Comparative study of posterior tibial slope & metaphysio-diaphyseal angle in osteoarthritis knee and normal knee attending tertiary care centre in North-east India

The purpose of this study is to establish normal values and explore potential correlations of the posterior tibial slope(PTS) and metaphysio-diaphyseal angle(MDA) within the study population. These measurements are critical for assessing knee joint biomechanics, which influence various orthopaedic surgical outcomes and rehabilitation processes. We conducted a cross-sectional study involving 347 adults from various regions across North-east India. Participants were selected based on inclusion criteria that excluded previous knee surgeries or Fractures around knee involving proximal tibia. The PTS and metaphysio-diaphyseal angle were measured using x-ray knee lateral view. Each image was analysed using advanced software to ensure precise angle determination. The data are tabulated in Microsoft excel and analysed with SPSS V.24 software. our study shows that mean posterior tibial slope and mean MDA in normal group are 9.78°(±2.40) and 19.58°(±4.27) respectively. Mean PTS and MDA in osteoarthritic group are 14°(±2.26) and 24.59°(±3.95) respectively. There is linear relationship between MDA and PTS with correlation coefficient (r) is 0.620. Sensitivity and specificity of MDA for detecting OA are 81.1 % and 75.4 %, respectively. Sensitivity and specificity of PTS for detecting OA are 91.2 % and 68.5 %, respectively. MDA and PTS are comparatively higher in value in osteoarthritic group when compared to normal group. It also serves as a good marker to detect OA and there is a linear correlation between PTS and MDA.