Is Posterior Femoral Neck Cortex an Obstacle in Achieving Sagittal Plane Balance of Uncemented Straight Femoral Stem?

Abstract

There is a paucity of the literature that aims to improve sagittal plane balance of femoral stem in hip arthroplasty. We have comparatively evaluated the effect of trimming the posterior cortex left in situ after femoral neck osteotomy and counter-clockwise rotation of starting awl with respect to their ability to achieve neutral alignment of femoral stem in sagittal plane. (1) Which of the two techniques under reference is more reliable in achieving a sagittal plane balance of the femoral stem in the femoral canal? (2) Does either of the two techniques have the potential to adversely affect other parameters for the optimum placement of femoral stem? This prospective study involved a total of 60 patients (age group of 18 to 60years) who underwent primary total hip arthroplasty (THA) through a standard posterolateral approach. They were randomized into groups (1) PNCT (n = 30): femoral canal preparation was done by posterior neck cortex trimming method; (2) CCRA (n = 30): femoral canal preparation was done by counter-clockwise rotation of starting awl. Postoperatively, radiographs and computed tomography were obtained and angle of femoral stem with the femoral canal in coronal and sagittal plane, femoral stem tip deviation in coronal and sagittal plane, anteversion of the femoral stem, duration of canal preparation and blood loss were analyzed between the two groups. Based on our results, there is a significantly better sagittal alignment of the femoral stem within the femoral canal, both in terms of angle of the femoral stem with the femoral canal (p < 0.001) and the deviation of the femoral stem tip from the center of the medullary canal (p < 0.001) when the posterior neck cortex was trimmed. Canal preparation by trimming the posterior neck cortex took a mean of 11.93min (range 8-15min) against the mean duration of 6.87min (range; 5min to 9min) in the other group (p < 0.001). Trimming the posterior femoral neck cortex after neck osteotomy results in better sagittal plane balance of uncemented straight femoral stem. III.