05-19-2022, 12:18 PM
(05-18-2022, 06:05 PM)jabor Wrote:
- I certainly appreciate your very reasonable viewpoint to look at the studies currently available
, which clearly showed no consensus. Just an FYI, I had googled and read the summaries of a few studies before I posted and sided with wearing a brace.
- In my mind, the benefit is not protecting the knee from the full weight of a 300 lb guy falling on it; I don't know if that's how most knee injuries occur. I am more interested in reducing stress at the limits of the knee, especially if it's been injured before.
- As for relying on team Drs... I'm absolutely fine with that. However, don't be that person (NOT "you" specifically) who bitches and questions the medical team's treatment and recovery strategy when an injury occurs/recurs because those damn Drs "obviously" let that player come back too soon
Yes, no consensus. As in no consensus bracing prevents ACL tears. If they prevented ACL tears, then there would be a consensus.
To understand why there isn't a consensus you need to understand the mechanism of injury that causes an ACL tear. Then you can understand how the brace can stabilize the knee. And also, how the brace can't.
Mechanism of ACL Tear : Wheeless' Textbook of Orthopaedics (wheelessonline.com)
Quote: - ACL tears most often occur during football and basketball in younger patients, and occur most often from skiing injuries in older patients;
- substantial anterior tibial shear forces that stress ACL are produced from quadriceps contraction, esp in 0-30 deg of extension;
- typically, the ACL is torn in a noncontact deceleration situation that produces a valgus twisting injury;
- this usually occurs when the athlete lands on the leg and quickly pivots in the opposite direction. (see pivot shift)
- mechanisms reported as possibly able to disrupt ACL w/ minimal injury to other structures are:
- extension or hyperextension
- marked internal rotation of tibia on femur (may be most important);
- pure deceleration
- valgus position
The ACL prevents the tibia from sliding forward past the femur (translation) and stabilizes rotation. When an athlete changes direction suddenly they decelerate and plant their outside foot this creates shear forces in that tibial translation plane. They are also going to rotate their upper body towards the new direction which causes shear forces in that rotational plane. The femur and tibia are going in two opposite directions in two different planes. Functional ACL bracing might help stabilize translation if it doesn't slip at all. But they do very little to stabilize rotation. If you can't prevent over rotation, you can't prevent an ACL tear. And 0-30 degrees of knee extension is normal range of motion.
Test it yourself. Go get yourself a cheap hinged knee brace and put it on correctly. Bend your knee slightly. Without putting weight on that leg try rotating your foot in and out. If you can rotate your foot, you can tear your ACL. Or just stand on the one leg which is braced. Turn you upper body left and right. If you can rotate your body that brace can't prevent a twisting injury to the knee.
