Background In osteoarthritis knee joint distraction (KJD) provides clinical benefit and tissue structure modification at 1 year and beyond. During the previous regime of an 8-week distraction period patients visited every 2 weeks day care practice for temporarily removal of the distraction frame. 8 weeks of intermittent KJD with frequent hospital visits is perceived as a considerable burden. This study evaluates whether 6 weeks of continuous KJD gives similar tissue structure repair and clinical benefit compared to eight weeks of KJD at 1-year follow-up.
Methods Both groups consisted of 20 patients with knee OA and were treated with 5 mm joint distraction by use of an external fixator for 8 weeks with every 2 weeks CPM or 6 weeks continuously. WOMAC questionnaires were assessed, representing the clinical outcome. Structural outcome was quantified as mean joint space width (JSW) on standardized semi-flexed x-rays at baseline and one-year of follow-up using KIDA. T-tests were applied to analyze change over time.
Results Clinical improvement compared to baseline (BL) was observed in both groups. The 6-week group showed a comparable increase from 53±17 points at BL to 76±17 points at one-year follow up (p<0.001) as the 8-week group (from 45±16 points at BL to 77±21 points at the 1-year follow-up; p<0.001). The structural parameters revealed parallel improvements between both groups. The mean JSW of the most affected compartment of the six-week group increased from 1.80±1.61mm to 2.86±1.59mm at 1 year (p=0.001) vs. 2.63±1.62mm to 3.55±0.99mm at 1 year (p=0.006) for the 8-week group. No significant statistical difference between the two groups (p=0.729) was observed.
Conclusions Six weeks of continuous KJD gives significant clinical and structural improvement. Moreover, 6-weeks of continuous distraction treatment does not lead to a stiffer knee in comparison with the “intermittent” 8-week treatment.
Acknowledgements ZonMw (The Netherlands Organisation for Health Research and Development) and the Dutch Arthritis Association support this study.
Disclosure of Interest None declared