Restoring global offset and lower limb length with a 3 offset option double-tapered stem

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiographic Analysis

Background:

• Restoring hip biomechanics is crucial for successful total hip arthroplasty (THA) outcomes.
• A reduction in global hip offset (GO) greater than 5mm post-surgery can negatively impact hip function.
• This study investigates GO restoration using a cementless femoral stem with variable offset options.

Purpose of the Study:

• To evaluate the restoration of the global hip offset (GO) radiographic parameter after primary total hip arthroplasty (THA).
• To assess the effectiveness of a cementless femoral stem with three distinct offset options in restoring hip biomechanics.
• To correlate radiographic findings with clinical outcomes using the Harris hip score (HHS).

Main Methods:

• A consecutive series of 201 patients undergoing primary cementless THA were analyzed.
• Eighty patients with a minimum 3-year follow-up underwent radiographic evaluation for GO and limb length (LL).
• Clinical evaluation included the Harris hip score (HHS); patients received a specific femoral stem with three offset options (-5mm, +5mm).

Main Results:

• Postoperatively, mean GO significantly increased by 3mm (P<0.05) and mean LL increased by 5mm (P<0.05).
• The Harris hip score (HHS) significantly improved from 56.3 preoperatively to 95.8 postoperatively (P<0.001).
• Femoral stem offset options B (74%) and C (25%) were predominantly used, with option A used in 1% of cases.

Conclusions:

• The cementless femoral stem effectively lateralizes the femur by approximately 5mm, restoring native hip biomechanical parameters like GO.
• The use of this 3-offset option femoral stem is effective in restoring global hip offset.
• Two offset options appear sufficient for restoring GO, indicating flexibility in achieving desired biomechanical restoration.