SUBCHONDRAL BONE IN OSTEOARTHRITIS OF THE KNEE

Subchondral bone changes seem to contribute to the progression of knee osteoarthritis (OA). The study aimed to analyze subchondral bone microstructure in specimens of late-stage knee OA in respect to articular cartilage damage, meniscus integrity and knee joint alignment. Methods and Materials: 30 proximal tibiae of 30 patients (20 female and 10 male) with late-stage OA retrieved during total knee arthroplasty (TKA) were scanned using a high-resolution MicroComputed Tomography (μCT). The scans were semi-automatically segmented into five volumes of interest (VOIs). The VOIs were than further analyzed using commercially available software. The degree of articular cartilage damage was assessed semi-quantitatively by magnetic resonance imaging (MRI) before surgery. Results: The mean bone fraction volume (BV/TV) in all weight bearing locations was significantly higher compared to the non weight-bearing reference point below the anterior cruciate ligament (p=0,000). The mean BV/TV in the medial compartment was significantly higher compared to the lateral compartment (p=0,007). The BV/TV in intact menisci, there was a significantly lower subchondral BV/TV compared to subluxated or luxated menisci in the medial (p=0,020) and lateral compartment (p=0,005). Varus alignment had a significantly higher subchondral BV/TV in the medial compartment, whereas valgus alignment had a significantly higher subchondral BV/TV in the lateral compartment (p=0,011). Conclusion: The results show significant differences of subchondral bone microstructural parameters in respect to cartilage damage, meniscus’ structural integrity and knee joint alignment. Therefore, subchondral bone changes seem to be a secondary process in the late-stage OA of knee caused by mechanical changes.