Anatomical variation of posterior slope of tibial plateau in adult Eastern Indian population

BACKGROUND Upper surface of the proximal tibial end, tibial plateau, has a slope directed posteroinferiorly relative to the long axis of the middle of the shaft. It has important consideration in surgeries such as knee arthroplasty, high tibial osteotomy, and medical imaging of the knee joint. The aim of the present study was to estimate the tibial plateau angle (TPA) by plain radiograph in the adult Eastern Indian population as during literature review, we were unable to find any study, except one (without specific reference axis), on this variable among the Indian population. MATERIALS AND METHODS A sample was taken from adult patients attending the outpatient department of orthopedics of the institute with minor knee problems. Measurement of the TPA was done in the true lateral radiographs of the knee joints of the selected subjects by a standardized method. RESULTS TPA varied widely from 6° to 24°, with the mean ± standard deviation value 13.6° ±3.5°. Student's unpaired t-test revealed no significant difference of TPA between left and right knees, both in male (P = 0.748) and female (P = 0.917) separately and in the entire study population irrespective of gender (P = 0.768). Comparison of TPA between male (13.3° ± 3.3°) and female (13.9° ± 3.4°) by Student's unpaired t-test showed no sexual dimorphism (P = 0.248). There were poor correlations of TPA with age and body mass index. CONCLUSION The present study described the variations of the TPA in the adult Eastern Indian population (range 6°-24°, mean ± SD 13.6° ± 3.5°, no laterality, no sexual dimorphism, poor correlation with age and BMI). Knowledge of this study could be used in different orthopedic surgeries and imaging technique in or around the knee joint.