [12] (10.1177/175899830000500202)
• [L4] Across large claims-based cohorts, TRT in adult males is associated with higher odds of tendon and ligament injuries, with estimates of similar magnitude at one and two years where both were reported. [13] (10.1177/2325967126s00289)
• [L4] In cases of tendon graft, the time to surgery should be considered, and there is concern over extension lag of MP joint. [14] (10.1186/s12891-022-05815-7)
• [L4] Chronic UCL injuries are traditionally managed with tendon graft ligament reconstruction or tendon transfers, though evidence is limited to case reports and retrospective series. [15] (10.1016/j.jhsa.2011.06.004)
• [L3] Both techniques provided excellent short- to mid-term clinical and functional outcomes. [16] (10.1177/17585732261441889)
• [L3] These procedures should be considered in symptomatic patients with chronic tears that are not amenable to primary repair. [18] (10.1177/23259671251383094)
• [L5] According to a review of injuries of the myotendinous junction, this area is prone to stretching injury because of its microanatomical structure. [19] (10.1016/0020-1383(95)00139-5)
• [L4] Even after clinically successful flexor tendon autograft, tendons may still be at risk of degeneration and rupture a decade or more after reconstruction. [20] (10.1177/15589447221131846)
• [L5] Secondary reconstruction remains an important and useful technique for complicated flexor tendon injuries or those that have failed primary repair. [21] (10.1016/j.jhsa.2007.08.018)
• [L5] Pulley rupture or insufficiency is a diagnostic and therapeutic dilemma owing to the overall rarity of the injury as well as the lack of comparative clinical studies describing its diagnosis, treatment, and outcome. [23] (10.1016/j.jhsa.2012.07.021)
• [L4] RME plus and RME only are used interchangeably depending on surgeon preferences and patient/tendon factors. [26] (10.1016/j.jht.2019.12.016)
• [L5] Primary tendon repair is permissible only when strict criteria are met, including early presentation, minimal contamination, and favorable wound conditions; otherwise, secondary repair via tendon graft is recommended. [27] (10.2106/00004623-195941040-00001)
• [L5] The scaphotrapezial ligament consists of three distinct fascicles, including a deep fascicle that attaches 3.3 mm from the most distal point of the scaphoid. [28] (10.1016/j.jhsa.2025.09.010)
• [L4] Surgical release of the extensor retinaculum of the first dorsal extensor compartment with the presence of anomalous musculature provides successful treatment without recurrence. [29] (10.1007/s11552-013-9580-z)
• [L5] Different tendons express unique growth-factor profiles after similar, simultaneous injuries. [30] (10.1016/j.jhsg.2022.04.006)
• [Case_report] Closed rupture of the flexor tendon should be recognized as a complication in patients with asymptomatic Kienböck disease, and plain radiographs are important in the assessment of patients presenting with closed flexor tendon rupture. [31] (10.1177/1558944718795511)
• [L4] A repair using the tendo achillis itself has been suggested. [32] (10.2106/00004623-195638010-00011)
• [L4] The present scoping review shows contradictory results regarding tendon-related outcomes although studies point to increasing tendon function after rehabilitation. [33] (10.1186/s12891-025-08734-5)
• [L3] Surgical treatment is the treatment of choice and should be recommended for more active patients due to significantly better functional results and a lower incidence of reruptures compared to non-surgical treatment. [34] (10.2106/00004623-197658070-00015)
• [L5] Tendon adhesion and joint contracture are the most common complications after flexor tendon repair, managed through prevention, meticulous surgical technique, and thoughtful rehabilitation protocols. [35] (10.1016/j.hcl.2014.12.004)
• [L4] Completely ruptured collateral ligaments frequently result in prolonged disability when treated non-operatively, whereas surgical repair of fourteen fingers with complete rupture yielded satisfactory results with restored joint stability and pain relief. [36] (10.2106/00004623-196749020-00009)
• [L5] [37] (10.2106/00004623-194830030-00025)
• [L4] Injured UCL ligaments were naturally stable after reduction and did not need surgical repair. [38] (10.1177/1753193418790502)
• [L5] [44] (10.1177/17531934251321748)
• [L4] This protocol achieves good results in range of motion and early return of function of the hand. [45] (10.1177/1558944720964961)
• [L2] The BPT appears to be highly accurate in the clinical diagnosis of distal biceps tendon pathology. [46] (10.1016/j.jhsa.2020.12.012)
• [Paper] [48] (10.1016/j.eats.2019.11.022)
• [L4] [49] (10.1016/j.jhsg.2023.04.010)
• [L5] Most closed extensor tendon injuries can be treated conservatively in the acute phase, but chronic injuries often require operative intervention. [50] (10.1016/j.csm.2014.09.005)
• [L5] Published clinical results have demonstrated significant improvements in upper limb function, confirming the procedure's safety and efficacy, with donor site morbidity that is typically mild and transient. [51] (10.1177/17531934251314640)
• [L5] Most authors agree that both acute and chronic grade 3 RCL tears should be surgically treated. [53] (10.1016/j.jhsa.2008.01.037)
• [L5] Estrogen improves muscle mass and strength and increases collagen content in connective tissues, but decreases stiffness in tendons and ligaments, which can decrease power and increase the risk of catastrophic ligament injury. [54] (10.3389/fphys.2018.01834)
• [L4] FRACTURE, especially FRACTURE VR, provided excellent visualization of both flexor and extensor tendons, enabling 3-dimensional comprehension of all hand and finger tendons and instantaneous recognition of previously unnoticed anatomical variations or anomalous muscles. [55] (10.1016/j.jhsg.2025.100773)
• [L5] Recent repair and motion protocols lead to remarkably more reliable repairs, with over 80% good or excellent outcomes achieved rather consistently after Zone 2 repair along with infrequent need of tenolysis. [58] (10.1177/17531934211053757)
• [L5] The authors propose a simpler classification system for extensor tendon zones to align with current treatment strategies, such as conservative splinting for closed injuries and strong surgical repair for open injuries. [59] (10.1177/17531934241274112)
• [L5] Tendon lengthening and transfer are indicated for neuromuscular disorders, nerve injuries, and congenital or traumatic lesions. [60] (10.1016/j.otsr.2014.07.033)
• [L5] [61] (10.5435/jaaos-d-16-00316)
• [L3] Although repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, the repair of the flexor digitorum superficialis together with flexor digitorum profundus is not mandatory. [62] (10.1177/1753193420932446)
• [Letter] The authors advocate that novel flexor tendon repair techniques, including barbed suture, should be tested cyclically in a manner that closely mimics in vivo conditions during postoperative rehabilitation before clinical adoption. [63] (10.1016/j.jhsa.2015.02.034)
• [L2] Clinical outcome was compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle. [64] (10.1177/23259671231196875)
• [L4] There is considerable variability in published protocols for in vitro testing of flexor tendon repairs, with no standardized method currently in place. [65] (10.1177/17531934221139068)
• [L3] Acute repair is recommended for patients desiring return to sports, while nonoperative management with delayed reconstruction is an option for low-demand patients. [66] (10.1177/2325967113s00061)
• [L1] [67] (10.1016/j.jht.2018.10.003)
• [L5] [69] (10.2106/00004623-197254040-00003)
• [L4] They emphasize that ultrasound is superior to MRI for dynamic evaluation and that surgical release is a viable treatment to prevent tendon rupture. [73] (10.1016/j.jhsa.2011.02.004)
• [L3] Forty-seven (96 per cent) of the forty-nine shoulders had a good clinical result after distal release of the contracture. [74] (10.2106/00004623-199802000-00010)
• [L3] [106] (10.1177/17531934221074514)
• [L4] [107] (10.2106/jbjs.rvw.n.00070)
• [L4] The authors propose an additional category (Type 3) to the Türker classification system to encompass rare findings of two radial-sided accessory extensor tendons in the same individual, which were not previously represented in existing classifications. [109] (10.1016/j.jhsg.2023.10.005)
• [L4] Individual FDS contractions, particularly of the index and middle fingers, contribute most to stabilization against valgus stress. [110] (10.1186/s13018-020-01640-7)
• [L4] Based on the results of this survey, a revisit of the popular extensor tendon zone classifications systems may be necessary for future clinical practice and communication among surgeons. [111] (10.1177/17531934241253137)
• [L5] Achieving consistent, satisfactory results remains an elusive goal, but recent studies demonstrate that tendon grafts will tolerate early motion therapy if the proximal and distal tenorrhaphy junctures are strong enough. [112] (10.1016/j.jhsa.2015.04.016)
• [L1] Proximal hamstring tendon repair is associated with an overall complication rate of 15.4%, including a 4.6% rate of major complications. [114] (10.1177/2325967123s00208)
• [L4] Loss of the abductor pollicis longus and extensor pollicis brevis motor units had no functional effect upon thumb pinch-strength or hand grip, and only a minimal adverse effect upon thumb movement. [116] (10.1054/jhsb.2001.0744)
• [L5] The ulnar slip of the EDM tendon is the major contributor to aberrant abduction with active small finger extension, producing almost twice as much abduction as the radial slip. [120] (10.1177/1558944717729220)
• [L5] The quadriga phenomenon, caused by interconnected flexor digitorum profundus tendons, significantly affects clinical situations including strength testing, movement assessment, and rehabilitation exercise selection; understanding its anatomy and biomechanics improves diagnosis and treatment. [121] (10.1177/1753193411430810)
• [L5] [122] (10.1016/j.eats.2025.103849)
• [L5] Tang's simplified classification is expected to enhance the accuracy of operative evaluations and provide valuable insights into surgical outcomes for anatomically diverse extensor tendon injuries, though future studies are needed to validate its effectiveness. [125] (10.1177/17531934251326850)
• [L2] Fibril morphology is abnormal in tendinopathy, but tendon mechanical properties are not. [133] (10.1177/0363546509350915)
• [L3] Both bridge tendon grafts and end-to-side tendon transfers have comparable and satisfactory outcomes after surgical treatment of closed rupture of the flexor tendons in the little finger. [134] (10.1177/17531934211073751)
• [L5] The authors agree that more stringent criteria, such as Tang's criteria, are necessary as results move toward more ideal functional outcomes, and that surgeon expertise should always be considered when comparing outcomes. [135] (10.1177/1753193416634602)
• [L1] EAM leads to a quicker recovery in terms of grip strength and patient-reported outcomes, but both regimens lead to similar results at 12 months. [136] (10.1177/17531934231166336)
• [L5] The use of a skin hook is a simple and effective technique to retrieve proximal flexor tendons, with minimal morbidity and without a palmar incision. [137] (10.1177/17531934251324347)
• [L5] The author suggests that a classification of extensor tendon zones based on the presence of the extensor retinaculum is preferable to those based on the wrist joint, as it simplifies treatment discussion and aligns with flexor tendon zoning. [138] (10.1177/17531934241232066)
• [L3] Although further evaluation of the efficacy of EGR in complex tears is indicated, both approaches can be used successfully. [139] (10.1016/j.arth.2020.03.013)
• [L4] This repair theoretically prevents tendon subluxation while providing acceptable relief of tenosynovitis with no increase in recurrence rates over the baseline. [140] (10.1177/15589447231218403)
• [L5] These results suggest that the anterior bundle, posterior bundle, and common tendon each can be classified into an independent form and an unclear form. [141] (10.1177/2325967120952415)
• [L4] [142] (10.1177/1753193415575985)
• [L4] This review provides a contemporary perspective on sagittal band injuries and describes a modification to the most prevalent classification system to guide treatment and allow standardization in documenting and describing injuries. [143] (10.1016/j.jhsa.2021.09.011)
• [L4] Extensor tendon salvage and reconstruction using a tendon from an unsalvageable finger may be a reasonable remedy for reconstruction of tendon loss or gaps in zone I, offering advantages over other traditional techniques in certain cases. [145] (10.1016/j.jhsa.2014.01.029)
• [L3] [147] (10.1054/jhsb.1998.0175)
• [L4] Patients with chronic injuries or those failing nonoperative management may benefit from surgical exploration. [149] (10.1177/1558944719895622)
• [L5] The incidence of an anomalous slip of tendon to the long finger might be higher than previously reported, with a combined incidence of 25% in this cadaveric study. [152] (10.1016/j.jhsa.2012.02.014)
• [L4] They suggest that MRI might be worth considering in revision cases, as 43% of those cases with clinical signs of olecranon bursitis had previous surgery. [153] (10.1016/j.arthro.2014.11.005)
• [Case_report] Avulsion of the subscapularis tendon may be more common than literature suggests, and the radiographic appearance of a bone fragment beneath the humeral head is a valuable sign. [159] (10.2106/00004623-198769090-00024)
• [L4] However, magnetic resonance imaging indicates that the donor site is resurfaced with fibrous tissue. [160] (10.1177/0363546507306465)
• [Paper] In the foetus it was a little less than this value: There were only minor differences for different sites. (Embalmed tendon can give a misleading impression, its strength being increased to three times that of normal tendon.) [166] (10.1016/s0020-1383(71)80045-1)

See Also

• Flexor tendon repair
• Trigger Finger
• Dupuytren's Disease

References

[1] Does the intramuscular tendon act like a free tendon?. British Journal of Sports Medicine. 2018. DOI: 10.1136/bjsports-2017-098834

[2] The “50% Rule”. Arthroscopy. 2011. DOI: 10.1016/j.arthro.2011.10.003

[3] Congenital Flexion Deformity of the Long, Ring, and Little Fingers With an Aberrant Origin of the Flexor Digitorum Profundus: Case Report. The Journal of Hand Surgery. 2008. DOI: 10.1016/j.jhsa.2008.04.013

[4] Chapter 62 Tendons and Ligaments. 2019.

[5] Partial rupture of the flexor hallucis longus tendon in classical ballet dancers. The Journal of Bone & Joint Surgery. 1979. DOI: 10.2106/00004623-197961010-00031

[6] Tendon: Biology, Biomechanics, Repair, Growth Factors, and Evolving Treatment Options. The Journal of Hand Surgery. 2008. DOI: 10.1016/j.jhsa.2007.09.007

[8] Management of Complications of Extensor Tendon Injuries. Hand Clinics. 2015. DOI: 10.1016/j.hcl.2014.12.006

[10] Primary Open Abductor Reconstruction: A 5 to 10-Year Study. The Journal of Arthroplasty. 2020. DOI: 10.1016/j.arth.2019.11.012

[11] Lumbrical muscle tear: clinical presentation, imaging findings and outcome. Journal of Hand Surgery (European Volume). 2018. DOI: 10.1177/1753193418765716

[12] The Role of Ultrasound in the Treatment of Surgically Repaired Tendon Injuries of the Hand: A Literature Review. The British Journal of Hand Therapy. 2000. DOI: 10.1177/175899830000500202

[13] Paper 31. Testosterone Replacement Therapy and Risk of Tendinous and Ligamentous Injuries: A Systematic Review. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00289

[14] Long-term clinical outcome of tendon transfer and tendon graft for extensor tendon ruptures in rheumatoid hands. BMC Musculoskeletal Disorders. 2022. DOI: 10.1186/s12891-022-05815-7

[15] Chronic Thumb Metacarpophalangeal Joint Ulnar Collateral Ligament Insufficiency. The Journal of Hand Surgery. 2012. DOI: 10.1016/j.jhsa.2011.06.004

[16] Distal biceps tendon repair using cortical button with or without interference screw: A comparative study. Shoulder & Elbow. 2026. DOI: 10.1177/17585732261441889

[18] Clinical Outcomes After Proximal Hamstring Repair With Allograft Augmentation or Interposition for Chronic Tears: A Multicenter Propensity-Matched Analysis. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/23259671251383094

[19] Complete avulsion of a tendon of flexor digitorum profundus from its myotendinous junction. Injury. 1995. DOI: 10.1016/0020-1383(95)00139-5

[20] Two Cases of Delayed Flexor Tendon Rupture Decades After Reconstruction. HAND. 2022. DOI: 10.1177/15589447221131846

[21] Secondary Flexor Tendon Reconstruction, A Review. The Journal of Hand Surgery. 2007. DOI: 10.1016/j.jhsa.2007.08.018

[23] A2 Pulley Insufficiency. The Journal of Hand Surgery. 2013. DOI: 10.1016/j.jhsa.2012.07.021

[25] Pectoralis Major Muscle: Function of Sternal Portion and Mechanism of Rupture of Normal Muscle: Case Reports.. The Journal of Bone and Joint Surgery. American Volume. 1961.

[26] Relative motion extension management of zones V and VI extensor tendon repairs: Does international practice align with the current evidence?. Journal of Hand Therapy. 2021. DOI: 10.1016/j.jht.2019.12.016

[27] Primary Tendon Repair. The Journal of Bone & Joint Surgery. 1959. DOI: 10.2106/00004623-195941040-00001

[28] Anatomy of the Scaphotrapezial Ligament Complex and its Implications for Distal Scaphoid Resection. The Journal of Hand Surgery. 2026. DOI: 10.1016/j.jhsa.2025.09.010

[29] Anomalous Muscles within the First Dorsal Extensor Compartment of the Wrist. HAND. 2013. DOI: 10.1007/s11552-013-9580-z

[30] Growth Factor Expression During Healing in 3 Distinct Tendons. Journal of Hand Surgery Global Online. 2022. DOI: 10.1016/j.jhsg.2022.04.006

[31] Comments on “Flexor Tendon Rupture Due to Previously Undiagnosed Kienböck Disease: A Case Report”. HAND. 2018. DOI: 10.1177/1558944718795511

[32] REPAIR OF DEFECTS IN THE TENDO ACHILLIS. The Journal of Bone & Joint Surgery. 1956. DOI: 10.2106/00004623-195638010-00011

[33] The impact of blood flow restriction training on tendon adaptation and tendon rehabilitation – a scoping review. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-08734-5

[34] Ruptures of the tendo achillis. An objective assessment of surgical and non-surgical treatment. The Journal of Bone & Joint Surgery. 1976. DOI: 10.2106/00004623-197658070-00015

[35] Management of Complications of Flexor Tendon Injuries. Hand Clinics. 2015. DOI: 10.1016/j.hcl.2014.12.004

[36] Rupture of a Collateral Ligament of the Proximal Interphalangeal Joint of the Fingers. The Journal of Bone & Joint Surgery. 1967. DOI: 10.2106/00004623-196749020-00009

[37] EXPERIMENTAL DEGENERATION OF THE SUPRASPINATUS TENDON. The Journal of Bone & Joint Surgery. 1948. DOI: 10.2106/00004623-194830030-00025

[38] Arthroscopic findings of injured ulnar and radial collateral ligaments in the thumb metacarpophalangeal joint. Journal of Hand Surgery (European Volume). 2018. DOI: 10.1177/1753193418790502

[40] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Evaluation, Clinical Examination, and Imaging > Evaluation and Clinical Examination: Current Concepts.

[42] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 9Hand Surgery > Image DISORDERS OF THE MUSCULATURE OF THE HAND.

[44] Black holes in hand anatomy: exploring research areas in hand surgery. Journal of Hand Surgery (European Volume). 2025. DOI: 10.1177/17531934251321748

[45] Autonomous Patient-Controlled Mobilization Protocol After Flexor Tendon Repair: A Case Series. HAND. 2020. DOI: 10.1177/1558944720964961

[46] Distal Biceps Provocation Test. The Journal of Hand Surgery. 2021. DOI: 10.1016/j.jhsa.2020.12.012

[47] Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Tendon Problems in Athletic Individuals+.. The Journal of Bone and Joint Surgery. American Volume*. 1997.

[48] Endoscopic Proximal Hamstring Tendon Repair for Nonretracted Tears: An Anatomic Approach and Repair Technique. Arthroscopy Techniques. 2020. DOI: 10.1016/j.eats.2019.11.022

[49] Anomalous Extensor Digiti Minimi with Multiple Slips and Bulbous Appearance. Journal of Hand Surgery Global Online. 2023. DOI: 10.1016/j.jhsg.2023.04.010

[50] Extensor Tendons Injuries. Clinics in Sports Medicine. 2015. DOI: 10.1016/j.csm.2014.09.005

[51] Harnessing the uninjured hemisphere for treatment of the stroke or brain-injured patient – evolution of the contralateral C7 transfer. Journal of Hand Surgery (European Volume). 2025. DOI: 10.1177/17531934251314640

[53] Radial Collateral Ligament Injuries of the Thumb. The Journal of Hand Surgery. 2008. DOI: 10.1016/j.jhsa.2008.01.037

[54] Effect of Estrogen on Musculoskeletal Performance and Injury Risk. Frontiers in Physiology. 2019. DOI: 10.3389/fphys.2018.01834

[55] Enhanced Diagnostic Accuracy of Fast-Field Echo Resembling a Computed Tomography Using Restricted Echo-Spacing for Hand Tendon Injuries: A Comparative Study. Journal of Hand Surgery Global Online. 2025. DOI: 10.1016/j.jhsg.2025.100773

[58] Flexor tendon repair: recent changes and current methods. Journal of Hand Surgery (European Volume). 2021. DOI: 10.1177/17531934211053757

[59] Extensor tendons: can we design a simpler classification zone system?. Journal of Hand Surgery (European Volume). 2024. DOI: 10.1177/17531934241274112

[60] Tendon lengthening and transfer. Orthopaedics & Traumatology: Surgery & Research. 2015. DOI: 10.1016/j.otsr.2014.07.033

[61] Flexor Tendon Injuries. Journal of the American Academy of Orthopaedic Surgeons. 2018. DOI: 10.5435/jaaos-d-16-00316

[62] Flexor digitorum profundus with or without flexor digitorum superficialis tendon repair in acute Zone 2B injuries. Journal of Hand Surgery (European Volume). 2020. DOI: 10.1177/1753193420932446

[63] Letter Regarding “Biomechanical Analysis of Flexor Tendon Repair Using Knotted Kessler and Bunnell Techniques and the Knotless Bunnell Technique”. The Journal of Hand Surgery. 2015. DOI: 10.1016/j.jhsa.2015.02.034

[64] Structural Musculotendinous Parameters That Predict Failed Tendon Healing After Rotator Cuff Repair. Orthopaedic Journal of Sports Medicine. 2023. DOI: 10.1177/23259671231196875

[65] In vitro testing of flexor tendon repair models: variability in the current literature. Journal of Hand Surgery (European Volume). 2022. DOI: 10.1177/17531934221139068

[66] Functional Outcomes Following Surgical Repair of Acute and Chronic Ruptures of the Proximal Hamstring Tendons. Orthopaedic Journal of Sports Medicine. 2013. DOI: 10.1177/2325967113s00061

[67] A randomized clinical trial comparing early active motion programs: Earlier hand function, TAM, and orthotic satisfaction with a relative motion extension program for zones V and VI extensor tendon repairs. Journal of Hand Therapy. 2020. DOI: 10.1016/j.jht.2018.10.003

[69] The Functional Anatomy of the Extensor Mechanism of the Finger. The Journal of Bone & Joint Surgery. 1972. DOI: 10.2106/00004623-197254040-00003

[72] Chapter 30 Flexor and Extensor Tendon Injuries. 2019.

[73] Stenosing Synovitis of the Extensor Pollicis Longus Tendon. The Journal of Hand Surgery. 2011. DOI: 10.1016/j.jhsa.2011.02.004

[74] Contracture of the Deltoid Muscle. The Journal of Bone and Joint Surgery (American Volume). 1998. DOI: 10.2106/00004623-199802000-00010

[77] Green S Operative Hand Surgery. Interosseous and Hypothenar Muscles.

[83] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 9Hand Surgery > FLEXOR TENDON INJURY.

[91] Dupuytren S Disease And Related Hyperproliferative Disorders. 54. The Future of Dupuytren’s Research and Treatment > 54.4 Mechanical Measurements and Procedures > 54.4.4 Imaging.

[106] Repair of flexor digitorum profundus avulsions including the palmar plate: a retrospective comparative study of 56 cases. Journal of Hand Surgery (European Volume). 2022. DOI: 10.1177/17531934221074514

[107] Assessment and Treatment of Extensor Carpi Ulnaris Tendon Pathology. JBJS Reviews. 2015. DOI: 10.2106/jbjs.rvw.n.00070

[109] Accessory Extensor Pollicis Longus Tendon Classification Modification. Journal of Hand Surgery Global Online. 2024. DOI: 10.1016/j.jhsg.2023.10.005

[110] Valgus stability is enhanced by flexor digitorum superficialis muscle contraction of the index and middle fingers. Journal of Orthopaedic Surgery and Research. 2020. DOI: 10.1186/s13018-020-01640-7

[111] Extensor tendon zones: a survey of views in a hand surgery department. Journal of Hand Surgery (European Volume). 1934. DOI: 10.1177/17531934241253137

[112] Single-Stage Flexor Tendon Grafting: Refining the Steps. The Journal of Hand Surgery. 2015. DOI: 10.1016/j.jhsa.2015.04.016

[114] Poster 224: Complications Associated with Proximal Hamstring Tendon Repair: A Systematic Review. Orthopaedic Journal of Sports Medicine. 2023. DOI: 10.1177/2325967123s00208

[116] Thumb Function without the Abductor Pollicis Longus and Extensor Pollicis Brevis. Journal of Hand Surgery. 2002. DOI: 10.1054/jhsb.2001.0744

[120] The Relative Contribution to Small Finger Abduction of the Ulnar Versus Radial Slip of the EDM: Implications for Tendon Transfers. HAND. 2017. DOI: 10.1177/1558944717729220

[121] The quadriga phenomenon: a review and clinical relevance. Journal of Hand Surgery (European Volume). 2011. DOI: 10.1177/1753193411430810

[122] Arthroscopically Assisted Anatomic Repair of a Medial Gastrocnemius Proximal Tendon Avulsion. Arthroscopy Techniques. 2025. DOI: 10.1016/j.eats.2025.103849

[125] Re: Tang JB. Clarification and classification of extensor tendon zones in the hand. J Hand Surg Eur. 2024, 49: 1041–4. Journal of Hand Surgery (European Volume). 2025. DOI: 10.1177/17531934251326850

[133] Fibril Morphology and Tendon Mechanical Properties in Patellar Tendinopathy. The American Journal of Sports Medicine. 2010. DOI: 10.1177/0363546509350915

[134] Comparison of bridge graft and end-to-side transfer for treatment of closed rupture of the flexor tendons in the little finger. Journal of Hand Surgery (European Volume). 2022. DOI: 10.1177/17531934211073751

[135] Re: Moriya K, Yoshizu T, Tsubokawa N, et al. Outcomes of release of the entire A4 pulley after flexor tendon repairs in zone 2A followed by early active mobilization. J Hand Surg Eur. 2016, 41: 400–5.. Journal of Hand Surgery (European Volume). 2016. DOI: 10.1177/1753193416634602

[136] Rehabilitation following flexor tendon injury in Zone 2: a randomized controlled study. Journal of Hand Surgery (European Volume). 2023. DOI: 10.1177/17531934231166336

[137] A simple and effective technique to retrieve a retracted flexor tendon without a palmar incision. Journal of Hand Surgery (European Volume). 2025. DOI: 10.1177/17531934251324347

[138] Clarification and classification of extensor tendon zones in the hand. Journal of Hand Surgery (European Volume). 2024. DOI: 10.1177/17531934241232066

[139] Equivalent Mid-Term Results of Open vs Endoscopic Gluteal Tendon Tear Repair Using Suture Anchors in Forty-Five Patients. The Journal of Arthroplasty. 2020. DOI: 10.1016/j.arth.2020.03.013

[140] Fascial Lengthening at the Time of Surgical Release for de Quervain’s Tenosynovitis to Prevent Postsurgical Tendon Subluxation. HAND. 2024. DOI: 10.1177/15589447231218403

[141] Morphological Features of the Ulnar Collateral Ligament of the Elbow and Common Tendon of Flexor-Pronator Muscles. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967120952415

[142] The lost art of single-stage flexor tendon grafting. Journal of Hand Surgery (European Volume). 2015. DOI: 10.1177/1753193415575985

[143] Sagittal Band Injuries: A Review and Modification of the Classification System. The Journal of Hand Surgery. 2022. DOI: 10.1016/j.jhsa.2021.09.011

[145] Zone I Extensor Reconstruction With Tendon Salvaged From Another Finger. The Journal of Hand Surgery. 2014. DOI: 10.1016/j.jhsa.2014.01.029

[147] Long Term Outcome of Early Active Mobilization Following Flexor Tendon Repair in Zone 2. Journal of Hand Surgery. 1999. DOI: 10.1054/jhsb.1998.0175

[149] Treatment of Sagittal Band Injuries and Extensor Tendon Subluxation: A Systematic Review. HAND. 2020. DOI: 10.1177/1558944719895622

[152] Anomalous Extensor Tendons to the Long Finger: A Cadaveric Study of Incidence. The Journal of Hand Surgery. 2012. DOI: 10.1016/j.jhsa.2012.02.014

[153] Authors' Reply. Arthroscopy. 2015. DOI: 10.1016/j.arthro.2014.11.005

[159] Avulsion of the subscapularis tendon. A case report. The Journal of Bone & Joint Surgery. 1987. DOI: 10.2106/00004623-198769090-00024

[160] Donor Site Evaluation after Autologous Osteochondral Mosaicplasty for Cartilaginous Lesions of the Elbow Joint. The American Journal of Sports Medicine. 2007. DOI: 10.1177/0363546507306465

[166] Tensile strenth of tendon. Injury. 1971. DOI: 10.1016/s0020-1383(71)80045-1