The aim of this ongoing study is to examine, on end-stage knee osteoarthritis (OA) patients, the relationships between knee joint loads measured in vivo using gait analysis prior to knee replacement surgery, and the 3D bone microarchitecture of their excised tibial plateau quantified with micro-computed tomography (micro-CT).
Twenty-three knee-OA patients (age 67±7 years, mean±SD) underwent pre-operative walking gait analysis: peak external (ERM) and internal rotation moments, knee adduction moment (KAM) and tibio-femoral joint contact force were determined. After surgery, their entire tibial plateaus were retrieved and scanned with micro-CT (17 µm/pixel): subchondral bone 3D microarchitecture (bone volume fraction (BV/TV), trabecular thickness, trabecular number and structure model index (SMI)) was analysed in four subregions, in antero-medial, antero-lateral, postero-medial and postero-lateral condyles. Subregional bone microarchitecture differences, and correlations between gait measurements and bone microarchitecture, were examined.
The subchondral bone microarchitecture differed significantly among the four knee subregions (p<0.05): antero-medially, highest BV/TV (up to +89%), trabecular number (+51%), trabecular thickness (+27%), and lowest SMI (-67%) were found, compared to other subregions. The BV/TV correlated negatively and the SMI positively with the peak ERM, in particular in the antero-medial (r=-0.81, p<0.01, r=0.79, p<0.01) and postero-medial (r=-0.79, p<0.01, r=0.56, p<0.01) condyles. The BV/TV Medial:Lateral ratio was significantly associated with KAM (r=-0.57, p<0.01).
This is the first study examining relationships between joint loading in vivo and knee bone microarchitecture, on the same patient. Our results suggest that in knee-OA, during stance, peak ERM is significantly correlated with subchondral BV/TV in the antero-medial and postero-medial tibial plateau, the anatomical locations where BV/TV was highest. This could be linked to microstructural bone adaptation to altered loading patterns that generate increased stresses in this condyle. Analysis is ongoing and if confirmed, ERM could be suggested as a non-invasive indicator of disease progression.