Mylène Jansen

MRI cartilage thickness up to ten years after KJD 255 13 Introduction End-stage knee osteoarthritis (OA) is often treated with a total knee arthroplasty (TKA), which generally shows improvement in knee pain and function. 1 However, in younger patients (<65 years), TKA treatment brings an increased risk of a complex and costly revision surgery later in life. 2 In these patients, a joint-preserving treatment could postpone a first TKA and possibly prevent a future revision surgery. One such joint-preserving surgical treatment is knee joint distraction (KJD). In distraction surgery, the 2 bony ends of a joint are temporarily placed at a small distance from each other by an external frame, which is fixed to the bones with bone pins. 3 KJD has been evaluated in a limited number of clinical studies, including 2 randomized controlled trials, where the treatment has shown good results comparable to those after alternative surgical treatments (TKA and high tibial osteotomy). 4–10 KJD has also been applied in regular care, where it has shown clinical improvement as well. 11 Besides clinical effects, cartilage restoration activity was demonstrated on radiographs and MRI scans, especially in the first 2 years after treatment. 12–16 The first long-term clinical analyses showed beneficial results up to 9 years after treatment, and MRI scans up to 5 years after treatment showed better results in patients treated with KJD than in untreated OA patients from the osteoarthritis initiative (OAI). 14,15 However, despite the many studies that have been performed, MRI scans have not been evaluated long-term more than 5 years after KJD. The objective of this study was to evaluate MRI cartilage thickness up to 10 years after KJD treatment, looking not only at (sub)regional cartilage thickness measurements, but primarily at the whole articular area in 3D using a surface-based approach. 17 Methods Patients Between 2006 and 2008, 20 patients with end-stage knee OA were included in an open prospective study. Inclusion criteria were age <60 years old, Visual Analogue Scale of pain ≥60 mm, radiographic signs of joint damage, and primarily tibiofemoral OA. Exclusion criteria were severe symptoms in both knees, history of inflammatory or septic arthritis, and severe malalignment (>10°). Patients were in regular care indicated for TKA surgery but treated with KJD instead because of their young age. KJD treatment was performed using an external fixation frame consisting of 2 monotubes (Stryker), fixed to the femur and tibia on the lateral and medial side of the joint with 4 pairs of bone pins. The joint was distracted 2 mm at surgery, and gradually extended by 1 mm per day over the next 3 days until 5 mm distraction was reached, confirmed radiographically. After full distraction was completed, patients were discharged from the hospital, and encouraged to load the distracted joint, using crutches if necessary. After 2 months, the frame and pins were