Templating femoral offset in patients with coxa valga and antetorta undergoing THA: Critical need for a minimum 5 mm increase.

INTRODUCTION

Total hip arthroplasty (THA) is a common procedure in which accurate restoration of femoral offset is crucial to prevent complications. In patients with coxa valga and antetorta (CVA), excessive femoral antetorsion may lead to inaccurate prediction of femoral offset during digital templating. The purpose of this study was to assess the accuracy of templated femoral offset in patients with CVA compared to a control group.

MATERIAL AND METHODS

A retrospective analysis was conducted on 35 CVA patients and 56 controls who underwent cementless THA. Preoperative and postoperative pelvis radiographs were taken following a standardized procedure. A CVA group was defined by a caput-collum-diaphyseal (CCD) angle >140°, while the control group had a CCD angle of 125°-135°. Femoral antetorsion was assessed using the size of the lesser trochanter on pelvis radiographs. Preoperative templating was performed with mediCAD, and radiographs were analyzed for femoral offset, neck resection level, and leg length discrepancy. Intraoperative head length changes and 90-day postoperative adverse events were also recorded.

RESULTS

CVA patients had a significantly lower native femoral offset than controls (34.9 mm vs. 41.7 mm; p < 0.001). Postoperatively, CVA patients showed an offset increase of only 1.1 mm, despite a templated increase of 5.1 mm (p < 0.001), while the control group had no significant difference between templated and postoperative offsets (p = 0.893). Larger head sizes than templated were used twice as often in the CVA group. No significant leg length differences were observed.

DISCUSSION

Digital templating for femoral offset in CVA patients proves to be inaccurate, with postoperative radiographs showing a significant reduction compared to the templated femoral offset. To prevent postoperative offset reduction and associated complications, a templated femoral offset increase of at least 5 mm should be targeted when performing THA in CVA patients.