Association between knee alignment, osteoarthritis disease severity, and subchondral trabecular bone microarchitecture in patients with knee osteoarthritis: a cross-sectional study

Abstract

Background: Knee osteoarthritis (OA) is a common disabling disease involving the entire joint tissue, and its onset and progression are affected by many factors. However, the current number of studies investigating the relationship between subchondral trabecular bone (STB), knee alignment, and OA severity is limited. We aimed to investigate the variation in tibial plateau STB microarchitecture in end-stage knee OA patients and their association with knee alignment (hip-knee-ankle, HKA, angle) and OA severity.

Methods: Seventy-one knee OA patients scheduled for total knee arthroplasty (TKA) underwent preoperative radiography to measure the HKA angle and Kellgren-Lawrence grade. Tibial plateaus collected from TKA were scanned using micro-computed tomography to analyze the STB microarchitecture. Histological sections were used to assess cartilage degeneration (OARSI score). Correlations between the HKA angle, OA severity (OARSI score, Kellgren-Lawrence grade), and STB microarchitecture were evaluated. Differences in STB microstructural parameters between varus and valgus alignment groups based on the HKA angle were examined.

Results: The HKA angle was significantly correlated with all STB microarchitecture parameters (p < 0.01). The HKA angle was more correlated with the medial-to-lateral ratios of the microarchitecture parameters than with the medial or lateral tibia plateaus. The HKA angle and all STB microarchitecture parameters are significantly correlated with both the OARSI score and Kellgren-Lawrence grade (p < 0.01).

Conclusions: The STB microarchitecture is associated with the HKA angle and OA severity. With the increase of the knee alignment deviation and OA severity, the STB of the affected side tibial plateau increased in bone volume, trabecular number, and trabecular thickness and decreased in trabecular separation.

Keywords: Hip-knee-ankle angle; Knee osteoarthritis; Micro-CT; Microarchitecture; Subchondral trabecular bone.

Fig. 1

Measurement of knee alignment (hip-knee-ankle angle) based on full-leg standing anteroposterior radiographs. a The center of the femoral head. b The center of the femoral condyles. c The center of the tibial plateau. d The center of the superior surface of the talus

Fig. 2

a Macroscopic, micro-CT and histological images of tibial plateaus from an excised right knee tibial plateau. Red squares represent the location of volumes of interest (VOIs) of the medial and lateral tibial plates. b 3D micro-CT image of the excised tibial plateau. c 2D coronal micro-CT transverse image of the tibial plateau. d Specimen from the medial tibial plateau showing high bone volume fraction (BV/TV = 51%). e Specimen from the lateral tibial plateau showing low bone volume fraction (BV/TV = 14%). f and g are histological photographs corresponding to d and e, respectively

Fig. 3

Scatter plot for Pearson’s correlations between hip-knee-ankle angle and subchondral trabecular bone microarchitecture parameters. BV/TV, bone volume fraction; Tb.N, trabecular number; Tb.Th, trabecular thickness; Tb.Sp, trabecular separation; BS/BV, specific bone surface

Fig. 4

Comparisons of subchondral trabecular bone microarchitecture parameters among knee alignment (hip-knee-ankle angle, HKA angle) groups. BV/TV, bone volume fraction; Tb.N, trabecular number; Tb.Th, trabecular thickness; Tb.Sp, trabecular separation; BS/BV, specific bone surface. Significant differences are indicated by brackets (p < 0.05)