Biomechanical evaluation of different ankle orthoses in a simulated lateral ankle sprain in two different modes

Ankle orthoses are commonly used for prevention of recurrent ankle sprains. While there are some data on their functional performance or restriction of range of motion, there is little knowledge on the quantifiable passive mechanical effectiveness of various devices. This study aimed to determine the prophylactic stabilization effect for commonly prescribed ankle orthoses in a simulated recurrent ankle sprain. Eleven anatomic lower leg specimens were tested in plantar flexion and hindfoot inversion in a simulated ankle sprain in a quasi-static and dynamic test mode at 0.5 degrees/s and 50 degrees/s internal rotation, respectively. Tests included intact specimens, same specimens with the ruptured anterior talofibular ligament (ATFL), followed by stabilization with five different semi-rigid orthoses: AirGo Ankle Brace, Air Stirrup Ankle Brace, Dyna Ankle 50S1, MalleoLoc, and Aequi. Compared to the injured and unprotected state, two orthoses (AirGo and Air Stirrup) significantly reinforced the ankle. The Aequi ankle brace restored stability comparable to an intact joint. Dyna Ankle 50S1 and MalleoLoc provided insufficient resistance to applied internal rotation compared to the ankle with ruptured ATFL. Ankle orthoses varied significantly in their ability to stabilize the unstable ankle during an ankle sprain in both testing modes. Presented objective data on passive stabilization reveal a lack of supporting evidence for clinical application of ankle orthoses.