Tibial plateau 3D bone microarchitecture: links to in vivo joint loads in end-stage knee osteoarthritis — ASN Events
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Tibial plateau 3D bone microarchitecture: links to in vivo joint loads in end-stage knee osteoarthritis (#194)

Egon Perilli 1 , Bryant C Roberts 1 , Dominic Thewlis 2 , Bogdan Solomon 3 , Graham Mercer 4 , Karen J Reynolds 1
  1. The Medical Device Research Institute, School of Computer Science, Engineering & Mathematics, Flinders University, Adelaide, SA, Australia
  2. School of Health Sciences, University of South Australia, Adelaide, SA, Australia
  3. Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, SA, Australia
  4. Department of Orthopaedic Surgery, Repatriation General Hospital, Adelaide, SA, Australia

Introduction:

This ongoing study aims to examine, on end-stage knee osteoarthritis (OA) patients, 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).

Materials&Methods:

Twenty-five knee-OA patients (age 68±7 years, mean±SD) underwent pre-operative walking gait analysis: peak external (ERM) rotation moment, knee adduction moment (KAM) and mechanical axis deviation (MAD) 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, and compared among them. Relationships between gait measurements and subregional bone microarchitecture were examined. 

Results:

The four anatomical subregions differed significantly in tibial subchondral bone microarchitecture (p<0.05): antero-medial followed by postero-medial, exhibited highest BV/TV (up to +75% and +43%, respectively), trabecular number, trabecular thickness and lowest SMI, compared to other subregions. The BV/TV correlated negatively and the SMI positively with the peak ERM, in particular in the antero-medial (r=-0.74, p<0.01, r=0.67, p<0.01) and postero-medial (r=-0.55, p<0.01, r=0.53, p<0.01) condyles. Medial:lateral BV/TV ratio was significantly associated with ERM, KAM and MAD (r=-0.74, r=-0.60 and r=0.74, p<0.01).

Discussion:

This study is the first examining relationships between joint loading in vivo and knee bone microarchitecture, on the same patient. Our findings 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 mechanical stresses in this condyle. Analysis is ongoing and if confirmed, gait analysis parameters could be suggested as non-invasive indicators of disease progression.