Arthroscopy - 2026-03-11 - Journal Article
Tönnis Grade 1 Is Associated With Higher Total Hip Arthroplasty Conversion Than Tönnis Grade 0 at 10-Year Follow-Up After Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity-Matched Cohort Analysis.
Gosnell GG, Berzolla E, Lezak BA, Mercer NP, Morgan AM, Ruff G, Lott A, Youm T
Topics
Key Takeaway
Tönnis grade 1 patients undergoing hip arthroscopy for FAIS had a 31.25% combined failure rate (THA conversion 15.63%, revision 15.63%) versus 3.13% in Tönnis grade 0 patients at minimum 10-year follow-up, despite equivalent PRO improvements in survivors.
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Summary
This propensity-matched retrospective cohort compared 10-year outcomes of hip arthroscopy for FAIS in Tönnis grade 1 versus grade 0 patients, matching on age, sex, BMI, labral treatment, capsular management, LCEA, and alpha angle. Both groups achieved significant mHHS and NAHS improvements with equivalent MCID rates (~88–94%), but Tönnis grade 1 patients had a 31.25% failure rate versus 3.13% in grade 0 (P=.006), driven by 5 THA conversions (15.63%) and 5 revisions (15.63%) in the grade 1 cohort versus 0 THA conversions and 1 revision in grade 0.
Key Limitation
The 10-year attrition from a 152-patient database down to 64 matched patients raises concern for survivorship bias, as patients who converted to THA early or were lost to follow-up may systematically differ from those analyzed.
Original Abstract
PURPOSE
To compare 10-year outcomes of hip arthroscopy in patients with Tönnis grade 1 versus grade 0 osteoarthritis, with specific focus on patient-reported outcomes, rates of minimal clinically important difference, Patient Acceptable Symptom State, Substantial Clinical Benefit, and arthroscopic revision and total hip arthroplasty (THA) conversion rates.
METHODS
Patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) were prospectively enrolled. A 1:1 propensity score match based on age, sex, body mass index, smoking status, labral treatment, capsular management, lateral center edge angle, and preoperative alpha angle matched Tönnis grade 1 patients to Tönnis grade 0 patients. Inclusion criteria were symptomatic FAIS with radiographic deformity, failure of nonoperative treatment, and ≥10-year follow-up. Patients were excluded for prior ipsilateral hip arthroscopy, Tönnis grade >1, incomplete data, dysplasia (lateral center edge angle < 18°), developmental hip disorders, or concomitant procedures. Modified Harris hip score (mHHS), Non-Arthritic Hip Score (NAHS), minimal clinically important difference, Patient Acceptable Symptom State, Substantial Clinical Benefit, and failure (revision arthroscopy or THA conversion) rates at 10 years were assessed.
RESULTS
Out of a total database of 152 patients, the study matched 32 Tönnis grade 1 patients (mean age 40.79 ± 10.1 years; body mass index 25.13 ± 3.73; follow-up 12.16 ± .96 years [range, 10.08-13.59]) to 32 Tönnis grade 0 patients (mean age 41.82 ± 11.66; body mass index 25.63 ± 3.53; follow-up 11.42 ± 1.23 years [range: 10.02-13.58]) for a total of 64 included patients within this study. Baseline characteristics were well matched with the only significantly different variable being follow-up time (P = .009), though all patients reached a minimum follow-up of 10-years. Both cohorts showed significant improvements in mHHS and NAHS at 10 years (P < .0001), with no significant differences between groups at 10-years (mHHS P = .509; NAHS P = .339) or any other time point. MCID achievement rates were high for both mHHS (Tönnis 0: 87.5%; Tönnis 1: 90.6%; P = .689) and NAHS (Tönnis 0: 87.5%; Tönnis 1: 93.8%; P = .391). Tönnis grade 1 patients showed higher failure (THA/revision) rates compared to Tönnis grade 0 patients (31.25% vs 3.13%; P = .006). Analyzed separately, Tönnis grade 1 patients had 5 cases (15.63%) of THA conversion compared to 0 cases in the Tönnis grade 0 cohort (P = .05), while revision rates were similarly elevated in the Tönnis grade 1 group (5/32; 15.63%) compared to Tönnis grade 0 patients (1/32; 3.13%) (P = .196).
CONCLUSIONS
Hip arthroscopy yields significant long-term improvements for FAIS patients with Tönnis grade 1 and 0 osteoarthritis. However, increased failure rates in Tönnis grade 1 patients suggests that preoperative osteoarthritis may predispose patients to greater rates of subsequent THA conversion or revision.
LEVEL OF EVIDENCE
Level III, retrospective comparative matched case series.