Morphological factors of medial compartment knee osteoarthritis

Abstract

Objective To evaluate the factors contributing to medial compartment knee osteoarthritis and the possible correlations between them. Methods Radiographic images were collected for analysis of 840 patients who had sought medical attention from January to July 2017 for 1,422 sides of knees varus at Department of Orthopedic Surgery, The Third Hospital of Hebei Medical University. They were aged from 17 to 87 years(average, 61.0 years), involving 323 knees in males and 1,099 knees in females. The alignments and parameters of lower extremity were measured, including hip-knee-ankle angle (HKA), mechanical medial distal femoral angle (mMDFA), medial proximal tibial angle (MPTA) and joint line convergence angle (JLCA). The measurements were compared between HKA values and genders for correlation analysis. Results HKA, mMDFA, MPTA and JLCA were respectively 172.85°±4.27°, 90.99°±2.59°, 84.78°±2.82° and 2.83°±2.33° for males, and 172.13°±4.63°, 91.11°±2.74°, 84.58°±3.30° and 3.48°±2.58° for females. The females had significantly smaller HKA and significantly larger JLCA than males (P 0.05). Pearson correlation test showed that there were significant correlations between HKA and mMDFA, MPTA and JLCA (rmale1=0.526, rmale2=0.545, rmale3=-0.562; rfemale1=0.547, rmale2=0.610, rmale3=-0.485; P<0.01). mMDFA (βmale=0.491, βfemale=0.464, P<0.01) and MPTA (βmale=0.487, βfemale=0.560, P<0.01) had significantly positive influences on HKA; the influence of JLCA was negative (βmale=-0.463, βfemale=-0.450, P<0.01). Conclusions Femoral mechanical axis varus, increased JLCA and collapse of medial tibial plateau all significantly contribute to the varus gonarthrosis. The effects of mMDFA, MPTA and JLCA on HKA may be almost the same. Key words: Knee joint; Knee osteoarthritis; Knee varus; Radiology; Morphology