The SuperPATH approach for total hip arthroplasty (THA) is promoted as tissue-preserving, but objective evidence of its impact on periarticular muscles is lacking. This study aimed to evaluate periarticular muscle damage one year after THA performed via the SuperPATH approach.

The hypothesis was that the SuperPATH approach causes no damage to the muscles surrounding the hip joint.

A retrospective, single-surgeon study included 41 patients who underwent primary unilateral THA via the SuperPATH approach for osteonecrosis or osteoarthritis. All patients underwent preoperative and 12-month postoperative 3.0 Tesla MRI scans. Muscle condition was assessed by quantifying fatty infiltration (FI) using the Goutallier classification (with grade ≥2 defined as significant) and measuring muscle size [cross-sectional area (CSA) for gluteus medius/minimus and maximal transverse diameter (MTD) for piriformis, obturator internus, and quadratus femoris]. Statistical comparisons were made using paired t-tests and chi-square tests.

One year postoperatively, a significant increase in significant FI (Goutallier grade ≥2) was observed in the piriformis (2.4% vs. 80.5%, p   <  0.001), gluteus minimus (7.3% vs. 61.0%, p   <  0.001), and obturator internus (4.9% vs. 85.4%, p   <  0.001). Concurrently, these muscles showed a significant decrease in muscle size (CSA or MTD). The quadratus femoris showed no FI and a slight increase in MTD. The gluteus medius showed no significant change in FI (2.4% vs. 7.3%, p = 0.608) and a non-significant increase in CSA. Tendon discontinuities were observed postoperatively in the piriformis (15 cases) and obturator internus (25 cases). All patients were pain-free and walking without a limp at one year.

Our hypothesis was not confirmed: the SuperPATH technique results in significant radiological evidence of damage to the piriformis, obturator internus, and gluteus minimus muscles at one year postoperatively, characterized by increased fatty infiltration and atrophy.

IV; Retrospective Case Series.