Mylène Jansen

Summary and general discussion 405 19 insufficient for KJDto be eligible for reimbursement. 28 Specifically, they couldnot concludewith enough certainty whether KJD is non-inferior to TKA with respect to clinical outcome because of limited number of treated patients, and whether KJD can sufficiently long postponement a TKA, because of insufficiently long follow-up data available. As the latter takes years to even decades to proof, it can only be addressed as more patients, including those from the previous prospective and RCT studies, reach longer follow-up. Additionally, it is important that more trials are performed, ideally comparing KJD to (T)KA, to increase numbers of treated patients. Further follow-up in the RCTs ( chapter 4 ) and the currently ongoing prospective study evaluating results after treatment with the KneeReviver ( chapter 9 ) will add long-term data of more than 100 additional patients. In the UK a new multicenter RCT comparing KJD with (T)KA, financed by the NHS, is currently recruiting patients, eventually treating 344 patients with KJD or (T)KA in a 1:1 ratio, providing direct comparison with (T)KA in a relatively large group of patients. 29 For the Netherlands, a funding request specifically meant to provide the data to enable reimbursement by the NZa was submitted. This involves a multicenter RCT in which 1200 patients are randomized (1:1) to treatment with either KJD or (TK)A. As such, it can be expected that in the forthcoming years (decade), more data will become available on whether KJD is indeed non-inferior with respect to clinical outcome after (T)KA and provides sufficiently long postponement of a first (T)KA. This will provide the required information to enable reimbursement and with that foundation for implementation in regular care. An important point of discussion in both of these RCTs and the process of obtaining reimbursement, however, is whether KJD even has to be non-inferior in clinical outcome compared to (T)KA. KJD is not meant to be an alternative to TKA, but instead is meant to postpone it (see Figure 1). In fact, KJD should only be used in younger (<65 years) patients for whom TKA would bring an increased risk of revision surgery later in life. 24 KJD is in that perspective more comparable to UKA. KJD could even precede a UKA before undergoing TKA, worthwhile especially since receiving UKA at a younger age increases the chance for revision as well. 30 Evidently, defining when KJD treatment is successful (enough) is difficult, but important to evaluate soundly and robustly. In the end, KJD is an invasive treatment with a relative heavy burden for patients, even after efforts to reduce this burden ( chapter 7 and chapter 8 ). Ensuring the highest chance of treatment success is vital, and can perhaps only be done by improving patient selection. For this, not only larger number of treated patients with longer follow-up is needed, but also better understanding of the working mechanisms. Moving forward with KJD can only happen by improving our understanding of the different processes taking place in the osteoarthritic joint before, during, and after treatment. KJD might be explained simply as unloading that stimulates regeneration of cartilage that, before treatment, had degenerated as a result of overloading. This is an oversimplification leaving out important aspects of the treatment ( chapter 10 ), such as SF pressure oscillation purposefully induced by resilience in the frame, or even the possible effect of drilling pins in the femur