Mylène Jansen

192 Chapter 10 the Dynamic Monotubes, the first-year results reported in 2017. In one RCT, 22 medial compartmental OA patients indicated for high tibial osteotomy (HTO) were treated with KJD and compared with HTO treatment. 24 In another RCT, 20 OA patients indicated for total knee arthroplasty (TKA) were treated with the same type of 6-week distraction and compared with TKA treatment. 26 Both studies showed clinical improvement and tissue structure repair upon KJD. Lastly, a retrospective study on 84 OA patients treated with distraction in regular care using the Dynamic Monotubes was published in 2020. 13 Of 41 of these patients patient- reported outcome measures (PROMs) were available one year after treatment and showed also in regular care a clear improvement. Most recently a prospective study was started, in which 65 patients were treated with distraction using the KneeReviver frame (ArthroSave) and will be followed for 5 years. A preliminary analysis showed that the first 39 patients reaching one year of follow-up showed significant improvement in clinical parameters and tissue structure repair, which was generally shown to be comparable and non-inferior to results obtained with 39 patients treated with the Dynamic Monotubes (personal observation based upon interim analyses). 27 Lastly, in the UK a national multicenter study (KARDS) initiated by the NIHS, in which 344 patients will be randomized in a 1:1 ratio to KJD or knee arthroplasty using different distraction devices, has started 2021 (personal communication with Prof H Pandit, Leeds, United Kingdom). Throughout the studies, different distraction techniques and postoperative rehabilitation protocols (if imposed) were used. Only Deie et al. and Abouheif et al. used hinged distraction, allowing flexion and extension of the knee joint, and continuous passive motion was applied for two weeks after placement of the distraction device. 14,19 All other studies used distraction frames that did not allow joint flexion, although in the study of Intema et al. the frame was removed every two weeks and continuous passive motion was applied for 3-4 hours, after which the frame was replaced and distraction was installed again. 21 In this study the clinical effects and tissue structure repair were slightly better than in the following RCTs. 28 This could have been related to the flexion (see below), although also the baseline characteristics and the total distraction duration differed between these studies. It should be noticed that for the knee also a personalized hinged device was developed and mechanically approved feasible 29 ; however, clinical feasibility could not be demonstrated, mainly due to painful motion of soft tissues along the bone pins. 30 The distraction duration varied from 4 weeks to 3 months. 15,19 The distraction distance, i.e. the number of millimeters the bones are separated, was not clearly described by Deie et al. and Abouheif et al. , while Aly et al. described a distraction of one mm/day for four weeks. All other KJD studies used a fixed distance of 5 mm. However, it remains unclear how this distance was exactly measured, e.g. bone to bone distance or increase above the original bone to bone distance. Also, correction of the mechanical leg axis has been performed during distraction, providing more distance at either side in case of predominantly