Accuracy of Leg Length and Hip Offset Measurements Using a Fluoroscopic Grid During Anterior Approach Total Hip Arthroplasty

Abstract

Background: Minimizing leg length (LLD) and hip offset (OD) discrepancies is critical for tissue tension and implant longevity in total hip arthroplasty (THA). The direct anterior approach (DAA) helps surgeons recreate these values under fluoroscopy. Several methods to accomplish this have been described, with no consensus on which is superior. This study evaluated the ability to minimize LLD and OD using a surgeon-controlled, adjustable fluoroscopic grid. We hypothesized that this tool would recreate parameters to within 10 mm of the contralateral side. Methods: One hundred eleven primary THAs performed with an adjustable radiopaque grid to equalize leg length and hip offset were retrospectively reviewed. These values were measured on postoperative radiographs and compared to the contralateral hip. Patients were excluded if they had inadequate imaging, revision arthroplasty, preexisting deformities, or underwent approaches other than DAA. Results: Mean age was 59.1 ± 11.1 years, 63.1% of patients were female, and average body mass index was 27.8 ± 7.0. Mean LLD was 3.7 ± 3.0 mm, while mean OD was 4.6 ± 3.6 mm. 95.5% of hips showed LLD < 10 mm, while 93.7% of hips had OD < 10 mm. Furthermore, 76.6% of hips had LLD < 5 mm, while 62.2% of hips had OD < 5 mm. Conclusions: The described technique restored limb length and hip offset during DAA THA. This technique yields consistent results and offers an inexpensive alternative to costly digital software and more cumbersome fixed grid systems.

Keywords

• Total hip arthroplasty
• Grid
• Limb length
• Hip offset
• Discrepancy