Biomechanical Analysis of Transosseous Repair Versus Combined Transosseous With Capsular Repair for Triangular Fibrocartilage Complex Tears With Instability.

Purpose: This study compared the biomechanical stability of transosseous repair and transosseous combined with capsular repair techniques to reattach the triangular fibrocartilage complex (TFCC) for distal radioulnar joint instability.

Methods: Eight adult cadaveric upper-extremity specimens were studied. Each underwent peripheral ulnar-sided detachment of the deep and superficial TFCC fibers and repair. Four groups were prepared sequentially: intact TFCC, disrupted TFCC, transosseous repair, and combined transosseous with capsular repair. Forearm rotational torque was measured in three wrist positions: 60° flexion, neutral position, and 60° extension. Maximum dorsal and palmar ulnar translations in response to a 20-N traction load were measured at nine wrist positions after stabilizing the humerus and radius. Measurements were taken before and after TFCC disruption and following repair.

Results: Clear instability of the radius relative to the ulna was observed after sectioning the deep and superficial fibers of the TFCC, and stability was markedly improved after reconstruction in all positions. Compared with the normal group, rotational torque was similar between the two repair methods. In the pronation palmar flexion and supination dorsal extension positions, dorsal-palmar translation was smaller in the combined transosseous with capsular repair group than in the transosseous repair-alone group.

Conclusions: Triangular fibrocartilage complex deep fibers are the primary stabilizing structure of the distal radioulnar joint. In this cadaveric study, the combined transosseous with capsular repair technique demonstrated less dorsal-palmar translation compared with the transosseous-alone repair technique.

Clinical Relevance: Combined transosseous with capsular repair is expected to provide improved postoperative stability for patients with peripheral TFCC tears and distal radioulnar joint instability.