Aims. Acetabular retroversion is a recognized cause of hip impingement and can be influenced by pelvic tilt (PT), which changes in different functional positions. Positional changes in PT have not previously been studied in patients with acetabular retroversion. Methods. Supine and standing anteroposterior (AP) pelvic radiographs were retrospectively analyzed in 69 patients treated for symptomatic acetabular retroversion. Measurements were made for acetabular index (AI), lateral centre-edge angle (LCEA), crossover index, ischial spine sign, and posterior wall sign. The change in the angle of PT was measured both by the sacro-femoral-pubic (SFP) angle and the pubic symphysis to sacroiliac (PS-SI) index. Results. In the supine position, the mean PT (by SFP) was 1.05° (SD 3.77°), which changed on standing to a PT of 8.64° (SD 5.34°). A significant increase in posterior PT from supine to standing of 7.59° (SD 4.5°; SFP angle) and 5.89° (SD 3.33°; PS-SI index) was calculated (p < 0.001). There was a good correlation in PT change between measurements using SFP angle and PS-SI index (0.901 in the preoperative group and 0.815 in the postoperative group). Signs of retroversion were significantly reduced in standing radiographs compared to supine: crossover index (0.16 (SD 0.16) vs 0.38 (SD 0.15); p < 0.001), crossover sign (19/28 hips vs 28/28 hips; p < 0.001), ischial spine sign (10/28 hips vs 26/28 hips; p < 0.001), and posterior wall sign (12/28 hips vs 24/28 hips; p < 0.001). Conclusion. Posterior PT increased from supine to standing in patients with symptomatic acetabular retroversion. The features of acetabular retroversion were less evident on standing radiographs. The low PT angle in the supine position is a factor in the increased appearance of acetabular retroversion. Patients presenting with symptoms of hip impingement should be assessed by supine and standing pelvic radiographs to highlight signs of acetabular retroversion, and to assist with optimizing acetabular correction at the time of surgery. Cite this article: Bone Joint J 2022;104-B(7):786–791

Aims. Slipped upper femoral epiphysis (SUFE) has well documented biochemical and mechanical risk factors. Femoral and acetabular morphologies seem to be equally important. Acetabular retroversion has a low prevalence in asymptomatic adults. Hips with dysplasia, osteoarthritis, and Perthes’ disease, however, have higher rates, ranging from 18% to 48%. The aim of our study was to assess the prevalence of acetabular retroversion in patients presenting with SUFE using both validated radiological signs and tomographical measurements. Methods. A retrospective review of all SUFE surgical cases presenting to the Royal Children’s Hospital, Melbourne, Australia, from 2012 to 2019 were evaluated. Preoperative plain radiographs were assessed for slip angle, validated radiological signs of retroversion, and standardized postoperative CT scans were used to assess cranial and mid-acetabular version. Results. In all, 116 SUFEs presented in 107 patients who underwent surgical intervention; 47 (52%) were male, with a mean age of 12.7 years (7.5 to 16.6). Complete radiological data was available for 91 patients (99 hips) with adequate axial CT imaging of both hips. Overall, 82 patients (82%) underwent pinning in situ (PIS), with subcapital realignment surgery (SRS) performed in 17 patients (18%) (slip angles > 75°). Contralateral prophylactic PIS was performed in 72 patients (87%). On the slip side, 62 patients (68%) had one or more radiological sign of retroversion. Tomographical acetabular retroversion was more pronounced cranially than caudally of the acetabulum on both the affected side and the contralateral side (p < 0.001) as expected in the normal population. Increasing severity of the slip was found to be directly proportional to the degree of reduction in cranial and central acetabular version (p < 0.05) in the SUFE hips. Conclusion. Acetabular retroversion is more prevalent in patients with SUFE than previously reported, and have been shown be correlated to the severity of the slip presentation. The presence of radiological signs of acetabular retroversion could be used to justify prophylactic contralateral pinning. Cite this article: Bone Jt Open 2022;3(2):158–164

Aims. The aim of this study is to evaluate whether acetabular retroversion (AR) represents a structural anatomical abnormality of the pelvis or is a functional phenomenon of pelvic positioning in the sagittal plane, and to what extent the changes that result from patient-specific functional position affect the extent of AR. Methods. A comparative radiological study of 19 patients (38 hips) with AR were compared with a control group of 30 asymptomatic patients (60 hips). CT scans were corrected for rotation in the axial and coronal planes, and the sagittal plane was then aligned to the anterior pelvic plane. External rotation of the hemipelvis was assessed using the superior iliac wing and inferior iliac wing angles as well as quadrilateral plate angles, and correlated with cranial and central acetabular version. Sagittal anatomical parameters were also measured and correlated to version measurements. In 12 AR patients (24 hips), the axial measurements were repeated after matching sagittal pelvic rotation with standing and supine anteroposterior radiographs. Results. Acetabular version was significantly lower and measurements of external rotation of the hemipelvis were significantly increased in the AR group compared to the control group. The AR group also had increased evidence of anterior projection of the iliac wing in the sagittal plane. The acetabular orientation angles were more retroverted in the supine compared to standing position, and the change in acetabular version correlated with the change in sagittal pelvic tilt. An anterior pelvic tilt of 1° correlated with 1.02° of increased cranial retroversion and 0.76° of increased central retroversion. Conclusion. This study has demonstrated that patients with symptomatic AR have both an externally rotated hemipelvis and increased anterior projection of the iliac wing compared to a control group of asymptomatic patients. Functional sagittal pelvic positioning was also found to affect AR in symptomatic patients: the acetabulum was more retroverted in the supine position compared to standing position. Changes in acetabular version correlate with the change in sagittal pelvic tilt. These findings should be taken into account by surgeons when planning acetabular correction for AR with periacetabular osteotomy. Cite this article: Bone Joint J 2024;106-B(2):128–135

Orthopaedic surgeons have accepted various radiological signs to be representative of acetabular retroversion, which is the main characteristic of focal over-coverage in patients with femoroacetabular impingement (FAI). Using a validated method for radiological analysis, we assessed the relevance of these signs to predict intra-articular lesions in 93 patients undergoing surgery for FAI. A logistic regression model to predict chondral damage showed that an acetabular retroversion index (ARI) > 20%, a derivative of the well-known cross-over sign, was an independent predictor (p = 0.036). However, ARI was less significant than the Tönnis classification (p = 0.019) and age (p = 0.031) in the same model. ARI was unable to discriminate between grades of chondral lesions, while the type of cam lesion (p = 0.004) and age (p = 0.047) were able to. Other widely recognised signs of acetabular retroversion, such as the ischial spine sign, the posterior wall sign or the cross-over sign were irrelevant according to our analysis. Regardless of its secondary predictive role, an ARI > 20% appears to be the most clinically relevant radiological sign of acetabular retroversion in symptomatic patients with FAI. Cite this article: Bone Joint J 2013;95-B:893–9

Aims. The effect of pelvic tilt (PT) and sagittal balance in hips with pincer-type femoroacetabular impingement (FAI) with acetabular retroversion (AR) is controversial. It is unclear if patients with AR have a rotational abnormality of the iliac wing. Therefore, we asked: are parameters for sagittal balance, and is rotation of the iliac wing, different in patients with AR compared to a control group?; and is there a correlation between iliac rotation and acetabular version?. Methods. A retrospective, review board-approved, controlled study was performed including 120 hips in 86 consecutive patients with symptomatic FAI or hip dysplasia. Pelvic CT scans were reviewed to calculate parameters for sagittal balance (pelvic incidence (PI), PT, and sacral slope), anterior pelvic plane angle, pelvic inclination, and external rotation of the iliac wing and were compared to a control group (48 hips). The 120 hips were allocated to the following groups: AR (41 hips), hip dysplasia (47 hips) and cam FAI with normal acetabular morphology (32 hips). Subgroups of total AR (15 hips) and high acetabular anteversion (20 hips) were analyzed. Statistical analysis was performed using analysis of variance with Bonferroni correction. Results. PI and PT were significantly decreased comparing AR (PI 42° (SD 10°), PT 4° (SD 5°)) with dysplastic hips (PI 55° (SD 12°), PT 10° (SD 6°)) and with the control group (PI 51° (SD 9°) and PT 13° (SD 7°)) (p < 0.001). External rotation of the iliac wing was significantly increased comparing AR (29° (SD 4°)) with dysplastic hips (20°(SD 5°)) and with the control group (25° (SD 5°)) (p < 0.001). Correlation between external rotation of the iliac wing and acetabular version was significant and strong (r = 0.81; p < 0.001). Correlation between PT and acetabular version was significant and moderate (r = 0.58; p < 0.001). Conclusion. These findings could contribute to a better understanding of hip pain in a sitting position and extra-articular subspine FAI of patients with AR. These patients have increased iliac external rotation, a rotational abnormality of the iliac wing. This has implications for surgical therapy with hip arthroscopy and acetabular rim trimming or anteverting periacetabular osteotomy (PAO). Cite this article: Bone Jt Open 2021;2(10):813–824

Excessive acetabular cover secondary to a retroverted acetabulum causes pincer impingement, which may cause early osteoarthritis of the hip. Our aim was to determine if there was a relationship between acetabular version and osteoarthritis of the hip. Using image processing and analysis software we studied 117 CT images of the hip in patients aged less than 65 years who had undergone a CT virtual colonoscopy. The mean CT joint space of the 18 hips with acetabular retroversion was narrower compared with the 99 hips with normal acetabular alignment (p < 0.0001). A correlation of r = 0.46 (p < 0.01) was found between right hip acetabular version and the mean right hip joint space and of r = 0.31 (p = 0.02) between left hip acetabular version and the mean left hip joint space. Acetabular retroversion is associated with radiological evidence of osteoarthritis of the hip. An understanding of the mechanical basis of osteoarthritis of the hip allows early treatment of the underlying structural abnormality and prevents progression of the degenerative condition

This study examined the relationship between the cross-over sign and the true three-dimensional anatomical version of the acetabulum. We also investigated whether in true retroversion there is excessive femoral head cover anteriorly. Radiographs of 64 hips in patients being investigated for symptoms of femoro-acetabular impingement were analysed and the presence of a cross-over sign was documented. CT scans of the same hips were analysed to determine anatomical version and femoral head cover in relation to the anterior pelvic plane after correcting for pelvic tilt. The sensitivity and specificity of the cross-over sign were 92% and 55%, respectively for identifying true acetabular retroversion. There was no significant difference in total cover between normal and retroverted cases. Anterior and posterior cover were, however, significantly different (p < 0.001 and 0.002). The cross-over sign was found to be sensitive but not specific. The results for femoral head cover suggest that retroversion is characterised by posterior deficiency but increased cover anteriorly

Aims. The frequency of severe femoral retroversion is unclear in patients with femoroacetabular impingement (FAI). This study aimed to investigate mean femoral version (FV), the frequency of absolute femoral retroversion, and the combination of decreased FV and acetabular retroversion (AR) in symptomatic patients with FAI subtypes. Methods. A retrospective institutional review board-approved observational study was performed with 333 symptomatic patients (384 hips) with hip pain due to FAI evaluated for hip preservation surgery. Overall, 142 patients (165 hips) had cam-type FAI, while 118 patients (137 hips) had mixed-type FAI. The allocation to each subgroup was based on reference values calculated on anteroposterior radiographs. CT/MRI-based measurement of FV (Murphy method) and AV were retrospectively compared among five FAI subgroups. Frequency of decreased FV < 10°, severely decreased FV < 5°, and absolute femoral retroversion (FV < 0°) was analyzed. Results. A significantly (p < 0.001) lower mean FV was found in patients with cam-type FAI (15° (SD 10°)), and in patients with mixed-type FAI (17° (SD 11°)) compared to severe over-coverage (20° (SD 12°). Frequency of decreased FV < 10° was significantly (p < 0.001) higher in patients with cam-type FAI (28%, 46 hips) and in patients with over-coverage (29%, 11 hips) compared to severe over-coverage (12%, 5 hips). Absolute femoral retroversion (FV < 0°) was found in 13% (5 hips) of patients with over-coverage, 6% (10 hips) of patients with cam-type FAI, and 5% (7 hips) of patients with mixed-type FAI. The frequency of decreased FV< 10° combined with acetabular retroversion (AV < 10°) was 6% (8 hips) in patients with mixed-type FAI and 5% (20 hips) in all FAI patients. Of patients with over-coverage, 11% (4 hips) had decreased FV < 10° combined with acetabular retroversion (AV < 10°). Conclusion. Patients with cam-type FAI had a considerable proportion (28%) of decreased FV < 10° and 6% had absolute femoral retroversion (FV < 0°), even more for patients with pincer-type FAI due to over-coverage (29% and 13%). This could be important for patients evaluated for open hip preservation surgery or hip arthroscopy, and each patient requires careful personalized evaluation. Cite this article: Bone Jt Open 2022;3(7):557–565

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

Aims. Hip arthroscopy has gained prominence as a primary surgical intervention for symptomatic femoroacetabular impingement (FAI). This study aimed to identify radiological features, and their combinations, that predict the outcome of hip arthroscopy for FAI. Methods. A prognostic cross-sectional cohort study was conducted involving patients from a single centre who underwent hip arthroscopy between January 2013 and April 2021. Radiological metrics measured on conventional radiographs and magnetic resonance arthrography were systematically assessed. The study analyzed the relationship between these metrics and complication rates, revision rates, and patient-reported outcomes. Results. Out of 810 identified hip arthroscopies, 359 hips were included in the study. Radiological risk factors associated with unsatisfactory outcomes after cam resection included a dysplastic posterior wall, Tönnis grade 2 or higher, and over-correction of the α angle. The presence of acetabular retroversion and dysplasia were also significant predictors for worse surgical outcomes. Notably, over-correction of both cam and pincer deformities resulted in poorer outcomes than under-correction. Conclusion. We recommend caution in performing hip arthroscopy in patients who have three positive acetabular retroversion signs. Acetabular dysplasia with a lateral centre-edge angle of less than 20° should not be treated with isolated hip arthroscopy. Acetabular rim-trimming should be avoided in patients with borderline dysplasia, and care should be taken to avoid over-correction of a cam deformity and/or pincer deformity. Cite this article: Bone Joint J 2024;106-B(8):775–782

Aims. The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors?. Methods. This was an institutional review board-approved, single-centre, retrospective, case-control, comparative study, which included 388 symptomatic hips in 357 patients who presented to our tertiary centre for joint preservation between January 2011 and December 2015. Their mean age was 26 years (SD 2; 23 to 29) and 50% were female. They were allocated to 12 different morphological subgroups. The study group was compared with a control group of 20 asymptomatic hips in 20 patients. APP-PT was assessed in all patients based on supine anteroposterior pelvic radiographs using validated HipRecon software. Values in the two groups were compared using an independent-samples t-test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. The minimal clinically important difference (MCID) for APP-PT was defined as > 1 SD. Results. There were no significant differences in APP-PT between the control group and the overall group (1.1° (SD 3.0°; -4.9° to 5.9°) vs 1.8° (SD 3.4°; -6.9° to 13.2°); p = 0.323). Acetabular retroversion and overcoverage groups showed higher mean APP-PTs compared with the control group (p = 0.001 and p = 0.014) and were the only diagnoses with a significant influence on APP-PT in the stepwise multiple regression analysis. All differences were below the MCID. The age, sex, height, weight, and BMI showed no influence on APP-PT. Conclusion. APP-PT showed no radiologically significant variation across different pathomorphologies of the hip in patients being assessed for joint-preserving surgery. Cite this article: Bone Joint J 2024;106-B(5 Supple B):3–10

Aims. This study sought to establish the prevalence of the cross over sign (COS) and posterior wall sign (PWS) in relation to the anterior pelvic plane (APP) in an asymptomatic population through reliable and accurate 3D-CT based assessment. Materials and Methods. Data from pelvic CT scans of 100 asymptomatic subjects (200 hips) undertaken for conditions unrelated to disorders of the hip were available for analysis in this study. A previously established 3D analysis method was applied to assess the prevalence of the COS and PWS in relation to the APP. Results. Of the 200 included hips, 24% (48) presented a positive COS and 5.5% (11) presented a positive PWS. A combination of COS and PWS was observed in 1% (two) of all hips (1%). . Conclusion. The high incidence of acetabular retroversion, determined by the COS, shows that this anatomic configuration may not differ in frequency between asymptomatic individuals and patients with symptomatic femoroacetabular impingement (FAI). Patients presenting with hip pain and evidence of FAI should be subjected to strict diagnostic scrutiny and evaluated in the sum of their clinical and radiological presentation. In our cohort of asymptomatic adults, the COS showed a higher incidence than the PWS or a combined COS/PWS. Cite this article: Bone Joint J 2017;99-B:1584–9

Aims. This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD. Methods. We identified 42 hips in 40 patients treated between January 2009 and January 2016 with BHD defined as a lateral centre-edge angle (LCEA) of ≥ 18° but < 25°. A minimum five-year follow-up was available. Patient-reported outcomes (PROMs) including Tegner score, subjective hip value (SHV), modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed. The following morphological parameters were evaluated: LCEA, acetabular index (AI), α angle, Tönnis staging, acetabular retroversion, femoral version, femoroepiphyseal acetabular roof index (FEAR), iliocapsularis to rectus femoris ratio (IC/RF), and labral and ligamentum teres (LT) pathology. Results. The mean follow-up was 96 months (67 to 139). The SHV, mHHS, WOMAC, and Tegner scores significantly improved (p < 0.001) at last follow-up. According to SHV and mHHS, there were three hips (7%) with poor results (SHV < 70), three (7%) with a fair score (70 to 79), eight (19%) with good results (80 to 89), and 28 (67%) who scored excellent (> 90) at the last follow-up. There were 11 subsequent operations: nine implant removals due to local irritation, one resection of postoperative heterotopic ossification, and one hip arthroscopy for intra-articular adhesions. No hips were converted to total hip arthroplasty at last follow-up. The presence of preoperative labral lesions or LT lesions did not influence any PROMs at last follow-up. From the three hips that had poor PROMs, two have developed severe osteoarthritis (> Tönnis II), presumably due to surgical overcorrection (postoperative AI < -10°). Conclusion. PAO is reliable in treating BHD with favourable mid-term outcomes. Concomitant LT and labral lesions did not negatively influence outcomes in our cohort. Technical accuracy with avoidance of overcorrection is essential in achieving successful outcomes. Cite this article: Bone Joint J 2023;105-B(7):735–742

Aims. Periacetabular osteotomy (PAO) is widely recognized as a demanding surgical procedure for acetabular reorientation. Reports about the learning curve have primarily focused on complication rates during the initial learning phase. Therefore, our aim was to assess the PAO learning curve from an analytical perspective by determining the number of PAOs required for the duration of surgery to plateau and the accuracy to improve. Methods. The study included 118 consecutive PAOs in 106 patients. Of these, 28 were male (23.7%) and 90 were female (76.3%). The primary endpoint was surgical time. Secondary outcome measures included radiological parameters. Cumulative summation analysis was used to determine changes in surgical duration. A multivariate linear regression model was used to identify independent factors influencing surgical time. Results. The learning curve in this series was 26 PAOs in a period of six months. After 26 PAO procedures, a significant drop in surgical time was observed and a plateau was also achieved. The mean duration of surgery during the learning curve was 103.8 minutes (SD 33.2), and 69.7 minutes (SD 18.6) thereafter (p < 0.001). Radiological correction of acetabular retroversion showed a significant improvement after having performed a total of 93 PAOs, including anteverting PAOs on 35 hips with a retroverted acetabular morphology (p = 0.005). Several factors were identified as independent variables influencing duration of surgery, including patient weight (β = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p < 0.001), learning curve procedure phase of 26 procedures (β = 34.0 (95% CI 24.3 to 43.8); p < 0.001), and the degree of lateral correction expressed as the change in the lateral centre-edge angle (β = 0.7 (95% CI 0.001 to 1.3); p = 0.048). Conclusion. The learning curve for PAO surgery requires extensive surgical training at a high-volume centre, with a minimum of 50 PAOs per surgeon per year. This study defined a cut-off value of 26 PAO procedures, after which a significant drop in surgical duration occurred. Furthermore, it was observed that a retroverted morphology of the acetabulum required a greater number of procedures to acquire proficiency in consistently eliminating the crossover sign. These findings are relevant for fellows and fellowship programme directors in establishing the extent of training required to impart competence in PAO. Cite this article: Bone Joint J 2024;106-B(4):336–343

Aims. This paper aims to review the evidence for patient-related factors associated with less favourable outcomes following hip arthroscopy. Methods. Literature reporting on preoperative patient-related risk factors and outcomes following hip arthroscopy were systematically identified from a computer-assisted literature search of Pubmed (Medline), Embase, and Cochrane Library using Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and a scoping review. Results. Assessment of these texts yielded 101 final articles involving 90,315 hips for qualitative analysis. The most frequently reported risk factor related to a less favourable outcome after hip arthroscopy was older age and preoperative osteoarthritis of the hip. This was followed by female sex and patients who have low preoperative clinical scores, severe hip dysplasia, altered hip morphology (excess acetabular retroversion or excess femoral anteversion or retroversion), or a large cam deformity. Patients receiving workers’ compensation or with rheumatoid arthritis were also more likely to have a less favourable outcome after hip arthroscopy. There is evidence that obesity, smoking, drinking alcohol, and a history of mental illness may be associated with marginally less favourable outcomes after hip arthroscopy. Athletes (except for ice hockey players) enjoy a more rapid recovery after hip arthroscopy than non-athletes. Finally, patients who have a favourable response to local anaesthetic are more likely to have a favourable outcome after hip arthroscopy. Conclusion. Certain patient-related risk factors are associated with less favourable outcomes following hip arthroscopy. Understanding these risk factors will allow the appropriate surgical indications for hip arthroscopy to be further refined and help patients to comprehend their individual risk profile. Cite this article: Bone Joint J 2020;102-B(7):822–831

Aims. What represents clinically significant acetabular undercoverage in patients with symptomatic cam-type femoroacetabular impingement (FAI) remains controversial. The aim of this study was to examine the influence of the degree of acetabular coverage on the functional outcome of patients treated arthroscopically for cam-type FAI. Patients and Methods. Between October 2005 and June 2016, 88 patients (97 hips) underwent arthroscopic cam resection and concomitant labral debridement and/or refixation. There were 57 male and 31 female patients with a mean age of 31.0 years (17.0 to 48.5) and a mean body mass index (BMI) of 25.4 kg/m. 2. (18.9 to 34.9). We used the Hip2Norm, an object-oriented-platform program, to perform 3D analysis of hip joint morphology using 2D anteroposterior pelvic radiographs. The lateral centre-edge angle, anterior coverage, posterior coverage, total femoral coverage, and alpha angle were measured for each hip. The presence or absence of crossover sign, posterior wall sign, and the value of acetabular retroversion index were identified automatically by Hip2Norm. Patient-reported outcome scores were collected preoperatively and at final follow-up with the Hip Disability and Osteoarthritis Outcome Score (HOOS). Results. At a mean follow-up of 2.7 years (1 to 8, . sd. 1.6), all functional outcome scores significantly improved overall. Radiographically, only preoperative anterior coverage had a negative correlation with the improvement of the HOOS symptom subscale (r = -0.28, p = 0.005). No significant difference in relative change in HOOS subscale scores was found according to the presence or absence of radiographic signs of retroversion. Discussion. Our study demonstrated the anterior coverage as an important modifier influencing the functional outcome of arthroscopically treated cam-type FAI. Cite this article: Bone Joint J 2018;100-B:831–8

Aims. Periacetabular osteotomy is an effective way of treating symptomatic hip dysplasia. We describe a new minimally invasive technique using a modification of the Smith-Peterson approach. We performed a prospective, longitudinal cohort study to assess for any compromise in acetabular correction when using this approach, and to see if the procedure would have a higher complication rate than that quoted in the literature for other approaches. We also assessed for any improvement in functional outcome. Patients and Methods. From 168 consecutive patients (189 hips) who underwent acetabular correction between March 2010 and March 2013 we excluded those who had undergone previous pelvic surgery for DDH and those being treated for acetabular retroversion. The remaining 151 patients (15 men, 136 women) (166 hips) had a mean age of 32 years (15 to 56) and the mean duration of follow-up was 2.8 years (1.2 to 4.5). In all 90% of cases were Tönnis grade 0 or 1. Functional outcomes were assessed using the Non Arthritic Hip Score (NAHS), University of California, Los Angeles (UCLA) and Tegner activity scores. Results. The mean pre-operative lateral centre-edge angle was 14.2° (-5° to 30°) and the mean acetabular index was 18.4° (4° to 40°). Post-operatively these were 31° (18° to 46°) and 3° (-7° to 29°), respectively, a significant improvement in both (p < 0.001). Allogenic blood transfusion was required in two patients (1.2%). There were no major nerve or vascular complications, and no wound infections. At the time of last follow-up, we noted a significant improvement in functional outcome scores: UCLA improved by 2.31 points, Tegner improved by 1.08 points, and the NAHS improved by 25.4 points (p < 0.001 for each). Hypermobility and longer duration of surgery were significant negative predictors for a good post-operative UCLA score, while residual retroversion was a positive predictor of post-operative UCLA score. Conclusion. We have found this approach to be safe and effective, facilitating early recovery from surgery. Cite this article: Bone Joint J 2017;99-B:22–8

Aims

The aims of this study were to characterize the incidence and risk factors associated with stress fractures following periacetabular osteotomy, and to determine their effect on osteotomy union.

Aims

Ganz’s studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes’ disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach.

Aims

The objective of this study was to present the outcomes of rotational acetabular osteotomy (RAO) over a 30-year period for osteoarthritis (OA) secondary to dysplasia of the hip in pre- or early-stage OA.