Despite growing evidence on the role of the posterior ulnar collateral ligament (pMUCL) in elbow stability, current ligament bracing techniques are mainly focused on the anterior ulnar collateral ligament (aMUCL).
The purpose was to biomechanically compare aMUCL bracing, Dual Bracing that addressed aMUCL as well as pMUCL, and aMUCL reconstruction. It was hypothesized that lesser joint gapping would occur after Dual Bracing in higher degrees of elbow flexion and that Dual Bracing provides equal primary valgus stability.
21 unpaired human elbows (11 right, 10 left; 57.19 ± 11.72 years) were randomized into 3 groups. Laxity testing was performed with 25 N applied 12 cm distal to the elbow joint for 30 seconds at randomized flexion angles (0°, 30°, 60°, 90°, and 120°). After assessment of the native condition the laxity test protocol was repeated for each surgical technique. A calibrated motion capture system (Vicon®) was used for assessment. Repairs were then cyclically tested through a materials testing machine (Bionix 858; MTS Systems) starting with 20 N for 200 cycles at a rate of 0.5 Hz. The load was increased stepwise by 10 N for 200 cycles until displacement reached 5.0 mm or complete failure occurred.
aMUCL bracing and Dual Bracing resulted in significantly (p = 0.045) lower joint gapping in 120° of flexion than aMUCL reconstruction. Between the surgical techniques no significant differences for valgus laxity were found. Each type of surgical repair showed no significant differences between the native and the postoperative state for valgus laxity and joint gapping. There was no significant difference between the different types of surgery for cycles to failure and failure load.
Dual bracing of the medial ulnar collateral was able to restore native valgus joint laxity and medial joint gapping. Furthermore, it was able to restore joint gapping in higher flexion significantly better than aMUCL reconstruction. Dual Bracing reached similar primary stability regarding failure outcomes.