Related Experiment Video
Updated: May 25, 2026
The Transition to an Anterior-Based Muscle Sparing Approach Improves Early Postoperative Function but is Associated with a Learning Curve
Published on: September 7, 2022
Early Postoperative Gait Metrics After Superior Transverse Anatomic Reconstruction (STAR) versus Direct Anterior
Carmelo Burgio1, Karlos Zepeda1, Shrey Vachhani1
1Adult Reconstruction and Joint Replacement Service, Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York.
Background:
The direct anterior approach (DAA) is a widely used muscle-sparing technique for total hip arthroplasty (THA) designed to minimize soft-tissue injury and support early recovery. The Superior Transverse Anatomic Reconstruction (STAR) approach is a piriformis-preserving modification of the postero-lateral approach that aims to combine the visualization advantages of posterior access with the muscle-sparing benefits of DAA. This study evaluated whether piriformis preservation through the STAR approach achieves early postoperative gait symmetry and spatio-temporal recovery comparable to DAA THA.
Methods:
In this prospective cohort study, 47 patients undergoing primary, unilateral THA were enrolled at a single high-volume academic center between November 2024 and September 2025. Of these, 31 underwent STAR approach and 16 underwent DAA. In-office gait analysis was conducted preoperatively and at six weeks postoperatively. The primary outcomes were step-length and single-limb support symmetry ratios; secondary outcomes included spatio-temporal gait parameters, Timed Up and Go, and Forgotten Joint Score. Between-group differences were evaluated using analysis of covariance, adjusted for confounders.
Results:
Baseline demographics and preoperative gait were similar. At six weeks, both STAR and DAA achieved symmetric gait, with postoperative step-length symmetry measured as 1.03 (range 0.87 to 1.34) in STAR and 1.02 (0.96 to 1.10) in DAA and single-limb support symmetry measured as 0.99 (0.83 to 1.16) and 1.01 (0.88 to 1.09), respectively. Nearly all patients achieved near-normal symmetry, with greater than 96.8% meeting step-length thresholds and greater than 93.5% achieving single-limb support symmetry. Adjusted analyses demonstrated no statistically significant between-group differences in step-length symmetry (+0.03, P = 0.15) and single-limb support symmetry (-0.01, P = 0.78). Similarly, spatio-temporal gait parameters and other functional outcomes showed no statistical differences (P > 0.05).
Conclusion:
Both piriformis-preserving approaches yielded comparable early postoperative gait symmetry and spatio-temporal parameters, supporting the hypothesis that muscle preservation through STAR can achieve similar gait recovery to DAA. Further studies with larger cohorts and extended follow-up are needed to confirm these findings.
