High-resolution peripheral quantitative computed tomography (HR-PQCT) and dual energy X-ray absorptiometry (DXA) measurements of proximal tibia in patients undergoing total knee arthroplasty

Abstract

The aim of the study was to assess bone morphometric indices of the proximal tibia and compare it with bone mineral density (BMD) at hip and lumbar spine and compare with the pQCT. Fifty consecutive patients who underwent total knee arthroplasty (TKA) had a dual energy X-ray absorptiometry (DXA) scan of the upper femur and lumbar spine. Upper tibial cuts were harvested from the tibial condyles and a DXA of tibial cuts was done during TKA. Bone morphometry studies were carried out using HR-pQCT. The bone mineral density at the hip was 0.54 ± 0.08 g/cm2 and spine was 0.73 ± 0.1 with a T score at the hip -2.23 ± 0.44 and spine -2.61 ± 0.45. The bone mineral density of the tibial cut was 0.356 ± 0.03 g/cm2 (P < 0.001) and Tscore was-6.58 ± 2.87 (P < 0.001). The average bone volume (BV) was 115.27 ± 40.45 mm3, trabecular number (Tb.N) was 1.45 ± 0.32 (1.009-2.37) and trabecular thickness (Tb.Th) was 0.181 ± 0.03 mm (0.111-0.268). The mean bone mineral density measured was 206.24 ± 50.58 mg HA/ccm. This study shows that there is highly significant difference between BMD measured by DXA and pQCT, and that bone morphometric analysis indicates that there is marked decrease in the mechanical properties of the bone in the proximal tibia due to knee Osteoarthritis and Osteoporosis indicating poor bone architecture and quality.