Morphological Features of the Ulnar Collateral Ligament of the Elbow and Common Tendon of Flexor-Pronator Muscles

Morphologic analysis of the sublime tubercle: considerations in the approach to ulnar collateral ligament reconstruction

Background

Given the increased incidence of ulnar collateral ligament (UCL) injuries and the projected increase in reconstruction procedures, a robust understanding of the morphologic location of the sublime tubercle is paramount to anatomic reconstruction. There is limited research evaluating the morphology of the sublime tubercle of the proximal ulna in an anterior-to-posterior plane.

Methods

Twenty-five computed tomography (CT) scans of intact proximal elbow joints for patients were selected using a de-identified database. Cases with history of fracture or surgical intervention to the elbow joint were excluded. These CT scans were then imported into the Mimics Innovation Suite 24.0 software to analyze the sublime tubercle angle from the midpoint of the trochlear notch. All left elbow angle and clock-face values were converted to right elbow values for analysis.

Results

The average sublime tubercle angle from the midpoint of the trochlear notch was 282.53 degrees. The angle was converted to a clock face descriptor which located the sublime tubercle at 9.42. Our findings demonstrate that, in the non-throwing population, the morphology of the sublime tubercle can be expected to have a consistent medial location between 9 and 10 o'clock or 2 and 3 o'clock on the contralateral elbow.

Conclusions

In relation to the proximal ulnar landmarks, the sublime tubercle, in the non-throwing population, has a consistent relative location.

Elbow valgus stability of the transverse bundle of the ulnar collateral ligament

Background

The purpose of this study was to clarify elbow valgus stability of the transverse bundle (TB). We hypothesized that the transverse bundle is involved in elbow valgus stability.

Methods

Twelve elbows of six Japanese Thiel-embalmed cadavers were evaluated. The skin, subcutaneous tissue and origin of forearm flexors were removed from about 5 cm proximal to the elbow to about 5 cm distal to the elbow, and the ulnar collateral ligament was dissected (intact state). The cut state was defined as the state when the TB was cut in the middle. The joint space of the humeroulnar joint (JS) was measured in the intact state and then in the cut state. With the elbow flexed to 30°, elbow valgus stress was gradually increased to 30, 60 N using the Telos Stress Device, and the JS was measured by ultrasonography under each load condition. Paired t-testing was performed to compare the JS between the intact and cut states under each load.

Results

No significant difference in JS was identified between the intact and cut state at start limb position. The JS was significantly higher in the cut state than in the intact state at both 30 N and 60 N.

Conclusion

The findings from this study suggested that the TB may be involved in elbow valgus stability.

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.

The Effects of Differences in the Morphologies of the Ulnar Collateral Ligament and Common Tendon of the Flexor-Pronator Muscles on Elbow Valgus Braking Function: A Simulation Study

The anterior bundle (AB) and posterior bundle (PB) of the ulnar collateral ligament and the anterior common tendon (ACT) and posterior common tendon (PCT) of the flexor-pronator muscles have an independent form and an unclear form. The purpose of this study was to clarify the effect of differences in the morphologies of the AB, PB, ACT, and PCT on the elbow valgus braking function. This investigation examined three elbows. In the classification method, the AB, PB, ACT, and PCT with independent forms constituted Group I; the AB, ACT, and PCT with independent forms and the PB with an unclear form constituted Group II; the AB, PB, ACT, and PCT with unclear forms constituted Group III. The strains were calculated by simulation during elbow flexion at valgus at 0° and 10°. At 0° valgus, Group I and Group II showed similar AB and PCT strain patterns, but Group III was different. At 10° valgus, most ligaments and tendons were taut with increasing valgus angle. The average strain patterns of all ligaments and tendons were similar for the groups. The AB, PB, ACT, and PCT may cooperate with each other to contribute to valgus braking.