Outcomes of cup revision for ilio-psoas impingement after total hip arthroplasty: Retrospective study of 46 patients

Background: Impingement of the ilio-psoas tendon on the acetabular component is a cause of pain after total hip arthroplasty (THA). Studies of cup revision for ilio-psoas impingement (IPI) are scarce and limited in size. We therefore conducted a large multicentre retrospective study with the following objectives: to assess the effectiveness of cup replacement in resolving the impingement syndrome, to determine the frequency and nature of complications after cup revision for IPI, and to identify pre-operative factors associated with good outcomes of cup revision for IPI. Hypothesis: Cup revision is effective in resolving the pain due to IPI in selected patients. Methods: This retrospective multicentre study included 46 patients who underwent cup revision because of IPI. Before the revision, 38 (83%) patients had prominence of the anterior cup rim (mean, 9.9 +/- 4.5 mm (range, 2-22 mm) by radiography and 35 (76%) had cup malposition (anteversion < 10 and/or inclination > 50). Mean follow-up was 21 months (range, 6 months to 6 years) and no patient was lost to follow-up. Outcomes at last follow-up were assessed based on the Oxford Hip Score (OHS), patient satisfaction index, complications, and revisions. Results: At last follow-up, 39 (85%) patients were satisfied with the revision procedure, a significant improvement versus baseline was noted in the OHS (mean, 43 +/- 6; range, 25-48; P<0.001), and 41 patients were free of pain during hip flexion (P< 0.001 versus baseline). Complications occurred in 3 (6.5%) patients, but only one complication was severe (deep infection). Recurrent groin pain was reported by 4 (8.7%) patients at last follow-up. None of the factors studied predicted the outcome of revision surgery. Discussion: Cup revision for IPI after THA is effective in relieving the groin pain in 80% of patients with anterior cup rim prominence and/or cup malposition. However, complications can occur. Tenotomy may be preferable when the diagnosis is in doubt and/or cup position is acceptable. Level of evidence: IV, retrospective observational study. Published by Elsevier Masson SAS.