Factors That Determine Supination Strength Following Distal Biceps Repair

Abstract

Supination weakness commonly occurs after a distal biceps repair. The goal of this study was to identify factors that could influence postoperative supination strength through a full arc of forearm rotation. Fifteen patients were prospectively studied and underwent a biceps repair using a posterior approach; this cohort was compared with a randomized selection of 17 anterior repair subjects. All patients underwent postoperative magnetic resonance imaging (MRI). Quantitative MRI analysis determined the insertion site angle of the tendon and supinator fat content. Supination strength was measured in 3 forearm positions. A multiple linear regression analysis was performed to determine the effect of all factors on supination strength. The anterior group had a significantly higher nonanatomic insertion site angle of the tendon than the control group and the posterior group (p < 0.001). The posterior group had significantly greater supinator fat content (p ≤ 0.019) than both the control group and the anterior group. After repair, the posterior group had significantly greater supination strength than the anterior group (p = 0.027). Multiple regression analysis (r = 0.765) found that an anatomic reinsertion of the ruptured tendon (β = 1.159; p < 0.001), posterior approach (β = 0.484; p = 0.043), and limited supinator muscle fat content (β = 0.360; p = 0.013) were significant predictors of the restoration of supination strength in 60° of supination. Future directions for distal biceps tendon repair techniques should focus on restoring an anatomic reattachment site while limiting supinator damage. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.