Mylène Jansen

Systematic review and meta-analysis of KJD as treatment for OA 33 2 Discussion Overall, this review shows that KJD induces cartilaginous tissue regeneration and clinical improvement on short and intermediate-long term. The effect sizes are large, so the small patient number is sufficient to demonstrate effects. The various clinical outcome measures showed similar results, as did the structural outcomes. The total number of patients is still limited, especially for long-term data, available in only 1 patient cohort. It is shown that prolonged treatment effect results in 75% of patients after 5 years and half of patients after 9 years still not undergoing TKA. 18 This implicates a clear reduction in survival over the long term. Longer follow-up is necessary to evaluate whether successfully postponing this first TKA over a sufficient period of time can indeed prevent a revision TKA as intended and reduce healthcare costs. 3 KJD provides cartilaginous tissue repair demonstrated by radiographs and MRI, results that are supported by biochemical marker studies that showed a net increase in systemic collagen type II markers and by large animal in vivo studies. 20,24 First-year post-treatment structural benefit, male sex and more severe OA before treatment seem predictive for long-term benefit (survival). 18,25 Also for ankle distraction male sex favored clinical outcome. 26 In contrast, young males perform less well after TKA compared to older females. 2 Young active males with severe damage might provide a more specific indication for KJD, although future cohorts and registries should confirm this. Despite promising outcomes, KJD should not be perceived as an easy treatment for patients. The knee is immobilized for 6 weeks, and there is a high risk of pin tract skin infections. It is of importance that methods are found to decrease this risk as these can result in osteomyelitis, lead to significant use of oral antibiotics, and have a great impact on patients burden. However, these infections do not seem to cause problems for future TKA. Wiegant et al. showed that TKA years after KJD did not result in extra complications whereas clinical benefit was not different from matched TKA patients without prior KJD. 27 Future studies to reduce pin tract infection rates are needed, and preliminary results seem to make this feasible. 28 Apart from pin tract infections there were not many complications, but the few that did occur were relatively serious. While the number of complications after KJD besides pin tract infections was not that different than those in the control groups HTO and TKA, it is of importance to keep monitoring complications after KJD in larger studies and when introduced in regular care. The included studies used different distraction periods (4 – 12 weeks). What effects this difference has and what period is ideal, is not known with certainty. No statistically significant difference between 6 and 8 weeks of distraction was observed, although at 6 weeks the benefit was slightly less. 29 This resulted in a 6-week distraction chosen for regular care. 12