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It is the most important portion of the ligament complex when treating elbow valgus instability
7%
104/1422
Exhibits the most significant change in ligament tension from flexion to extension
39%
549/1422
Of the other ligaments labeled, it is the predominant restraint to varus stress
4%
55/1422
It is further stratified into anterior and posterior bands
12%
166/1422
None of the above statements are true
37%
533/1422
Select Answer to see Preferred Response
Label B in Figure A depicts the posterior bundle of the medial ulnar collateral ligament (MUCL), which exhibits the most significant change in ligament tension from flexion to extension. The MUCL complex is the primary soft tissue stabilizer of the elbow to valgus stress. It is composed of 3 bundles; of which the anterior oblique bundle (AOL) is the most important to the overhead throwing motion and is taut as the elbow flexes past 30 degrees. The AOL itself is composed of 3 distinct bands (anterior, central, and posterior), of which the anterior is most important in AOL stability. The posterior bundle is a fan-like thickening of the capsule that becomes taut as the elbow flexes well past 90 degrees and exhibits the most change in tension from flexion to extension. The transverse oblique ligament does not confer any stability to the elbow. Schwab et al. investigated the role of the MUCL in the biomechanics of elbow instability. They reported that the AOL component of the MUCL of the elbow is the mainstay of joint stability. They highlighted that repair of chronic elbow instability is best performed by restitution of MUCL function. Morrey et al. performed cadaveric elbow dissections to pinpoint the origin and insertion of both the medial and lateral stabilizing ligaments of the elbow. They discovered and reported that the AOL of the MUCL was isometric throughout the flexion/extension arc of motion, the posterior bundle of the MUCL became elongated with elbow flexion, and demonstrated the greatest change in length from flexion to extension of all the elbow ligaments. Callaway et al. investigated the functional role of the individual MUCL bundles to valgus elbow stability. They sequentially sectioned individual bundles of cadaveric elbows and discovered the AOL contributed to valgus stability for 30-120 degrees of flexion and the posterior bundle contributed past 120 degrees. This landmark finding clarified which bundle necessitated reconstruction in cases of valgus instability. Figure A is a clinical schematic of the medial elbow. Labels A, B, and C depict the anterior, posterior, and transverse bundles of the MUCL, respectively. Incorrect Answers: Answer 1 and 3: The AOL portion of the MUCL is most important when treating valgus elbow instability. Answer 3: The MUCL (and specifically the AOL) is the predominant restraint to valgus (not varus) stress. Answer 4: The AOL (not posterior bundle) is further composed of anterior, posterior, and central bands. Answer 5: Answer choice 2 is correct, making this choice incorrect.
2.2
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