Biomechanical Analysis of Internal Bracing for Treatment of Medial Knee Injuries.

ABSTRACT

The internal brace technique uses a high-strength suture tie to augment injured tissues or a primary repair, allowing early rehabilitation. Anatomic repair with internal bracing is a novel and promising treatment for femoral-sided medial knee avulsion injuries of the medial collateral ligament and posterior oblique ligament. Unfortunately, biomechanical and clinical data are lacking. To evaluate this technique compared with other treatment options, 3 assays of 9 cadaveric matched pairs (54 knees) were tested to failure at 30° under valgus load in a biomechanical testing apparatus. The primary outcome measure was moment at failure (Nm), with secondary outcome measures of stiffness (Nm/°), valgus angulation at 10 Nm (°), and valgus angulation at failure (°). Repair with internal bracing was compared with the intact state, repair alone, and allograft reconstruction. The mean moment to failure (62.5±24.9 Nm) for internal bracing was significantly lower than that for intact specimens (107.2±39.7 Nm) (P=.009). Mean moment to failure and valgus angle at failure were significantly greater for internal bracing (95±31.9 Nm) than for repair (73.4±27.6 Nm) (P=.05). Internal bracing was similar to reconstruction for the primary outcome measure (53.5±26.3 Nm vs 66.9±28.8 Nm) (P=.227) and for all secondary outcome measures. These findings indicate that posteromedial knee repair with internal bracing for femoral-sided avulsions is superior to repair alone and is similar to allograft reconstruction for all parameters measured; however, this technique did not recreate biomechanical properties equivalent to the intact state. [Orthopedics. 2016; 39(3)e532-e537.].