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Propensity-Matched Patients Undergoing Revision Hip Arthroscopy Older Than the Age of 40 Years Had Greater Risk of Conversion to Total Hip Arthroplasty Compared With Their Primary Counterparts

      Purpose

      To report patient-reported outcomes (PROs) and survivorship following revision hip arthroscopy in patients aged ≥40 years and to compare these results with a propensity-matched primary hip arthroscopy control group.

      Methods

      Data were prospectively collected and retrospectively reviewed for all patients who underwent revision hip arthroscopy between June 2008 and January 2019. Patients were included if they were ≥40 years of age at the time of surgery and had minimum 2-year follow-up for the modified Harris Hip Score, Nonarthritic Hip Score, Visual Analog Scale for pain, and the Hip Outcome Score-Sports Specific Subscale. Patients who had a previous hip condition, or those who lacked minimum 2-year follow-up, were excluded. The revision group was further analyzed by conducting a 1:1 propensity-matched sub-analysis to a primary hip arthroscopy control group based on age, sex, body mass index, and acetabular labrum articular disruption grade. Statistical significance was set at P < .05.

      Results

      Eighty-nine hips (92.7% follow-up) were included, with 66.3% being females. The mean age, body mass index, and follow-up time were 49.4 ± 8.0 years, 26.6 ± 4.1, and 62.7 ± 38.5 months, respectively. Significant improvement in all PROs (P < .001) was reported, and 71.8%, 58 74.4%, and 65.2% achieved the minimal clinically important difference for the modified Harris Hip Score, Nonarthritic Hip Score, and Hip Outcome Score-Sports Specific Subscale, respectively. Eighty-seven revision hips were successfully propensity-matched to 87 primary hips. Both groups reported similar improvement for all PROs, but the relative risk of conversion to total hip arthroplasty was 2.63 times greater (95% confidence interval 1.20-5.79) for the revision group.

      Conclusions

      Patients aged ≥40 years who underwent revision hip arthroscopy reported significant improvement in all PROs at a mean follow-up of 62.7 months with favorable rates of achieving the minimal clinically important difference. When compared to the propensity-matched control group, both achieved similar rates of improvement, but the revision group was 2.63 times more likely to convert to total hip arthroplasty.

      Level of Evidence

      III. case-control study.
      The increase in the number of primary hip arthroscopies has led to an increase in the number of revision hip arthroscopies performed.
      • Makhni E.C.
      • Ramkumar P.N.
      • Cvetanovich G.
      • Nho S.J.
      Approach to the patient with failed hip arthroscopy for labral tears and femoroacetabular impingement.
      There is an inherent complexity with revision hip arthroscopy cases that may require advanced arthroscopic hip labral restoration techniques including labral reconstruction and sometimes salvage procedures for bone over-resection.
      • Arner J.W.
      • Ruzbarsky J.J.
      • Soares R.
      • Briggs K.
      • Philippon M.J.
      Salvage revision hip arthroscopy including remplissage improves patient-reported outcomes after cam over-resection.
      ,
      • Bodendorfer B.M.
      • Alter T.D.
      • Wolff A.B.
      • et al.
      Multicenter outcomes after revision hip arthroscopy: Comparative analysis of 2-year outcomes after labral repair versus labral reconstruction.
      Significant improvement in patient-reported outcome (PROs) scores have been reported in this setting; nevertheless, revision results are inferior, with a greater rate of conversion to total hip arthroplasty (THA) when compared with the primary context.
      • Maldonado D.R.
      • Kyin C.
      • Rosinsky P.J.
      • et al.
      Minimum 5-year outcomes for revision hip arthroscopy with a prospective subanalysis against a propensity-matched control primary group.
      Older age has been associated with failure following primary hip arthroscopy for the treatment of femoroacetabular impingement syndrome.
      • Domb B.G.
      • Chen S.L.
      • Go C.C.
      • et al.
      Predictors of clinical outcomes after hip arthroscopy: 5-Year follow-up analysis of 1038 patients.
      ,
      • Rosinsky P.J.
      • Go C.C.
      • Shapira J.
      • Maldonado D.R.
      • Lall A.C.
      • Domb B.G.
      Validation of a risk calculator for conversion of hip arthroscopy to total hip arthroplasty in a consecutive series of 1400 patients.
      Patients aged ≥50 years with a hip joint space narrowing ≤2 mm is an accurate predictor for THA conversion at mean 3-year follow-up.
      • Philippon M.J.
      • Schroder E.
      • Souza B.G.
      • Briggs K.K.
      Hip arthroscopy for femoroacetabular impingement in patients aged 50 years or older.
      The literature has established there is a greater rate of conversion to THA in patients aged ≥40 years than patients <40 years old.
      • Horner N.S.
      • Ekhtiari S.
      • Simunovic N.
      • Safran M.R.
      • Philippon M.J.
      • Ayeni O.R.
      Hip arthroscopy in patients age 40 or older: A systematic review.
      This rate increases with each decade of life as the THA conversion rate was 18.1%, 23.1%, and 25.2% in patients older than 40, 50, and 60 years old, respectively, at short-term follow-up.
      • Horner N.S.
      • Ekhtiari S.
      • Simunovic N.
      • Safran M.R.
      • Philippon M.J.
      • Ayeni O.R.
      Hip arthroscopy in patients age 40 or older: A systematic review.
      Outcomes and the conversion to THA after revision hip arthroscopy in patients aged ≥40 years have become a major concern. The current data on this situation are scarce, without clear and objective answers to this conundrum.
      • O’Connor M.
      • Steinl G.K.
      • Padaki A.S.
      • Duchman K.R.
      • Westermann R.W.
      • Lynch T.S.
      Outcomes of revision hip arthroscopic surgery: A systematic review and meta-analysis.
      The purposes of the present study were to report PROs and survivorship following revision hip arthroscopy in patients aged ≥40 years and to compare these results with a propensity-matched primary hip arthroscopy control group. It was hypothesized that (1) patients aged 40 years or older would report significant improvement for all the PROs collected, (2) when compared with the propensity-matched primary control group, inferior improvement and lower achievement rate for the minimal clinically important difference (MCID) and the patient acceptable symptomatic state (PASS) would be reported for the revision study group, and (3) the rate of conversion to THA would be greater for the revision propensity-matched study group.

      Methods

      Patient Selection

      This study was performed in accordance with the ethical standards in the 1964 Declaration of Helsinki. This study was carried out in accordance with relevant regulations of the U.S. Health Insurance Portability and Accountability Act. Details that might disclose the identity of the subjects under study have been omitted. This study was approved by our institutional review board (ID: 5276).
      Prospectively collected data on all patients who underwent revision hip arthroscopy between June 2008 and January 2019 were retrospectively reviewed. Patients were included if they were at least 40 years of age at the time of surgery and had minimum 2-year follow-up for the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS),
      • Christensen C.P.
      • Althausen P.L.
      • Mittleman M.A.
      • Lee J ann
      • McCarthy J.C.
      The nonarthritic hip score: Reliable and validated.
      and the Hip Outcome Score-Sports Specific Subscale (HOS-SSS)
      • Martin R.L.
      • Philippon M.J.
      Evidence of validity for the hip outcome score in hip arthroscopy.
      and Visual Analog Scale for pain (VAS).
      • Delgado D.
      • Lambert B.
      • Boutris N.
      • et al.
      Validation of digital visual analog scale pain scoring with a traditional paper-based visual analog scale in adults.
      Postoperative International Hip Outcome Tool-12 (iHOT-12)
      • Griffin D.R.
      • Parsons N.
      • Mohtadi N.G.H.
      • Safran M.R.
      Multicenter Arthroscopy of the Hip Outcomes Research Network. A short version of the International Hip Outcome Tool (iHOT-12) for use in routine clinical practice.
      also was included as preoperative values were not available for all patients. Patients who had a previous hip condition (such as fractures, slipped capital femoral epiphysis, avascular necrosis, or Legg–Calve–Perthes disease), or those who lacked minimum 2-year follow-up, were excluded. The patient selection process is outlined in Figure 1.

      Participation in the (American Hip Institute) Hip Preservation Registry

      While the contemporary study represents a unique analysis of unpublished data, some subjects have been included in previously published investigations.

      Radiographic Evaluation

      The anterosuperior pelvic view, the 45° Dunn view,
      • Barton C.
      • Salineros M.J.
      • Rakhra K.S.
      • Beaulé P.E.
      Validity of the alpha angle measurement on plain radiographs in the evaluation of cam-type femoroacetabular impingement.
      and the false-profile view
      • Lequesne M.
      • de Seze
      False profile of the pelvis. A new radiographic incidence for the study of the hip. Its use in dysplasias and different coxopathies.
      were used to obtain radiographic measurements. The anterosuperior pelvic view was used to obtain the lateral center-edge angle as described by Wiberg and modified by Ogata et al.,
      • Ogata S.
      • Moriya H.
      • Tsuchiya K.
      • Akita T.
      • Kamegaya M.
      • Someya M.
      Acetabular cover in congenital dislocation of the hip.
      acetabular inclination,
      • Clohisy J.C.
      • Carlisle J.C.
      • Beaulé P.E.
      • et al.
      A systematic approach to the plain radiographic evaluation of the young adult hip.
      and grade of osteoarthritis according to the Tönnis classification system.
      • Tönnis D.
      Normal values of the hip joint for the evaluation of X-rays in children and adults.
      The alpha angle was measured using the 45° Dunn view
      • Barton C.
      • Salineros M.J.
      • Rakhra K.S.
      • Beaulé P.E.
      Validity of the alpha angle measurement on plain radiographs in the evaluation of cam-type femoroacetabular impingement.
      ; angles exceeding 55° indicated the presence of residual cam-type morphology.
      • Harris M.D.
      • Kapron A.L.
      • Peters C.L.
      • Anderson A.E.
      Correlations between the alpha angle and femoral head asphericity: Implications and recommendations for the diagnosis of cam femoroacetabular impingement.
      ,
      • Mansor Y.
      • Perets I.
      • Close M.R.
      • Mu B.H.
      • Domb B.G.
      In search of the spherical femoroplasty: cam overresection leads to inferior functional scores before and after revision hip arthroscopic surgery.
      The anterior center-edge angle was assessed using the false profile view.
      • Clohisy J.C.
      • Carlisle J.C.
      • Beaulé P.E.
      • et al.
      A systematic approach to the plain radiographic evaluation of the young adult hip.
      Labral tears as well as other intra- and extra-articular pathologies were assessed using magnetic resonance arthrography in all patients.

      Revision Hip Arthroscopy Indication

      Revision arthroscopic surgery was indicated by a board-certified hip orthopaedic surgeon specializing in hip preservation (B.G.D.) for patients whose radiographic imaging, history, and physical examination demonstrated evidence of symptomatic residual femoroacetabular impingement syndrome and labral tears. Before pursuing surgery, patients had to attempt at least 3 months of nonsurgical treatment including physical therapy, nonsteroidal anti-inflammatory medication, intra-articular ultrasound-guided injections, and activity modification. In addition, surgery indication was reserved for patients without evidence of advanced osteoarthritis (Tönnis grade >1) on preoperative diagnostic imaging.
      • Briggs K.K.
      • Bolia I.K.
      Hip arthroscopy: An evidence-based approach.
      ,
      • Griffin D.R.
      • Dickenson E.J.
      • Wall P.D.H.
      • et al.
      Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): A multicentre randomised controlled trial.

      Surgical Technique

      All arthroscopic hip surgeries began with the induction of general anesthesia with the patient in the modified supine position on a traction table with a well-padded perineal post.
      • Lall A.C.
      • Saadat A.A.
      • Battaglia M.R.
      • Maldonado D.R.
      • Perets I.
      • Domb B.G.
      Perineal pressure during hip arthroscopy is reduced by use of Trendelenburg: A prospective study with randomized order of positioning.
      A minimum of 3 portals were created including an anterolateral, modified mid-anterior portal, and distal anterolateral accessory.
      • Maldonado D.R.
      • Chen J.W.
      • Walker-Santiago R.
      • et al.
      Forget the greater trochanter! hip joint access with the 12 o’clock portal in hip arthroscopy.
      ,
      • Matsuda D.K.
      • Villamor A.
      The modified mid-anterior portal for hip arthroscopy.
      An additional posterolateral portal was created when required.
      • Robertson W.J.
      • Kelly B.T.
      The safe zone for hip arthroscopy: A cadaveric assessment of central, peripheral, and lateral compartment portal placement.
      The hip joint was accessed in an inside-out fashion from the central compartment.
      • Maldonado D.R.
      • Chen J.W.
      • Walker-Santiago R.
      • et al.
      Forget the greater trochanter! hip joint access with the 12 o’clock portal in hip arthroscopy.
      A diagnostic arthroscopy was performed after gaining access to the central compartment. The type and degree of labral tearing was defined using the Seldes classification system
      • Seldes R.M.
      • Tan V.
      • Hunt J.
      • Katz M.
      • Winiarsky R.
      • Fitzgerald R.H.
      Anatomy, histologic features, and vascularity of the adult acetabular labrum.
      and the location of the tear was described using the clockface method.
      • Blankenbaker D.G.
      • De Smet A.A.
      • Keene J.S.
      • Fine J.P.
      Classification and localization of acetabular labral tears.
      Acetabular cartilage damage at the chondrolabral junction was classified using the acetabular labrum articular disruption (ALAD) grading system while all other cartilage damage on the acetabulum or femoral head was graded using the Outerbridge classification.
      • Outerbridge R.E.
      The etiology of chondromalacia patellae.
      The type and degree of tearing of the ligamentum teres was described according to the system described by Villar.
      • Bardakos N.V.
      • Villar R.N.
      The ligamentum teres of the adult hip.
      Residual femoroacetabular impingement morphology was addressed under fluoroscopic guidance. When indicated, acetabuloplasty was performed using a motorized burr to correct acetabular overcoverage or pincer morphology.
      • Colvin A.C.
      • Koehler S.M.
      • Bird J.
      Can the change in center-edge angle during pincer trimming be reliably predicted?.
      Similarly, femoroplasty was performed to correct cam-type morphology by achieving an alpha angle less than 55° while maintaining the spherical contour of the head–neck junction.
      • Mansor Y.
      • Perets I.
      • Close M.R.
      • Mu B.H.
      • Domb B.G.
      In search of the spherical femoroplasty: cam overresection leads to inferior functional scores before and after revision hip arthroscopic surgery.
      ,
      • Neumann M.
      • Cui Q.
      • Siebenrock K.A.
      • Beck M.
      Impingement-free hip motion: the “normal” angle alpha after osteochondroplasty.
      When possible, labral repair was performed. However, selective labral debridement was performed in the presence of a stable tear with the goal of preserving as much tissue as possible. When the labrum was deemed irreparable, labral reconstruction was performed using autograft or allograft.
      • MacInnis L.E.
      • Al Hussain A.
      • Coady C.
      • Wong I.H.
      Labral gracilis tendon allograft reconstruction and cartilage regeneration scaffold for an uncontained acetabular cartilage defect of the hip.
      ,
      • Matsuda D.K.
      • Burchette R.J.
      Arthroscopic hip labral reconstruction with a gracilis autograft versus labral refixation: 2-year minimum outcomes.
      Additionally, if a patient was found to have a full-thickness cartilage defect, the area was first debrided to achieve stable borders before undertaking microfracture.
      • Maldonado D.R.
      • Chen J.W.
      • Lall A.C.
      • et al.
      Microfracture in hip arthroscopy. Keep it simple.

      Postoperative Rehabilitation Protocol

      Postoperative rehabilitation varied slightly according to intraoperative procedures. However, all patients were required to use an X-Act ROM brace (DJO Global, Vista, CA) while limiting flat-foot weight-bearing to 20 pounds and use crutches for 2 to 6 weeks. In cases of microfracture or labral reconstruction, a longer duration was prescribed. Physical therapy began day 1 postoperatively, regardless of intraoperative procedures.

      PRO Scores

      The present study reports on the following PROs: mHHS, NAHS, and HOS-SSS. Pain was assessed using the VAS ranging from 0 to 10, where 0 was no pain and 10 was the worst pain imaginable.
      • Chandrasekaran S.
      • Gui C.
      • Walsh J.P.
      • Lodhia P.
      • Suarez-Ahedo C.
      • Domb B.G.
      Correlation between changes in visual analog scale and patient-reported outcome scores and patient satisfaction after hip arthroscopic surgery.
      All PROs and VAS were recorded preoperatively and postoperatively at 3 months, 1 year, and annually thereafter. These scores were collected via encrypted email, clinic visit, or telephone interviews. Postoperative questionnaires also included iHOT-12.
      • Griffin D.R.
      • Parsons N.
      • Mohtadi N.G.H.
      • Safran M.R.
      Multicenter Arthroscopy of the Hip Outcomes Research Network. A short version of the International Hip Outcome Tool (iHOT-12) for use in routine clinical practice.
      Patients included in this study had minimum 2-year follow-up; however, the scores from their most recent follow-up time point were reported. Postoperative patient satisfaction also was included and was rated on a scale of 0 to 10, with 0 being completely dissatisfied and 10 being completely satisfied. Throughout the follow-up period, any complications, revision procedures, or conversion to THA were reported and recorded. The MCID was calculated for the mHHS, NAHS, and HOS-SSS using the method described and validated by Norman et al.
      • Norman G.R.
      • Sloan J.A.
      • Wyrwich K.W.
      Interpretation of changes in health-related quality of life: The remarkable universality of half a standard deviation.
      The PASS values were used using previously established values for the mHHS (≥74),
      • Chahal J.
      • Thiel G.S.V.
      • Mather R.C.
      • Lee S.
      • Salata M.J.
      • Nho S.J.
      The minimal clinical important difference (MCID) and patient acceptable symptomatic state (PASS) for the Modified Harris Hip Score and Hip Outcome Score among patients undergoing surgical treatment for femoroacetabular impingement.
      NAHS (≥85.6),
      • Rosinsky P.J.
      • Kyin C.
      • Maldonado D.R.
      • et al.
      Determining clinically meaningful thresholds for the nonarthritic hip score in patients undergoing arthroscopy for femoroacetabular impingement syndrome.
      and HOS-SSS (≥75).
      • Chahal J.
      • Thiel G.S.V.
      • Mather R.C.
      • Lee S.
      • Salata M.J.
      • Nho S.J.
      The minimal clinical important difference (MCID) and patient acceptable symptomatic state (PASS) for the Modified Harris Hip Score and Hip Outcome Score among patients undergoing surgical treatment for femoroacetabular impingement.

      Statistical Analysis

      To ensure that adequate power was achieved, an a priori power analysis was performed. Under the assumption that a mean difference of 10 points in mHHS was statistically significant, this analysis indicated that the study required at least 36 patients in each group to achieve 80% power. Propensity-score matching was performed using R (Version 3.4.0; R Foundation for Statistical Computing, Vienna, Austria) to decrease the influence of potentially confounding variables and therefore, further increase the study’s external validity.
      All other statistical analyses were performed using Microsoft Excel (Microsoft Corp., Redmond, WA) and the Real Statistics Add-in. When we examined continuous data, normality was assessed using the Shapiro–Wilk test and variance was compared using the F-test. Additionally, the mean and standard deviation were reported for all continuous data. Comparisons between pre- and postoperative PROs were made using a 2-tailed paired t test. Independent cohorts were compared using a student’s t test or its nonparametric equivalent, the Mann–Whitney U test. Further, the Welch test was employed in cases of nonparametric data with unequal variances. Categorical data were analyzed using a χ2 or Fisher exact test. Statistical significance was set at P < .05.

      Propensity-Score Matching Process for the Subanalysis

      Using a nearest-neighbor (Euclidean distance) match algorithm, patients were propensity-matched on the logit of the propensity score. The study group patients (revisions) were propensity-matched 1:1 to control group patients (primaries) using greedy matching without replacement with a caliper of 0.3; hence, once a study patient had been propensity-matched to a control patient, they were no longer available to be propensity-matched to additional control patients. This method has been established as the ideal method for estimating differences between groups in the literature.
      • Maldonado D.R.
      • Kyin C.
      • Rosinsky P.J.
      • et al.
      Minimum 5-year outcomes for revision hip arthroscopy with a prospective subanalysis against a propensity-matched control primary group.
      Propensity-matching was performed on a basis of age at surgery, sex, body mass index, and ALAD.

      Results

      Patient Demographics and Radiographic Findings

      Ninety-six hips satisfied the inclusion criteria for the study, of which 89 (92.7%) had minimum two-year follow-up. Demographic data are outlined in Table 1. The mean age at the time of surgery and body mass index were 49.4 ± 8.0 years and 26.6 ± 4.1, respectively. The mean follow-up time was 62.7 ± 38.5 (24.0-142.5) months. Table 2 describes the radiographic characteristics of the study cohort.
      Table 1Patient Demographic Data of the Revision Cohort
      Demographics
      Hips included in study
       Left39 (43.8%)
       Right50 (56.2%)
      Sex
       Female59 (66.3%)
       Male30 (33.7%)
      Age at surgery, y, mean, SD [95% CI]49.4 ± 8.0 [48.8-50.0]
      Body mass index, mean, SD [95% CI]26.6 ± 4.1 [26.3-26.9]
      Follow-up time, mo, mean, SD [95% CI]62.7 ± 38.5 [60.0-65.5]
      CI, confidence interval; SD, standard deviation.
      Table 2Radiologic Findings Data of the Revision Cohort
      Radiographic Findings
      Tönnis grade, n (%)
       069 (77.5%)
       120 (22.5%)
      LCEA, °29.8 ± 6.0 [29.4, 30.3]
      Acetabular inclination, °5.0 ± 3.9 [4.7, 5.3]
      ACEA, °29.9 ± 7.1 [29.4, 30.4]
      Alpha angle, °52.1 ± 11.7 [51.3, 53.0]
      NOTE. Values presented as mean ± standard deviation [95% confidence interval] unless otherwise noted.
      ACEA, anterior center-edge angle; LCEA, lateral center-edge angle.

      Intraoperative Findings and Procedures

      Tables 3 and 4 outline the intraoperative findings and procedures, respectively. The most common type (42.7%) of labral tearing observed in this cohort was Seldes 2. In total, 47.2% of patients were found to have ALAD and acetabular Outerbridge ≥2. Further, 24.7% of patients were found to have some degree of cartilage damage to the femoral head. The group that did not convert to THA had the following ALAD grades (grade 0: 15 hips, grade 1: 21 hips, grade 2: 16 hips, grade 3: 10 hips, grade 4: 3 hips). The group that converted to THA had similar ALAD grades (grade 0: 6 hips, grade 1: 5 hips, grade 2: 5 hips, grade 3: 6 hips, grade 4: 2 hips, P = .653). Labral treatment (repair, selective debridement, or reconstruction) was performed in 82% of patients.
      Table 3Intraoperative Findings Data of the Revision Cohort
      Intraoperative Findings
      Seldes
       018 (20.2%)
       110 (11.2%)
       238 (42.7%)
       1 and 223 (25.9%)
      ALAD
       021 (23.6%)
       126 (29.2%)
       221 (23.6%)
       316 (18.0%)
       45 (5.6%)
      Outerbridge (acetabulum)
       021 (23.6%)
       126 (29.2%)
       221 (23.6%)
       310 (11.2%)
       411 (12.4%)
      Outerbridge (femoral head)
       067 (75.3%)
       10 (0.0%)
       210 (11.2%)
       38 (9.0%)
       44 (4.5%)
      LT villar
       046 (51.7%)
       19 (10.1%)
       219 (21.3%)
       315 (16.9%)
      NOTE. Values presented as n (%).
      ALAD, acetabular labral articular disruption; LT, ligamentum teres.
      Table 4Surgical Procedures Data of the Revision Cohort
      Surgical Procedures
      Labral treatment
       None16 (18.0%)
       Debridement45 (50.6%)
       Repair18 (20.2%)
       Reconstruction10 (11.2%)
      Capsular Treatment
       Interportal capsulotomy without repair67 (75.3%)
       Repair22 (24.7%)
      Femoroplasty51 (57.3%)
      Acetabuloplasty36 (40.4%)
      Acetabular microfracture7 (7.9%)
      Femoral head microfracture2 (2.2%)
      LT debridement26 (29.2%)
      NOTE. Values presented as n (%).
      LT, ligamentum teres.

      PRO Scores

      Patients demonstrated statistically significant improvement in mHHS, HOS-SSS, NAHS, and VAS at a mean follow-up of 62.7 ± 38.5 months. The mean improvement was 21.6 points (P <.001) for mHHS, 24.6 (P <.001) for HOS-SSS, 22.3 (P <.001) for NAHS, and –3.0 (P <.001) for VAS. Mean patient satisfaction was 7.4 out of 10. Table 5 depicts preoperative and postoperative PROs.
      Table 5Patient-Reported Outcomes Data of the Revision Cohort
      Patient-Reported Outcomes
      mHHS
       Preoperative51.7 ± 14.3 [50.7-52.7]
       Latest74.0 ± 19.7 [72.6-75.4]
       Pre- to postoperative P value< .001
       Improvement21.6 ± 20.4 [20.1-23.0]
      HOS-SSS
       Preoperative29.2 ± 22.4 [27.6-30.8]
       Latest55.8 ± 29.0 [53.7-57.9]
       Pre- to postoperative P value<.001
       Improvement24.6 ± 31.2 [22.4-26.8]
      VAS
       Preoperative6.4 ± 1.9 [6.3-6.6]
       Latest3.3 ± 2.5 [3.1-3.5]
       Pre- to postoperative P value<.001
       Improvement–3.0 ± 2.6 [–3.2 to –2.8]
      NAHS
       Preoperative50.5 ± 16.6 [49.3-51.7]
       Latest73.7 ± 17.9 [72.4-75.0]
       Pre- to postoperative P value<.001
       Improvement22.3 ± 20.8 [20.8-23.8]
      iHOT-1259.2 ± 26.9 [57.3-61.2]
      Satisfaction7.4 ± 2.7 [7.2-7.6]
      NOTE. Values presented as mean ± standard deviation (SD) [95% confidence interval] unless otherwise noted.
      HOS-SSS, Hip Outcome Score-Sports Specific Scale; iHOT-12, International Hip Outcome Tool; mHHS, Modified Harris Hip Score; NAHS, Non-Arthritic Hip Score; VAS, visual analog scale.
      Fifty-six (71.8%) and 45 (65.2%) met or exceeded the MCID for the mHHS (≥7.1) and HOS-SSS (≥11.2), respectively. Additionally, 75 (96.2%) and 58 (74.4%) met or exceeded the MCID for the VAS (≥0.9) and NAHS (≥8.3), respectively. Forty-three (55.1%) and 22 (31.9%) achieved PASS for the mHHS and HOS-SSS, respectively. In addition, 25 (32.1%) patients achieved PASS for the NAHS.

      End Points

      Ten (11.2%) hips required re-revision arthroscopy at a mean 42.1 ± 35.0 months. Twenty-four (27.0%) hips underwent conversion to THA at a mean 28.7 ± 29.3 months.

      Propensity-Matched Subanalysis

      Eighty-seven study group hips were successfully propensity-matched to 87 control group hips. Demographic data for the propensity-matched groups is located in Table 6.
      Table 6Demographic Data for the Propensity-Matched Groups
      DemographicsStudy GroupControl GroupP Value
      Hips included in study.646
       Left39 (44.8%)36 (41.4%)
       Right48 (55.2%)51 (58.6%)
      Sex.872
       Female58 (66.7%)59 (67.8%)
       Male29 (33.3%)28 (32.2%)
      Age at surgery, y, mean ± SD [CI]49.5 ± 8.0 [47.8-51.2]50.3 ± 7.0 [48.8-51.8].221
      Body mass index, mean ± SD [CI]26.6 ± 4.1 [25.7-27.5]26.4 ± 5.1 [25.3-27.5].810
      Follow-up time, mo, mean ± SD [CI]63.5 ± 38.6 [55.4-71.6]66.1 ± 36.8 [58.4-73.8].627
      NOTE. Values presented as mean ± standard deviation [95% CI] unless otherwise noted.
      CI, confidence interval; SD, standard deviation.
      The groups were fairly similar upon examination of radiographs; however, the primary control group was found to have a significantly greater alpha angle 60.3 ± 10.7° (compared with 52.1 ± 11.7°, P < .001). Radiographic findings are further outlined in Table 7.
      Table 7Radiologic Findings for the Propensity-Matched Groups
      Radiological FindingsStudy GroupControl GroupP Value
      Tönnis grade.853
       068 (78.2%)69 (79.3%)
       119 (21.8%)18 (20.7%)
      LCEA, °30.0 ± 6.0 [28.7-31.3]31.2 ± 6.5 [29.8-32.6].221
      Acetabular inclination, °4.9 ± 4.0 [4.1-5.7]5.4 ± 5.3 [4.3-6.5].548
      ACEA, °29.9 ± 7.2 [28.4-31.4]31.0 ± 8.2 [29.3-32.7]0.446
      Alpha angle, °52.1 ± 11.7 [49.6-54.6]60.3 ± 10.7 [58.0-62.5]<.001
      NOTE. Values in bold indicate statistical significance (P < .05). Values presented as mean ± standard deviation [95% confidence interval] unless otherwise noted.
      ACEA, anterior center-edge angle; LCEA, lateral center-edge angle.
      The intraoperative findings and procedures differed between the groups. The study and control groups had significantly different labral tears classified using the Seldes system (P < .001). The labral treatment differed between the groups with more study patients undergoing selective debridement and more control patients undergoing labral repair (P < .001). The study group had a significantly lower rate of capsular repair than the control group (24.1% vs 49.4%, P = .001). The study group also underwent significantly lower rates of femoroplasty and acetabuloplasty than the control group (57.5% vs 88.5%, P < .001) and (41.4% vs 65.5%, P = .001). Data on intraoperative findings and procedures for both groups can be found in Tables 8 and 9, respectively.
      Table 8Intraoperative Findings for the Propensity-Matched Groups
      Intraoperative FindingsStudy Group, n (%)Control Group, n (%)P Value
      Seldes<.001
       018 (20.7%)2 (2.3%)
       110 (11.5%)21 (24.1%)
       237 (42.5%)28 (32.2%)
       1 and 222 (25.3%)36 (41.4%)
      ALAD.683
       021 (24.1%)20 (23.0%)
       125 (28.7%)26 (29.9%)
       221 (24.1%)26 (29.9%)
       315 (17.2%)8 (9.2%)
       45 (5.7%)7 (8.0%)
      Outerbridge (acetabulum).822.
       021 (24.1%)20 (23.0%)
       125 (28.7%)26 (29.9%)
       221 (24.1%)26 (29.9%)
       39 (10.3%)8 (9.2%)
       411 (12.6%)7 (8.0%)
      Outerbridge (femoral head).875
       066 (75.9%)67 (77.0%)
       10 (0.0%)1 (1.1%)
       210 (11.5%)10 (11.5%)
       37 (8.0%)4 (4.6%)
       44 (4.6%)5 (5.7%)
      LT villar.082
       044 (50.6%)33 (37.9%)
       19 (10.3%)4 (4.6%)
       219 (21.8%)25 (28.7%)
       315 (17.2%)25 (28.7%)
      NOTE. Values in bold indicate statistical significance (P < .05). Values presented as n (%).
      ALAD, acetabular labral articular disruption; LT, ligamentum teres.
      Table 9Surgical Procedures for the Propensity-Matched Groups
      Surgical ProceduresStudy Group n (%)Control Group, n (%)P Value
      Labral treatment<.001
       None16 (18.4%)2 (2,2%)
       Selective debridement45 (51.7%)30 (34.5%)
       Repair18 (20.7%)51 (58.6%)
       Reconstruction8 (9.2%)4 (4.6%)
      Capsular treatment.001
      Interportal capsulotomy without repair66 (75.9%)44 (50.6%)
       Repair21 (24.1%)43 (49.4%)
      Femoroplasty50 (57.5%)77 (88.5%)<.001
      Acetabuloplasty36 (41.4%)57 (65.5%).001
      Acetabular microfracture7 (8.0%)6 (6.9%).773
      Femoral head microfracture2 (2.3%)1 (1.1%).623
      LT debridement26 (29.9%)30 (34.5%).522
      NOTE. Values in bold indicate statistical significance (P < .05). Values presented as n (%).
      LT, ligamentum teres.
      Both groups demonstrated statistically significant improvement in mHHS, HOS-SSS, NAHS, and VAS at latest follow-up. The study group demonstrated lower mHHS, NAHS, and VAS preoperatively and lower mHHS, NAHS, VAS, HOS-SSS, and iHOT-12 postoperatively compared to the control group (P < .05). Patient satisfaction was greater in the control group (8.2 ± 2.6 vs 7.5 ± 2.5, P = .017). However, the improvement (delta value) was similar for all PROs (Table 10). The study group and the control group had comparable rates of achieving MCID for the mHHS (study = 7.1 and control = 6.9) (55 [72.4%] vs 60 [72.3%], P = .991), HOS-SSS (study = 11.2 and control = 12.4) (45 [66.2%] vs 47 [71.2%], P = .530), VAS (study = 0.9 and control = 1.0) (63 [82.9%] vs 59 [71.1%], P = .078), and NAHS (study = 8.3 and control = 8.8) (56 [79.4%] vs 58 [76.9%], P = .679). The study group achieved PASS at a lower rate than the control group, (42 [55.3%] vs 59 [71.1%], P = .038). The study group also achieved lower rates of PASS for the HOS-SSS (20 [29.4%] vs 38 [57.6%], P = .001). PASS rates were lower in the study group for the NAHS (24 [31.6%] vs 49 [59.8%], P <.001).
      Table 10Patient-Reported Outcomes for the Propensity-Matched Groups
      Patient-Reported OutcomesRevision, mean [95% CI]Control, mean [95% CI]P value
      mHHS
       Preoperative52.2 ± 14.6 [48.9-55.5]61.9 ± 13.8 [58.9-64.9]<.001
       Latest74.0 ± 19.6 [69.6-78.4]82.7 ± 18.6 [78.7-86.7].006
       Pre- to postoperative P value<.001<.001
       Improvement21.8 ± 20.5 [17.2-26.4]20.7 ± 21.0 [16.2-25.2].748
      HOS-SSS
       Preoperative29.6 ± 21.9 [24.4-34.8]37.0 ± 24.7 [31.0-43.0].060
       Latest54.4 ± 28.7 [47.6-61.2]69.6 ± 34.3 [61.3-77.9].002
       Pre- to postoperative P value<.001<.001
       Improvement24.8 ± 31.4 [17.3-32.3]32.6 ± 35.6 [24.0-41.2].180
      VAS
       Preoperative6.3 ± 1.9 [5.9-6.7]5.0 ± 2.1 [4.6-5.5]<.001
       Latest3.3 ± 2.4 [2.8-3.8]2.4 ± 2.8 [1.8-3.0].005
       Pre- to postoperative P value<.001<.001
       Improvement–3.0 ± 2.5 [–3.6 to –2.4]–2.6 ± 3.1 [–3.3 to –1.9].327
      NAHS
       Preoperative51.3 ± 16.3 [47.6-55.0]59.9 ± 17.6 [56.1-63.7].001
       Latest73.7 ± 17.9 [69.7-77.7]81.8 ± 18.7 [77.8-85.8].002
       Pre- to postoperative P value<.001<.001
       Improvement22.4 ± 21.1 [17.7-27.1]21.9 ± 22.5 [17.1-26.7].884
      iHOT-1259.4 ± 26.6 [53.3-65.5]73.7 ± 27.2 [67.7-79.7]<.001
      Satisfaction7.5 ± 2.5 [6.9-8.1]8.2 ± 2.6 [7.6-8.8].017
      NOTE. Values in bold indicate statistical significance (P < .05). Values presented as mean ± standard deviation [95% confidence interval] unless otherwise noted.
      HOS-SSS, Hip Outcome Score-Sports Specific Scale; iHOT-12, International Hip Outcome Tool; mHHS, Modified Harris Hip Score; NAHS, Non-Arthritic Hip Score; VAS, visual analog scale.
      The relative risk of conversion to THA was 2.63 times greater (95% confidence interval 1.20-5.79) for the revision group. Twenty-four (27.6%) hips in the study group and 11 (12.6%) hips in the control group underwent conversion to THA (P = .013). The average time for the conversion to THA for the study and control groups was (28.7 ± 29.3 [17.0-40.4] months and 26.4 ± 21.1 [13.9-38.9] months, respectively, P = .560). Figure 2 details a survivorship curve for the study and control groups.
      Figure thumbnail gr2
      Fig 2Total hip arthroplasty conversion survivorship curve for revision and control groups.

      Discussion

      The main findings of the present investigation were that patients aged 40 years and older who underwent revision hip arthroscopy reported significant PROs improvement and high rate of achievement for the MCID for all PROs at a mean follow-up of 62.7 ± 38.5 months. The percentage of patients that survived was found to be 73%. The secondary subanalysis demonstrated that, although lower postoperative PROs were obtained for the propensity-matched revision study group; the improvement for each metric was comparable to the primary control group. In addition, the revision group had a 2.63 times greater risk of THA conversion than the primary group.
      Older age has previously been reported as a factor that negatively influenced the outcomes after hip arthroscopy.
      • Horner N.S.
      • Ekhtiari S.
      • Simunovic N.
      • Safran M.R.
      • Philippon M.J.
      • Ayeni O.R.
      Hip arthroscopy in patients age 40 or older: A systematic review.
      In the primary setting, patients older than 45 years of age performed worse than younger patients.
      • Frank R.M.
      • Lee S.
      • Bush-Joseph C.A.
      • Salata M.J.
      • Mather R.C.
      • Nho S.J.
      Outcomes for hip arthroscopy according to sex and age: A comparative matched-group analysis.
      In a retrospective cohort study following 390 patients, 260 younger than 40 years of age were propensity-matched and compared with 130 patients older than 40 years of age, Yacovelli et al.
      • Yacovelli S.
      • Sutton R.
      • Vahedi H.
      • Sherman M.
      • Parvizi J.
      High risk of conversion to THA after femoroacetabular osteoplasty for femoroacetabular impingement in patients older than 40 years.
      demonstrated a mean improvement and postoperative mHHS score of 11 and 65, respectively, with an overall THA conversion rate of 16% within 2 years of surgery for the late group. Based on these results, these authors recommended avoiding this procedure in this patient population. Martin et al.
      • Martin S.D.
      • Abraham P.F.
      • Varady N.H.
      • et al.
      Hip arthroscopy versus physical therapy for the treatment of symptomatic acetabular labral tears in patients older than 40 years: A randomized controlled trial.
      reported in a randomized controlled trial that patients older than 40 years with limited osteoarthritis, hip arthroscopy with labral repair, and postoperative physical therapy led to better outcomes than physical therapy alone. O’Connor et al.
      • O’Connor M.
      • Steinl G.K.
      • Padaki A.S.
      • Duchman K.R.
      • Westermann R.W.
      • Lynch T.S.
      Outcomes of revision hip arthroscopic surgery: A systematic review and meta-analysis.
      systematically reviewed 4,316 patients (4765 hips) undergoing revision hip arthroscopy, the rates of additional surgery were reported to be between 5% and 14%, the mean rates of conversion to THA and re-revision arthroscopic surgery were 8.3%, and 7.5%, respectively, but as high as 14% for both. The patient mean age for the 15 studies included was 32.23 years. Age may be one of the reasons of why the THA conversion rate was almost the double (27%) in the present study. In terms of PROs improvement, revision hip arthroscopy seems to be a suitable option for patients aged ≥40 years; nevertheless this patient population must be counseled of the greater risk for THA conversion. The data reported in the present study can be used in the clinical practice to provide guidance during the surgical decision-making process.
      Noteworthy strengths of the present study have to be acknowledged. This is one of the few studies reporting data on PROs and psychometric tools following revision hip arthroscopy in this specific patient population, using multiple validated functional PROs designed for hip preservation surgery, and the MCID and the PASS, respectively. In addition, the propensity-matched sub-analysis minimizes the effect of confounding variables

      Limitations

      The present study is not without limitations. It is important to highlight that the reproducibility of the results may be affected, as data were obtained from a single institution and a single hip arthroscopy surgeon.
      • Mehta N.
      • Chamberlin P.
      • Marx R.G.
      • et al.
      Defining the learning curve for hip arthroscopy: A threshold analysis of the volume-outcomes relationship.
      Surgeon expertise, experience, and learning curve play a critical role in the approach for the failed hip arthroscopy, and the decision-making process for treatment in revision hip arthroscopy.
      • Makhni E.C.
      • Ramkumar P.N.
      • Cvetanovich G.
      • Nho S.J.
      Approach to the patient with failed hip arthroscopy for labral tears and femoroacetabular impingement.
      ,
      • Maldonado D.R.
      • Kyin C.
      • Rosinsky P.J.
      • et al.
      Minimum 5-year outcomes for revision hip arthroscopy with a prospective subanalysis against a propensity-matched control primary group.
      Using the age of 40 years old as a cut-off was selected by the authors based on prior studies
      • Horner N.S.
      • Ekhtiari S.
      • Simunovic N.
      • Safran M.R.
      • Philippon M.J.
      • Ayeni O.R.
      Hip arthroscopy in patients age 40 or older: A systematic review.
      ,
      • Martin S.D.
      • Abraham P.F.
      • Varady N.H.
      • et al.
      Hip arthroscopy versus physical therapy for the treatment of symptomatic acetabular labral tears in patients older than 40 years: A randomized controlled trial.
      ,
      • White B.J.
      • Patterson J.
      • Scoles A.M.
      • Lilo A.T.
      • Herzog M.M.
      Hip arthroscopy in patients aged 40 years and older: greater success with labral reconstruction compared with labral repair.
      ; notwithstanding, it remains an arbitrary decision. The potential confounding effect of several variables that were not included in the matching process including diagnosis may have influenced the results presented. The retrospective nature of the analysis introduced bias. Additionally, the entire study cohort was unable to be matched. Patients in the revision group that required re-revision arthroscopic surgery or conversion to THA, and patients in the primary group that required secondary surgeries were considered an endpoint; hence, not included within the PROs analysis. A PROs comparison according to sex was not performed. Surgical technique and indications have evolved over time; therefore, patients that may have originally received an interportal capsulotomy with labral debridement may now have a underwent capsular repair with labral repair, reconstruction, or augmentation. As expected, there were significant differences in the intraoperative findings and surgical procedures in the sub-analysis between the study and control group. Lastly, the sample size was modest.

      Conclusions

      Patients aged ≥40 years who underwent revision hip arthroscopy reported significant improvement in all PROs at a mean follow-up of 62.7 months with favorable rates of achieving the MCID. When compared with the propensity-matched control group, both achieved similar rates of improvement, but the revision group was 2.63 times more likely to convert to THA.

      Supplementary Data

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