2015 ISAKOS Biennial Congress ePoster #1378
Do Functional Knee Braces Protect Critical Knee Structures in the ACL Deficient Knee?
Sebastian Tomescu, MD, Toronto, ON CANADA
Ryan Bakker, BASc, Waterloo, ON CANADA
David Wasserstein, MD, MSc, FRCSC, Toronto, ON CANADA
Jaskarndip Chahal, MD FRCSC, Toronto, ON CANADA
Naveen Chandrashekar, PhD, Waterloo, ON CANADA
Paul H. Marks, BA, MD, FRCSC, Toronto, ON CANADA
University of Waterloo, Waterloo, Ontario, CANADA
FDA Status Not Applicable
Summary: Functional knee braces can have a protective effect on the medial meniscus and articular cartilage in the ACL deficient knee during athletic maneuvers.
Anterior Cruciate Ligament (ACL) injury is one of the most common knee sport injuries. Many patients elect not to undergo reconstruction and have successful short term outcomes with rehabilitation alone. The natural history of ACL deficient knees often involves repeated instability leading to meniscal injury and arthritic changes. Thus, cartilage preservation through prevention of further injury is a key treatment goal for patients with ACL injuries.
One commonly prescribed non-operative treatment for ACL deficient patients to facilitate return to sport, or for those who are awaiting surgery, is a Functional Knee Brace (FKB). Although FKBs have been shown to reduce subjective instability, no data exists to demonstrate whether they prevent further meniscal and articular cartilage injury. The aim of this study was to use a cadaver-based dynamic knee simulator to determine the effectiveness of bracing at reducing meniscal strain and cartilage pressure in the ACL deficient knee during a common athletic movement.
A combined in-vivo/in-vitro approach was used to capture an amateur athlete performing a jump-landing maneuver and replicate the motion and muscle forces on an instrumented cadaver knee.
The brace was mounted on top of a foam mold made prior to dissecting the specimen. The specimen was tested under three conditions: ACL intact, unbraced ACL deficient, and braced ACL deficient. Three trials were repeated for each condition. Meniscal strain was measured with a DVRT sensor inserted in the posterior horn of the medial meniscus, and articular contact pressure was measured with a Tekscan pressure sensor placed in the medial tibiofemoral joint.
The peak meniscal strain in the ACL intact condition was 3.17%. Sectioning the ACL led to a more than double increase in strain to 7.81%. Following application of the brace, the strain decreased to 3.81%. The peak contact pressure in the braced, ACL deficient condition was 13.3% lower than in the unbraced, ACL deficient condition. Lastly, the center for force on the tibial plateau translated 5 mm further posteriorly with the ACL cut, but only 3 mm while braced.
While the conclusions of these tests are limited by the use of a single cadaver, the results suggest that functional knee braces can have a protective effect on the medial meniscus and articular cartilage in the ACL deficient knee. The brace decreased meniscal strain and articular pressure, and provided increased stability by limiting translation of the center of force. Further testing with a larger sample size will help confirm these preliminary results.