Mylène Jansen

194 Chapter 10 of the SF-36 did not show any change. A few studies compared KJD with control groups. Aly et al. compared 19 patients treated with KJD and debridement with 42 patients treated with debridement alone. Contrary to KJD patients, those treated with debridement alone did not show a significant improvement in pain or walking capacity. 15 In the KJD vs HTO RCT, 22 KJD patients were compared with 45 HTO patients, and results were generally comparable between the two groups. 24,25 Return to sports and work five years after treatment was comparable between the groups as well. 34 In the other RCT, 20 KJD patients were compared with 36 TKA patients. While after one year there were no significant differences between the two groups, the patients treated with TKA after 2 years showed significantly better results than the KJD patients in almost all PROMs. 25,26 TKA is generally accepted as a treatment that results in highly significant improvements in PROMs, however, because of wear and tear and loosening of the prosthesis a revision surgery later in life may be needed. The odds of needing this revision are much higher in younger patients, aged <65 years, who show a lifetime risk of revision between 15 and 35%, compared to older patients with a lifetime risk of on average ~5%. 35 Therefore, it is specifically this population of relatively young and still active patients that is indicated for KJD. The average age in all studies fits this consideration (Table 1), although not much data is present on the effects of KJD in the older population. Also, a repeated KJD treatment with several years interval has for the knee never been studied, although this was anecdotally found to be effective for the ankle in case of a second distraction. Cartilaginous tissue restoration The most evaluated parameter for cartilage restoration was radiographic joint space width (JSW), measured on weight-bearing radiographs, as a surrogate measure for cartilage thickness change. While Abouheif et al. only mentions joint space preservation after 4.5 years 19 , the other studies quantified this by measuring the mean or minimum JSW. 14–16,21–26 All studies showed a group average increase in JSW measurements after KJD treatment, at all measured time points, and almost all were statistically significant. The largest increase was seen in the study by Aly et al. , who measured a 2.5 mm average JSW pre-treatment and 4.3 mm at 5.5 years post-treatment. 15 The studies that evaluated multiple time points all showed the same general pattern: an initial significant one-year increase in JSW of around 0.5-1.0 mm, sustaining at a similar level over the second year of follow-up. 21,22,24–26 The first-year increase in minimum JSW was reported in a post-hoc analysis to predict long-term survival of KJD treatment to postpone TKA. 23 At five and seven years after treatment, the JSW was still increased compared to baseline, statistically significantly in case of the minimum JSW but not the mean JSW of the most affected compartment. 16,23 Apparently, the advantage of the initial one- to two-year increase in JSW is maintained, despite the fact that natural OA progression is taking over again.