Relationship between morphology of transverse bundle of ulnar collateral ligament and adjacent tissues.

PURPOSE: The purpose of this study was to clarify the incidence of the transverse bundle (TB) of the ulnar collateral ligament (UCL), the relationships between TB morphology and morphology of the anterior bundle (AB) or posterior bundle (PB) of the UCL, and the relationship between the TB and the posterior common tendon (PCT). METHODS: This study examined 38 elbows from 23 cadavers. TB, AB, and PB were classified morphologically. The TB was classified as: type I, TB does not continue the entire length of the AB; or type II, TB continues the entire length of the AB. The AB and PB were classified as: type I, could be separated as single bundles; or type II, could not be separated. We also observed specimens by focusing on the continuity between the TB and PCT. Fisher's exact test was used to examine the relationship between TB type and AB or PB type. RESULTS: A TB was identified in all 38 elbows (100%), and continued to the AB in all specimens. No significant relationship was evident between TB type and AB or PB type. Continuity of TB fibers and the PCT was seen in 26 elbows (72%). CONCLUSION: This study suggested that the morphology of the transverse bundle may be unrelated to the morphology of the anterior bundle or posterior bundle.

Thumb Metacarpophalangeal Ulnar and Radial Collateral Ligament Injuries.

Thumb metacarpophalangeal collateral ligament injuries are common in athletes and occur via forced abduction or hyperextension. Management primarily depends on the grade of ligamentous injury and the presence of a Stener lesion or large avulsion fracture. Surgeons should consider the athlete's position, hand dominance, duration of season remaining, and goals. Shared decision making regarding timing of surgery is imperative. Acutely, primary ligamentous repair with or without augmentation is achievable. Chronic collateral ligament injuries are effectively treated with ligament reconstruction. Numerous surgical techniques have been described without 1 showing superiority. Postoperative rehabilitation protocols vary based on repair quality and sports-specific considerations.

Morphological features of the posterior oblique ligament of the ulnar collateral ligament of the elbow joint.

PURPOSE: The purpose of this basic research study was to clarify the morphological characteristics of the posterior oblique fibers (POL) of the ulnar collateral ligament using a large number of specimens. METHODS: This study examined 50 arms from 25 Japanese cadavers. Type classification was performed by focusing on the positional relationship between POL morphology and the joint capsule. The morphological features measured were fiber bundle length, width, and thickness. RESULTS: The POL was classified as follows: Type I, the POL's anterior and posterior edges are located on the surface of the joint capsule and can be separated as a single fiber bundle; Type II-a, the POL anterior edge can be separated, but the posterior edge cannot be separated; Type II-b, the POL posterior edge can be separated, but the anterior edge cannot be separated; and Type III, the POL cannot be separated from the joint capsule. Type I was seen in 23 elbows (46%), Type II-a in 6 elbows (12%), Type II-b in 7 elbows (14%), and Type III in 14 elbows (28%). CONCLUSION: The results of this study suggested that the POL could be classified into an independent type and an unclear type, and the presence of the unclear type was one of the factors that caused morphological variation.

Sexual dimorphism in the anatomy of the ulnar collateral thumb ligament.

BACKGROUND: Treatment of ruptured ulnar collateral thumb metacarpophalangeal (MCP) joint ligaments (UCL) necessitate a profound anatomic knowledge for optimal surgical repair in order to preserve range of motion and ensure postoperative joint stability. Therefore, knowledge of the angle between the UCL and the longitudinal axis of the first metacarpal bone could be useful. METHODS: In this study 46 ulnar collateral thumb MCP joint ligaments in 15 male and 15 female embalmed anatomic specimens were dissected and the angles between the longitudinal axis of the first metacarpal bone and the proper (PUCL) as well as the accessory ulnar collateral thumb MCP ligament (AUCL) were measured. RESULTS: In male specimens the angle for the PUCL measured on average 133.5° (±2.35°) and 122.75° (±3.8°) for the AUCL. A significantly different angle was measured for female specimens which showed on average 137.88° (±3.51°) for the PUCL and 128.65° (±4.14°) for the AUCL. CONCLUSIONS: Optimal surgical repair or reconstruction of torn ulnar collateral thumb MCP joint ligaments should aim for an angle of approximately 135° in PUCL and 126° in AUCL in relation to the longitudinal axis of the metacarpal bone. Differences in men and women should be considered if possible. LEVEL OF EVIDENCE: IV (anatomic study).

The naked capitellum: a surgeon's guide to intraoperative identification of posterolateral rotatory instability.

HYPOTHESIS: This study's purpose was to provide a reproducible way for surgeons to intraoperatively assess the elbow's lateral ulnar collateral ligament origin and determine whether there is posterolateral rotatory instability (PLRI) despite an intact common extensor origin (CEO). We hypothesized that we could re-create clinically relevant disruption of lateral supporting structures despite an intact CEO and illustrate progressive elbow PLRI. METHODS: The relationship of the lateral capsule to the capitellum articular surface was noted in 8 cadaveric upper extremities. The lateral capsule and extensor origin were sequentially sectioned at 4 stages: intact, release to the lateral epicondyle, release of the posterior capsular insertion, and release of the CEO. Posterior and lateral translation of the radial head (RH) relative to the capitellum was measured with the forearm in extension and supination. RESULTS: The average specimen age was 78.9 years. The lateral capsule originated within 1 to 2 mm of the capitellum articular surface. Lateral capsular sectioning to the 6-o'clock position of the lateral epicondyle created an unstable elbow with posterior and lateral RH translation. Sequential sectioning of the posterior capsular insertion created significant additional RH translation posteriorly (P < .05). With release of the capsule and the extensor origin, the elbow was grossly unstable. CONCLUSIONS: The elbow's lateral capsuloligamentous complex plays an important role in preventing PLRI. Larger degrees of elbow laxity are associated with further peel back of the capsuloligamentous complex despite an intact CEO. The surgeon must retract the extensor origin intraoperatively to assess for lateral ulnar collateral ligament and/or lateral capsule disruption to prevent a missed case of PLRI.

Mechanical Properties and Microstructural Collagen Alignment of the Ulnar Collateral Ligament During Dynamic Loading.

BACKGROUND: The ulnar collateral ligament (UCL) microstructural organization and collagen fiber realignment in response to load are unknown. PURPOSE/HYPOTHESIS: The purpose was to describe the real-time microstructural collagen changes in the anterior bundle (AB) and posterior bundle (PB) of the UCL with tensile load. It was hypothesized that the UCL AB is stronger and stiffer with more highly aligned collagen during loading when compared with the UCL PB. STUDY DESIGN: Descriptive laboratory study. METHODS: The AB and PB from 34 fresh cadaveric specimens were longitudinally sectioned to allow uniform light passage for quantitative polarized light imaging. Specimens were secured to a tensile test machine and underwent cyclic preconditioning, a ramp-and-hold stress-relaxation test, and a quasi-static ramp to failure. A division-of-focal-plane polarization camera captured real-time pixelwise microstructural data of each sample during stress-relaxation and at the zero, transition, and linear points of the stress-strain curve. The SD of the angle of polarization determined the deviation of the average direction of collagen fibers in the tissue, while the average degree of linear polarization evaluated the strength of collagen alignment in those directions. Since the data were nonnormally distributed, the median ± interquartile range are presented. RESULTS: The AB has larger elastic moduli than the PB ( P < .0001) in the toe region (median, 2.73 MPa [interquartile range, 1.1-5.6 MPa] vs 0.65 MPa [0.44-1.5 MPa]) and the linear region (13.77 MPa [4.8-40.7 MPa] vs 1.96 MPa [0.58-9.3 MPa]). The AB demonstrated larger stress values, stronger collagen alignment, and more uniform collagen organization during stress-relaxation. PB collagen fibers were more disorganized than the AB during the zero ( P = .046), transitional ( P = .011), and linear ( P = .007) regions of the stress-strain curve. Both UCL bundles exhibited very small changes in collagen alignment (SD of the angle of polarization) with load. CONCLUSION: The AB of the UCL is stiffer and stronger, with more strongly aligned and more uniformly oriented collagen fibers, than the PB. The small changes in collagen alignment indicate that the UCL response to load is due more to its static collagen organization than to dynamic changes in collagen alignment. CLINICAL RELEVANCE: The UCL collagen organization may explain its susceptibility to injury with repetitive valgus loads.

The lateral collateral ligament complex of the elbow: quantitative anatomic analysis of the lateral ulnar collateral, radial collateral, and annular ligaments.

BACKGROUND: Injury to the lateral ulnar collateral ligament (LUCL) complex of the elbow often results in posterolateral rotatory instability. Although surgical reconstruction of the LUCL is often required, gaps in our understanding of the LUCL complex remain. The purpose of this study was to provide a robust and accurate characterization of the lateral elbow ligamentous complex. METHODS: The LUCLs, radial collateral ligaments, and annular ligaments in 10 cadaveric elbows were 3-dimensionally digitized and reconstructed using computed tomography. Surface areas, origin and insertion footprint areas, distances between perceived footprint centers and geometric footprint centroids, distances to key landmarks, and ligament isometry were measured. RESULTS: The mean surface area of the LUCL was 229.3 mm2. The mean origin and insertion footprint areas were 26.0 mm2 and 22.9 mm2, respectively. The mean distance between the apparent centers and the geometric centroids of the footprints was 1 mm. The center of the LUCL origin was 10.7 mm distal to the lateral epicondyle and 8.2 mm from the capitellar articular margin. The center of the LUCL insertion was 3.3 mm distal to the apex of the supinator crest. The LUCL showed anisometric properties as elbow flexion increased (P < .001). CONCLUSIONS: The LUCL origin center was 10.7 mm from the lateral epicondyle, whereas the insertion center was 3.3 mm from the apex of the supinator crest. The visually estimated footprint centers were generally within 1 mm of the geometric centroid. These geometries and distances to key landmarks will be informative for surgeons seeking to perform anatomic ligament reconstruction procedures.

Intramuscular Tendon of the Adductor Pollicis and Underlying Capsule of the Metacarpophalangeal Joint: An Anatomical Study With Possible Implications for the Stener Lesion.

PURPOSE: To identify the layered relationship anatomically between the musculotendinous structures of the adductor pollicis, the ulnar collateral ligament, and the capsule of the metacarpophalangeal joint in terms of understanding the pathomechanism of a Stener lesion. METHODS: We macroscopically analyzed 37 cadaveric thumbs to identify the intramuscular tendon of the adductor pollicis and bony attachments of the joint capsule including the ulnar collateral ligament. In addition, we histologically analyzed 3 thumbs and made a 3-dimensional image of 3 other thumbs, using micro-computed tomography. RESULTS: The adductor pollicis has 3 components of an intramuscular tendon (dorsal, palmar, and distal), which connect to form a lambda shape. The dorsal part inserts into the joint capsule dorsal to the ulnar sesamoid. The palmar part inserts into the ulnar sesamoid. The distal part inserts into the lateral tubercle of the proximal phalanx. The thickened and cord-like part of the joint capsule, which has generally been referred to as the proper ulnar collateral ligament, has a distinct bony attachment on the proximal slope of the lateral tubercle of the proximal phalanx separate from the adductor pollicis insertion. CONCLUSIONS: Of the 3 components of the intramuscular tendon of the adductor pollicis muscle, the dorsal part inserted into not only the aponeurosis but also the joint capsule. CLINICAL RELEVANCE: The results of the current study suggest the anatomic basis for a possible pathomechanism of the Stener lesion.

Qualitative and Quantitative Analyses of the Dynamic and Static Stabilizers of the Medial Elbow: An Anatomic Study.

BACKGROUND: The anterior bundle of the medial ulnar collateral ligament (UCL) and the forearm flexors provide primary static and dynamic stability to valgus stress of the elbow in overhead-throwing athletes. Quantitative anatomic relationships between the dynamic and static stabilizers have not been described. PURPOSE: To perform qualitative and quantitative anatomic evaluations of the medial elbow-UCL complex with specific attention to pertinent osseous and soft tissue landmarks. STUDY DESIGN: Descriptive laboratory study. METHODS: Ten nonpaired, fresh-frozen human cadaveric elbows (mean age, 54.1 years [range, 42-64 years]; all male) were utilized for this study. Quantitative analysis was performed with a 3-dimensional coordinate measuring device to quantify the location of pertinent bony landmarks and tendon and ligament footprints on the humerus, ulna, and radius. RESULTS: The anterior bundle of the UCL attached 8.5 mm (95% CI, 6.9-10.0) distal and 7.8 mm (95% CI, 6.6-9.1) lateral to the medial epicondyle, 1.5 mm (95% CI, 0.5-2.5) distal to the sublime tubercle, and 7.3 mm (95% CI, 6.1-8.5) distal to the joint line on the ulna along the ulnar ridge. The flexor digitorum superficialis (FDS) ulnar tendinous insertion was closely related and interposed within the anterior bundle of the UCL, overlapping with 45.6% (95% CI, 38.1-53.6) of the length of the anterior bundle of the UCL. The flexor carpi ulnaris (FCU) attached 1.9 mm (95% CI, 0.8-2.9) posterior and 1.3 mm (95% CI, 0.6-3.2) proximal to the sublime tubercle and overlapped with 20.9% (95% CI, 7.2-34.5) of the area of the distal footprint of the anterior bundle of the UCL. CONCLUSION: The anterior bundle of the UCL had consistent attachment points relative to the medial epicondyle and sublime tubercle. The ulnar limb of the FDS and FCU tendons demonstrated consistent insertions onto the ulnar attachment of the anterior bundle of the UCL. These anatomic relationships are important to consider when evaluating distal UCL tears both operatively and nonoperatively. Excessive stripping of the sublime tubercle should be avoided during UCL reconstruction to prevent violation of these tendinous attachments. CLINICAL RELEVANCE: The findings of this study enhance the understanding of valgus restraint in throwing athletes and provide insight into the difference in nonoperative outcomes between proximal and distal tears of the UCL.

Reinvestigation of the Morphological Characteristics of the Lateral Ulnar Collateral Ligament in Humans.

To clarify the cause of posterolateral rotatory instability after damage to the lateral ulnar collateral ligament (LUCL), the morphological characteristics of the LUCL were reinvestigated and three-dimensional (3D) image of the ligament was reconstructed using 35 human elbows. The results were as follows: 1) the insertion point of the LUCL on the humerus was almost at the center of the capitellum, and its width was 2.61 ± 1.02 mm. The insertion point of the LUCL on the ulna was located from the lesser sigmoid notch to the supinator crest and had a width of 9.0 ± 2.8 mm. The proximal insertion of the LUCL on the ulna was 7.0 ± 3.0 mm, and the distal part was on the articular surface of the radial head. 2) Three-dimensional imaging of the LUCL revealed an anterior curved shape that covered the radial head. Based on these results, it was clear that both the supinator crest and the lesser sigmoid notch could be useful as osseous landmarks. We think that these anatomical results are useful for surgeons performing LUCL reconstruction.

Return to Play Following Ulnar Collateral Ligament Reconstruction.

Ulnar collateral ligament injury in the overhead athlete typically presents as activity-related pain with loss of velocity and control. Treatment options range from nonoperative rehabilitation to ligament reconstruction. Surgical reconstruction is frequently required to allow the athlete to return to competition and many surgical techniques have been described. The rehabilitation process to return back to overhead athletics, in particular pitching, is prolonged and requires progression through multiple phases. Despite this, surgical treatment has been shown by multiple investigators to be successful at returning athletes to their previous level of competition.