JOA - 2026-09-08 - Journal Article
Magnetic Resonance Imaging Assessment of Muscle Damage After Postero-lateral Versus Supercapsular Percutaneously-Assisted Total Hip Approaches: A Randomized Controlled Trial.
Gan F, Zhang Q, Luo H, Li L, Zheng F, Lin X, Qin H
Topics
Key Takeaway
SuperPATH THA produced significantly less quadratus femoris fatty infiltration than posterolateral approach at 12 months (7.3% vs 85.4%, P<0.001), though 1-year HHS and VAS scores were equivalent.
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Summary
This RCT randomized primary unilateral THA patients to SuperPATH or posterolateral approach (PLA) and used 12-month MRI to quantify periacetabular muscle damage. SuperPATH demonstrated dramatically less quadratus femoris fatty infiltration (7.3% vs 85.4%, P<0.001), less atrophy (P=0.008), and superior tendon continuity (100% vs 56.1%, P<0.001), with no significant differences in piriformis, obturator internus, or gluteus minimus. SuperPATH had superior early VAS and HHS at 1 month (P<0.05), longer operative time, and greater blood loss, but equivalent 12-month clinical scores and two dislocations occurred only in the PLA group.
Key Limitation
The 12-month endpoint may be insufficient to determine whether quadratus femoris structural differences translate into long-term functional advantages or reduced revision rates, and the study was not powered to detect differences in dislocation incidence.
Original Abstract
BACKGROUND
The supercapsular percutaneously-assisted total hip approach for total hip arthroplasty (THA) may reduce soft-tissue injury, but objective evidence comparing muscle damage with a conventional postero-lateral approach (PLA) is limited. This randomized controlled trial compared postoperative periacetabular muscle damage using magnetic resonance imaging (MRI).
METHODS
Patients undergoing primary unilateral THA were randomized to SuperPATH or PLA. The primary outcome was the between-group difference in quadratus femoris muscle fatty infiltration at 12 months on MRI. The secondary outcomes included atrophy and tendon integrity of multiple periacetabular muscles, perioperative variables, Visual Analog Scale (VAS), and Harris Hip Score (HHS). There were 82 patients who completed follow-up.
RESULTS
At 12 months, MRI showed no significant differences in fatty infiltration or atrophy of the piriformis, obturator internus, or gluteus minimus muscles between groups. However, the minimally invasive approach better preserved the quadratus femoris muscle, with major less fatty infiltration (7.3 and 85.4%, P < 0.001), less atrophy (P = 0.008), and superior tendon continuity (100 and 56.1%, P < 0.001). The minimally invasive approach had a longer operative time and greater blood loss, but a smaller incision and superior early clinical outcomes (VAS and HHS at one month, P < 0.05); these differences were not significant at 12 months. There were two early dislocations that occurred in the PLA group.
CONCLUSION
The minimally invasive approach provides better structural preservation of the quadratus femoris muscle than the PLA, although 1-year clinical outcomes were similar. These structural findings may partly explain the superior early functional outcomes observed in the minimally invasive approach; however, their long-term clinical significance remains to be determined.