Mylène Jansen

74 Chapter 4 with TKA and with HTO, a prospective uncontrolled study has evaluated outcomes of 20 patients indicated for TKA that were treated with KJD. 8–10 The 2-year clinical results were comparable with the 2 years follow-up data from this study and in particular with the KJD TKA group, which is expected since the 20 patients in the uncontrolled study were indicated for a TKA as well. Given the similar pattern in the first 2 years of the prospective study, the continued clinical benefit that was found up to 5 years 10 and even 9 years 22 after treatment should become evident in the follow-up of the current RCTs as well. Despite the fact that TKA shows better clinical benefit, 12 patients (age range 52 – 86 years) with varied clinical history attended a ‘patient partners’ meeting and were informed on the difference in clinical outcome between KJD and TKA. They were asked if, with KJD not giving as much pain reduction as TKA, they would still consider KJD over a tried and tested TKA procedure. Patients said that retaining their own knee was of utmost importance and they would choose KJD over TKA (prof Pandit H, orthopedic surgeon, University of Leeds, personal communication March 2018). The clinical and structural benefit at 2 years corresponds with a significantly increased net collagen type II synthesis, which suggests formation of (hyaline) cartilage. The increase in collagen type II synthesis at 2 years is caused by significantly increased levels of PIIANP, while the synthesis decrease seen at 3 months is the result of a significant initial increase in CTXII. It is important to keep in mind that while CTXII is a cartilage breakdown marker, it is also a marker for (subchondral) bone turnover. Subchondral bone density decrease and bone normalization have been shown after distraction of the knee and the ankle, and the initial increase in CTXII could be a result of this bone remodeling process as well, alone or in combination with cartilage breakdown. 9,23 The repair of hyaline cartilage upon KJD is supported by canine in vivo studies demonstrating beneficial changes in proteoglycan and collagen turnover. 24 Moreover, beneficial changes regarding proteoglycan content in these canine studies is supported by recent dGEMRIC evaluation in clinical KJD studies. 25 A clear limitation of this study is the limited amount of patients in both trials, which were powered only for a non-inferiority study between the 2 patients groups. However, this is thus far the largest group of KJD patients followed over time and the results presented here clearly warrant further research with a bigger amount of patients. In conclusion, evidence up to 2 years suggests KJD can be considered a valid alternative to HTO in knee OA patients with (<10°) varus malalignment and a method to postpone primary total knee arthroplasty, potentially preventing revision surgery later in life. While future follow-up of these patients will provide additional insight into long term follow- up, the results presented in this study indicate KJD is a clinically useful joint-preserving strategy for relatively young patients with knee OA.