The Supercapsular Percutaneously Assisted Total Hip Approach Does Not Provide Any Clinical Advantage Over the Conventional Posterior Approach for THA in a Randomized Clinical Trial.

BACKGROUND: The supercapsular percutaneously assisted total hip (SuperPATH) approach was designed to be a less-invasive surgical approach to THA. This approach may have advantages, including less pain, more rapid mobilization, and shorter hospital length of stay. However, few published studies have compared the SuperPATH technique to existing standard approaches in a randomized, controlled manner.

QUESTIONS/PURPOSES: In this study, we asked: (1) Do patients with SuperPATH demonstrate improved early function, using the timed up and go (TUG) and timed stair climbing (TSC) tests as instruments for assessment during the first 100 days postoperatively? (2) Are patient-reported outcomes, in the form of Oxford Hip Scores, better for the SuperPATH group during the first 3 months postoperatively? (3) Are opioid consumption and pain score in the first month postoperatively different between patients undergoing SuperPATH and patients undergoing a standard posterior approach? (4) Are patients with SuperPATH able to discontinue using mobility aids and return to work more quickly?

METHODS: Between February 2017 and May 2019, 46% (46 of 101) of patients were recruited among 101 patients who met our inclusion criteria. Those 46 patients were randomized into two groups on the day of surgery; 54% (25 of 46) were assigned to the study group (SuperPATH approach) and 46% (21 of 46) were assigned to the control group (posterior approach). The SuperPATH technique uses the plane between the gluteus medius and the external rotators while preserving the piriformis and the superior aspect of the capsule. A percutaneous accessory portal is required for acetabular reaming and cup insertion. The posterior approach involves releasing short rotators and partially releasing the quadratus femoris while retaining the gluteus maximus's insertion site. The two groups did not differ in BMI, gender, American Society of Anesthesiologists class, surgical side, or diagnosis. The length of stay, component position, and blood loss were similar between the groups, but the operative time was longer in the SuperPATH group than in the group with the posterior approach. One patient from the control group was lost to follow-up and was excluded. Three patients in the study group had complications. The TUG and TSC tests are timed tasks for the patient. In the TUG test, patients stand from sitting, walk 3 meters and turn, walk back, and sit down. The TSC test measures the time taken to ascend and descend 10 steps. Patients were followed for 24 months for any complications.

RESULTS: The TUG time at 100 days was 8.9 ± 2.6 seconds in the SuperPATH group and 8.7 ± 2.2 seconds in the posterior group (mean difference -0.2 seconds [95% CI -1.8 to 1.4]; p = 0.98); results were similar at other timepoints. The TSC time at 100 days was 11.6 ± 4.7 seconds in the SuperPATH group and 10.8 ± 3.6 seconds in the posterior group (mean difference -0.7 seconds [95% CI -3.5 to 2.1]; p = 0.88), and there were no differences between the two groups at all timepoints. The Oxford Hip Score showed no difference at any point postoperatively. At 6 weeks, it was 36 ± 5.9 points in the SuperPATH group and 38 ± 8.6 in the posterior group (mean difference 1.7 points [95% CI -2.7 to 6.1]; p = 0.51). At 3 months, it was 42± 6.7 points in the SuperPATH group and 41 ± 10.2 points in the posterior group (mean difference 0.7 points [95% CI -6.2 to 4.9]; p = 0.34). Patients' pain scores did not show any differences at all tested timepoints (mean difference 1 [95% CI -0.2 to 2.2]; p = 0.102). Total opioid consumption in the posterior group was higher in the first 2 weeks than that in the SuperPATH group (mean difference 6 [95% CI 2.3 to 9.9]; p = 0.001), but there was no difference in either group by week 4 (mean difference 0.4 [95% CI -0.5 to 1.4]; p = 0.36). There was no difference in return to work between the SuperPATH group and the posterior approach group (mean difference 6 days [95% CI -29 to 41]; p = 0.74). Discontinuation of mobility aids was similar between the two groups (mean difference 0.9 days [95% CI -25 to 27]; p = 0.94).

CONCLUSION: The SuperPATH approach had no clinical advantages over the posterior approach, resulted in more complications, and only showed a short-term reduction in pain. The results of our small randomized controlled trial can be used to calculate future sample sizes, but our data suggest that any differences favoring the SuperPATH approach are likely to be small and transient. This approach should not be used routinely in clinical practice until an adequately powered trial shows clinically important differences in patient-relevant endpoints. The improved postoperative recovery is likely multifactorial and not dependent on the invasiveness of the approach.

LEVEL OF EVIDENCE: Level II, therapeutic study.