OP0060 Knee joint distraction compared with high tibial osteotomy and total knee arthroplasty: two-year clinical, structural, and biomarker outcomes
Authors: M. Jansen, N. Besselink, R. Van Heerwaarden, R. Custers, J.-T. Van der Woude, K. Wiegant, S. Spruijt, P. Emans, P. Van Roermund, S. Mastbergen, F. Lafeber
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Knee joint distraction (KJD) is a new joint-preserving surgery technique that, like high tibial osteotomy (HTO), aims to delay total knee arthroplasty (TKA) especially in younger patients with knee osteoarthritis (OA). One year after treatment, KJD demonstrated similar beneficial outcomes compared to HTO and compared to TKA.<sup>1 2</sup> <h3>Objectives</h3> To compare radiographic joint space width and clinical outcome over two-years for KJD vs TKA and for KJD vs HTO and to additionally study KJD cartilage repair by evaluation of systemic collagen type II markers. <h3>Methods</h3> End-stage knee OA patients considered for TKA were randomised to KJD (n=20; KJD<sub>TKA</sub>) or TKA (n=40). Medial compartmental knee OA patients with a varus deviation of &lt;10° considered for opening wedge HTO were randomised to KJD (n=23; KJD<sub>HTO</sub>) or HTO (n=46). Distraction surgery was performed by use of two external fixators with built in springs, placed lateral and medial of the knee joint. The knee was distracted 5 mm for 6 weeks and weight-bearing was encouraged. WOMAC questionnaires (100 best) and VAS pain scores (0 best) were assessed at baseline (0), 3, 6, 12, 18 and 24 months. In the KJD groups, serum PIIANP and urine CTXII levels, as markers for collagen type II synthesis and breakdown, were determined over time. Normalised Z-indexes were calculated (Z<sub>index</sub>=Z<sub>PIIANP</sub> – Z<sub>CTXII</sub>) to express net collagen type II synthesis. The minimum and mean joint space width (JSW) of the most affected compartment (MAC) were measured with KIDA software on standardised radiographs taken at 0, 12 and 24 months. <h3>Results</h3> Of the 129 included patients, 1, 6, 3, and 5 patients were lost in the KJD<sub>TKA</sub>, TKA, KJD<sub>HTO</sub>, and HTO group respectively, for various reasons. One-year structural and clinical outcomes were statistically significantly improved as reported before, and these beneficial effects sustained for at least two years after treatment when compared to baseline (figure 1A-C). At 24 months, there were no significant differences between the KJD<sub>HTO</sub> and HTO groups (all p&gt;0.25) and between the KJD<sub>TKA</sub> and TKA group, except for VAS pain score in favour of TKA at 24 months (p=0.037; figure 1B). Compared to baseline, the ratio of synthesis over breakdown of collagen type II biomarkers (figure 1D) was significantly decreased at 3 months (−0.45±0.20; p=0.032) after which this reversed towards an increase over time (at 24 months+0.59±0.19; p=0.004). <h3>Conclusions</h3> Sustained improvement of clinical benefit and increase in JSW after KJD is demonstrated for over 2 years of follow-up in case of treatment of patients with medial compartmental knee OA indicated for HTO or patients with end-stage knee OA indicated for TKA. The structural cartilage repair observed on radiographs is supported by a beneficial change in systemic biomarkers for collagen type II. For the HTO-indicated population, results of KJD patients were similar to those of HTO. For the TKA-indicated patients, TKA appeared to result in a slightly better clinical outcome, however at the expense of the native knee joint. <h3>References</h3> [1] vd Woude JA, et al. Bone Joint J2017;99-B(1):51–58. [2] vd Woude JA, et al. Knee Surg Sports Traumatol Arthrosc2017;25(3):876–886. <h3>Disclosure of Interest</h3> None declared