Skip to content

Tendons, Ligaments and Muscles

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

Overview

Tendon and ligament repair protocols have evolved to prioritize functional outcomes through early motion. Recent repair and motion protocols lead to remarkably more reliable flexor tendon repairs, with over 80% good or excellent outcomes achieved consistently after Zone 2 repair and infrequent need for tenolysis [20]. However, the '50% rule' for tendon and ligament disruption should not be considered an exact rule due to the subjective nature of clinical evaluations and lack of high intraobserver and interobserver reliability [1]. More stringent criteria, such as Tang's criteria, are necessary as results move toward more ideal functional outcomes in flexor tendon repairs, and surgeon expertise should always be considered when comparing outcomes [61].

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 [19]. Secondary flexor tendon reconstruction remains an important and useful technique for complicated flexor tendon injuries or those that have failed primary repair [63]. In cases of tendon graft for extensor tendon ruptures in rheumatoid hands, the time to surgery should be considered, and there is concern over extension lag of the MP joint [9]. For late-stage congenital flexion deformity of the long, ring, and little fingers with an aberrant origin of the flexor digitorum profundus, both local release and thorough muscle sliding are preferred [4].

Specific anatomical considerations dictate surgical choice. Repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, but repair of the flexor digitorum superficialis together with flexor digitorum profundus is not mandatory in acute Zone 2B injuries [22]. Relative motion extension (RME) plus and RME only protocols for zones V and VI extensor tendon repairs are used interchangeably depending on surgeon preferences and patient/tendon factors [59]. Procedures using allograft augmentation or interposition should be considered in symptomatic patients with chronic proximal hamstring tears that are not amenable to primary repair [17]. Chronic thumb metacarpophalangeal joint ulnar collateral ligament insufficiency is traditionally managed with tendon graft ligament reconstruction or tendon transfers, though evidence is limited to case reports and retrospective series [23]. Follow-up studies on eleven of eighteen Achilles tendons treated with the plantaris tendon as a reinforcing membrane revealed excellent results [2].

Anatomy & Pathophysiology

Kinematics and Muscle Function

Hand kinematics are governed by the complex interplay between intrinsic and extrinsic muscle groups. Intrinsic vs. Extrinsic Dominance: Two distinct patterns of finger flexion exist in healthy individuals: extrinsic dominant (initiated at PIP/DIP joints) and intrinsic dominant (initiated at MCP joint) [41]. The intrinsic muscles, particularly the lumbricales, are most important for stabilizing the metacarpophalangeal joint and contributing to the force of the final phase of grasp, although their importance is often overrated [46]. Specifically, the first two lumbricals may be functionally more important than the ulnar two, specifically for precision pinch movements [45]. Simultaneous activation of the flexor digitorum profundus (FDP) and intrinsic muscles results in a more functional hand closing compared with FDP activation alone due to altered kinematics and larger fingertip-to-palm distances [38]. Individual extrinsic flexors and extensors generate distinct quantitative motion trajectories at the index finger phalangeal joints [36].

Reconstruction and Biomechanics

Reconstruction strategies must balance strength with the preservation of native joint mechanics. Intrinsic Reconstruction: Active and passive intrinsic reconstruction methods improve basic grasp and release kinematics in experimental cadaver hand models [29]. Both intrinsic balancing techniques improve grasp, but only the House procedure restores hand kinematics approximating those of an intrinsic-activated hand [31]. Regarding thumb reconstruction, both ST and SA constructs recapitulate native thumb ulnar collateral ligament joint stiffness, but repair with ST demonstrated the greatest biomechanical strength in stiffness and load-to-failure [44]. Surgical methods must prioritize joint integrity; a method risking normal DIP joint kinematics should not be popularized until proven otherwise, while methods meeting strength needs without interfering with joint kinematics should be considered [33]. Progressive metacarpal shortening produces proportionally greater loss of fingertip flexion force at increasing amounts of finger flexion [37].

Ligamentous and Joint Anatomy

Accurate diagnosis and management of hand and carpal fractures and dislocations are predicated on a thorough physical examination and appropriate imaging to limit joint stiffness while preserving mobility and function [40]. Recent information regarding the anatomy, physiology, and biomechanics of the ligamentous joint capsule of the MCP, PIP, and DIP joints informs new clinical approaches for these common problems [42]. Three-dimensional analysis of internal forces in thumb joints during pinch and grasp provides information on tensile forces in functioning tendons, contact and shear forces, and constraining moments acting on the joints [32]. The estimated lengths of principal ligaments stabilizing the thumb carpometacarpal (CMC) joint change substantially during thumb motions in vivo [34]. Understanding physical force and biological mechanisms in hand anatomy offers research avenues to manage unsolved problems or optimize outcomes [30].

Rehabilitation and Therapy

Rehabilitation protocols and anatomical understanding guide functional recovery. An autonomous patient-controlled mobilization protocol achieves good results in range of motion and early return of function of the hand [39]. Hand surgery and hand therapy practice interventions, including the use of relative motion flexion (RMF) orthoses for non-surgical and surgical extensor mechanism (EM) injuries, may benefit from an in-depth look at EM zone III and IV anatomy and biomechanics [43]. Current biomechanical models investigating the effect of forearm shortening on finger flexion are initial attempts, and an in vivo model incorporating active muscle contraction would be ideal [35].

Classification

Tendon and Ligament Disruption: The '50% rule' for tendon and ligament disruption is not an exact rule due to the subjective nature of clinical evaluations and lack of high intraobserver and interobserver reliability [1]. Normal tendons typically rupture at the musculotendinous junction or tendon insertion due to excessive weight application when the muscle is holding at maximum power [16]. Surgical reconstruction of degenerate abductor tendons is considered in the presence of an MRI-confirmed separation where clinical findings are consistent with known tendon disruption [10].

Tendon Insertion Anatomy: Tendon and ligament insertions are delineated by a four-zone model consisting of tendon, fibrocartilage, mineralized fibrocartilage, and bone [13].

Extensor Tendon Zones: Extensor tendon injuries are graded based on specific clinical and imaging findings to determine suitable therapy [8]. Tang's simplified classification of extensor tendon zones is expected to enhance the accuracy of operative evaluations and provide insights into surgical outcomes for anatomically diverse injuries [55]. A simpler classification system for extensor tendon zones is proposed to align with current treatment strategies, such as conservative splinting for closed injuries and strong surgical repair for open injuries [57]. 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 [62]. An additional category (Type 3) is proposed to the Türker classification system to encompass rare findings of two radial-sided accessory extensor tendons in the same individual [49].

Sagittal Band Injuries: A modification to the most prevalent classification system for sagittal band injuries is described to guide treatment and allow standardization in documenting and describing injuries [69].

Medial Knee Ligament: The medial side of the knee demonstrates a consistent three-layered anatomical pattern, suggesting specific nomenclature for the superficial medial ligament and posteromedial capsule rather than the term 'posterior oblique ligament' [60].

Ulnar Collateral Ligament of the Elbow: The anterior bundle, posterior bundle, and common tendon of the ulnar collateral ligament of the elbow and common tendon of flexor-pronator muscles can each be classified into an independent form and an unclear form [65].

Other Considerations:

Clinical Presentation

History and Mechanism: Normal tendons typically rupture only at the musculotendinous junction or insertion due to excessive load during maximal muscle power [16]. Pathological presentations include partial rupture of the flexor hallucis longus in classical ballet dancers [6] and lumbrical muscle tears, which exhibit specific clinical and imaging findings for grading and therapy determination [8]. Congenital flexion deformity of the long, ring, and little fingers may indicate an aberrant origin of the flexor digitorum profundus [4], while congenital shortening of this muscle can present with symptoms that resolve after transection and suturing to the adjacent tendon under appropriate tension [47].

Inspection and Palpation: Extensor tendon injuries are common, requiring early recognition for effective management [5]. Triggering of the lateral slip of the extensor mechanism may be caused by a Bouchard’s node [3]. Degenerative changes in hip abductor tendon tears affect both the tendon and enthesis, with deeper layers predominantly involved [18]. The distal biceps provocation test appears highly accurate for the clinical diagnosis of distal biceps tendon pathology [48].

Stability, Special Tests, and Imaging: The '50% rule' for clinical evaluations of tendon and ligament disruption is not considered exact due to subjective evaluations and lack of high intraobserver and interobserver reliability [1]. Pulley rupture or insufficiency presents as a diagnostic and therapeutic dilemma due to injury rarity and lack of comparative clinical studies [15]. Surgical reconstruction of degenerate abductor tendons should be considered when MRI confirms separation and clinical findings are consistent with known tendon disruption [10]. The use of ultrasound in treating surgically repaired hand tendon injuries lacks substantial support in controlled studies [12].

Biological and Structural Context: Understanding native tendon biology and organization is necessary to improve treatment modalities [11]. The pathophysiology of tendinosis is characterized by degenerative, rather than inflammatory, changes, with susceptibility related to activity and age [52]. Normal tendon and ligament insertions follow a four-zone model: tendon, fibrocartilage, mineralized fibrocartilage, and bone [13]. The most dramatic feature of failed healing at the tendon-to-bone interface is the lack of transitional tissue between the healing tendon and bone [7]. The scaphotrapezial ligament consists of three distinct fascicles, including a deep fascicle attaching 3.3 mm from the most distal point of the scaphoid [53]. Tendon grafts for extensor tendon ruptures in rheumatoid hands carry concern over extension lag of the metacarpophalangeal joint [9].

Investigations

Clinical evaluations of tendon and ligament disruption are relatively subjective and lack high intraobserver and interobserver reliability [1]. Consequently, the '50% rule' should not be considered an exact rule in medical science due to this subjectivity and low reliability [1].

Plain radiography: Plain radiographs are important in the assessment of patients presenting with closed flexor tendon rupture, which can be a complication of asymptomatic Kienböck disease [79]. The radiographic appearance of a bone fragment beneath the humeral head is a valuable sign for avulsion of the subscapularis tendon [78].

MRI: Magnetic resonance imaging indicates that the donor site after autologous osteochondral mosaicplasty is resurfaced with fibrous tissue [80]. MRI might be worth considering in revision cases of olecranon bursitis, as 43% of cases with clinical signs had previous surgery [75]. Clinicians must maintain a high index of suspicion and avoid over-reliance on diagnostic imaging for long head biceps pathology [76].

Ultrasound: Ultrasound is superior to MRI for dynamic evaluation of stenosing synovitis of the extensor pollicis longus tendon [73]. The use of ultrasound in the treatment of musculoskeletal disorders is based on empirical experience but lacks substantial support in controlled studies [12].

Other Considerations: Evaluation of specific clinical and imaging findings is recommended to grade lumbrical muscle tears and determine suitable therapy [8]. Surgical release is a viable treatment for stenosing synovitis of the extensor pollicis longus tendon to prevent rupture [73]. Pulley rupture or insufficiency presents as a diagnostic and therapeutic dilemma due to the rarity of the injury and lack of comparative clinical studies [15].

The normal morphology of tendon and ligament insertions can be delineated using light and electron microscopy [13]. A four-zone model for tendon and ligament insertions consists of the tendon, fibrocartilage, mineralized fibrocartilage, and bone [13]. Degenerative changes in hip abductor tendon tears occur in both the tendon and enthesis, with deeper layers predominantly affected [18].

Treatment

Non-Operative

Conservative management is appropriate for specific tendon and ligament pathologies. Most closed extensor tendon injuries can be treated conservatively in the acute phase [64]. Triggering of the lateral slip of the extensor mechanism on a Bouchard’s node may be managed with physiological treatment that preserves tendon balance, with no recurrence of symptoms at 10-month follow-up [3]. Injured ulnar collateral ligaments of the thumb metacarpophalangeal joint were naturally stable after reduction and did not need surgical repair [72]. Nonoperative management with delayed reconstruction is an option for low-demand patients with proximal hamstring ruptures [27]. Release of the flexor retinaculum permits the flexor hallucis longus tendon to move smoothly in its track, but the prognosis is guarded as the tendon is weakened [6]. The use of ultrasound in the treatment of musculoskeletal disorders is based on empirical experience but lacks substantial support in controlled studies [12].

Operative

Indications: Surgical repair of a spontaneously ruptured posterior tibial tendon yields fair functional results [14]. 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 [68]. Acute repair of proximal hamstring ruptures is recommended for patients desiring return to sports [27]. Proximal hamstring repair with allograft augmentation or interposition should be considered in symptomatic patients with chronic tears that are not amenable to primary repair [17]. Surgical repair of complete proximal hamstring tendon avulsions with a nonbracing rehabilitation protocol for patients over 40 years demonstrated intact repairs with no reruptures [70]. Completely ruptured collateral ligaments of the proximal interphalangeal joint frequently result in prolonged disability when treated non-operatively [24]. Chronic extensor tendon injuries often require operative intervention [64]. Tendon lengthening and transfer are indicated for neuromuscular disorders, nerve injuries, and congenital or traumatic lesions [58].

Surgical Approach / Technique: 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 [19]. Repair of a torn Achilles tendon using the plantaris tendon as a reinforcing membrane can yield excellent results [2]. Repair using the tendo achillis itself has been suggested for defects in the tendo achillis [56]. 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 [71]. Contralateral C7 transfer demonstrates significant improvements in upper limb function, confirming the procedure's safety and efficacy, with donor site morbidity that is typically mild and transient [54].

Adjuncts: Recent repair and motion protocols lead to remarkably more reliable flexor tendon repairs, with over 80% good or excellent outcomes achieved consistently after Zone 2 repair and infrequent need for tenolysis [20]. Achieving consistent, satisfactory results in single-stage flexor tendon grafting 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 [50]. Repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, but repair of the flexor digitorum superficialis together with flexor digitorum profundus is not mandatory in acute Zone 2B injuries [22].

Other Considerations: Early recognition and treatment are key to managing extensor tendon injuries [5]. Evaluation of specific clinical and imaging findings is recommended to grade lumbrical muscle injuries and determine suitable therapy [8]. The most dramatic feature of the failed healing response at the tendon-to-bone interface is the lack of a transitional tissue between the healing tendon and bone [7]. The '50% rule' for clinical evaluations of tendon and ligament disruption should not be considered an exact rule due to subjective evaluations and lack of high intraobserver and interobserver reliability [1]. Studies on blood flow restriction training point to increasing tendon function after rehabilitation, although results regarding tendon-related outcomes are contradictory [21].

Complications

Tendon and Ligament Integrity: The '50% rule' for clinical evaluations of tendon and ligament disruption lacks high intraobserver and interobserver reliability and should not be considered an exact rule in medical science [1]. Estrogen decreases stiffness in tendons and ligaments, which can decrease power and increase the risk of catastrophic ligament injury [67]. Degeneration in human supraspinatus tendons is caused by trauma incurred during the life of the individual [26]. Tendons may still be at risk of degeneration and rupture a decade or more after clinically successful flexor tendon autograft reconstruction [25].

Surgical Outcomes and Complications: Proximal hamstring tendon repair is associated with an overall complication rate of 15.4%, including a 4.6% rate of major complications [51]. Clinical outcome was compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle after rotator cuff repair [66]. Functional results were fair following surgical repair of spontaneous rupture of the posterior tibial tendon [14]. In cases of tendon graft for extensor tendon ruptures in rheumatoid hands, there is concern over extension lag of the MP joint and the time to surgery should be considered [9]. Release of the flexor retinaculum permits smooth tendon movement in partial rupture of the flexor hallucis longus tendon in classical ballet dancers, but the prognosis is guarded as the tendon is weakened [6].

Anatomical Variants and Congenital Issues: 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 a cadaveric study [74]. For late-stage congenital flexion deformity of the long, ring, and little fingers with an aberrant origin of the flexor digitorum profundus, both local release and thorough muscle sliding are preferred [4]. A rare case of triggering caused by a Bouchard's node was treated with a physiological treatment that preserved tendon balance, with no recurrence of symptoms at 10-month follow-up [3].

Healing and Reconstruction: The most dramatic feature of the failed healing response at the tendon-to-bone interface is the lack of a transitional tissue between the healing tendon and bone [7]. Follow-up studies on eleven of eighteen tendons treated with the plantaris tendon as a reinforcing membrane revealed excellent results [2]. Chronic thumb metacarpophalangeal joint ulnar collateral ligament insufficiency is traditionally managed with tendon graft ligament reconstruction or tendon transfers, though evidence is limited to case reports and retrospective series [23]. Forty-seven (96 per cent) of forty-nine shoulders had a good clinical result after distal release of deltoid muscle contracture [28].

Recovery

Light activity (weeks): Evidence does not provide specific week ranges for light activity or desk work. Clinical evaluations of tendon and ligament disruption rely on subjective assessments, and the '50% rule' is not considered an exact rule in medical science due to a lack of high intraobserver and interobserver reliability [1].

Full activity (months): Specific month ranges for full activity are not defined in the available evidence. However, functional outcomes vary significantly by pathology and intervention. For example, functional results following surgical repair of a ruptured posterior tibial tendon are reported as fair [14]. In contrast, a patient with a ruptured flexor digitorum profundus tendon of the small finger recovered completely, improving her professional tennis ranking from number 80 to number 28 within 1 year [77].

Complete recovery / outcome plateau (months): Long-term stability is not guaranteed even after successful reconstruction. Even after clinically successful flexor tendon autograft, tendons may still be at risk of degeneration and rupture a decade or more after reconstruction [25]. Degeneration in human supraspinatus tendons is caused by trauma incurred during the life of the individual [26].

Rehabilitation protocol: Rehabilitation strategies must be tailored to the specific injury and surgical technique. For late-stage congenital flexion deformity of the long, ring, and little fingers with an aberrant origin of the flexor digitorum profundus, both local release and thorough muscle sliding are preferred [4]. Release of the flexor retinaculum permits the flexor hallucis longus tendon to move smoothly in its track, but the prognosis is guarded as the tendon is weakened [6]. For triggering caused by a Bouchard's node, physiological treatment preserving tendon balance resulted in no recurrence of symptoms at 10-month follow-up [3].

Functional milestones: Outcomes depend heavily on patient selection and timing. In cases of tendon graft for extensor tendon ruptures in rheumatoid hands, the time to surgery should be considered, and there is concern over extension lag of the MP joint [9]. A scoping review shows contradictory results regarding tendon-related outcomes for blood flow restriction training, although studies point to increasing tendon function after rehabilitation [21]. Different tendons express unique growth-factor profiles after similar, simultaneous injuries [81].

Other Considerations: Surgical decision-making requires careful consideration of patient demands and anatomical realities. Completely ruptured collateral ligaments of the proximal interphalangeal joint frequently result in prolonged disability when treated non-operatively, whereas surgical repair yielded satisfactory results with restored joint stability and pain relief [24]. Acute repair is recommended for proximal hamstring tendon ruptures in patients desiring return to sports, while nonoperative management with delayed reconstruction is an option for low-demand patients [27]. Forty-seven (96 per cent) of forty-nine shoulders had a good clinical result after distal release of deltoid muscle contracture [28]. Follow-up studies on eleven of eighteen Achilles tendons treated with the plantaris tendon as a reinforcing membrane revealed excellent results [2]. The most dramatic feature of the failed healing response at the tendon-to-bone interface is the lack of a transitional tissue between the healing tendon and bone [7]. Understanding the biology and organization of the native tendon and the process of morphogenesis of tendon tissue is necessary to improve current treatment modalities [11].

Key Evidence

  • [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. (10.1016/j.arthro.2011.10.003)
  • [L4] Follow-up studies on eleven of eighteen tendons so treated revealed excellent results. (10.2106/00004623-196648020-00005)
  • [L4] The authors describe a rare case of triggering caused by a Bouchard's node and propose a physiological treatment that preserves tendon balance, noting no recurrence of symptoms at 10-month follow-up. (10.1177/1753193410397860)
  • [Case_report] For late-stage cases, both local release and a thorough muscle sliding were preferred. (10.1016/j.jhsa.2008.04.013)
  • [L5] Extensor tendon injuries are common and early recognition and treatment are key to the management of such injuries. (10.1016/j.hcl.2014.12.006)
  • [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. (10.2106/00004623-197961010-00031)
  • [L4] The authors recommend evaluation of specific clinical and imaging findings to grade the injuries and determine suitable therapy. (10.1177/1753193418765716)
  • [L4] In cases of tendon graft, the time to surgery should be considered, and there is concern over extension lag of MP joint. (10.1186/s12891-022-05815-7)
  • [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. (10.1016/j.arth.2019.11.012)
  • [L5] Understanding the biology and organization of the native tendon and the process of morphogenesis of tendon tissue is necessary to improve current treatment modalities. (10.1016/j.jhsa.2007.09.007)
  • [L4] The use of ultrasound in the treatment of musculoskeletal disorders is based on empirical experience but lacks substantial support in controlled studies. (10.1177/175899830000500202)
  • [L4] The functional results were fair following surgical repair of the ruptured tendon. (10.2106/00004623-196951040-00014)
  • [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. (10.1016/j.jhsa.2012.07.021)
  • [L3] These procedures should be considered in symptomatic patients with chronic tears that are not amenable to primary repair. (10.1177/23259671251383094)
  • [L5] Degenerative changes occur in both the tendon and enthesis, with the deeper layers predominantly affected. (10.1186/s12891-020-03784-3)
  • [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. (10.2106/00004623-195941040-00001)
  • [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. (10.1177/17531934211053757)
  • [L4] The present scoping review shows contradictory results regarding tendon-related outcomes although studies point to increasing tendon function after rehabilitation. (10.1186/s12891-025-08734-5)
  • [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. (10.1177/1753193420932446)
  • [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. (10.1016/j.jhsa.2011.06.004)
  • [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. (10.2106/00004623-196749020-00009)
  • [L4] Even after clinically successful flexor tendon autograft, tendons may still be at risk of degeneration and rupture a decade or more after reconstruction. (10.1177/15589447221131846)
  • [L5] The study concludes that degeneration in human supraspinatus tendons is caused by trauma incurred during the life of the individual. (10.2106/00004623-194830030-00025)
  • [L3] Acute repair is recommended for patients desiring return to sports, while nonoperative management with delayed reconstruction is an option for low-demand patients. (10.1177/2325967113s00061)
  • [L3] Forty-seven (96 per cent) of the forty-nine shoulders had a good clinical result after distal release of the contracture. (10.2106/00004623-199802000-00010)
  • [L5] Active and passive intrinsic reconstruction methods improved basic grasp and release kinematics in experimental cadaver hand models. (10.1016/j.jhsa.2014.09.031)
  • [L5] These 'black holes' in hand anatomy offer possible research avenues to manage unsolved problems in hand surgery or to optimize outcomes by understanding why we are the way we are and capitalizing on physical force and biological mechanisms. (10.1177/17531934251321748)
  • [L5] Both intrinsic balancing techniques improved grasp, but only the House procedure restored hand kinematics approximating those of an intrinsic-activated hand. (10.1016/j.jhsa.2013.08.098)
  • [L5] This three-dimensional analysis of the internal forces in the thumb joints during pinch and grasp provides new information concerning the tensile forces in functioning tendons, the contact and shear forces, and the constraining moments acting on the joints. (10.2106/00004623-198769070-00033)
  • [Commentary] A method risking normal DIP joint kinematics should not be popularized until proven otherwise; readers should consider other published methods that meet the needs of strength without interfering with joint kinematics. (10.1016/j.jhsa.2014.08.002)
  • [L4] The estimated lengths of principal ligaments stabilizing the CMC joint change substantially during thumb motions in vivo. (10.1016/j.jhsa.2010.11.007)
  • [Letter] The authors acknowledge that their biomechanical model represents an initial attempt to investigate the effect of forearm shortening on finger flexion and agree that an in vivo model incorporating active muscle contraction would be ideal. (10.1016/j.jhsa.2026.01.017)
  • [L5] The study documents the quantitative motion generated by individual extrinsic flexors and extensors at the index finger phalangeal joints, revealing distinct motion trajectories for each muscle. (10.1186/1749-799x-3-27)
  • [L5] At increasing amounts of finger flexion, progressive metacarpal shortening produces proportionally greater loss of fingertip flexion force. (10.1177/1753193412461589)
  • [L5] Simultaneous activation of the FDP and the intrinsic muscles results in an apparently more functional hand closing compared with FDP activation alone because of altered kinematics and larger fingertip-to-palm distances. (10.1016/j.jhsa.2013.08.099)
  • [L4] This protocol achieves good results in range of motion and early return of function of the hand. (10.1177/1558944720964961)
  • [L4] The study identified two distinct patterns of finger flexion in healthy individuals: extrinsic dominant (initiated at PIP/DIP joints) and intrinsic dominant (initiated at MCP joint). (10.1177/1753193415619774)
  • [L5] This review focuses on recent information regarding the anatomy, physiology, and biomechanics of the ligamentous joint capsule of the MCP, PIP, and DIP joints with a view to new clinical approaches for these common problems. (10.1016/j.jhsa.2017.08.024)
  • [L5] Hand surgery and hand therapy practice interventions, including use of RMF orthoses for management of non-surgical and surgical EM injuries may benefit from an in-depth look at the EM zone III and IV anatomy and biomechanics. (10.1016/j.jht.2023.01.002)
  • [L5] Although both ST and SA constructs recapitulate native joint stiffness, repair with ST demonstrated the greatest biomechanical strength in stiffness and load-to-failure. (10.1016/j.jhsa.2021.09.028)
  • [L5] The first two lumbricals may be functionally more important than the ulnar two, specifically for precision pinch movements. (10.1016/j.jhsa.2013.06.029)
  • [L5] The investigation concludes that the intrinsic muscles, particularly the lumbricales, are most important for stabilizing the metacarpophalangeal joint and contributing to the force of the final phase of grasp, and that their importance is often overrated. (10.2106/00004623-195436010-00001)
  • [L4] The symptoms resolved completely after the affected tendon was transected and sutured to the adjacent FDP tendon under appropriate tension. (10.1016/j.jhsa.2006.10.006)
  • [L2] The BPT appears to be highly accurate in the clinical diagnosis of distal biceps tendon pathology. (10.1016/j.jhsa.2020.12.012)
  • [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. (10.1016/j.jhsg.2023.10.005)
  • [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. (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. (10.1177/2325967123s00208)
  • [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. (10.1016/j.jhsa.2025.09.010)
  • [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. (10.1177/17531934251314640)
  • [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. (10.1177/17531934251326850)
  • [L4] A repair using the tendo achillis itself has been suggested. (10.2106/00004623-195638010-00011)
  • [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. (10.1177/17531934241274112)
  • [L5] Tendon lengthening and transfer are indicated for neuromuscular disorders, nerve injuries, and congenital or traumatic lesions. (10.1016/j.otsr.2014.07.033)
  • [L4] RME plus and RME only are used interchangeably depending on surgeon preferences and patient/tendon factors. (10.1016/j.jht.2019.12.016)
  • [L5] The study delineated a consistent three-layered anatomical pattern of the medial knee, suggesting the use of specific nomenclature for the superficial medial ligament and posteromedial capsule rather than the term 'posterior oblique ligament'. (10.2106/00004623-197961010-00011)
  • [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. (10.1177/1753193416634602)
  • [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. (10.1177/17531934241232066)
  • [L5] Secondary reconstruction remains an important and useful technique for complicated flexor tendon injuries or those that have failed primary repair. (10.1016/j.jhsa.2007.08.018)
  • [L5] Most closed extensor tendon injuries can be treated conservatively in the acute phase, but chronic injuries often require operative intervention. (10.1016/j.csm.2014.09.005)
  • [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. (10.1177/2325967120952415)
  • [L2] Clinical outcome was compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle. (10.1177/23259671231196875)
  • [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. (10.3389/fphys.2018.01834)
  • [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. (10.2106/00004623-197658070-00015)
  • [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. (10.1016/j.jhsa.2021.09.011)
  • [L4] Surgical repair of complete proximal hamstring tendon avulsions with a nonbracing rehabilitation protocol for patients .40 years demonstrated intact repairs with no reruptures. (10.1177/23259671251326604)
  • [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. (10.1016/j.jhsa.2014.01.029)
  • [L4] Injured UCL ligaments were naturally stable after reduction and did not need surgical repair. (10.1177/1753193418790502)
  • [L4] They emphasize that ultrasound is superior to MRI for dynamic evaluation and that surgical release is a viable treatment to prevent tendon rupture. (10.1016/j.jhsa.2011.02.004)
  • [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. (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. (10.1016/j.arthro.2014.11.005)
  • [L5] Clinicians must maintain a high index of suspicion and avoid over-reliance on diagnostic imaging in establishing a diagnosis or indicating surgery for long head biceps pathology. (10.1016/j.arthro.2015.12.008)
  • [L4] The patient recovered completely and improved her professional tennis ranking from number 80 to number 28 within 1 year. (10.1177/03635465020300062501)
  • [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. (10.2106/00004623-198769090-00024)
  • [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. (10.1177/1558944718795511)
  • [L4] However, magnetic resonance imaging indicates that the donor site is resurfaced with fibrous tissue. (10.1177/0363546507306465)
  • [L5] Different tendons express unique growth-factor profiles after similar, simultaneous injuries. (10.1016/j.jhsg.2022.04.006)

See Also

References

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

[2] Repair of the Torn Achilles Tendon, Using the Plantaris Tendon as a Reinforcing Membrane. The Journal of Bone & Joint Surgery. 1966. DOI: 10.2106/00004623-196648020-00005

[3] Triggering of the lateral slip of the extensor mechanism on a Bouchard’s node. Journal of Hand Surgery (European Volume). 2011. DOI: 10.1177/1753193410397860

[4] 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

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

[6] 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

[7] Chapter 62 Tendons and Ligaments. 2019.

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

[9] 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

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

[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] Tendon and Ligament Insertion: A LIGHT AND ELECTRON MICROSCOPIC STUDY.. The Journal of Bone and Joint Surgery. American Volume. 1970.

[14] Spontaneous Rupture of the Posterior Tibial Tendon. The Journal of Bone & Joint Surgery. 1969. DOI: 10.2106/00004623-196951040-00014

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

[16] 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.

[17] 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

[18] The pathological features of hip abductor tendon tears – a cadaveric study. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-020-03784-3

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

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

[21] 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

[22] 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

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

[24] 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

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

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

[27] 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

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

[29] The Effect of Intrinsic Loading and Reconstruction Upon Grip Capacity and Finger Extension Kinematics. The Journal of Hand Surgery. 2015. DOI: 10.1016/j.jhsa.2014.09.031

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

[31] Intrinsic Hand Muscle Function, Part 2: Kinematic Comparison of 2 Reconstructive Procedures. The Journal of Hand Surgery. 2013. DOI: 10.1016/j.jhsa.2013.08.098

[32] Biomechanical Measurement in Orthopaedic Practice. The Journal of Bone & Joint Surgery. 1987. DOI: 10.2106/00004623-198769070-00033

[33] Commentary on “Reattachment of Flexor Digitorum Profundus Avulsion: Biomechanical Performance of 3 Techniques”. Zone I Flexor Tendon Repairs: More Strength Not Worth Altered Joint Kinematics. The Journal of Hand Surgery. 2014. DOI: 10.1016/j.jhsa.2014.08.002

[34] In Vivo Length and Changes of Ligaments Stabilizing the Thumb Carpometacarpal Joint. The Journal of Hand Surgery. 2011. DOI: 10.1016/j.jhsa.2010.11.007

[35] Response to Letter to the Editor Regarding “The Effect of Forearm Shortening on Finger Flexion: A Biomechanical Study”. The Journal of Hand Surgery. 2026. DOI: 10.1016/j.jhsa.2026.01.017

[36] Finger joint motion generated by individual extrinsic muscles: A cadaveric study. Journal of Orthopaedic Surgery and Research. 2008. DOI: 10.1186/1749-799x-3-27

[37] The effect of metacarpal shortening on digital flexion force. Journal of Hand Surgery (European Volume). 2012. DOI: 10.1177/1753193412461589

[38] Intrinsic Hand Muscle Function, Part 1: Creating a Functional Grasp. The Journal of Hand Surgery. 2013. DOI: 10.1016/j.jhsa.2013.08.099

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

[40] Chapter 29 Hand/Carpal Fractures and Dislocations. 2021.

[41] Extrinsic versus intrinsic hand muscle dominance in finger flexion. Journal of Hand Surgery (European Volume). 2016. DOI: 10.1177/1753193415619774

[42] The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment. The Journal of Hand Surgery. 2017. DOI: 10.1016/j.jhsa.2017.08.024

[43] An in-depth look at zone III and IV anatomy of the finger extensor mechanism and some clinical implications for use of the relative motion flexion orthosis. Journal of Hand Therapy. 2023. DOI: 10.1016/j.jht.2023.01.002

[44] Biomechanical Comparison of 3 Thumb Ulnar Collateral Ligament Repair Methods. The Journal of Hand Surgery. 2023. DOI: 10.1016/j.jhsa.2021.09.028

[45] A Biomechanical and Evolutionary Perspective on the Function of the Lumbrical Muscle. The Journal of Hand Surgery. 2014. DOI: 10.1016/j.jhsa.2013.06.029

[46] THE ANATOMY AND FUNCTION OF THE INTRINSIC MUSCULATURE OF THE FINGERS. The Journal of Bone & Joint Surgery. 1954. DOI: 10.2106/00004623-195436010-00001

[47] Congenital Shortening of the Flexor Digitorum Profundus Muscle. The Journal of Hand Surgery. 2007. DOI: 10.1016/j.jhsa.2006.10.006

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

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

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

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

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

[53] 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

[54] 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

[55] 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

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

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

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

[59] 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

[60] The supporting structures and layers on the medial side of the knee. The Journal of Bone & Joint Surgery. 1979. DOI: 10.2106/00004623-197961010-00011

[61] 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

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

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

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

[65] 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

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

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

[68] 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

[69] 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

[70] Functional Outcomes of Proximal Hamstring Tendon Repair in Patients Over 40 Treated Without Postoperative Bracing. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/23259671251326604

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

[72] 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

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

[74] 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

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

[76] Editorial Commentary: Long Head Biceps Pathology: How Do We Find It?. Arthroscopy. 2016. DOI: 10.1016/j.arthro.2015.12.008

[77] Rupture of the Flexor Digitorum Profundus Tendon of the Small Finger. The American Journal of Sports Medicine. 2002. DOI: 10.1177/03635465020300062501

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

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

[80] 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

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

Creative Commons BY-NC 4.0

CC Creative Commons licence
BY Attribution — you must credit the source
NC NonCommercial — not for commercial use

Attribution-NonCommercial 4.0 International

Creative Commons Corporation ("Creative Commons") is not a law firm and does not provide legal services or legal advice. Distribution of Creative Commons public licenses does not create a lawyer-client or other relationship. Creative Commons makes its licenses and related information available on an "as-is" basis. Creative Commons gives no warranties regarding its licenses, any material licensed under their terms and conditions, or any related information. Creative Commons disclaims all liability for damages resulting from their use to the fullest extent possible.

Using Creative Commons Public Licenses

Creative Commons public licenses provide a standard set of terms and conditions that creators and other rights holders may use to share original works of authorship and other material subject to copyright and certain other rights specified in the public license below. The following considerations are for informational purposes only, are not exhaustive, and do not form part of our licenses.

Considerations for licensors: Our public licenses are intended for use by those authorized to give the public permission to use material in ways otherwise restricted by copyright and certain other rights. Our licenses are irrevocable. Licensors should read and understand the terms and conditions of the license they choose before applying it. Licensors should also secure all rights necessary before applying our licenses so that the public can reuse the material as expected. Licensors should clearly mark any material not subject to the license. This includes other CC- licensed material, or material used under an exception or limitation to copyright. More considerations for licensors: wiki.creativecommons.org/Considerations_for_licensors

Considerations for the public: By using one of our public licenses, a licensor grants the public permission to use the licensed material under specified terms and conditions. If the licensor's permission is not necessary for any reason--for example, because of any applicable exception or limitation to copyright--then that use is not regulated by the license. Our licenses grant only permissions under copyright and certain other rights that a licensor has authority to grant. Use of the licensed material may still be restricted for other reasons, including because others have copyright or other rights in the material. A licensor may make special requests, such as asking that all changes be marked or described. Although not required by our licenses, you are encouraged to respect those requests where reasonable. More considerations for the public: wiki.creativecommons.org/Considerations_for_licensees

Creative Commons Attribution-NonCommercial 4.0 International Public License

By exercising the Licensed Rights (defined below), You accept and agree to be bound by the terms and conditions of this Creative Commons Attribution-NonCommercial 4.0 International Public License ("Public License"). To the extent this Public License may be interpreted as a contract, You are granted the Licensed Rights in consideration of Your acceptance of these terms and conditions, and the Licensor grants You such rights in consideration of benefits the Licensor receives from making the Licensed Material available under these terms and conditions.

Section 1 -- Definitions.

a. Adapted Material means material subject to Copyright and Similar Rights that is derived from or based upon the Licensed Material and in which the Licensed Material is translated, altered, arranged, transformed, or otherwise modified in a manner requiring permission under the Copyright and Similar Rights held by the Licensor. For purposes of this Public License, where the Licensed Material is a musical work, performance, or sound recording, Adapted Material is always produced where the Licensed Material is synched in timed relation with a moving image.

b. Adapter's License means the license You apply to Your Copyright and Similar Rights in Your contributions to Adapted Material in accordance with the terms and conditions of this Public License.

c. Copyright and Similar Rights means copyright and/or similar rights closely related to copyright including, without limitation, performance, broadcast, sound recording, and Sui Generis Database Rights, without regard to how the rights are labeled or categorized. For purposes of this Public License, the rights specified in Section 2(b)(1)-(2) are not Copyright and Similar Rights.

d. Effective Technological Measures means those measures that, in the absence of proper authority, may not be circumvented under laws fulfilling obligations under Article 11 of the WIPO Copyright Treaty adopted on December 20, 1996, and/or similar international agreements.

e. Exceptions and Limitations means fair use, fair dealing, and/or any other exception or limitation to Copyright and Similar Rights that applies to Your use of the Licensed Material.

f. Licensed Material means the artistic or literary work, database, or other material to which the Licensor applied this Public License.

g. Licensed Rights means the rights granted to You subject to the terms and conditions of this Public License, which are limited to all Copyright and Similar Rights that apply to Your use of the Licensed Material and that the Licensor has authority to license.

h. Licensor means the individual(s) or entity(ies) granting rights under this Public License.

i. NonCommercial means not primarily intended for or directed towards commercial advantage or monetary compensation. For purposes of this Public License, the exchange of the Licensed Material for other material subject to Copyright and Similar Rights by digital file-sharing or similar means is NonCommercial provided there is no payment of monetary compensation in connection with the exchange.

j. Share means to provide material to the public by any means or process that requires permission under the Licensed Rights, such as reproduction, public display, public performance, distribution, dissemination, communication, or importation, and to make material available to the public including in ways that members of the public may access the material from a place and at a time individually chosen by them.

k. Sui Generis Database Rights means rights other than copyright resulting from Directive 96/9/EC of the European Parliament and of the Council of 11 March 1996 on the legal protection of databases, as amended and/or succeeded, as well as other essentially equivalent rights anywhere in the world.

l. You means the individual or entity exercising the Licensed Rights under this Public License. Your has a corresponding meaning.

Section 2 -- Scope.

a. License grant.

1. Subject to the terms and conditions of this Public License, the Licensor hereby grants You a worldwide, royalty-free, non-sublicensable, non-exclusive, irrevocable license to exercise the Licensed Rights in the Licensed Material to:

a. reproduce and Share the Licensed Material, in whole or in part, for NonCommercial purposes only; and

b. produce, reproduce, and Share Adapted Material for NonCommercial purposes only.

2. Exceptions and Limitations. For the avoidance of doubt, where Exceptions and Limitations apply to Your use, this Public License does not apply, and You do not need to comply with its terms and conditions.

3. Term. The term of this Public License is specified in Section 6(a).

4. Media and formats; technical modifications allowed. The Licensor authorizes You to exercise the Licensed Rights in all media and formats whether now known or hereafter created, and to make technical modifications necessary to do so. The Licensor waives and/or agrees not to assert any right or authority to forbid You from making technical modifications necessary to exercise the Licensed Rights, including technical modifications necessary to circumvent Effective Technological Measures. For purposes of this Public License, simply making modifications authorized by this Section 2(a) (4) never produces Adapted Material.

5. Downstream recipients.

a. Offer from the Licensor -- Licensed Material. Every recipient of the Licensed Material automatically receives an offer from the Licensor to exercise the Licensed Rights under the terms and conditions of this Public License.

b. No downstream restrictions. You may not offer or impose any additional or different terms or conditions on, or apply any Effective Technological Measures to, the Licensed Material if doing so restricts exercise of the Licensed Rights by any recipient of the Licensed Material.

6. No endorsement. Nothing in this Public License constitutes or may be construed as permission to assert or imply that You are, or that Your use of the Licensed Material is, connected with, or sponsored, endorsed, or granted official status by, the Licensor or others designated to receive attribution as provided in Section 3(a)(1)(A)(i).

b. Other rights.

1. Moral rights, such as the right of integrity, are not licensed under this Public License, nor are publicity, privacy, and/or other similar personality rights; however, to the extent possible, the Licensor waives and/or agrees not to assert any such rights held by the Licensor to the limited extent necessary to allow You to exercise the Licensed Rights, but not otherwise.

2. Patent and trademark rights are not licensed under this Public License.

3. To the extent possible, the Licensor waives any right to collect royalties from You for the exercise of the Licensed Rights, whether directly or through a collecting society under any voluntary or waivable statutory or compulsory licensing scheme. In all other cases the Licensor expressly reserves any right to collect such royalties, including when the Licensed Material is used other than for NonCommercial purposes.

Section 3 -- License Conditions.

Your exercise of the Licensed Rights is expressly made subject to the following conditions.

a. Attribution.

1. If You Share the Licensed Material (including in modified form), You must:

a. retain the following if it is supplied by the Licensor with the Licensed Material:

i. identification of the creator(s) of the Licensed Material and any others designated to receive attribution, in any reasonable manner requested by the Licensor (including by pseudonym if designated);

ii. a copyright notice;

iii. a notice that refers to this Public License;

iv. a notice that refers to the disclaimer of warranties;

v. a URI or hyperlink to the Licensed Material to the extent reasonably practicable;

b. indicate if You modified the Licensed Material and retain an indication of any previous modifications; and

c. indicate the Licensed Material is licensed under this Public License, and include the text of, or the URI or hyperlink to, this Public License.

2. You may satisfy the conditions in Section 3(a)(1) in any reasonable manner based on the medium, means, and context in which You Share the Licensed Material. For example, it may be reasonable to satisfy the conditions by providing a URI or hyperlink to a resource that includes the required information.

3. If requested by the Licensor, You must remove any of the information required by Section 3(a)(1)(A) to the extent reasonably practicable.

4. If You Share Adapted Material You produce, the Adapter's License You apply must not prevent recipients of the Adapted Material from complying with this Public License.

Section 4 -- Sui Generis Database Rights.

Where the Licensed Rights include Sui Generis Database Rights that apply to Your use of the Licensed Material:

a. for the avoidance of doubt, Section 2(a)(1) grants You the right to extract, reuse, reproduce, and Share all or a substantial portion of the contents of the database for NonCommercial purposes only;

b. if You include all or a substantial portion of the database contents in a database in which You have Sui Generis Database Rights, then the database in which You have Sui Generis Database Rights (but not its individual contents) is Adapted Material; and

c. You must comply with the conditions in Section 3(a) if You Share all or a substantial portion of the contents of the database.

For the avoidance of doubt, this Section 4 supplements and does not replace Your obligations under this Public License where the Licensed Rights include other Copyright and Similar Rights.

Section 5 -- Disclaimer of Warranties and Limitation of Liability.

a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.

b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION, NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES, COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.

c. The disclaimer of warranties and limitation of liability provided above shall be interpreted in a manner that, to the extent possible, most closely approximates an absolute disclaimer and waiver of all liability.

Section 6 -- Term and Termination.

a. This Public License applies for the term of the Copyright and Similar Rights licensed here. However, if You fail to comply with this Public License, then Your rights under this Public License terminate automatically.

b. Where Your right to use the Licensed Material has terminated under Section 6(a), it reinstates:

1. automatically as of the date the violation is cured, provided it is cured within 30 days of Your discovery of the violation; or

2. upon express reinstatement by the Licensor.

For the avoidance of doubt, this Section 6(b) does not affect any right the Licensor may have to seek remedies for Your violations of this Public License.

c. For the avoidance of doubt, the Licensor may also offer the Licensed Material under separate terms or conditions or stop distributing the Licensed Material at any time; however, doing so will not terminate this Public License.

d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

Creative Commons may be contacted at creativecommons.org.