Sometimes, being too flexible is not a good thing. In the February 21, 2018 edition of The Journal of Bone & Joint Surgery, Kim et al. show that patients with generalized joint laxity—those who can hyperextend their knees and elbows beyond 10°, for example—tend to have poorer knee-stability and functional outcomes after anterior cruciate ligament (ACL) reconstruction than those who have normal joint flexibility.
The authors studied 8-year outcomes among 163 patients who underwent a unilateral ACL reconstruction. In all cases, the same surgeon performed the same procedure (bone-patellar tendon-bone autograft), and all patients went through the same rehab program.
In terms of graft-rupture rates and contralateral ACL rupture rates over the study period, the authors found no statistically significant differences between the 122 patients without laxity and the 41 patients who were determined preoperatively to have generalized joint laxity. However, at the 8-year follow-up, the patients with laxity had less knee stability (as measured with Lachman and pivot-shift tests and an arthrometer) and worse knee function (as measured with the Lysholm and IKDC scales) than patients without laxity.
Taken together, these findings lead Kim et al. to conclude that “generalized joint laxity should be considered a risk factor for poor outcomes after ACL reconstruction.” We also noted that JBJS Deputy Editor Robert Marx, MD (@drrmarx) remarked on Twitter that “adding lateral ITB [iliotibial band] tenodesis may be helpful for more severe cases with significant knee hyperextension.”
Click here for a two-minute video summary of this study.