Prediction of cartilaginous tissue repair after knee joint distraction

For young patients (<65years), knee joint distraction (KJD) may be a joint-saving treatment option for end-stage knee osteoarthritis. Distracting the femur from the tibia by five millimeters for six to eight weeks using an external fixation frame results in cartilaginous tissue repair, in addition to clinical benefits. This study is a first attempt to predict the degree of cartilaginous tissue repair after KJD.

Fifty-seven consecutive patients received KJD. At baseline and at one year of follow-up, mean and minimum joint space width (JSW) of the most-affected compartment was determined on standardized radiographs. To evaluate the predictive ability of baseline characteristics for JSW at one year of follow-up, multivariable linear regression analysis was performed.

Mean JSW±SD of the most affected compartment increased by 0.95±1.23mm to 3.08±1.43mm at one year (P<0.001). The minimum JSW increased by 0.94±1.03mm to 1.63±1.21mm at one year of follow-up (P<0.001). For a larger mean JSW one year after KJD, only Kellgren & Lawrence grade (KLG) at baseline was predictive (Regression coefficient (β)=0.47, 95% CI=0.18 to 0.77, P=0.002). For a larger minimum JSW, KLG (β=0.46, 95% CI=0.19 to 0.73, P=0.001) and male gender (β=0.52, 95% CI=0.06 to 0.99, P=0.028) were statistically predictive. Eight weeks of distraction time neared significance (β=0.44, 95% CI=-0.05 to 0.93, P=0.080).

In our cohort of patients treated with KJD, males with higher KLG had the best chance of cartilaginous tissue repair by distraction.