Anterior cruciate ligament functional brace use in sports.

The routine use of functional knee braces in the anterior cruciate ligament-deficient, injured, or reconstructed knee, lacks biomechanical support. Although subjective reports favoring bracing are plentiful, objective proof of significant control of tibial translation is not. This in vivo study was designed to assess the effect of six popular braces on anterior tibial translation, isokinetic performance, and neuromuscular function in five chronically unstable anterior cruciate ligament-deficient knees. A knee stress test was performed on a specially designed device that allowed free tibial movement while monitoring anterior tibial translation and muscle function in the quadriceps, hamstring, and gastrocnemius muscles. Results show that braces can decrease anterior tibial translation between 28.8% and 39.1% without the stabilizing contractions of the hamstring, quadriceps, and gastrocnemius muscles. With lower extremity muscle activation and bracing, anterior tibial translation was decreased between 69.8% and 84.9%. Some improvement in spinal level muscle reaction times was seen with brace use, especially in the quadriceps muscle. Unfortunately, most braces appear to consistently slow hamstring muscle reaction times at the voluntary level.