Mylène Jansen

398 Chapter 19 Summary In a population with a steadily increasing life expectancy that prefers to stay active at on older age, the ability to postpone a unilateral or total knee arthroplasty (UKA/TKA) in case of knee osteoarthritis (OA) as long as possible is becoming increasingly valuable. 1 Ideally, this is done with a joint-preserving treatment that not only improves patients’ symptoms such as pain and stiffness, but is also able to actually modify tissue structure. As described in several previous PhD theses and many scientific publications, joint distraction in general and knee joint distraction (KJD) treatment more recently have the potential to provide clinical improvement as well as tissue structure modification. 2–9 The aim of the present thesis was to move forward with KJD as a treatment for relatively young knee osteoarthritis (OA) patients. These next steps are taken in 2 parts: I) evaluating newly available clinical outcome and improving treatment-related patient experience and II) elucidating the working mechanisms behind KJD and the joint processes that occur as a result of this treatment. Part I: Clinical outcome and patient experience Since the first scientific report on applying KJD to treat knee OA in 2007 10 , several clinical studies have been performed in multiple medical centers world-wide. To collectively assess all relevant outcome data available, a systematic review of all clinical studies evaluating at least 1 of the predefined primary outcome parameters was performed and results were combined in a meta-analysis, as described in chapter 2 . In total, 127 patients from 7 different studies were evaluated, and significant improvements in all primary parameters were found, comparable with control groups when used. However, this came along with frequently observed pin tract infections. While it was concluded that longer follow-up with more patients is necessary, the evidence showed KJD causes clear benefit, both short- and long-term. Attention for improving treatment indication was also considered important. The first long-term results after KJD were highlighted in more detail in chapter 3 , describing outcome and clinical success up to 9 years after treatment of 20 patients originally treated in the Netherlands. Half of the patients still had not undergone arthroplasty surgery after 9 years, despite being originally indicated for TKA. Interestingly, in male patients this was even more than 2 out of three. Patients who had not undergone additional surgery still showed significantly improved clinical and structural (radiographic joint space width; JSW) outcomes 9 years after treatment. Even in those who did receive TKA, clinical outcome was still significantly improved in the year prior. Interestingly, initial (first-year) cartilage repair activity appeared to be important for long-term (9-year) clinical success. In order to compare KJD to alternative surgical treatments, chapter 4 evaluated clinical and tissue structure benefit up to 2 years after KJD, TKA and high tibial osteotomy (HTO), in patients treated in 2 separate randomized controlled trials (RCTs). All treatments showed