Outcomes of Hip Arthroscopic Surgery in Patients with Tönnis Grade 1 Osteoarthritis with a Minimum 2-Year Follow-up

Abstract

Background: There are limited studies on the effect of mild osteoarthritis (OA) on outcomes of hip arthroscopic surgery. Purpose: To conduct a matched-pair analysis with a minimum 2-year follow-up to evaluate outcomes after hip arthroscopic surgery in patients with Tönnis grade 1 OA. Study Design: Cohort study; Level of evidence, 3. Methods: Data were prospectively collected on patients who underwent hip arthroscopic surgery between April 2008 and December 2012. Patients were excluded if they had previous hip conditions. The remaining patients were divided into either Tönnis 0 or 1 grade OA groups and were matched in a 1-to-1 ratio according to age within 5 years, sex, body mass index category, labral treatment, and capsular treatment. Four patient-reported outcome (PRO) scores, as well as the visual analog scale (VAS) score for pain, patient satisfaction, and rates of revision arthroscopic surgery and conversion to total hip arthroplasty (THA), were recorded. Results: A total of 1412 hip arthroscopic procedures were performed during the study period, of which 1036 met the inclusion criteria and 892 (86.1%) had 2-year follow-up. There were 738 and 154 patients with Tönnis grade 0 and 1, respectively; 93 patients were matched in each group. The Tönnis grade 0 group had a mean follow up of 28.7 months (range, 23.5-67.9 months), and the Tönnis grade 1 group had a mean follow up of 31.5 months (range, 23.6-63.5 months). Both groups demonstrated a significant improvement in all PROs and the VAS at a minimum 2-year follow-up. For the Tönnis grade 0 group, the improvements (in points) in the PROs were as follows: modified Harris Hip Score (mHHS), 15.51; Nonarthritic Hip Score (NAHS), 20.65; Hip Outcome Score-Activities of Daily Living (HOS-ADL), 16.83; and Hip Outcome Score-Sport-Specific Subscale (HOS-SSS), 20.91. The VAS score for the Tönnis grade 0 group decreased by 2.82 points. For the Tönnis grade 1 group, the improvements (in points) in the PROs were as follows: mHHS, 19.52; NAHS, 20.96; HOS-ADL, 18.20; and HOS-SSS, 21.61. The VAS score for the Tönnis grade 1 group decreased by 2.84 points. No significant difference was found between the mean change in PROs, VAS, or patient satisfaction between the groups (P >.05). There was no significant difference in subsequent rates for revision arthroscopic surgery or conversion to THA between the groups (P =.3 and.6, respectively). The rates for revision arthroscopic surgery and conversion to THA were 9.68% and 9.68%, respectively, in the Tönnis grade 0 group and 5.38% and 11.83%, respectively, in the Tönnis grade 1 group. Conclusion: At 2-year follow-up, patients with Tönnis grade 1 OA had improved outcomes after hip arthroscopic surgery, with no significant difference compared with a matched control group of patients with Tönnis grade 0 OA. However, further studies are underway to determine if the results of the Tönnis grade 1 cohort will deteriorate over longer term follow-up.