Is a periacetabular osteotomy as efficacious in retroversion as it is in dysplasia?

Aims Periacetabular osteotomy (PAO) is an established treatment for acetabular dysplasia. It has also been proposed as a treatment for patients with acetabular retroversion. By reviewing a large cohort, we aimed to test whether outcome is equivalent for both types of morphology and identify factors that influenced outcome. Methods A single-centre, retrospective cohort study was performed on patients with acetabular retroversion treated with PAO (n = 62 hips). Acetabular retroversion was diagnosed clinically and radiologically (presence of a crossover sign, posterior wall sign, lateral centre-edge angle (LCEA) between 20° and 35°). Outcomes were compared with a control group of patients undergoing PAO for dysplasia (LCEA < 20°; n = 86 hips). Femoral version was recorded. Patient-reported outcome measures (PROMs), complications, and reoperation rates were measured. Results The mean Non-Arthritic Hip Score (NAHS) preoperatively was 58.6 (SD 16.1) for the dysplastic hips and 52.5 (SD 12.7) for the retroverted hips (p = 0.145). Postoperatively, mean NAHS was 83.0 (SD 16.9) and 76.7 (SD 17.9) for dysplastic and retroverted hips respectively (p = 0.041). Difference between pre- and postoperative NAHS was slightly lower in the retroverted hips (18.3 (SD 22.1)) compared to the dysplastic hips (25.2 (SD 15.2); p = 0.230). At mean 3.5 years’ follow-up (SD 1.9), one hip needed a revision PAO and no hips were converted to total hip arthroplasty (THA) in the retroversion group. In the control group, six hips (7.0%) were revised to THA. No differences in complications (p = 0.106) or in reoperation rate (p = 0.087) were seen. Negative predictors of outcome for patients undergoing surgery for retroversion were female sex, obesity, hypermobility, and severely decreased femoral anteversion. Conclusion A PAO is an effective surgical intervention for acetabular retroversion and produces similar improvements when used to treat dysplasia. Femoral version should be routinely assessed in these patients and when extremely low (< 0°), as an additional procedure to address this abnormality may be necessary. Females with signs of hypermobility should also be consulted of the likely guarded improvement. Cite this article: Bone Jt Open 2021;2(9):757–764.

Arthroscopic Treatment and Outcomes of Borderline Dysplasia With Acetabular Retroversion: A Matched-Control Study From the MASH Study Group

Background: Although acetabular retroversion (AR) occurs in dysplasia, management of the crossover sign (COS) or outcomes in borderline dysplasia (BD) with AR have not been reported. Purpose: To report any differences in the management of the COS in BD and nondysplastic hips and to report comparative outcomes of BD with AR with matched controls with BD or AR (ie, focal pincer femoroacetabular impingement [FAI]). Study design: Cohort study; Level of evidence, 3. Methods: A multicenter matched-pair study was performed with data from a large prospectively collected database. Inclusion criteria were patients who had undergone primary unilateral hip arthroscopy including labral repair for FAI and/or chondral pathology without significant osteoarthritis (ie, Tönnis grade 0 or 1). The study group (BD+AR) was defined radiographically by lateral center-edge angle (LCEA) on standing anteroposterior pelvis of 18° to 25° and positive COS. A 1:1:1 matching on age, sex, and body mass index was performed with a control group with BD and another control group with AR (LCEA, >25°+COS). Acetabuloplasty rates were determined for each group. Mean 2-year outcomes including the 12-Item International Hip Outcome Tool (iHOT-12), minimally clinical important difference (MCID), substantial clinical benefit (SCB), and Patient Acceptable Symptom State (PASS) scores were compared. Subanalysis of the study group both with and without acetabuloplasty was performed. Results: There were 69 patients, with 23 in the study group and 23 in each control group. The effect of dysplasia with or without the presence of the COS resulted in changes in acetabuloplasty rates, with 0% performed in the BD group, 35% in the BD+AR study group, and 91% in the AR group ( P = .001). Arthroscopic outcomes demonstrated similar and significant mean 2-year improvement of iHOT-12 patient-reported outcomes, MCID, SCB, and PASS scores in the study and both control groups. There was a trend within the study group toward greater postoperative iHOT-12 scores in patients who received anterior-based acetabuloplasty than those who did not receive acetabuloplasty (81.7 and 70.4, respectively; P = .11). Conclusion: Acetabular coverage influences the management of the COS, with significantly lower acetabuloplasty rates in BD with AR compared with AR without BD (focal pincer impingement). Symptomatic patients with combined BD and AR had similar significant successful outcomes to those of patients with BD and those with AR (focal pincer impingement), whether treated without acetabuloplasty or, less frequently, with limited anterior-based acetabuloplasty.

Prevalence of Morphological Variations Associated With Femoroacetabular Impingement According to Age and Sex: A Study of 1878 Asymptomatic Hips in Nonprofessional Athletes

Background: Radiographic findings related to the cam and pincer variants of femoroacetabular impingement (FAI) include measurements of the alpha angle and lateral center-edge angle (LCEA). The function of these radiographic findings has been put into question because of high heterogeneity in reported studies. Purpose: The aim of this study was 3-fold: (1) to determine the prevalence of cam and pincer variants according to sex and age on anteroposterior (AP) pelvic radiographs from an asymptomatic nonathletic population, (2) to identify the most common radiographic signs of cam- and pincer-type variants, and (3) to determine if there are variations in the prevalence of these radiographic signs according to sex and age. Study Design: Cross-sectional study; Level of evidence, 3. Methods: There were 3 independent observers who retrospectively analyzed the 939 AP pelvic radiographs (1878 hips) of patients aged 18 to 50 years who did not have hip symptoms and who were not professional athletes. The prevalence of the cam and pincer variants according to the alpha angle and LCEA, respectively, and the presence of other radiographic signs commonly associated with these variables were determined in the overall population and by subgroup according to sex and age group (18-30, 31-40, and 41-50 years). Descriptive and inferential statistics were used to analyze the study sample. Results: The mean age of the included population was 31.0 ± 9.2 years, and 68.2% were male. The prevalence of the cam-type variant was 29.7% (558/1878), and that of the pincer-type variant was 24.3% (456/1878). The radiographic signs that were most associated with the cam and pincer variants were a pistol-grip deformity and the crossover sign, respectively. Significant differences ( P < .001) in the prevalence of these variants were identified between men and women in both variants. No differences were observed in the alpha angle or LCEA according to sex or age. Conclusion: Radiographic findings suggestive of FAI had significant variations with respect to sex and age in this study sample. This study provides information to determine the prevalence of these anatomic variants in the general population.

The Ischial Spine in Developmental Hip Dysplasia: Unraveling the Role of Acetabular Retroversion in Periacetabular Osteotomy

Purpose. Radiological diagnosis of acetabular retroversion (AR) is based on the presence of the crossover sign (COS), the posterior wall sign (PWS), and the prominence of the ischial spine sign (PRISS). The primary purpose of the study is to analyze the clinical significance of the PRISS in a sample of dysplastic hips requiring periacetabular osteotomy (PAO) and evaluate retroversion in symptomatic hip dysplasia. Methods. In a previous paper, we reported the classic coxometric measurements of 178 patients with symptomatic hip dysplasia undergoing PAO where retroversion was noted in 42% of the cases and was not found to be a major factor in the appearance of symptoms. In the current study, we have added the retroversion signs PRISS and PWS to our analysis. Among the retroverted dysplastic hips, we studied the association of the PRISS with the hips requiring PAO. We also defined the ischial spine index (ISI) and studied its relationship to the coxometric measurements and AR. Results. In hips with AR, the operated hips were significantly associated with the PRISS compared to the nonoperated ones (χ2 = 4.847). Additionally, the ISI was able to classify acetabular version (anteverted, neutral, and retroverted acetabula). A direct correlation between the ISI and the retroversion index (RI) was found, and the highest degree of retroversion was found when the 3 signs of acetabular retroversion were concomitantly present (RI = 33.6%). Conclusion. The PRISS, a radiographic sign reflecting AR, was found to be significantly associated with dysplastic hips requiring PAO where AR was previously not considered a factor in the manifestation of symptoms and subsequent requirement for surgery. Moreover, the PRISS can also serve as an adequate radiographic sign for estimating acetabular version on pelvic radiographs.

Borderline Dysplasia with Acetabular Retroversion: Key Findings from a Large Hip Arthroscopy Study Group

Objectives: The radiographic crossover sign (COS) is an indicator of acetabular retroversion, classically representing anterosuperior overcoverage often treated with acetabuloplasty which could exacerbate acetabular hypovolemia in dysplasia. No prior study has investigated the prevalence of acetabular retroversion in patients with dysplasia undergoing hip arthroscopy, acetabuloplasty rates, and outcomes in this setting. Study objectives are to report the prevalence of acetabular retroversion in dysplasia, the influence of the COS on arthroscopic acetabuloplasty rates, and relative outcomes compared with control groups. Methods: A retrospective cohort study was performed from a prospectively collected multi-center database. Patients undergoing isolated hip arthroscopic surgery were assigned to dysplasia (lateral center-edge angle (LCEA) ≤ 25°) or one of two control groups: normal(LCEA 26-38°), or pincer femoroacetabular impingement (FAI)(LCEA ≥ 39°). The prevalence of COS and acetabuloplasty rates between and within study and control groups were compared (Chi square analysis). Minimum 2 year outcomes utilizing iHOT-12 were compared (analysis of variance). Results: Of 401 study patients, 64 (16%) comprised the dysplasia group, 273 (68%) normal group, and 64 (16%) pincer group. Mean LCEAs were 22.3°, 31.5°, and 42.4°, respectively (p<0.001). COS prevalence was similar between groups at 31%, 26%, and 33%, respectively (p=0.873). Acetabuloplasty rates were dependent on the amount of acetabular coverage with lowered rate in the dysplasia group(40%) and increasing rates in the normal(52%) and the pincer(90%) groups (p=0.013). Post-operative iHOT-12 scores improved in all groups (68, 74, and 77, respectively, p=0.222). Patients with a COS plus rendered acetabuloplasty reported similar scores that improved to 77, 74, and 79, respectively,(p=0.949). Patients with dysplasia with COS averaged 73.1(SD 23.3) iHOT-12 score compared to 67.1(SD: 28.7) for the patients with dysplasia without COS (p=0.466). Within the dysplasia with COS subgroup, there was no significant difference in iHOT-12 scores between the group with acetabuloplasty (77.0;SD:17.1) and without acetabuloplasty (70.4;SD:27.4,p=0.580). Conclusion: Acetabular retroversion occurs with similar prevalence in borderline dysplasia compared with non-dysplastic hips undergoing hip arthroscopy but with lower acetabuloplasty rates not influenced by the COS. Arthroscopic outcomes of dysplasia with retroversion are similarly successful and comparable with those of dysplasia and non-dysplastic hips. Although infrequently performed, acetabuloplasty did not compromise outcomes in dysplasia with retroversion.

DIFFERENCES IN RADIOGRAPHIC MEASUREMENTS ON STANDING VERSUS SUPINE PELVIC RADIOGRAPHS

Background: Accurate pelvic radiographic measurements is of clear clinical importance, as these measurements can drive the indications for surgery, the surgical approach utilized, and/or the degree of correction during hip preservation surgery. Currently, there are a large number of measurements available and reported on the literature when referencing anterior-posterior (AP) pelvic radiographs. However, there is no standardization of whether these pelvic radiographs are obtained in the standing or supine position. Hypothesis/Purpose: Standing vs. Supine radiographs, obtained in the same patient, will result in different value for standard radiographic measurements used in making hip pathology diagnoses. Methods: All new patients who presented for evaluation of hip pain between September 2016 and July 2018 were retrospectively reviewed. Inclusion criteria included age 18-50, no prior hip surgery/injury, and both standing and supine AP pelvis radiographs dated within 2 years of each other. Measurements were obtained on 26 radiographs (52 hips), blinded to patient demographics and standing versus supine radiograph. Measurements included minimum joint space, lateral center edge angle (LCEA), acetabular depth, acetabular inclination, Tönnis Grade, crossover sign, posterior wall sign, ischial spine sign. Results: Standing films resulted in significantly lower LCEA and acetabular depth measurements, and higher acetabular inclination. Supine measurements for crossover sign were 5.69 times more likely to be positive than standing measurements. Similarly, supine measurements for ischial spine were 7.93 times more likely to be positive (see Table 1). Conclusion: Based on our study, supine films are almost 6 times more likely to give a positive crossover sign and almost 8 times more likely to give a positive ischial spine sign than a standing film in the same patient. Additionally, LCEA, acetabular depth will be lower and acetabular inclination will be higher on standing films. As such, our recommendation is to obtain standing AP pelvis radiographs to obtain the most accurate pelvic radiographic measurements in hip preservation patients. Tables: [Table: see text]