Short Term Evaluation Of The Effects Of Femoral Offset And Head Size On Joint Stability And Functional Outcome After Total Hip Arthroplasty

Abstract

Background: Total Hip Arthroplasty (THA) is a widely performed procedure for various hip pathologies. Femoral offset and head size are critical factors influencing joint stability and functional outcomes. This study evaluated the short-term effects of femoral offset and head size on joint stability and functional outcomes after THA.

Methodology: This prospective study included 35 patients undergoing THA. Demographic data, surgical details and implant characteristics were recorded. Intraoperative internal and external rotation measurements were taken to assess joint stability. Femoral offset and head size were measured from postoperative radiographs. Functional outcomes were evaluated using the Modified Harris Hip Score (HHS) preoperatively and postoperatively. Statistical analysis included paired t-tests, descriptive statistics and Pearson correlation coefficients.

Results: The mean age of participants was 52.3 years, with a balanced gender distribution (54% males, 46% females). The mean femoral head size was 29.89 mm (SD 2.3), and the mean femoral offset was 42.69 mm (SD 5.2). A significant difference was found between high and standard offset neck internal (mean 48.37°) and external (mean 37.74°) rotation measurements (p<0.001). A strong positive correlation was observed between femoral offset and intraoperative internal rotation (r=0.859, p<0.001), while femoral head size showed a weaker correlation (r=0.325, p=0.05). The mean Modified HHS improved significantly from 14.6 preoperatively to 79.8 postoperatively (p<0.001).

Conclusion: Femoral offset, rather than head size, is a primary determinant of joint stability in THA. Optimizing femoral offset is crucial for surgical planning and implant selection. While THA significantly improves function, long-term studies are needed to evaluate the durability of these findings and their impact on patient-reported outcomes.