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Following ACL reconstruction, knee flexion should be tested at various walking speeds
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PHILADELPHIA — Testing for knee flexion angles following ACL reconstruction typically involves patients walking at self-selected or comfortable walking speeds. However, researchers have identified important changes in the amount of knee flexion when the tests are performed at different speeds.
“Over recent years, we have had increased interest in understanding the biomechanical function of the knee following ACL reconstruction, as well as ACL injury,” Kenneth C. Lam, ScD, ATC, from A.T. Still University, said at the National Athletic Trainers’ Association 2010 Annual Meeting & Clinical Symposia, here.
Systematic manipulation of velocity
Lam and colleagues aimed to identify changes in the amount and timing of knee flexion during stance phase, more than 1 year after ACL reconstruction, using a systematic manipulation of velocity as a frame of reference.
Their study included nine patients who had undergone ACL reconstruction more than 1 year ago and 11 healthy controls.
“We started our subjects walking at 0.3 meters per second, and every minute, we increased the velocity by 0.3 meters per second. That way we captured slow walking, comfortable walking, jogging as well as running. Once they completed a single session at 2.7 meters per second, we decreased the velocity in a similar manner for a total of 17 conditions,” Lam said.
Single- vs. double-bundle surgery
At 1.2 meters per second, which Lam referred to as a comfortable walking speed, knee flexion angles and maximum knee flexions during stance phase were similar between the two groups. However, Lam stated that the ACL reconstruction group demonstrated lower flexion angles at higher speeds and higher flexion angles at lower speeds, compared with the control group.
“One of the hypotheses in terms of why they [the ACL reconstruction patients] display more knee flexion angle at the lower speed is probably because that posterior lateral bundle is not corrected during the single-bundle reconstructive surgery because they want to stay away from those last 10° of extension,” Lam told ORTHOSuperSite.com. “So, I wouldn’t suggest them changing practice; however, I would love to see the research that is going to come out in terms of the double-bundle procedure. It will be interesting to see what kind of outcomes they have and whether or not they can correct these differences.”
- Reference:
Lam KC. Identifying kinematic and coordinative changes in the lower extremities during walking and running more than one year after anterior cruciate ligament reconstructive surgery. Presented at the National Athletic Trainers’ Association 2010 Annual Meeting & Clinical Symposia. June 22-25, 2010. Philadelphia, Pa.
This study was funded by the NATA Foundation Doctoral Research Grant (2007).
