POSITIONING OF ACETABULAR AND FEMORAL COMPONENT IN PRIMARY TOTAL HIP ARTHROPLASTY USING CT EVALUATED PATIENT NATIVE ANATOMY

In total hip arthroplasty, component orientation is an important task for stability. Acetabular and femoral component orientation is the key factor for outcome of total hip arthroplasty. The aim of this study is to assess the clinical and radiological effectiveness of positioning of acetabulum and femoral components in primary total hip replacement using CT evaluated patient native anatomy. Subjects of this study were 36 patients with nonunion neck of femur fractures or arthritic hip based on inclusion and exclusion criteria and treated with cemented or uncemented total hip arthroplasty. Pre operative CT scan with 3D reconstruction was done for all patients and the acetabular inclination and version was measured in coronal and axial planes. Femoral anteversion was measured in mid axial image. Transverse acetabular notch (TAN) and anterior acetabular notch (AAN) were identied intra operatively to reproduce the pre operative angles. Post operatively CT scan was done and all angles were measured as before. All patients were followed up and analyzed using Harris Hip Score. The mean preoperative Harris Hip Score is 34.5. The mean postoperative Harris Hip Score is 88.19. Mean acetabular cup inclination is 39.80°, Mean cup anteversion is 15.1° and mean femoral anteversion is 14.75°. No Dislocation was noted during follow up. No hips show clinical and radiological evidence of femoral and acetabular component loosening. All Postoperative CT measurements of angles are within the safe zone by Lewinnek et al. Preoperative CT guided parameters, intra operative anatomical landmarks (TAN&AAN) and the digital protractor device can aid better positioning of the acetabular and femoral component of THA and is independent of the position of the patient. It also provides a precise planning for component placement resulting in less intra operative time thereby reducing the chances of infection and decreases the dislocation rate and wear and tear and improves the functional outcome