Mylène Jansen

One-year follow-up after KJD treatment with the KneeReviver 179 9 long-term results will be critical in order to fully determine the clinical effectiveness as well as tissue structure repair and non-inferiority of the KneeReviver in comparison with other devices. A clear limitation of this study is that the 2 patient groups were not randomized. In fact, almost all baseline clinical scores were significantly worse for the KneeReviver patients, which would indicate that they had a higher clinical disease activity. However, baseline radiographic JSW measurements indicate the opposite, showing less severe joint tissue damage. While the LAC JSW was statistically significantly lower in patients treated with the KneeReviver, their MAC JSW and minimum JSW were clearly higher, in case of the minimum JSW even double. Apparently, different types of patients were included in the 2 studies, with patients treated in the open prospective study with the KneeReviver experiencing more complaints but less joint damage, and those treated in the RCTs with the Dynamic Monotubes showing an opposite profile with more joint damage and less pain. The difference between complaint-driven patients in the KneeReviver group and damage-driven patients in the Monotubes group can only be speculated on. The patients treated with the Dynamic Monotubes were randomized against alternative surgical treatments with significant impact in contrast to those in the open prospective KJD study without randomization. As such, these patients may have had more advanced joint damage, despite the same inclusion criteria, enough to considered a demanding surgical treatment in regular care as alternative. It might have been that the indication TKA or HTO in the 2 RCTs has resulted in large baseline differences. However, when comparing the KneeReviver patients to the 2 groups treated with the Dynamic Monotubes (those indicated for HTO and for TKA) separately, the KneeReviver patients at baseline show in both cases more complaints (total WOMAC: KneeReviver 41.2 (SD 14.9); Monotubes from the TKA trial 50.3 (11.1); Monotubes from the HTO trial 56.5 (18.1)) and also in both cases less joint damage (minimum JSW: KneeReviver 1.0 (1.2); Monotubes from the TKA trial 0.6 (1.2); Monotubes from the HTO trial 0.5 (0.8)). So, the difference in baseline characteristics between the 2 RCTs is not explanatory, as both show the same differences compared to the patients in the KneeReviver study. The difference may be related to the gradual change in considerations of the orthopedic surgeon which patient to include changing gradually from a more tissue structure damage driven OA to a more pain driven OA, specifically for the latter without proven effective alternative treatments, in contrast to the earlier included patients where TKA or, in case of axis deviation, a HTO were good alternatives. This remarkable difference in patients characteristics between the 2 RCTs with the Dynamic Monotubes and the open prospective KneeReviver study would likely not have been introduced in case a randomized study between both devices would have been performed. However, the ethical committee of the UMC Utrecht did not allow such a direct comparison since the KneeReviver was considered and later shown to be more user friendly. 12 Long-term results might indicate whether the different type of patients included matters or not, and conclusions on the long-term