Understanding the medial ulnar collateral ligament of the elbow: Review of native ligament anatomy and function

Variable Return to Play and Sport Performance After Elbow Ulnar Collateral Ligament Reconstruction in Baseball Players: A Systematic Review

PURPOSE

To evaluate return to play (RTP) and return to same level of play (RTSP) rates as well as preoperative and postoperative in-game performance metrics in baseball pitchers who underwent ulnar collateral ligament reconstruction (UCLR). Secondarily, this review sought to assess outcomes based on primary versus revision UCLR as well as level of competition.

METHODS

This review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed/MEDLINE, Embase, Web of Science, and Cochrane Database of Systematic Reviews were queried to identify articles evaluating UCLR in baseball players between January 2002 and October 2022. Data included RTP, RTSP, and performance metrics including earned run average, innings pitched, walks and hits per inning pitched, batting average against, strikeouts per 9 innings, walks per 9 innings, percentage of fastballs thrown, and average fastball velocity. The Methodological Index for Non-randomized Studies criteria were used for quality assessment.

RESULTS

Analysis included 25 articles reporting on 2,100 elbows. After primary UCLR, RTP ranged from 336 to 615 days (57% to 100% achieved) and RTSP ranged from 330 to 513 days (61% to 95%). After revision UCLR, RTP ranged from 381 to 631 days (67% to 98%) and RTSP ranged from 518 to 575 days (42% to 78%). When stratifying primary UCLR outcomes by competitive level, RTP and RTSP ranged respectively from 417 to 615 days (75% to 100%) and 513 days (73% to 87%) for Major League Baseball only, 409 to 615 days (57% to 100%) and 470 to 513 days (61% to 95%) for Major League Baseball plus Minor League Baseball, and 336 to 516 days (73% to 85%) and 330 days (55% to 74%) for college plus high school. Heterogeneity was seen in postoperative sports performance metrics.

CONCLUSIONS

Although more than half of baseball players appear able to RTP after primary and revision UCLR, RTSP rates after revision UCLR were as low as 42% in the literature. Preoperative and postoperative performance metrics varied.

LEVEL OF EVIDENCE

Level IV, systematic review.

Shear wave elastography of the ulnar collateral ligament in division IA pitchers across a competitive collegiate season

Background

The ulnar collateral ligament (UCL) is a commonly injured elbow stabilizer during throwing. Shear wave elastography (SWE) is a technique that may reveal structural changes in the UCL that are indicative of ligament health and injury risk. The purpose of this study was to assess preseason and inseason shear wave velocity (SWV) in the UCL of collegiate pitchers and to asses repeatability of this measurement technique in healthy volunteers.

Methods

Seventeen collegiate baseball pitchers and 11 sex-matched volunteers were recruited. Two-dimensional SWE of the UCL was performed by a single radiologist. In pitchers, SWV was measured at the proximal, midsubstance, and distal UCL for dominant and nondominant elbows preseason, midseason, and postseason, and Kerlan-Jobe Orthopaedic Clinic (KJOC) Shoulder and Elbow questionnaire scores were recorded. In volunteers, SWV was measured at UCL midsubstance in dominant elbows at 3 separate occasions over 1 week. An independent samples t-test was used to compare preseason midsubstance measures between pitchers and the healthy volunteers. A mixed-model analysis of covariance (covaried on preseason measures) was used to compare SWV measures at the preseason, midseason, and postseason time points. A similar generalized linear model for nonparametric data was used to compare KJOC scores. Type-I error was set at P < .05.

Results

Mean preseason midsubstance dominant arm UCL SWV did not significantly differ between the pitchers (5.40 ± 1.65 m/s) compared to the healthy volunteers (4.35 ± 1.45 m/s). For inseason measures among the pitchers, a decrease in midsubstance (-1.17 ± 0.99 m/s, P = .021) and proximal (-1.55 ± 0.91 m/s, P = .001) SWV was observed at midseason compared to preseason. The proximal measure was also observed to be significantly lower than the nondominant arm (-1.97 ± 0.95 m/s, P < .001). Proximal SWV remained reduced relative to the preseason and the postseason mark (-1.13 ± 0.91 m/s, P = .015). KJOC scores decreased at midseason compared to preseason (P = .003) but then increased to a similar preseason value at the postseason measurement (preseason = 92 ± 3, midseason = 87 ± 3, postseason = 91 ± 3). The repeatability coefficient of SWE in the volunteer cohort was 1.98 m/s.

Conclusion

Decreased SWV in the proximal and midsubstance of the dominant arm UCL at midseason suggests structural changes indicative of increasing laxity or 'softening' of the UCL. Associated decline in KJOC scores suggests that these changes are associated with functional decline. Future studies with more frequent sampling would be invaluable to further explore this observation and its significance for predicting and managing UCL injury risk.

Current concepts in the management of "Terrible Triad" injuries of the elbow

Terrible triad injuries of the elbow are complex injuries which can result in long term complications and significant disability. They must be identified correctly, and managed appropriately in order to maximise functional outcomes. A clear understanding of the bony and ligamentous anatomy is essential to plan appropriate surgical reconstruction to provide elbow stability. Urgent reduction of the elbow, followed by 3-dimensional imaging and surgical repair or replacement of the injured structures is the mainstay of treatment in the majority of cases. This review presents a summary of the relevant anatomy and the evidence for the management of these complex injuries.

The 50 most impactful articles on the medial ulnar collateral ligament: An altmetric analysis of online media

The purpose of this study was to use the Altmetric Attention Score to determine the 50 most impactful medial ulnar collateral ligament articles in online media and compare their characteristics to the most-cited medial ulnar collateral ligament articles in the scientific literature. The Altmetric database was queried to identify all published articles about the medial ulnar collateral ligament, and this list was stratified by the Altmetric Attention Score to identify the 50 highest scoring articles. Several data elements were extracted, including article topic, article type, journal name, and the number of online mentions on Facebook, Twitter, news, and other platforms. Each article's geographic origin was determined based on the institutional affiliation of the first author. Our index search yielded 1283 articles published between 1987 and 2020, from which the 50 articles with the highest Altmetric Attention Scores were included for analysis. Altmetric Attention Scores of the top 50 medial ulnar collateral ligament articles ranged from 20 to 482 (median: 32, interquartile range: 20-62). The most common article type was original research (72%), and the most common topic was epidemiology/risk factors (26%). A majority of studies were Level 3 (36%) or Level 4 evidence (36%). Of the top 50 medial ulnar collateral ligament articles, 94% originated from the United States. A few articles had a high Altmetric Attention Score, suggesting that medial ulnar collateral ligament research does not generate consistently high online attention. The lack of Level 1 studies suggests the need for high-level studies on the medial ulnar collateral ligament. Most studies originated in the United States and were published in the American Orthopaedic Society for Sports Medicine-affiliated journals. The medial ulnar collateral ligament articles included in this study differed substantially from a previous report of the most-cited medial ulnar collateral ligament articles in the literature, suggesting that alternative metrics add a unique dimension to understanding the overall impact of published research on the medial ulnar collateral ligament.

Change in humeral anchor position significantly affects isometry in ulnar collateral ligament repair: a 3-dimensional computer modeling study

BACKGROUND

Medial ulnar collateral ligament (UCL) repair utilization is increasing in recent years, bolstered by shorter rehabilitation and satisfactory clinical outcomes. Although previous literature has illustrated the importance of tunnel position on restoring graft isometry in reconstruction, there remains a paucity of literature guiding anchor placement in UCL repair. The purpose of this study is to design a 3-dimensional (3D) elbow model to understand the effect of anchor location on UCL repair isometry.

METHODS

A 3D computer model of an elbow joint was created using computed tomographic and magnetic resonance imaging MRI scans from a single patient. The humeral and ulnar attachments of the UCL were plotted using 3 methodologies: (1) geometric cloud mapping and (2) quantitative measurements from the anatomic studies by Camp et al and (3) Frangiamore et al. A 3.5-mm-diameter clockface was placed on each attachment site, which allowed for simulation of 12 distinct 1.75-mm deviations in anchor position. The 3 models were ranged through 0°-120° at 10° increments, and the 3D distances were measured between the ligament centroids. The humeral and ulnar anchors were sequentially repositioned around the clockfaces, and construct lengths were again measured to evaluate changes in isometry. A paired Student t test was performed to determine if there was a significant difference in isometry between the humeral and ulnar anchor deviations.

RESULTS

Using method 1, the UCL repair length at 90° of elbow flexion was 26.8 mm. This construct underwent 13.6 mm of total excursion for a 46.4% change in length throughout its arc of motion. Method 2 produced a 19.3-mm construct that underwent 0.8 mm of excursion for a 3.9% length change throughout the arc. Method 3 produced a 24.5-mm construct that underwent 2.3 mm of excursion for a 9.4% length change. Identifying ligament footprints using the quantitative anatomic measurements from Camp et al and Frangiamore et al improved construct isometry through 120° of flexion (length changes of 3.9% and 9.4%, respectively) when compared to using the geometric cloud technique alone (46.4% length change). Humeral anchor deviations produced a significant increase in repair construct excursion compared with ulnar anchor deviations (P < .001).

CONCLUSION

When performing UCL repair, small deviations in humeral anchor position may significantly influence ligament repair isometry. Using quantitative anatomic data may help identify anchor positions with improved repair isometry. Particularly when addressing detachments of the humeral footprint, surgeons should be critical of the humeral anchor position in order to restore native anatomy and optimal biomechanics.

Distal Humeral Trochlear Geometry Associated With the Spatial Variation of the Dynamic Elbow Flexion Axis

Background: The complexity of the spatial dynamic flexion axis (DFA) of the elbow joint makes the elbow prosthesis design and humeral component alignment challenging. This study aimed to 1) investigate the variations of the spatial DFA during elbow flexion and 2) investigate the relationship between the distal humeral trochlear geometry and the in vivo spatial variation of the DFA.

Methods: Ten healthy subjects participated in this study. Each subject performed a full elbow extension to maximum flexion with hand supination under dual fluoroscopic imaging system (DFIS) surveillance. The 2D fluoroscopic images and the 3D bone models were registered to analyze the in vivo elbow kinematics and DFAs. The spatial DFA positions were defined as inclination with the medial and lateral epicondyle axes (MLA) in the transverse and coronal planes. The range of the DFA positions was also investigated during different flexion phases. The Spearman correlation method was used to analyze the relationship between the distal humeral trochlear’s morphological parameters and the position of DFAs during different flexion phases.

Results: The pathway of the DFAs showed an irregular pattern and presented individual features. The medial trochlear depth (MTD) (r = 0.68, p = 0.03) was positively correlated with the range of the DFA position (2.8° ± 1.9°) in the coronal plane from full extension to 30° of flexion. Lateral trochlear height (LTH) (r = −0.64, p = 0.04) was negatively correlated with the DFA position (−1.4° ± 3.3°) in the transverse plane from 30° to 60° of flexion. A significant correlation was found between LTH with the DFA position in the coronal (r = −0.77, p = 0.01) and transverse planes (r = −0.76, p = 0.01) from 60° to 90° of flexion.

Conclusion: This study showed that the pathway of the dynamic flexion axis has an individual pattern. The medial and lateral trochlear sizes were the key parameters that might affect the elbow joint flexion function. When recovering complex distal humeral fractures or considering the implant design of total elbow arthroplasty, surgeons should pay more attention to the medial and lateral trochlea’s geometry, which may help restore normal elbow kinematics.

Anatomic Study of the Medial Collateral Ligament in Thai Population: A Cadaveric Study of 56 Elbows

PURPOSE

This study aims to elucidate basic anatomic and geometric features of MCL, providing more accurate and detailed information, as guidance for surgeons, to improve patient's outcome of the treatment.

METHODS

The anterior bundle (AB), posterior bundle (PB) and transverse bundle (TB) ligament of 56 fresh frozen Thai cadaveric elbows, were measured and recorded, comprise key ligament's geometric features, footprints and dimensions, and its relation to bony landmarks. Sagittal and coronal planes were used in respect of the anatomical position.

RESULTS

The mean distance between the center of AB origin and the apex of medial epicondyle is as follows: 2.97 ± 2.21 mm anteriorly, 4.73 ± 1.60 mm inferiorly in the sagittal plane, and 4.23 ± 1.13 mm deep from the epicondyle in the coronal plane. Its dimension is 6.23 ± 1.02 mm in width and 45.97 ± 6.75 mm in length. The ligament's insertion triangular shape has its base located 28.44 ± 3.51 mm anterior from the posterior olecranon border, and 22.52 ± 2.49 mm superior from the inferior ulnar border. The tip located 50.79 ± 4.86 mm anterior from the posterior olecranon border and 17.64 ± 2.80 mm superior from the inferior ulnar border.

CONCLUSION

Apprehension of the precise geometries and distances of the ligament's footprint relative to key anatomical point is crucial. This stereographically comprehended data are useful for surgeon as reference points to obtain stability, motion, kinetic, and kinematic properties of the elbow.

LEVEL OF EVIDENCE

Level V evidence.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-022-00648-x.

Posteromedial rotatory instability of the elbow: What the radiologist needs to know

Varus posteromedial rotatory instability of the elbow joint is a relatively new subject described for the first time in 2003. It occurs secondary to axial loading of the elbow with varus force and internal rotation of the forearm. There is usually a specific pattern of osseous and soft tissue injuries that can be recognized on imaging. This includes an anteromedial coronoid fracture and avulsion of the lateral collateral ligament complex from its humeral attachment. Ulnar collateral ligament complex injury is also reported, particularly its posterior bundle which plays an important role in posteromedial elbow joint stability. There is high incidence of early osteoarthritis secondary to the resultant varus instability and increased contact pressure at the ulnohumeral joint. Surgical fixation of the coronoid fracture and ligamentous reconstruction maybe indicated to prevent this recurrent instability. The article reviews the key radiological features of posteromedial rotatory instability with multiple examples from different imaging modalities. The relevant anatomy of the elbow joint stabilising structures will be illustrated, in particular the coronoid process anatomy and the O'Driscoll classification for coronoid process fractures. Radiologists should be familiar with the imaging findings of posteromedial rotatory instability.

Role of the transverse ligament of the ulnar collateral ligament of the elbow: a biomechanical study

Background

The ulnar collateral ligament (UCL) complex of the elbow plays a primary role in valgus and posteromedial stability of the elbow. The anterior oblique ligament (AOL) of the UCL is believed to provide the majority of resistance to external forces on the medial elbow. The transverse ligament (TL) of the UCL is generally thought to have minimal contribution to the elbow’s overall stability. However, recent studies have suggested a more significant role for the TL. The primary aim of this study was to identify the TL’s contribution to the stability of the elbow joint in determining the joint stiffness and neutral zone variation in internal rotation.

Methods

Twelve cadaveric elbows, set at a 90° flexion angle, were tested by applying an internal rotational force on the humerus to generate a medial opening torque at the level of the elbow. The specimens were preconditioned with 10 cycles of humeral internal rotation with sinusoidal torque ranging from 0 to 5 Nm. Elbow stiffness measures and joint neutral zone were first evaluated in its integrity during a final ramp loading. The test was subsequently repeated after cutting the TL at 33%, 66%, and 100% followed by the AOL in the same fashion.

Results

The native UCL complex joint stiffness to internal rotation measured 1.52 ± 0.51 Nm/°. The first observable change occurred with 33% sectioning of the AOL, with further sectioning of the AOL minimizing the joint stiffness to 1.26 ± 0.32 Nm/° (P = .004). A 33% resection of the TL found an initial neutral zone variation of 0.376 ± 0.23° that increased to 0.771 ± 0.41° (P < .01) at full resection. These values were marginal when compared with the full resection of the AOL for which we have found 3.69 ± 1.65° (P < .01).

Conclusion

The TL had no contribution to internal rotation elbow joint stiffness at a flexion angle of 90°. However, sequential sectioning of the TL was found to significantly increase the joint neutral zone when compared with the native cadaveric elbow at a flexion angle of 90°. This provides evidence toward the TL having some form of contribution to the elbow’s overall stability.

UCL Injury in the Non-throwing Athlete

PURPOSE OF REVIEW

Primarily reported in the overhead throwing athlete, ulnar collateral ligament (UCL) injuries have been extensively studied since Dr. Frank Jobe first described his technique for ulnar collateral ligament reconstruction on professional baseball pitcher Tommy John. While the framework for our understanding of UCL injury was initially established studying the repetitive valgus loading of the throwers' elbow, other sport-related activities in non-throwing athletes can impart similar valgus stress on the medial elbow placing the UCL at risk for injury. The purpose of this review is to evaluate the current literature on UCL injury specifically in the non-throwing athlete.

RECENT FINDINGS

In the four decades since Dr. Jobe's seminal description of UCL reconstruction, an abundance of literature has been published on UCL injury in the throwing athlete. The evidence evaluating the UCL specifically in the non-throwing athlete, however, is quite scarce. Several small retrospective studies have demonstrated good results with high rates of return to play with focused rehabilitation and non-operative management in non-throwing athletes. Recent evidence has also demonstrated that surgical repair and/or reconstruction of the UCL in this population can produce good outcomes. The level of evidence of these published studies is low and consists primarily of case series without control groups. Further investigation is warranted to determine the optimal treatment algorithm for UCL injury in the non-throwing athlete.

Reconstruction of the Medial Ulnar Collateral Ligament of the Elbow: Biomechanical Comparison of a Novel Anatomic Technique to the Docking Technique

Background:

In recent years, understanding of the anatomy of the ulnar collateral ligament (UCL) has evolved, demonstrating that the insertional footprint of the UCL on the ulna is more elongated and distally tapered than previously described. Current UCL reconstruction configurations do not typically re-create this native anatomy, which may represent a potential area for improvement.

Purpose/Hypothesis:

The purposes of this study were (1) to describe a novel anatomic UCL reconstruction technique designed to better replicate the native UCL anatomy and (2) to biomechanically compare this with the docking technique. The hypothesis was that the ultimate load to failure for the anatomic technique would not be inferior to the docking technique.

Study Design:

Controlled laboratory study.

Methods:

A total of 16 fresh-frozen cadaveric upper extremities (8 matched pairs) were utilized. One elbow in each pair was randomized to receive UCL reconstruction via the docking technique or the novel anatomic UCL reconstruction technique with palmaris tendon autograft. Following reconstruction, biomechanical testing was performed by applying valgus rotational torque at a constant rate of 5 deg/s until ultimate mechanical failure of the construct occurred. Maximal torque (N·m), rotation stiffness (N·m/deg), and mode/location of failure were recorded for each specimen.

Results:

The mean ultimate load to failure for elbows in the docking technique group was 23.8 ± 6.1 N·m, as compared with 31.9 ± 8.4 N·m in the anatomic technique group (P = .045). Mean rotational stiffness was 1.9 ± 0.7 versus 2.3 ± 0.9 N·m/deg for the docking and anatomic groups, respectively (P = .338). The most common mode of failure was suture pullout from the graft, which occurred in all 8 (100%) docking technique specimens and 7 of 8 (88%) specimens that underwent the anatomic UCL reconstruction technique.

Conclusion:

Ultimately, the anatomic UCL reconstruction technique demonstrated superior strength and resistance to valgus torque when compared with the docking technique, and this was comparable with that of the native UCL from prior studies. Increased initial strength may allow for earlier initiation of throwing postoperatively and potentially shorten return-to-play times.

Clinical Relevance:

Current UCL reconstruction techniques do not accurately reproduce the UCL insertional anatomy on the ulna. The novel anatomic technique described may result in more natural joint kinematics. This study demonstrated load-to-failure rates that are significantly higher than with the docking technique and consistent with the native ligament, as reported from previous studies. These findings may serve as a foundation for future clinical study and optimization of this technique.