ABSTRACT

It is unclear whether treatment of intraarticular pathology should be performed during periacetabular osteotomy (PAO) to improve outcomes. Therefore, we asked: (i) What are the clinical results of PAO in patients with and without intraarticular intervention? (ii) Is there a difference in reoperations with and without intraarticular intervention? and (iii) Is there a difference in clinical results and reoperations depending on preoperative Tönnis Grade if intraarticular intervention is performed? Prospective evaluation of 161 PAO in 146 patients was performed. The cohort was 84.5% female, mean age was 26.7 ± 7.9 years and mean follow-up was 2.4 years; 112 hips had Grade 0 changes and 49 hips had Grade 1 changes. Patients were classified into three groups based on treatments during PAO: major (labral repair, femoral head–neck osteochondroplasty), minor (labral debridement, femoral/acetabular chondroplasty) or no intervention. A subset of eight patient-reported outcome measures (PROMs) was analyzed to determine whether the minimal clinically important difference (MCID) was achieved. Major, minor and no intervention groups exceeded the MCID in 5, 8 and 8, of 8 PROMs (P ≥ 0.20), respectively; intraarticular interventions did not influence reoperation-free survival (P ≥ 0.35). By Tönnis Grade, PROMs exceeding MCID decreased in Grade 1 versus 0 receiving no intervention (P < 0.001) but did not decrease for either intervention (P ≥ 0.14); intraarticular interventions did not influence reoperation-free survival (P ≥ 0.38). Overall, intraarticular intervention was associated with excellent PROMs and reoperation-free survival. Although Grade 1 patients had fewer PROM which achieved MCID, intraarticular interventions attenuated this decrease, suggesting a therapeutic advantage of intraarticular procedures for more advanced pathology.

INTRODUCTION

Developmental dysplasia of the hip (DDH) is associated with premature degenerative changes in the joint [1]. Nearly one in three dysplastic hips without radiographic evidence of arthritis (Tönnis Grade 0) will develop mild arthritic changes (Tönnis Grade 1) by 10 years, with one in four Tönnis Grade 0 patients being converted to total hip arthroplasty by 20 years [1]. Pelvic reorientation may be achieved in skeletally mature dysplastic patients with preserved articular cartilage via the Bernese periacetabular osteotomy (PAO) [2]. PAO has been shown to change the natural history of DDH by decreasing the risk of THA and degenerative changes in Tönnis Grade 0 and 1 hips [1, 3].

While recent 20- and 30-year follow-up reports have confirmed PAO to be an effective treatment for DDH [4, 5], a number of preoperative factors can influence the longevity and durability of the procedure. Namely, advanced preoperative radiographic Tönnis Grade has been associated with failure of PAO [6–8]. Degenerative changes to the hip conferring advanced Tönnis Grades are both preceded and potentiated by acetabular labral disease [9]. Most commonly occurring along the articular margin of the anterior portion of the acetabulum, labral tears can cause disruption of chondrolabral continuity, initiating the process of acetabular cartilage delamination [10]. Although the incidence of labral lesions has been reported to be up to 90% in patients with dysplasia [11], there is no consensus on the preferred management of labral pathology either contemporaneous or staged with PAO versus no treatment at all. As such, it is necessary to assess whether the addition of intraarticular interventions to PAO confers a clinical benefit or an elevated risk of reoperation over PAO alone. Accordingly, we asked: (i) What are the clinical results of PAO in patients with and without intraarticular intervention at the time of surgery? (ii) Is there a difference in reoperation rates after PAO with and without intraarticular intervention? and (iii) Is there a significant difference in clinical results and achievement of MCID and reoperations depending on the preoperative radiographic Tönnis Grade if intraarticular intervention is performed?

METHODS

After obtaining Institutional Review Board (IRB No.: 17-001303) approval, we retrospectively reviewed all patients undergoing PAO at the Mayo Clinic in Rochester, Minnesota, between November 2009 and January 2016. All patients were treated by one of two senior hip preservation surgeons (R.T.T. or R.J.S.). Candidates for PAO had symptomatic DDH, defined by a lateral center-edge angle [12] <25°, acetabular index [13] >10° and anterior center-edge angle [14] <25°, with an age <50 years. We identified 171 patients (191 hips) patients who met these criteria. All patients undergoing surgical hip dislocation at the time of PAO were excluded (8 patients; 10 hips), all patients with non-DDH etiology of arthritic hip disease were excluded (13 patients, 16 hips) and all patients with Tönnis Grade ≥2 degenerative changes [15] were excluded (4 patients, 4 hips). Thus, the final cohort consisted of 146 patients (161 hips), with all patients having a diagnosis of symptomatic DDH.

As part of a prospectively collected hip preservation registry, 12 PROMs were recorded at the preoperative visit and each postoperative visit. In this cohort, the most recent clinical follow-up occurred at a mean of 2.4 years postoperatively (range: 0.8–5.7 years). PROMs included the University of California, Los Angeles (UCLA) activity score, Harris Hip Score, four subcomponents of the Hip Disability and Osteoarthritis Outcome Score (HOOS) [Pain, Activities of Daily Living (ADL), Sports and Recreation, Quality of Life], four subcomponents of the Western Ontario & McMaster Universities Questionnaire (WOMAC; Pain, Stiffness, Physical, Total) and two subcomponents of the SF-12 Health Survey (Physical and Mental). Each score has been used previously to assess the functional outcome of patients treated with PAO for symptomatic dysplasia [16–20]. For a subset of eight PROMs collected in this study, the preoperative to postoperative change was compared to the established minimal clinically important difference (MCID) reported in the literature [21].

Among the 146 patients (161 hips), 98 patients (105 hips) had preoperative Tönnis Grade 0 changes and 34 patients (42 hips) had Tönnis Grade 1 changes. Seven patients (14 hips) underwent staged bilateral PAO with side-to-side differences in Tönnis Grade. The cohort was 84.5% female, the mean age at the time of surgery was 26.7 ± 7.9 years (range: 12.7–47.7 years) and mean body mass index (BMI) was 25.5 ± 4.6 kg/m2 (range: 12.0–39.4 kg/m2) (Table I). During the study period, there was no defined indication for joint assessment. As per surgeon preference, either an arthrotomy or arthroscopy at the time of PAO was used to evaluate the joint. Labral repair and femoral head–neck osteochondroplasty were performed based on preoperative imaging identifying a tear or morphologic abnormality, respectively, in combination with patient symptomatology and functional goals following surgery. A femoral head–neck junction osteochondroplasty, for example, was added at the time of surgery to improve range of motion before impingement after correction. On this basis, each hip was subsequently re-classified by the extent of the intraarticular intervention performed at the time of PAO into either major (labral repair, femoral head–neck osteochondroplasty), minor (labral debridement, femoral/acetabular chondroplasty) or no intervention groups. By intraarticular intervention, Tönnis Grade 0 and Grade 1 groups did not differ by age, gender, BMI or the incidence of prior surgery to the affected hip (P ≥ 0.13) (Table I).

Table I.

Patient characteristics by Tönnis Grade and intraarticular intervention

. Tönnis Grade 0 . Tönnis Grade 1 .  .  . Major (n = 25) . Minor (n = 25) . No intervention (n = 62) . Adjusted P-value* . Major (n = 24) . Minor (n = 9) . No intervention (n = 16) . Adjusted P-value* . Total (n = 161) . Age at surgery (years)    0.23    0.15  Mean (SD) 26.8 (7.8) 26.5 (6.4) 24.1 (7.3)  30.9 (6.7) 34.1 (5.4) 26.6 (10.4)  26.7 (7.9) Median 25.3 24.5 22.8  31.0 34.0 24.5  25.3 Q1, Q3 22.0, 33.4 20.8, 32.0 17.9, 29.6  27.2, 35.2 32.8, 37.5 17.7, 35.0  20.1, 32.6 Range (15.4–42.3) (17.9–39.1) (14.0–43.3)  (19.2–46.1) (23.5–41.7) (12.7–47.7)  (12.7–47.7) Gender    0.54    0.13  F 20 (80.0%) 23 (92.0%) 56 (90.3%)  16 (66.7%) 8 (88.9%) 13 (81.3%)  136 (84.5%) M 5 (20.0%) 2 (8.0%) 6 (9.7%)  8 (33.3%) 1 (11.1%) 3 (18.8%)  25 (15.5%) BMI (lbs/in):    0.23    0.56  Mean (SD) 26.2 (4.1) 24.4 (5.0) 24.4 (4.3)  28.2 (4.6) 26.2 (4.2) 26.0 (4.9)  25.5 (4.6) Median 25.5 24.4 24.1  27.1 25.8 26.3  25.2 Q1, Q3 22.9, 29.1 20.9, 26.9 21.7, 26.7  25.0, 31.0 24.4, 27.9 22.7, 28.7  22.1, 27.9 Range (20.3–34.7) (17.6–39.4) (12.0–35.4)  (20.8–37.7) (20.4–34.7) (18.5–38.6)  (12.0–39.4) Side    0.32    0.27  Left 12 (48.0%) 9 (36.0%) 20 (32.3%)  14 (58.3%) 4 (44.4%) 6 (37.5%)  65 (40.4%) Right 13 (52.0%) 16 (64.0%) 42 (67.7%)  10 (41.7%) 5 (55.6%) 10 (62.5%)  96 (59.6%) Any prior surgery?    0.58    0.82  No 23 (92.0%) 22 (88.0%) 56 (90.3%)  19 (79.2%) 8 (88.9%) 11 (68.8%)  139 (86.3%) Yes 2 (8.0%) 3 (12.0%) 6 (9.7%)  5 (20.8%) 1 (11.1%) 5 (31.3%)  22 (13.7%) Method of joint interrogation Arthoscopy 4 (16.0%) 13 (52.0%) 2 (3.2%)  15 (62.5%) 3 (33.3%) 0 (0.0%)  37 (23.0%) Arthrotomy 21 (84.0%) 12 (48.0%) 43 (69.4%)  9 (37.5%) 6 (66.7%) 7 (43.8%)  98 (60.9%) None 0 (0.0%) 0 (0.0%) 17 (27.4%)  0 (0.0%) 0 (0.0%) 9 (56.2%)  26 (16.1%) AP pelvic tilt (mm)    0.37    0.26  Mean (SD) 47.3 (21.2) 54.4 (21.4) 54.3 (22.8)  45.1 (24.5) 42.0 (24.7) 36.7 (18.0)  49.3 (22.8) Median 48.0 56.0 57.0  48.0 53.0 40.0  51.8 Q1, Q3 34.0, 66.0 43.5, 74.5 42.7, 70.0  24.0, 67.0 18.0, 60.0 22.0, 52.0  35.5, 65.2 Range (0.0–79.0) (8.0–89.7) (4.3–106.0)  (2.5–87.0) (4.0–71.0) (4.5–60.0)  (0.0–106.0) AP pelvic rotation (mm)    0.77    0.52  Mean (SD) 4.6 (9.1) 2.7 (3.3) 4.0 (6.6)  1.6 (3.0) 3.6 (4.2) 3.3 (3.9)  3.4 (5.9) Median 1.0 0.0 4.0  0.0 2.0 2.0  0.0 Q1, Q3 0.0, 5.0 0.0, 5.0 0.0, 5.0  0.0, 2.0 0.0, 5.0 0.0, 7.0  0.0, 5.0 Range (0.0–41.2) (0.0–10.0) (0.0–43.1)  (0.0–10.0) (0.0–10.0) (0.0–10.0)  (0.0–43.1) Lateral center-edge angle (degrees)    0.58    0.27  Mean (SD) 17.0 (7.5) 16.5 (5.7) 15.2 (6.5)  15.7 (7.4) 14.5 (7.5) 12.8 (9.9)  15.5 (7.1) Median 17.0 19.0 15.0  16.5 18.0 15.0  16.0 Q1, Q3 11.0, 20.0 13.0, 20.0 10.0, 20.0  12.5, 21.0 10.0, 19.0 9.5, 19.3  11.0, 20.0 Range (4.0–37.4) (2.1–24.9) (0.0–29.0)  (−3.0–25.0) (0.0–25.0) (−18.0–23.0)  (−18.0–37.4) Acetabular inclination (degrees)    0.21    0.046  Mean (SD) 15.9 (6.5) 16.3 (8.1) 18.8 (7.2)  14.8 (6.2)a 21.7 (9.7)a 20.6 (8.8)a  17.7 (7.6) Median 15.0 14.0 17.0  12.6 24.0 21.5  15.0 Q1, Q3 11.0, 21.8 10.0, 21.0 13.0, 24.0  11.0, 17.0 15.0, 26.7 13.9, 23.5  12.0, 23.0 Range (2.3–25.0) (6.1–33.0) (6.5–40.0)  (5.0–29.0) (8.0–40.0) (8.6–40.0)  (2.3–40.0)  . Tönnis Grade 0 . Tönnis Grade 1 .  .  . Major (n = 25) . Minor (n = 25) . No intervention (n = 62) . Adjusted P-value* . Major (n = 24) . Minor (n = 9) . No intervention (n = 16) . Adjusted P-value* . Total (n = 161) . Age at surgery (years)    0.23    0.15  Mean (SD) 26.8 (7.8) 26.5 (6.4) 24.1 (7.3)  30.9 (6.7) 34.1 (5.4) 26.6 (10.4)  26.7 (7.9) Median 25.3 24.5 22.8  31.0 34.0 24.5  25.3 Q1, Q3 22.0, 33.4 20.8, 32.0 17.9, 29.6  27.2, 35.2 32.8, 37.5 17.7, 35.0  20.1, 32.6 Range (15.4–42.3) (17.9–39.1) (14.0–43.3)  (19.2–46.1) (23.5–41.7) (12.7–47.7)  (12.7–47.7) Gender    0.54    0.13  F 20 (80.0%) 23 (92.0%) 56 (90.3%)  16 (66.7%) 8 (88.9%) 13 (81.3%)  136 (84.5%) M 5 (20.0%) 2 (8.0%) 6 (9.7%)  8 (33.3%) 1 (11.1%) 3 (18.8%)  25 (15.5%) BMI (lbs/in):    0.23    0.56  Mean (SD) 26.2 (4.1) 24.4 (5.0) 24.4 (4.3)  28.2 (4.6) 26.2 (4.2) 26.0 (4.9)  25.5 (4.6) Median 25.5 24.4 24.1  27.1 25.8 26.3  25.2 Q1, Q3 22.9, 29.1 20.9, 26.9 21.7, 26.7  25.0, 31.0 24.4, 27.9 22.7, 28.7  22.1, 27.9 Range (20.3–34.7) (17.6–39.4) (12.0–35.4)  (20.8–37.7) (20.4–34.7) (18.5–38.6)  (12.0–39.4) Side    0.32    0.27  Left 12 (48.0%) 9 (36.0%) 20 (32.3%)  14 (58.3%) 4 (44.4%) 6 (37.5%)  65 (40.4%) Right 13 (52.0%) 16 (64.0%) 42 (67.7%)  10 (41.7%) 5 (55.6%) 10 (62.5%)  96 (59.6%) Any prior surgery?    0.58    0.82  No 23 (92.0%) 22 (88.0%) 56 (90.3%)  19 (79.2%) 8 (88.9%) 11 (68.8%)  139 (86.3%) Yes 2 (8.0%) 3 (12.0%) 6 (9.7%)  5 (20.8%) 1 (11.1%) 5 (31.3%)  22 (13.7%) Method of joint interrogation Arthoscopy 4 (16.0%) 13 (52.0%) 2 (3.2%)  15 (62.5%) 3 (33.3%) 0 (0.0%)  37 (23.0%) Arthrotomy 21 (84.0%) 12 (48.0%) 43 (69.4%)  9 (37.5%) 6 (66.7%) 7 (43.8%)  98 (60.9%) None 0 (0.0%) 0 (0.0%) 17 (27.4%)  0 (0.0%) 0 (0.0%) 9 (56.2%)  26 (16.1%) AP pelvic tilt (mm)    0.37    0.26  Mean (SD) 47.3 (21.2) 54.4 (21.4) 54.3 (22.8)  45.1 (24.5) 42.0 (24.7) 36.7 (18.0)  49.3 (22.8) Median 48.0 56.0 57.0  48.0 53.0 40.0  51.8 Q1, Q3 34.0, 66.0 43.5, 74.5 42.7, 70.0  24.0, 67.0 18.0, 60.0 22.0, 52.0  35.5, 65.2 Range (0.0–79.0) (8.0–89.7) (4.3–106.0)  (2.5–87.0) (4.0–71.0) (4.5–60.0)  (0.0–106.0) AP pelvic rotation (mm)    0.77    0.52  Mean (SD) 4.6 (9.1) 2.7 (3.3) 4.0 (6.6)  1.6 (3.0) 3.6 (4.2) 3.3 (3.9)  3.4 (5.9) Median 1.0 0.0 4.0  0.0 2.0 2.0  0.0 Q1, Q3 0.0, 5.0 0.0, 5.0 0.0, 5.0  0.0, 2.0 0.0, 5.0 0.0, 7.0  0.0, 5.0 Range (0.0–41.2) (0.0–10.0) (0.0–43.1)  (0.0–10.0) (0.0–10.0) (0.0–10.0)  (0.0–43.1) Lateral center-edge angle (degrees)    0.58    0.27  Mean (SD) 17.0 (7.5) 16.5 (5.7) 15.2 (6.5)  15.7 (7.4) 14.5 (7.5) 12.8 (9.9)  15.5 (7.1) Median 17.0 19.0 15.0  16.5 18.0 15.0  16.0 Q1, Q3 11.0, 20.0 13.0, 20.0 10.0, 20.0  12.5, 21.0 10.0, 19.0 9.5, 19.3  11.0, 20.0 Range (4.0–37.4) (2.1–24.9) (0.0–29.0)  (−3.0–25.0) (0.0–25.0) (−18.0–23.0)  (−18.0–37.4) Acetabular inclination (degrees)    0.21    0.046  Mean (SD) 15.9 (6.5) 16.3 (8.1) 18.8 (7.2)  14.8 (6.2)a 21.7 (9.7)a 20.6 (8.8)a  17.7 (7.6) Median 15.0 14.0 17.0  12.6 24.0 21.5  15.0 Q1, Q3 11.0, 21.8 10.0, 21.0 13.0, 24.0  11.0, 17.0 15.0, 26.7 13.9, 23.5  12.0, 23.0 Range (2.3–25.0) (6.1–33.0) (6.5–40.0)  (5.0–29.0) (8.0–40.0) (8.6–40.0)  (2.3–40.0) Table I.

Patient characteristics by Tönnis Grade and intraarticular intervention

. Tönnis Grade 0 . Tönnis Grade 1 .  .  . Major (n = 25) . Minor (n = 25) . No intervention (n = 62) . Adjusted P-value* . Major (n = 24) . Minor (n = 9) . No intervention (n = 16) . Adjusted P-value* . Total (n = 161) . Age at surgery (years)    0.23    0.15  Mean (SD) 26.8 (7.8) 26.5 (6.4) 24.1 (7.3)  30.9 (6.7) 34.1 (5.4) 26.6 (10.4)  26.7 (7.9) Median 25.3 24.5 22.8  31.0 34.0 24.5  25.3 Q1, Q3 22.0, 33.4 20.8, 32.0 17.9, 29.6  27.2, 35.2 32.8, 37.5 17.7, 35.0  20.1, 32.6 Range (15.4–42.3) (17.9–39.1) (14.0–43.3)  (19.2–46.1) (23.5–41.7) (12.7–47.7)  (12.7–47.7) Gender    0.54    0.13  F 20 (80.0%) 23 (92.0%) 56 (90.3%)  16 (66.7%) 8 (88.9%) 13 (81.3%)  136 (84.5%) M 5 (20.0%) 2 (8.0%) 6 (9.7%)  8 (33.3%) 1 (11.1%) 3 (18.8%)  25 (15.5%) BMI (lbs/in):    0.23    0.56  Mean (SD) 26.2 (4.1) 24.4 (5.0) 24.4 (4.3)  28.2 (4.6) 26.2 (4.2) 26.0 (4.9)  25.5 (4.6) Median 25.5 24.4 24.1  27.1 25.8 26.3  25.2 Q1, Q3 22.9, 29.1 20.9, 26.9 21.7, 26.7  25.0, 31.0 24.4, 27.9 22.7, 28.7  22.1, 27.9 Range (20.3–34.7) (17.6–39.4) (12.0–35.4)  (20.8–37.7) (20.4–34.7) (18.5–38.6)  (12.0–39.4) Side    0.32    0.27  Left 12 (48.0%) 9 (36.0%) 20 (32.3%)  14 (58.3%) 4 (44.4%) 6 (37.5%)  65 (40.4%) Right 13 (52.0%) 16 (64.0%) 42 (67.7%)  10 (41.7%) 5 (55.6%) 10 (62.5%)  96 (59.6%) Any prior surgery?    0.58    0.82  No 23 (92.0%) 22 (88.0%) 56 (90.3%)  19 (79.2%) 8 (88.9%) 11 (68.8%)  139 (86.3%) Yes 2 (8.0%) 3 (12.0%) 6 (9.7%)  5 (20.8%) 1 (11.1%) 5 (31.3%)  22 (13.7%) Method of joint interrogation Arthoscopy 4 (16.0%) 13 (52.0%) 2 (3.2%)  15 (62.5%) 3 (33.3%) 0 (0.0%)  37 (23.0%) Arthrotomy 21 (84.0%) 12 (48.0%) 43 (69.4%)  9 (37.5%) 6 (66.7%) 7 (43.8%)  98 (60.9%) None 0 (0.0%) 0 (0.0%) 17 (27.4%)  0 (0.0%) 0 (0.0%) 9 (56.2%)  26 (16.1%) AP pelvic tilt (mm)    0.37    0.26  Mean (SD) 47.3 (21.2) 54.4 (21.4) 54.3 (22.8)  45.1 (24.5) 42.0 (24.7) 36.7 (18.0)  49.3 (22.8) Median 48.0 56.0 57.0  48.0 53.0 40.0  51.8 Q1, Q3 34.0, 66.0 43.5, 74.5 42.7, 70.0  24.0, 67.0 18.0, 60.0 22.0, 52.0  35.5, 65.2 Range (0.0–79.0) (8.0–89.7) (4.3–106.0)  (2.5–87.0) (4.0–71.0) (4.5–60.0)  (0.0–106.0) AP pelvic rotation (mm)    0.77    0.52  Mean (SD) 4.6 (9.1) 2.7 (3.3) 4.0 (6.6)  1.6 (3.0) 3.6 (4.2) 3.3 (3.9)  3.4 (5.9) Median 1.0 0.0 4.0  0.0 2.0 2.0  0.0 Q1, Q3 0.0, 5.0 0.0, 5.0 0.0, 5.0  0.0, 2.0 0.0, 5.0 0.0, 7.0  0.0, 5.0 Range (0.0–41.2) (0.0–10.0) (0.0–43.1)  (0.0–10.0) (0.0–10.0) (0.0–10.0)  (0.0–43.1) Lateral center-edge angle (degrees)    0.58    0.27  Mean (SD) 17.0 (7.5) 16.5 (5.7) 15.2 (6.5)  15.7 (7.4) 14.5 (7.5) 12.8 (9.9)  15.5 (7.1) Median 17.0 19.0 15.0  16.5 18.0 15.0  16.0 Q1, Q3 11.0, 20.0 13.0, 20.0 10.0, 20.0  12.5, 21.0 10.0, 19.0 9.5, 19.3  11.0, 20.0 Range (4.0–37.4) (2.1–24.9) (0.0–29.0)  (−3.0–25.0) (0.0–25.0) (−18.0–23.0)  (−18.0–37.4) Acetabular inclination (degrees)    0.21    0.046  Mean (SD) 15.9 (6.5) 16.3 (8.1) 18.8 (7.2)  14.8 (6.2)a 21.7 (9.7)a 20.6 (8.8)a  17.7 (7.6) Median 15.0 14.0 17.0  12.6 24.0 21.5  15.0 Q1, Q3 11.0, 21.8 10.0, 21.0 13.0, 24.0  11.0, 17.0 15.0, 26.7 13.9, 23.5  12.0, 23.0 Range (2.3–25.0) (6.1–33.0) (6.5–40.0)  (5.0–29.0) (8.0–40.0) (8.6–40.0)  (2.3–40.0)  . Tönnis Grade 0 . Tönnis Grade 1 .  .  . Major (n = 25) . Minor (n = 25) . No intervention (n = 62) . Adjusted P-value* . Major (n = 24) . Minor (n = 9) . No intervention (n = 16) . Adjusted P-value* . Total (n = 161) . Age at surgery (years)    0.23    0.15  Mean (SD) 26.8 (7.8) 26.5 (6.4) 24.1 (7.3)  30.9 (6.7) 34.1 (5.4) 26.6 (10.4)  26.7 (7.9) Median 25.3 24.5 22.8  31.0 34.0 24.5  25.3 Q1, Q3 22.0, 33.4 20.8, 32.0 17.9, 29.6  27.2, 35.2 32.8, 37.5 17.7, 35.0  20.1, 32.6 Range (15.4–42.3) (17.9–39.1) (14.0–43.3)  (19.2–46.1) (23.5–41.7) (12.7–47.7)  (12.7–47.7) Gender    0.54    0.13  F 20 (80.0%) 23 (92.0%) 56 (90.3%)  16 (66.7%) 8 (88.9%) 13 (81.3%)  136 (84.5%) M 5 (20.0%) 2 (8.0%) 6 (9.7%)  8 (33.3%) 1 (11.1%) 3 (18.8%)  25 (15.5%) BMI (lbs/in):    0.23    0.56  Mean (SD) 26.2 (4.1) 24.4 (5.0) 24.4 (4.3)  28.2 (4.6) 26.2 (4.2) 26.0 (4.9)  25.5 (4.6) Median 25.5 24.4 24.1  27.1 25.8 26.3  25.2 Q1, Q3 22.9, 29.1 20.9, 26.9 21.7, 26.7  25.0, 31.0 24.4, 27.9 22.7, 28.7  22.1, 27.9 Range (20.3–34.7) (17.6–39.4) (12.0–35.4)  (20.8–37.7) (20.4–34.7) (18.5–38.6)  (12.0–39.4) Side    0.32    0.27  Left 12 (48.0%) 9 (36.0%) 20 (32.3%)  14 (58.3%) 4 (44.4%) 6 (37.5%)  65 (40.4%) Right 13 (52.0%) 16 (64.0%) 42 (67.7%)  10 (41.7%) 5 (55.6%) 10 (62.5%)  96 (59.6%) Any prior surgery?    0.58    0.82  No 23 (92.0%) 22 (88.0%) 56 (90.3%)  19 (79.2%) 8 (88.9%) 11 (68.8%)  139 (86.3%) Yes 2 (8.0%) 3 (12.0%) 6 (9.7%)  5 (20.8%) 1 (11.1%) 5 (31.3%)  22 (13.7%) Method of joint interrogation Arthoscopy 4 (16.0%) 13 (52.0%) 2 (3.2%)  15 (62.5%) 3 (33.3%) 0 (0.0%)  37 (23.0%) Arthrotomy 21 (84.0%) 12 (48.0%) 43 (69.4%)  9 (37.5%) 6 (66.7%) 7 (43.8%)  98 (60.9%) None 0 (0.0%) 0 (0.0%) 17 (27.4%)  0 (0.0%) 0 (0.0%) 9 (56.2%)  26 (16.1%) AP pelvic tilt (mm)    0.37    0.26  Mean (SD) 47.3 (21.2) 54.4 (21.4) 54.3 (22.8)  45.1 (24.5) 42.0 (24.7) 36.7 (18.0)  49.3 (22.8) Median 48.0 56.0 57.0  48.0 53.0 40.0  51.8 Q1, Q3 34.0, 66.0 43.5, 74.5 42.7, 70.0  24.0, 67.0 18.0, 60.0 22.0, 52.0  35.5, 65.2 Range (0.0–79.0) (8.0–89.7) (4.3–106.0)  (2.5–87.0) (4.0–71.0) (4.5–60.0)  (0.0–106.0) AP pelvic rotation (mm)    0.77    0.52  Mean (SD) 4.6 (9.1) 2.7 (3.3) 4.0 (6.6)  1.6 (3.0) 3.6 (4.2) 3.3 (3.9)  3.4 (5.9) Median 1.0 0.0 4.0  0.0 2.0 2.0  0.0 Q1, Q3 0.0, 5.0 0.0, 5.0 0.0, 5.0  0.0, 2.0 0.0, 5.0 0.0, 7.0  0.0, 5.0 Range (0.0–41.2) (0.0–10.0) (0.0–43.1)  (0.0–10.0) (0.0–10.0) (0.0–10.0)  (0.0–43.1) Lateral center-edge angle (degrees)    0.58    0.27  Mean (SD) 17.0 (7.5) 16.5 (5.7) 15.2 (6.5)  15.7 (7.4) 14.5 (7.5) 12.8 (9.9)  15.5 (7.1) Median 17.0 19.0 15.0  16.5 18.0 15.0  16.0 Q1, Q3 11.0, 20.0 13.0, 20.0 10.0, 20.0  12.5, 21.0 10.0, 19.0 9.5, 19.3  11.0, 20.0 Range (4.0–37.4) (2.1–24.9) (0.0–29.0)  (−3.0–25.0) (0.0–25.0) (−18.0–23.0)  (−18.0–37.4) Acetabular inclination (degrees)    0.21    0.046  Mean (SD) 15.9 (6.5) 16.3 (8.1) 18.8 (7.2)  14.8 (6.2)a 21.7 (9.7)a 20.6 (8.8)a  17.7 (7.6) Median 15.0 14.0 17.0  12.6 24.0 21.5  15.0 Q1, Q3 11.0, 21.8 10.0, 21.0 13.0, 24.0  11.0, 17.0 15.0, 26.7 13.9, 23.5  12.0, 23.0 Range (2.3–25.0) (6.1–33.0) (6.5–40.0)  (5.0–29.0) (8.0–40.0) (8.6–40.0)  (2.3–40.0) 

The number and the nature of postoperative reoperations and complications were confirmed in the medical record. Isolated hardware removal stemming from index PAO was not considered in the assessment of the incidence of reoperation. Subsequent hip arthroscopy after index PAO was performed on patients with persistent pain or dysfunction that failed non-operative treatment independent of their original procedure. The modified Dindo–Clavien Classification scheme was used to grade all recorded complications following PAO [22]. Briefly, Grade I complications required no treatment or alteration to the postoperative protocol, Grade II complications required pharmacological or additional outpatient follow-up, Grade III complications necessitated surgical intervention and Grade IV complications were untreatable and caused permanent disability or death. The reliability of this classification system has been previously demonstrated to grade complications following hip preservation surgery [23].

The data are presented as counts and percentages for categorical variables or means and standard deviations for continuous variables. Comparisons of baseline characteristics and PROM scores (preoperative, postoperative, the change from preoperative to postoperative and the difference between the preoperative to postoperative change and MCID) were made using generalized estimating equations to account for the fact that a patient may have more than one hip included in the analysis. Where appropriate, post hoc pairwise comparisons were conducted using the generalized estimating equations with P-values adjusted for multiple comparisons using the Benjamini–Hochberg false discovery rate method [24]. The PROM exceeding the MCID was compared between Tönnis Grades 0 and 1 using the Fisher’s exact test. Cox proportional hazards regression with a robust variance estimator was used to assess the incidence of reoperations following PAO. All analyses were performed using SAS version 9.4 (SAS Institute Inc., Cary, NC) and R version 3.4.2 (R Core Team, Vienna, Austria).

RESULTS

For the entire cohort, patients receiving major, minor or no intraarticular intervention at index PAO exceeded the MCID in 5, 8 and 8, of 8 PROMs (P ≥ 0.20), respectively (Table II).

Table II.

Preoperative and postoperative patient-reported outcome measures, by intraarticular intervention performed

. Major (n = 49) . Minor (n = 34) . No intervention (n = 78) . Total (n = 161) . Adjusted P-value* . UCLA score Preoperative 6.1 (2.3) 6.1 (2.5) 7.1 (2.6) 6.6 (2.5) 0.056 Postoperative 7.0 (2.2) 7.4 (2.2) 8.2 (1.8) 7.6 (2.1) 0.014 Change (post–pre) 1.1 (2.9) 1.4 (2.3) 0.9 (2.7) 1.1 (2.7) 0.75 P-value 0.024 0.005 0.020 <0.001  Harris Hip Score Preoperative 65.1 (14.0) 59.2 (14.3) 63.6 (14.7) 63.1 (14.5) 0.21 Postoperative 86.5 (15.1) 84.3 (16.5) 88.8 (11.9) 87.0 (14.1) 0.40 Change (post–pre) 23.2 (15.3) 24.8 (16.5) 23.3 (16.4) 23.6 (16.0) 0.91 P-value <0.001 <0.001 <0.001 <0.001  HOOS Total Pain Preoperative 56.5 (16.8) 48.8 (17.4) 58.1 (19.0) 55.7 (18.3) 0.061 Postoperative 85.2 (18.2) 82.9 (17.2) 87.4 (14.6) 85.7 (16.3) 0.49 Change (post–pre) 27.8 (19.1) 32.8 (18.6) 28.4 (21.7) 29.2 (20.2) 0.54 P-value <0.001 <0.001 <0.001 <0.001  MCID (10.3) P-value <0.001 <0.001 <0.001 <0.001  HOOS Total ADL Preoperative 70.4 (20.2) 63.4 (19.9) 73.4 (19.8) 70.5 (20.2) 0.10 Postoperative 90.2 (15.3) 88.6 (15.8) 93.8 (9.0) 91.5 (13.0) 0.19 Change (post–pre) 18.0 (21.1) 22.7 (18.0) 17.7 (19.5) 18.9 (19.6) 0.51 P-value <0.001 <0.001 <0.001 <0.001  MCID (10.8) P-value 0.054 0.002 0.011 <0.001  HOOS Total S&R Preoperative 40.2 (22.9) 34.4 (22.4) 46.4 (21.4) 42.0 (22.4) 0.039 Postoperative 78.2 (22.3) 74.8 (23.7) 81.4 (18.0) 78.9 (20.7) 0.42 Change (post–pre) 39.4 (30.5) 36.4 (26.6) 32.1 (25.1) 35.4 (27.2) 0.44 P-value <0.001 <0.001 <0.001 <0.001  MCID (12.6) P-value <0.001 <0.001 <0.001 <0.001  HOOS Total QOL Preoperative 29.3 (17.4) 26.2 (17.9) 34.2 (17.3) 31.0 (17.7) 0.090 Postoperative 68.9 (23.9) 67.2 (19.4) 74.8 (18.3) 71.3 (20.5) 0.19 Change (post–pre) 39.6 (26.8) 42.1 (21.3) 38.0 (24.6) 39.4 (24.4) 0.75 P-value <0.001 <0.001 <0.001 <0.001  MCID (11.2) P-value <0.001 <0.001 <0.001 <0.001  WOMAC Total Pain Preoperative 62.4 (17.9) 53.8 (18.4) 63.5 (19.3) 61.2 (18.9) 0.055 Postoperative 86.9 (17.7) 86.9 (15.7) 91.1 (12.7) 88.9 (15.0) 0.31 Change (post–pre) 23.7 (20.8) 32.3 (17.3) 25.5 (21.8) 26.5 (20.6) 0.17 P-value <0.001 <0.001 <0.001 <0.001  MCID (10.8) P-value <0.001 <0.001 <0.001 <0.001  WOMAC Total Stiffness Preoperative 58.5 (23.6) 49.6 (21.6) 59.8 (25.0) 57.3 (24.1) 0.10 Postoperative 76.3 (23.4) 78.6 (22.0) 83.5 (19.1) 80.2 (21.2) 0.26 Change (post–pre) 18.1 (31.8) 28.4 (19.5) 20.2 (26.3) 21.3 (26.9) 0.18 P-value 0.002 <0.001 <0.001 <0.001  MCID (12.9) P-value 0.33 <0.001 0.038 <0.001  WOMAC Total Physical Preoperative 70.4 (20.2) 63.4 (19.9) 73.4 (19.8) 70.5 (20.2) 0.10 Postoperative 90.3 (15.4) 88.9 (15.3) 93.9 (9.1) 91.7 (12.9) 0.20 Change (post–pre) 18.0 (21.4) 23.0 (18.0) 17.8 (19.4) 19.0 (19.7) 0.47 P-value <0.001 <0.001 <0.001 <0.001  MCID (10.8) P-value 0.061 0.001 0.009 <0.001  WOMAC Total Preoperative 68.1 (18.8) 60.0 (18.9) 70.3 (19.5) 67.6 (19.4) 0.072 Postoperative 88.6 (15.8) 87.3 (15.6) 92.7 (9.5) 90.2 (13.3) 0.16 Change (post–pre) 18.9 (20.3) 25.5 (17.2) 19.9 (19.4) 20.8 (19.2) 0.37 P-value <0.001 <0.001 <0.001 <0.001  bMCID (10.4) P-value 0.018 <0.001 <0.001 <0.001  SF12 Physical Preoperative 39.2 (10.2) 36.9 (11.0) 41.1 (10.2) 39.6 (10.4) 0.18 Postoperative 51.2 (8.9) 47.7 (11.7) 53.3 (7.1) 51.4 (9.1) 0.065 Change (post–pre) 12.6 (11.1) 11.0 (12.7) 11.7 (10.8) 11.8 (11.3) 0.86 P-value <0.001 <0.001 <0.001 <0.001  SF12 Mental Preoperative 52.5 (10.3) 54.8 (9.5) 53.1 (11.2) 53.3 (10.6) 0.56 Postoperative 49.1 (13.3) 57.2 (7.0) 52.5 (9.5) 52.5 (10.8) 0.008 Change (post–pre) −3.1 (12.9) 2.3 (11.1) −1.0 (10.6) −0.9 (11.6) 0.21 P-value 0.16 0.27 0.47 0.43   . Major (n = 49) . Minor (n = 34) . No intervention (n = 78) . Total (n = 161) . Adjusted P-value* . UCLA score Preoperative 6.1 (2.3) 6.1 (2.5) 7.1 (2.6) 6.6 (2.5) 0.056 Postoperative 7.0 (2.2) 7.4 (2.2) 8.2 (1.8) 7.6 (2.1) 0.014 Change (post–pre) 1.1 (2.9) 1.4 (2.3) 0.9 (2.7) 1.1 (2.7) 0.75 P-value