Knee joint distraction (KJD) is a surgical joint-preserving treatment in which the knee joint is temporarily distracted by an external frame. It is associated with joint tissue repair and clinical improvement. Initially, patients were submitted to an eight-week distraction period, and currently patients are submitted to a six-week distraction period. This study evaluates whether a shorter distraction period influences the outcome.
Both groups consisted of 20 patients. Clinical outcome was assessed by WOMAC questionnaires and VAS-pain. Cartilaginous tissue repair was assessed by radiographic joint space width (JSW) and MRI-observed cartilage thickness.
Baseline data between both groups were comparable. Both groups showed an increase in total WOMAC score; 24 ± 4 in the six-week group and 32 ± 5 in the eight-week group (both p < 0.001). Mean JSW increased 0.9 ± 0.3 mm in the six-week group and 1.1 ± 0.3 mm in the eight-week group (p = 0.729 between groups). The increase in mean cartilage thickness on MRI was 0.6 ± 0.2 mm in the eight-week group and 0.4 ± 0.1 mm in the six-week group (p = 0.277).
A shorter distraction period does not influence short-term clinical and structural outcomes statistically significantly, although effect sizes tend to be smaller in six week KJD as compared to eight week KJD.