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Pathology & Anatomy

Prearthritic intra-articular hip pathology, including FAI, dysplasia, microinstability, and ONFH, focusing on early diagnosis to prevent premature joint degeneration.

89 citationsUpdated Sep 2026

Overview

Comprehensive knowledge of hip anatomy and normal function is critical for identifying pathologies and developing successful treatment strategies [1]. While most orthopaedic surgeons are facile at treating hip joint disorders, it is essential to diagnose and manage the soft-tissue ailments surrounding the hip joint [94]. Understanding the etiology of intra- and extraarticular hip complaints requires comprehensive diagnosis and management of the spectrum of posterior hip diseases [91]. Genetic disorders affecting the musculoskeletal system are commonly encountered by the pediatric orthopaedic surgeon, requiring awareness of clinical and radiographic manifestations for appropriate diagnosis and treatment [99].

Surgical planning relies on reproducible anatomical landmarks. Described surgical landmarks for acetabular structures have reliable locations on radiographs, with distances between landmarks and reference lines being reproducible in both AP and false-profile views [6]. Quantitative descriptions of endoscopic landmarks for proximal femoral structures are reproducible in clinical views despite variation in cadaveric sizes [12]. Ten common radiographic views used to identify cam morphology visualize different clock-face positions of the head-neck junction [90]. In National Hockey League players, hip anatomy is characterized by highly prevalent cam-type morphology (>85%) and acetabular retroversion (>60%), with acetabular dysplasia (21%) being relatively common [100].

Soft-tissue anatomy informs portal selection and tendon assessment. The hip capsular ligaments have distinct and consistent arthroscopic locations within the hip joint and are associated with clearly identifiable landmarks in the central and peripheral compartments [4]. A more ventrally located 'mid-distal' portal provides sufficient distance from important neurovascular structures and can be used as an adjunct for accessing extra-articular pathologies of the iliopsoas tendon and bursitis of the greater trochanter [3]. Information regarding the anatomy and dimensions of the gluteus medius tendon insertion provides surgeons with a better understanding of the footprint anatomy when evaluating gluteus medius tendon tears [25].

Pathology management is constrained by specific anatomical and biological factors. No method of consistently restoring normal anatomy without damaging the femoral head or acetabulum is known for idiopathic slipped capital femoral epiphysis [5]. Dysregulated growth factor-related genes play a role in the occurrence and development of osteonecrosis of the femoral head, with potential clinical applications in tissue and genetic engineering for treatment [85]. Surgical anatomy of the hip includes pelvic landmarks, acetabular quadrant systems for screw placement, femoral geometry, and neurovascular relationships to guide total hip arthroplasty approaches and avoid complications [81].

Osseous Anatomy

Development and Morphology

Articular structures visible on newborn arthrograms are already present in the fourteen-week-old fetus and maintain stable relative sizes throughout development [29]. In later stages of acetabular rim bone apposition, new bone formation becomes indistinguishable from native bone, potentially causing the labrum to appear nearly absent on imaging [30]. Age-related changes in proximal femoral canal morphology persist beyond 80 years, particularly in females, characterized by asymmetric flaring and larger absolute dimensions [38].

Cam Morphology

Cam morphology is identified in a modest percentage of osteologic specimens using both alpha angle and anterior femoral neck offset, with associations among demographic, anthropometric, and anatomical parameters suggesting these metrics may identify different subsets of cam morphology [26]. Clinical and radiological hip parameters do not precede the development of cam morphology [28]. The severity of cam morphology serves as a primary predictor for the location and severity of chondral and labral damage [11].

Radiographic Landmarks and Imaging

Described surgical landmarks for acetabular structures demonstrate reliable locations on radiographs, with distances between landmarks and reference lines remaining reproducible in both AP and false-profile views [6]. Morphologic features measurable on anteroposterior pelvic radiographs do not correlate with ultrasound-measured hip flexion [9]. Magnetic resonance imaging proves accurate in all hips with histological proof of osteonecrosis and in those exhibiting medullary changes without necrotic bone [36].

Pathology and Biomechanics

Abnormal hip morphology predates arthrosis and is not secondary to the osteoarthritic process [31]. In femoroacetabular impingement treatment, resection depth is the most important determinant of bone resistance, being 325% more sensitive than lengthening and 70% more sensitive than widening [33].

Ligaments and Joint Capsule

Biomechanics and Function

The individual hip capsular ligaments act independently to resist end-range of motion [14]. These ligaments provide greater rotational restraint than the acetabular labrum and the ligamentum teres [45]. Within the complete range of movement, each capsular ligament serves as the primary restraint for hip rotation at specific points [45]. The ligamentum teres functions as a secondary restraint during high flexion, adduction, and external rotation [45]. Postoperative biomechanical function of the capsular ligaments is differentially affected by anterior versus posterior surgical approaches [22].

Anatomy and Pathology

The hip capsular ligaments occupy distinct and consistent arthroscopic locations within the joint [4]. They are associated with clearly identifiable landmarks in both central and peripheral compartments [4]. Pathologic thickening of the hip capsule may contribute to restricted hip mobility on clinical examination [23]. Capsular thickness and intra-substance changes of the anterior capsule vary, which could alter capsular management strategies [64]. Specifically, the anterior hip capsule is thinner in dysplastic hips [64]. In dislocated hips in infants, the capsule was the most common block to reduction [39]. The teres ligament was the second most common block to reduction, following the capsule [39]. Successful reduction of dislocated hips in infants can be achieved by removal of intra-articular tissues and nearly always a capsular release [39].

Ligamentum Teres

Understanding of the biomechanical function and reasons for ligamentum teres tears is still evolving [24]. Findings on posterior bony impingement as a cause of ligamentum teres tears will not result in major changes to current practice [24]. A completely torn ligamentum teres should raise suspicion for a history of trauma or soft tissue and/or osseous instability [75]. Ligamentum teres tears may, very uncommonly, be caused by impingement of the mid-part of the ligament against a prominent posterior acetabular femoral edge [78].

Surgical Considerations

The use of medial portals in hip arthroscopy did not cause any damage to the neurovascular structures evaluated [2]. Increased tissue damage at the anterior capsule was observed after subspine trimming using a transverse interportal capsulotomy [61]. Although the interportal capsular shift may generate modestly higher degrees of capsular reduction, the comparative biomechanical repercussions of each technique are not currently known [15]. Routine capsular closure cannot be universally recommended for interportal capsulotomy [74]. Hip arthroscopic surgery with labral preservation and capsular plication in patients with borderline hip dysplasia should be performed by surgeons with expertise in advanced arthroscopic techniques [65]. This procedure requires strict patient selection criteria [65].

Muscles and Tendons

Tendon Structure and Physiology

Tendons connect skeletal muscle to bone, transmitting forces generated by muscular contraction to permit movement [51]. These hypocellular tissues consist of a complex network of matrix proteins maintained by fibroblasts [51]. The smallest functional unit of the tendon extracellular matrix is the collagen fibril [51]. Collagen fibrils combine to form fibers, and groups of collagen fibers coalesce into tendon fascicles [51]. Tendon fascicles are enveloped by the endotenon, a loose connective tissue containing nerves, lymph nodes, and blood vessels [51]. These fascicles coalesce into the tendon proper, held together by an epithelial-like tissue layer called the epitendon that contains larger blood vessels and nerves [51]. Some tendons are enclosed by an outer, loose, fatty, and vascularized tissue referred to as the paratenon, which allows for free excursion within its fascial compartment [51]. In lieu of a well-developed paratenon, some tendons are enclosed in synovial sheaths to allow efficient gliding [51].

Tendons store elastic energy when stretched and release this energy upon shortening [51]. Displacement of tendons of less than 4% generally allows the tissue to return to its original length once the load is removed [51]. When tendon displacement is greater than 4%, collagen fibers can begin to fail [51]. Beyond 8% strain, the tendon is susceptible to rupture [51]. Intense, high-frequency cyclical stretching can prevent certain regions of tendon from efficiently dissipating heat, causing irreparable denaturing of matrix proteins that can lead to tendinopathy or acute tendon rupture [51].

Tendon fibroblasts, also referred to as tenocytes, are elongated cells with long cytoplasmic extensions [51]. During embryonic development, tendons originate from a compartment of progenitor cells in somites that express the transcription factor scleraxis [51]. Throughout adolescence, fibroblasts gradually lose scleraxis expression, terminally differentiate, and appear to be mostly incapable of re-entering the cell cycle in response to mechanical growth cues [51]. Pericytes, a population of stem cells existing in close proximity to the vasculature in the epitendon, are candidates for the stem cell population within tendon that gives rise to tenocytes [51]. The core of tendons appears to grow until the age of 17, after which protein synthesis and matrix turnover begin to decline markedly [51]. Low rates of protein turnover may contribute to the difficulty encountered when treating chronic tendinopathies and the poor rates of healing observed in some tendon tears [51].

Type I collagen is the main protein composing the tendon extracellular matrix, accounting for 65% to 80% of the tendon dry weight [51]. Type I collagen typically consists of two α1 and one α2 subunits [51]. Procollagen is secreted from the fibroblast into the tendon extracellular matrix, where its N- and C-terminal ends are cleaved to produce tropocollagen, which is cross-linked to form the mature collagen fibril [51]. Type I and III collagens are part of the fibrillar collagen family and play an important role in the longitudinal transmission of force during locomotion [51]. Type III collagen is smaller in diameter, less organized, and has decreased tensile strength compared to type I collagen [51]. Type III collagen can often be found at the rupture sites of highly stressed tendons and in greater abundance in tendons of the elderly [51]. Network type IV and VI collagens provide structural support for vascular and lymphatic tissue in the endotenon and epitendon [51]. Elastin is an abundant protein in tendon that contributes to sliding between tendon fascicles and stores recoil energy during mechanical loading [51]. The ground substance of tendon is composed of various matricellular proteins, proteoglycans, and glycosaminoglycans, including decorin, biglycan, fibromodulin, lumican, fibronectin, periostin, and tenascin C [51]. Matricellular proteins, proteoglycans, and glycosaminoglycans help orient other major structural proteins in tendon or have hydrophilic properties that allow them to retain water, helping the tendon dissipate heat and resist damage during intensive loading or exercise [51].

Hip Muscles and Tendons

The gluteus medius tendon insertion footprint anatomy provides surgeons with a better understanding when evaluating gluteus medius tendon tears [25]. Bony landmarks indicating the insertions and the running course of the short external rotator muscles were identified on the greater trochanter [87]. The iliacus and psoas major muscle groups have 2 distinct tendinous components [89]. A more ventrally located 'mid-distal' portal provides sufficient distance from important neurovascular structures and can be used as an adjunct for accessing extra-articular pathologies of the iliopsoas tendon and bursitis of the greater trochanter in hip arthroscopy [3]. The prevalence of femoroacetabular impingement is high in patients with symptomatic proximal hamstring tendon pathology [97].

Neurovascular Anatomy

Arterial Supply

The internal retinacular artery (IRA) occupies an elevated position relative to the femoral neck, a configuration that may protect it from injury during fracture [7]. In the humerus, intraosseous anastomoses provided primarily by the deep brachial artery maintain blood supply to the humeral head when circumflex vessels are interrupted [82]. Vascular density varies with age; specimens from three to ten-year-old white children exhibit fewer arteries on the anterior and medial mid-neck surfaces compared to younger children [83]. Surgical approaches that avoid further compromising the remaining blood supply may prevent osteonecrosis in some cases of traumatic separation of the proximal femoral epiphysis [88].

Nerve Anatomy and Innervation

The human acetabular labrum contains abundant free nerve endings and nerve end organs, with higher concentrations in the antero-superior and postero-superior zones [84]. During the anterior approach to the hip joint, the posterior branch of the lateral femoral cutaneous nerve is most vulnerable in the proximal aspect [16]. In minimally-invasive direct anterior approaches, the tensor fasciae latae muscle perforator serves as a reliable anatomical landmark to identify the Hueter interval and minimize the risk of iatrogenic nerve injury [86]. Patient stature influences surgical safety, as shorter patients have shorter distances from bony landmarks to adjacent nerves, prompting more careful retractor placement during total hip replacement surgery [21].

Arthroscopic Considerations

The use of medial portals in hip arthroscopy does not cause damage to the neurovascular structures evaluated [2]. A more ventrally located 'mid-distal' portal provides sufficient distance from important neurovascular structures and can be used as an adjunct for accessing extra-articular pathologies [3].

Biomechanics and Function

General Principles

A thorough understanding of normal anatomy and biomechanics is necessary to identify pathology and determine the appropriate course of treatment [34]. The hip is a complex multiaxial joint capable of producing large forces and moving the thigh through large ranges of motion [34]. Any alteration to joint morphology or function can place the hip at risk for pathology [34]. Understanding hip joint biomechanics provides an important background for diagnosing and treating hip disorders, allowing clinicians to assimilate the effects of motions and deformations resulting from forces acting on the joint to guide appropriate medical interventions [46]. Hip pain in the absence of osteoarthritis may be due to a complex combination of mechanical stresses, both dynamic and static [71].

Kinematics describes the motion of objects without regard to their mass or how their motion is brought about [27]. Kinetics is the study of motion and its causes, involving analysis of the effects of forces or moments that produce or modify the motion of the body [27]. Rigid body mechanics applies when the deformation caused by load is considered negligible [37]. Joint kinetics include calculations or measurements of joint forces and torques [37]. Extrinsic structural properties differ from intrinsic material properties because structural properties are influenced by both geometry and material [37]. Fatigue, wear, and corrosion are the three major types of failures that can occur in joint replacement components [37].

Kinematics and Range of Motion

The hip joint exhibits simultaneous triplanar motion, which makes analysis of the instant center impossible [40]. The average range of motion for hip flexion is 115 degrees, with a functional range of 90 degrees (120 degrees to squat) [40]. The average range of motion for hip extension is 30 degrees [40]. The average range of motion for hip abduction is 50 degrees, with a functional range of 20 degrees [40]. The average range of motion for hip adduction is 30 degrees [40]. The average range of motion for hip internal rotation is 45 degrees, with a functional range of 0 degrees [40]. The average range of motion for hip external rotation is 45 degrees, with a functional range of 20 degrees [40].

Male and female patients differ in their hip structure, biomechanics, and operative findings of symptomatic labral tears [18]. Impaired single-leg squat performance in patients with FAI syndrome is predominantly predicted by sagittal plane knee and hip biomechanics and hip external rotator strength, and less by frontal plane pelvic ROM and hip morphology [73].

Kinetics and Joint Forces

Joint reaction force (R) in the hip can reach three to six times body weight [40]. Joint reaction force (R) is primarily a result of the contraction of the muscles crossing the hip [40]. Joint reaction force (R) decreases with the use of a cane in the contralateral hand [40]. Joint reaction force (R) is correlated with predisposition to degenerative changes [35]. Joint contact pressure (stress) can be minimized by decreasing joint reaction force (R) or increasing contact area [35]. High joint congruence increases joint contact area, while low congruence decreases joint contact area [35]. Movement out of a position of congruence increases stress in cartilage and predisposes the joint to degeneration [35].

The coefficient of friction for human joints is 0.002 to 0.04 [35]. The coefficient of friction for metal-on-ultra-high-molecular-weight polyethylene joint arthroplasty is 0.05 to 0.15 [35]. Articular surfaces lubricated with synovial fluid have a coefficient of friction 10 times better than that of the best synthetic systems [35]. Elastohydrodynamic lubrication is the primary lubrication mechanism for articular cartilage during dynamic function [35].

Stability and Structural Constraints

The deep-seated ball-and-socket joint is intrinsically stable [40]. The sourcil is a condensation of subchondral bone under the superomedial acetabulum where joint reaction force (R) is maximal [40]. The gothic arch is remodeled bone supporting the acetabular roof, with the sourcil at its base [40]. Varus angulation of the neck-shaft angle decreases joint reaction force (R) and increases shear across the neck [40]. Varus angulation leads to shortening of the lower extremity and alters the resting length of the abductors, which may cause a persistent limp [40]. Valgus angulation of the neck-shaft angle increases joint reaction force (R) and decreases shear [40]. Neutral or valgus angulation is better for total hip arthroplasty because PMMA resists shear poorly [40].

Hip capsular strain varies between ligaments depending on both hip position and applied rotational force [72]. Although the capsule played a predominant role in joint constraint, the cam deformity provided 21% to 27% of the intact hip's resistance to torsional load in flexion and internal rotation [77].

Femoroacetabular Impingement (FAI) Biomechanics

The use of dynamic simulation software to determine the presence of motion-limiting deformities of the femoroacetabular joint is validated [67]. Complete cam resection results in significantly lower intraarticular hip contact pressures than incomplete cam resection and native cam morphology in a cadaveric hip model [68]. Excessive acetabular rim resection may lead to increased loads in the hip joint and may predispose to premature joint degeneration [70]. The available literature provides clear insight into the estimated stresses due to the cam deformity and provides an assessment of its risks leading to early joint degeneration [76]. Cam deformity is not commonly the result of remodeling after a slipped epiphysis; instead, it may be a structural adaptation to high impact loading during growth [79].

Other Biomechanical Considerations

Coring alone causes modest structural compromise if the tract does not extend near the subchondral plate [20]. The forces necessary to cause slipping of the femoral capital epiphyseal plate are within the physiological range generated in overweight children, suggesting that purely mechanical factors may play a major role in the etiology of slipped capital femoral epiphysis [69]. Improved histology at the tendon-to-bone interface is correlated with improved final construct strength at the 12-week time point [13]. The understanding of the biomechanical function and reasons for ligamentum teres tears is still evolving, and findings on posterior bony impingement will not result in major changes to current practice [24].

Common Sites of Injury

The treatment aim for femoral head fractures is the anatomical reduction of fragments [19]. However, no method exists for consistently restoring normal anatomy without damaging the femoral head or acetabulum [5]. The internal retinacular artery (IRA) occupies an elevated position relative to the femoral neck, which may protect it from injury during fracture [7]. In the context of arthroscopic access, the use of medial portals did not cause damage to the neurovascular structures evaluated [2].

Epidemiology and Economic Burden: The proportion of the population reporting musculoskeletal injuries increased from 76.0 million in 1996–1998 to 102.5 million in 2009–2011 [10]. The aggregate economic impact of these injuries from 2009 to 2011 was estimated at $796.3 billion [10]. In Swedish male first football league players, index and overuse injuries accounted for the majority of injuries and absence days [55]. Conversely, bony hip morphology was not associated with the risk of groin injuries in male professional soccer players [49].

Diagnostic Prevalence and Asymptomatic Findings: FAI morphology and labral injuries are commonly reported in asymptomatic individuals [43, 44]. Similarly, pathologic changes seen on MRI were symptomatic in less than two thirds of elite female ballet dancers [60]. Hip injuries in young athletes are being diagnosed with increasing frequency due to advancements in technology and understanding of pathomechanics [57].

Soft Tissue and Nerve Injuries: Approximately 20–25% of lateral femoral cutaneous nerve injuries may be avoidable by a 10-mm shortening of the proximal incision [48]. Bone morphology abnormalities and soft-tissue injuries adjacent to the AIIS, identified through sonographic evaluation, were associated with symptomatic subspine impingement [50].

Posttraumatic and Iatrogenic Complications: Posttraumatic OA accounts for at least 12% of OA cases [47], with the risk for development after injury estimated at 20% to 50% [47]. The prevalence of intra-articular damage, including labral injuries and pathologic conditions of cartilage, at the time of periacetabular osteotomy is substantial [52]. Radiation-induced bone injury involves mechanisms beyond simple microvascular injury or ischemic necrosis, characterized by progressive damage to haversian systems and a lack of recovery at fifty-two weeks [54].

Surgical Anatomy

Vascular Anatomy

The epiphyseal arterial network and the inferior retinacular artery (IRA) are critical to femoral head perfusion in adults with femoral neck fractures [59]. The IRA is located in an elevated position from the femoral neck and may be protected from injury during fracture [7]. To mitigate iatrogenic injury to the intraosseous vascular system, drilling and placing internal implants closer to the central region of the femoral head is recommended [59].

Nerve Anatomy

To protect the anterior branch of the lateral femoral cutaneous nerve, the skin incision should be as lateral as possible [16].

Ligamentous and Bony Landmarks

Described surgical landmarks for acetabular structures have reliable locations on radiographs [6]. Distances between acetabular landmarks and reference lines are reproducible in both AP and false-profile views [6].

Arthroscopic Portals and Access

Portal Selection: * A more ventrally located 'mid-distal' portal provides sufficient distance from important neurovascular structures and can be used as an adjunct for extra-articular pathologies [3]. * The modified midanterior portal enables central compartment access and extended posterior reach [62].

Technical Limitations: A technical limitation in arthroscopic treatment of synovial chondromatosis is the difficulty in approaching the posterolateral and posteromedial areas of the peripheral compartment [8].

Surgical Planning and Implant Considerations

Preoperative planning is essential to define anatomy and ensure suitable implants are available for total hip arthroplasty in adult hip dysplasia [63]. In Crowe IV hips, a higher level of neck cut may be required to accommodate wedge stems, as traditional low neck cuts may pose challenges or increase fracture risk [66]. Using the gradient map of the risk zone for preoperative evaluation is recommended to avoid iatrogenic perforation during femoral neck system insertion [53]. Double cortical screws could be placed safely in the danger zone through the middle window of the ilioinguinal approach to increase the stability of the acetabulum in quadrilateral plate fractures [56].

Key Evidence

• [L5] The use of the medial portals did not cause any damage to the neurovascular structures evaluated. [2] (10.1016/j.arthro.2013.09.004)
• [L5] Additionally, a more ventrally located 'mid-distal' portal provides sufficient distance from important neurovascular structures and can be used as an adjunct. [3] (10.1007/s00167-012-2137-9)
• [L5] The hip capsular ligaments have distinct and consistent arthroscopic locations within the hip joint and are associated with clearly identifiable landmarks in the central and peripheral compartments. [4] (10.1016/j.arthro.2011.01.007)
• [L5] No method of consistently restoring normal anatomy without damaging the femoral head or acetabulum is known. [5] (10.2106/jbjs.17.00015)
• [L5] The described surgical landmarks had reliable locations on radiographs, with distances between landmarks and reference lines being reproducible in both AP and false-profile views. [6] (10.1177/0363546515612083)
• [L5] The study defines the exact anatomical location of vessels arising from the MFCA supplying the femoral head, noting the IRA is in an elevated position from the femoral neck and may be protected from injury during fracture. [7] (10.1302/0301-620x.97b9.34704)
• [L4] However, a technical limitation is the difficulty in approaching the posterolateral and posteromedial areas of the peripheral compartment. [8] (10.1177/0363546512445150)
• [L4] Morphologic features that are measurable on anteroposterior pelvic radiographs do not correlate with ultrasound-measured hip flexion. [9] (10.2106/jbjs.19.01088)
• [L3] These data demonstrate that the severity of cam morphology is a primary predictor of location and severity of chondral and labral damage. [11] (10.1007/s00167-018-4861-2)
• [L5] In spite of the variation in cadaveric sizes, quantitative descriptions of endoscopic landmarks were reproducible in clinical views. [12] (10.1177/0363546515612436)
• [L5] Improved histology was correlated with improved final construct strength at the 12-week time point. [13] (10.1016/j.jse.2019.05.024)
• [L5] The individual hip capsular ligaments act independently of each other to resist end-ROM. [14] (10.1007/s00167-012-2255-4)
• [L5] Although the interportal capsular shift may generate modestly higher degrees of capsular reduction, the comparative biomechanical repercussions of each technique are not currently known. [15] (10.1016/j.arthro.2018.09.023)
• [L5] To protect the anterior branch, the skin incision should be as lateral as possible, as the posterior branch is most vulnerable in the proximal aspect of the anterior approach. [16] (10.2106/jbjs.15.01022)
• [L3] Male and female patients differ in their hip structure, biomechanics, and operative findings of symptomatic labral tears. [18] (10.1177/0363546514532226)
• [L4] The treatment aim should always be the anatomical reduction of the fragments. [19] (10.1186/s12891-023-06317-w)
• [L5] Coring alone causes modest structural compromise if the tract does not extend near the subchondral plate. [20] (10.2106/00004623-199309000-00011)
• [L4] Shorter patients will have shorter distances from bony landmarks to adjacent nerves, prompting more careful placement of retractors. [21] (10.1186/s13018-016-0365-2)
• [L5] The anterior and posterior approach differentially affect postoperative biomechanical function of the capsular ligaments. [22] (10.1302/0301-620x.101b4.bjj-2018-1321.r1)
• [L4] Pathologic thickening of the hip capsule may contribute to restricted hip mobility on clinical examination. [23] (10.1007/s00167-018-4915-5)
• [L5] The paper concludes that the understanding of the biomechanical function and reasons for ligamentum teres tears is still evolving, and while the findings on posterior bony impingement are interesting, they will not result in major changes to current practice. [24] (10.1016/j.arthro.2018.03.042)
• [L5] This information will provide surgeons with a better understanding of the footprint anatomy when evaluating gluteus medius tendon tears. [25] (10.1016/j.arthro.2007.11.015)
• [L4] Cam morphology was identified in a modest percentage of osteologic specimens by both alpha angle and anterior femoral neck offset, and associations of multiple demographic, anthropometric, and anatomical parameters suggest they may identify different subsets of cam morphology. [26] (10.1016/j.arthro.2024.07.016)
• [L2] These parameters did not precede cam morphology development. [28] (10.1007/s00167-020-06282-0)
• [L3] In later stages, this bone formation cannot be distinguished from the native bone and the labrum may appear to be nearly absent on imaging studies. [30] (10.2106/jbjs.j.01799)
• [L3] Abnormal hip morphology predates arthrosis and is not secondary to the osteoarthritic process. [31] (10.1016/j.arth.2008.01.283)
• [L5] Resection depth is the most important determinant of bone resistance, being 325% more sensitive than lengthening and 70% more sensitive than widening. [33] (10.1177/0363546512456011)
• [L3] Magnetic resonance imaging was accurate in all hips with histological proof of osteonecrosis and in those with medullary changes without necrotic bone. [36] (10.2106/00004623-198971050-00002)
• [L4] Age-related changes in proximal femoral canal morphology continue beyond 80 years of age, particularly in females, with asymmetric flaring and larger absolute dimensions. [38] (10.1016/j.arth.2015.06.020)
• [L4] The capsule was the most common block to reduction, followed by the teres ligament, and successful reduction can be achieved by removal of intra-articular tissues and nearly always a capsular release. [39] (10.1016/j.arthro.2014.12.019)
• [L5] FAI morphology and labral injuries are commonly reported in asymptomatic individuals, but it is unclear if such pathology is actually common or if radiologic signs need better refinement to determine what constitutes abnormal. [43] (10.1016/j.arthro.2015.04.077)
• [L4] FAI morphologic features and labral injuries are common in asymptomatic patients. [44] (10.1016/j.arthro.2014.11.042)
• [L5] Each of the capsular ligaments acted as the primary hip rotation restraint somewhere within the complete range of movement, and the ligamentum teres acted as a secondary restraint in high flexion, adduction and external rotation. [45] (10.1302/0301-620x.97b4.34638)
• [L5] An understanding of hip joint biomechanics constitutes an important background for the diagnosis and treatment of hip disorders, allowing clinicians to assimilate the effects of motions and deformations resulting from forces acting on the joint to guide appropriate medical interventions. [46] (10.1016/j.arthro.2010.01.027)
• [L5] Approximately 20–25% of these injuries may be avoidable by a 10-mm shortening of the proximal incision. [48] (10.1186/s12891-022-05224-w)
• [L2] Bony hip morphology was not associated with the risk of groin injuries. [49] (10.1177/0363546518763373)
• [L4] Bone morphology abnormalities and soft-tissue injuries adjacent to the AIIS through sonographic evaluation were associated with SSI. [50] (10.1016/j.arthro.2023.03.024)
• [L4] The prevalence of intra-articular damage, including labral injuries and pathologic conditions of cartilage, at the time of PAO is substantial. [52] (10.1016/j.arthro.2013.11.013)
• [L4] Using the gradient map of the risk zone for preoperative evaluation is recommended to avoid iatrogenic perforation. [53] (10.1186/s13018-023-04205-6)
• [L5] The study demonstrates that radiation-induced bone injury involves a combination of mechanisms beyond simple microvascular injury or ischemic necrosis, characterized by progressive damage to haversian systems and a lack of recovery at fifty-two weeks. [54] (10.2106/00004623-199405000-00014)
• [L2] Index and overuse injuries accounted for the majority of injuries and absence days, suggesting a focus on prevention is necessary. [55] (10.1007/s00167-019-05470-x)
• [L4] Double cortical screws could be placed safely in the danger zone through the middle window of the ilioinguinal approach to increase the stability of the acetabulum. [56] (10.1186/s12891-020-03265-7)
• [L5] Hip injuries in young athletes are being diagnosed with increasing frequency due to advancements in technology and understanding of pathomechanics. [57] (10.5435/jaaos-21-11-665)
• [L4] Increased efforts to protect these key structures during surgery, such as drilling and placing internal implants closer to the central region of the femoral head, might be helpful to reduce the effect of iatrogenic injury of the intraosseous vascular system. [59] (10.1007/s11999-017-5318-5)
• [L4] Pathologic changes seen on MRI were symptomatic in less than two thirds of the dancers. [60] (10.1016/j.arthro.2012.10.012)
• [L5] Increased tissue damage at the anterior capsule was observed after subspine trimming. [61] (10.1016/j.arthro.2019.06.040)
• [L4] The modified midanterior portal enables central compartment access and extended posterior reach, potentially making protrusio acetabuli a historical contraindication. [62] (10.1016/j.arthro.2012.02.028)
• [L5] Preoperative planning is essential to define anatomy and ensure suitable implants are available. [63] (10.2106/jbjs.k.00779)
• [L3] The clinical relevance of this study is that capsular thickness and intra-substance changes of the anterior capsule vary which could alter capsular management strategies. [64] (10.1007/s00167-022-07022-2)
• [L4] These procedures should be performed by surgeons with expertise in advanced arthroscopic techniques, using strict patient selection criteria, with emphasis on labral preservation and capsular plication. [65] (10.1177/0363546517743720)
• [L4] A higher level of neck cut may be required to accommodate wedge stems, as traditional low neck cuts may pose challenges or increase fracture risk. [66] (10.1186/s12891-024-08201-7)
• [L4] The use of this dynamic simulation software to determine the presence of motion limiting deformities of the femoroacetabular is validated. [67] (10.1186/s12891-015-0504-7)
• [L5] Complete cam resection results in significantly lower intraarticular hip contact pressures than incomplete cam resection and native cam morphology in a cadaveric hip model. [68] (10.1016/j.arthro.2020.05.021)
• [L5] The forces necessary to cause slipping are within the physiological range generated in overweight children, suggesting that purely mechanical factors may play a major role in the etiology of slipped capital femoral epiphysis. [69] (10.2106/00004623-197658010-00017)
• [L5] Excessive rim resection may lead to increased loads in the hip joint and may predispose to premature joint degeneration. [70] (10.1177/0363546515590400)
• [L5] Hip pain in the absence of osteoarthritis may be due to a complex combination of mechanical stresses, both dynamic and static. [71] (10.1016/j.arthro.2010.07.022)
• [L5] Hip capsular strain varies between ligaments depending on both hip position and applied rotational force. [72] (10.1007/s00167-020-06035-z)
• [L3] This impaired squat performance is predominantly predicted by sagittal plane knee and hip biomechanics and hip external rotator strength, and less by frontal plane pelvic ROM and hip morphology in patients with FAIS. [73] (10.1177/03635465211029032)
• [L1] Routine capsular closure cannot be universally recommended for interportal capsulotomy. [74] (10.1002/arj.70025)
• [L5] The study supports the complex coexistence of impingement and instability, suggesting that a completely torn ligamentum teres should raise suspicion for a history of trauma or soft tissue and/or osseous instability. [75] (10.1016/j.arthro.2016.05.003)
• [L1] The available literature provides clear insight into the estimated stresses due to the cam deformity and provides an assessment of its risks leading to early joint degeneration. [76] (10.1371/journal.pone.0147813)
• [L5] Although the capsule played a predominant role in joint constraint, the cam deformity provided 21% to 27% of the intact hip's resistance to torsional load in flexion and internal rotation. [77] (10.1177/0363546518815159)
• [L4] LT tears may, very uncommonly, be caused by impingement of the mid-part of the ligament against a prominent posterior AF edge. [78] (10.1016/j.arthro.2018.02.037)
• [L5] Cam deformity is not commonly the result of remodeling after a slipped epiphysis; instead, it may be a structural adaptation to high impact loading during growth. [79] (10.1177/0363546514528863)
• [Case_report] The absence of avascular necrosis suggests that intraosseous anastomoses provided for the most part by the deep brachial artery are relevant for the blood supply of the humeral head when the circumflex vessels are interrupted. [82] (10.2106/00004623-199608000-00018)
• [L4] Fewer arteries were present on the anterior and medial mid-neck surfaces in specimens from three to ten-year-old white children compared to younger children. [83] (10.2106/00004623-197658070-00011)
• [L4] The human acetabular labrum has abundant free nerve endings and nerve end organs, which are more abundant in the antero-superior and postero-superior zones. [84] (10.1186/1471-2474-15-41)
• [L4] This review summarizes dysregulated growth factor-related genes and their role in the occurrence and development of osteonecrosis of the femoral head, discussing their potential clinical applications in tissue and genetic engineering for treatment. [85] (10.3389/fgene.2022.1037190)
• [L5] The tensor fasciae latae muscle perforator serves as a reliable anatomical landmark to clearly identify the Hueter interval and minimize the risk for iatrogenic nerve injury. [86] (10.1186/s12891-016-0908-z)
• [L5] Bony landmarks indicating the insertions and the running course of the short external rotator muscles were identified on the greater trochanter. [87] (10.1016/j.arth.2013.11.008)
• [L4] With an understanding of the blood supply to the proximal femoral epiphysis and the use of a surgical approach that does not further compromise the remaining blood supply, the surgeon may be able to prevent the development of osteonecrosis in some cases. [88] (10.2106/jbjs.i.00464)
• [L5] The finding of 2 distinct tendinous components to the iliacus and psoas major muscle groups is an important discovery. [89] (10.1177/0363546513518414)
• [L3] Ten common radiographic views used to identify cam morphology visualized different clock-face positions of the head-neck junction. [90] (10.1016/j.arthro.2018.12.031)
• [L5] Understanding the etiology of and evolving research on intra- and extraarticular hip complaints requires comprehensive diagnosis and management of the spectrum of posterior hip diseases. [91] (10.5435/jaaos-d-15-00629)
• [L4] The prevalence of FAI is high in patients with symptomatic proximal hamstring tendon pathology. [97] (10.1016/j.arthro.2018.11.037)
• [L3] Hip anatomy in NHL players is characterized by highly prevalent cam-type morphology (>85%) and acetabular retroversion (>60%), with acetabular dysplasia (21%) being relatively common. [100] (10.1177/0363546517692542)

See Also

• Femoroacetabular impingement
• Hip arthroscopy
• Total hip replacement
• Periacetabular osteotomy

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