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. 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. 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

Abstract. Aim. Excessive glenoid retroversion and posterior wear leads to technical challenges when performing anatomic shoulder replacement. Various techniques have been described to correct glenoid version, including eccentric reaming, bone graft, posterior augmentation and custom prosthesis. Clinical outcomes and survivorship of a Stemless humeral component with cemented pegged polyethylene glenoid with eccentric reaming to partially correct retroversion are presented. Patients and Methods. Between 2010– 2019, 115 Mathys Affinis Stemless Shoulder Replacements were performed. 50 patients with significant posterior wear and retroversion (Walch type B1, B2, B3 and C) were identified. Measurement of Pre-operative glenoid retroversion and Glenoid component version on a post op axillary view was performed by method as described by Matsen FA. Relative correction was correlated with clinical and radiological outcome. Results. 4 were lost to follow up. 46 patients were therefore reviewed. The mean follow up was 4 years (2–8.9 years). Walch B1, Pre op Retroversion: 12 (8–20), post op retroversion :11.8 (−4 to 19), correction= 0.2. Walch B2, Pre op Retroversion :18.4 (10–32), post op retroversion: 13.2 (1 −22), correction= 5.2. Walch B3, Pre op Retroversion: 19.1 (13–32)post op retroversion : 16.1 (9–25), correction= 3.0. Walch C, Pre op Retroversion: 33.3 (28–42) post op retroversion: 16.0 (6–27), correction= 17.3. 3 patients required revision surgery for rotator cuff failure. Conclusion. Partial correction of glenoid retroversion with eccentric reaming and implantation of cemented pegged polyethylene component leads to satisfactory clinical outcomes at midterm follow up. No revisions for aseptic loosening of the glenoid were required

Femoroacetabular impingement (FAI) – enlarged, aspherical femoral head deformity (cam-type) or retroversion/overcoverage of the acetabulum (pincer-type) – is a leading cause for early hip osteoarthritis. Although anteverting/reverse periacetabular osteotomy (PAO) to address FAI aims to preserve the native hip and restore joint function, it is still unclear how it affects joint mobility and stability. This in vitro cadaveric study examined the effects of surgical anteverting PAO on range of motion and capsular mechanics in hips with acetabular retroversion. Twelve cadaveric hips (n = 12, m:f = 9:3; age = 41 ± 9 years; BMI = 23 ± 4 kg/m2) were included in this study. Each hip was CT imaged and indicated acetabular retroversion (i.e., crossover sign, posterior wall sign, ischial wall sign, retroversion index > 20%, axial plane acetabular version < 15°); and showed no other abnormalities on CT data. Each hip was denuded to the bone-and-capsule and mounted onto a 6-DOF robot tester (TX90, Stäubli), equipped with a universal force-torque sensor (Omega85, ATI). The robot positioned each hip in five sagittal angles: Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°; and performed hip internal-external rotations and abduction-adduction motions to 5 Nm in each position. After the intact stage was tested, each hip underwent an anteverting PAO, anteverting the acetabulum and securing the fragment with long bone screws. The capsular ligaments were preserved during the surgery and each hip was retested postoperatively in the robot. Postoperative CT imaging confirmed that the acetabular fragment was properly positioned with adequate version and head coverage. Paired sample t-tests compared the differences in range of motion before and after PAO (CI = 95%; SPSS v.24, IBM). Preoperatively, the intact hips with acetabular retroversion demonstrated constrained internal-external rotations and abduction-adduction motions. The PAO reoriented the acetabular fragment and medialized the hip joint centre, which tightened the iliofemoral ligament and slackenend the pubofemoral ligament. Postoperatively, internal rotation increased in the deep hip flexion positions of Flexion 60° (∆IR = +7°, p = 0.001) and Flexion 90° (∆IR = +8°, p = 0.001); while also demonstrating marginal decreases in external rotation in all positions. In addition, adduction increased in the deep flexion positions of Flexion 60° (∆ADD = +11°, p = 0.002) and Flexion 90° (∆ADD = +12°, p = 0.001); but also showed marginal increases in abduction in all positions. The anteverting PAO restored anterosuperior acetabular clearance and increased internal rotation (28–33%) and adduction motions (29–31%) in deep hip flexion. Restricted movements and positive impingement tests typically experienced in these positions with acetabular retroversion are associated with clinical symptoms of FAI (i.e., FADIR). However, PAO altered capsular tensions by further tightening the anterolateral hip capsule which resulted in a limited external rotation and a stiffer and tighter hip. Capsular tightness may still be secondary to acetabular retroversion, thus capsular management may be warranted for larger corrections or rotational osteotomies. In efforts to optimize surgical management and clinical outcomes, anteverting PAO is a viable option to address FAI due to acetabular retroversion or overcoverage

Acetabular retroversion is a recognised cause of hip impingement. Pelvic tilt influences acetabular orientation and is known to change in different functional positions. While previously reported in patients with developmental dysplasia of the hip, positional changes in pelvic tilt have not been studied in patients with acetabular retroversion. We retrospectively analysed supine and standing AP pelvic radiographs in 22 patients with preoperative radiographs and 47 with post-operative radiographs 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 pelvic tilt angle was measured both by the Sacro-Femoral-Pubic (SFP) angle and the Pubic Symphysis to Sacro-iliac (PS-SI) Index. In the supine position, the mean calculated pelvic tilt angle (by SFP) was 1.05° which changed on standing to a pelvic tilt of 8.64°. A significant increase in posterior pelvic tilt angle from supine to standing of 7.59° (SFP angle) and 5.89° (PS –SI index) was calculated (p<0.001;paired t-test). There was a good correlation in pelvic tilt change between measurements using SFP angle and PS-SI index (rho .901 in pre-op group, rho .815 in post-op group). Signs of retroversion were significantly reduced in standing x-rays compared to supine: Crossover index (0.16 vs 0.38; p<0.001) crossover sign (19/28 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 vs 24/28 hips; p<0.001). Posterior pelvic tilt increased from supine to standing in patients with symptomatic acetabular retroversion, in keeping with previous studies of pelvic tilt change in patients with hip dysplasia. The features of acetabular retroversion were much less evident on standing radiographs. The low pelvic tilt angle in the supine position is implicated in the appearance of acetabular retroversion in the supine position. Patients presenting with symptoms of hip impingement should be assessed by supine and standing pelvic radiographs so as not to miss signs of retroversion and to assist with optimising acetabular correction at the time of surgery

Acetabular retroversion is a recognised cause of hip impingement. Pelvic tilt influences acetabular orientation and is known to change in different functional positions. While previously reported in patients with developmental dysplasia of the hip, positional changes in pelvic tilt have not been studied in patients with acetabular retroversion. We retrospectively analysed supine and standing AP pelvic radiographs in 22 patients with preoperative radiographs and 47 with post-operative radiographs 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 pelvic tilt angle was measured both by the Sacro-Femoral-Pubic (SFP) angle and the Pubic Symphysis to Sacro-iliac (PS-SI) Index. In the supine position, the mean calculated pelvic tilt angle (by SFP) was 1.05° which changed on standing to a pelvic tilt of 8.64°. A significant increase in posterior pelvic tilt angle from supine to standing of 7.59° (SFP angle) and 5.89° (PS –SI index) was calculated (p<0.001;paired t-test). The mean pelvic tilt change of 6.51° measured on post-operative Xrays was not significantly different (p=.650). There was a good correlation in pelvic tilt change between measurements using SFP angle and PS-SI index (rho .901 in pre-op group, rho .815 in post-op group). Signs of retroversion were significantly reduced in standing x-rays compared to supine: Crossover index (0.16 vs 0.38; p<0.001) crossover sign (19/28 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 vs 24/28 hips; p<0.001). Posterior pelvic tilt increased from supine to standing in patients with symptomatic acetabular retroversion, in keeping with previous studies of pelvic tilt change in patients with hip dysplasia. The features of acetabular retroversion were much less evident on standing radiographs. The low pelvic tilt angle in the supine position is implicated in the appearance of acetabular retroversion in the supine position. Patients presenting with symptoms of hip impingement should be assessed by supine and standing pelvic radiographs so as not to miss signs of retroversion and to assist with optimising acetabular correction at the time of surgery

Acetabular retroversion (ARV) is a cause of femoroacetabular impingement leading to hip pain and reduced range of motion. We aimed to describe the radiological criteria used for diagnosing ARV in the literature and report on the outcomes of periacetabular osteotomy (PAO) and hip arthroscopy (HA) in its management. A systematic review using PRISMA guidelines was conducted on the MEDLINE, CINAHL, EMBASE, COCHRANE database in December 2022. English-language studies reporting outcomes of PAO, or open or arthroscopic interventions for ARV were included. From an initial 4203 studies, 21 non-randomised studies met the inclusion criteria. Eleven studies evaluated HA for ARV, with average follow-up ranging from 1 to 5 years, for a cumulative number of 996 patients. Only 3/11 studies identified ARV using AP standardized pelvic radiographs. The most frequent signs describing ARV identified were: Ischial Spine Sign (98% of patients), Posterior Wall Sign (PWS, 94%) and Crossover Sign (COS, 64%); with mean Acetabular Retroversion Index (ARI) ranging from 33% to 35%. 39% of HA patients had all three radiographic signs. Clinically significant outcomes were reached by 33–78% of patients. Eight studies evaluated PAO for ARV, with a follow-up ranging from 2 to 10 years, for a cumulative number of 379 patients. Five of the eight studies identified ARV using standardized radiographs. ISS, COS and PWS were positive in 54%, 97% and 81% of patients, respectively with 52% of PAO patients having all three radiographic signs. Mean ARI ranged from 36–41%. Clinically significant results were reported in 71%–78% of patients. The diagnostic criteria for ARV is poorly defined in the literature, and the quality of evidence is low. Studies on HA are more likely to have used lenient diagnostic criteria. It remains difficult to recommend which cases maybe more suitable for treatment by HA rather than PAO

Thoracic hyperkyphosis (TH – Cobb angle >40°) is correlated with rotator cuff arthropathy and associated with anterior tilting and protraction of scapula, impacting the glenoid orientation and the surrounding musculature. Reverse total shoulder arthroplasty (RTSA) is a reliable surgical treatment for patients with rotator cuff arthropathy and recent literature suggests that patients with TH may have comparable range of motion after RTSA. However, there exists no study reporting the possible link between patient-reported outcomes, humeral retroversion and TH after RTSA. While the risk of post-operative complications such as instability, hardware loosening, scapular notching, and prosthetic infection are low, we hypothesize that it is critical to optimize the biomechanical parameters through proper implant positioning and understanding patient-specific scapular and thoracic anatomy to improve surgical outcomes in this subset of patients with TH. Patients treated with primary RTSA at an academic hospital in 2018 were reviewed for a two-year follow-up. Exclusion criteria were as follows: no pre-existing chest radiographs for Cobb angle measurement, change in post-operative functional status as a result of trauma or medical comorbidities, and missing component placement and parameter information in the operative note. As most patients did not have a pre-operative chest radiograph, only seven patients with a Cobb angle equal to or greater than 40° were eligible. Chart reviews were completed to determine indications for RTSA, hardware positioning parameters such as inferior tilting, humeral stem retroversion, glenosphere size/location, and baseplate size. Clinical data following surgery included review of radiographs and complications. Follow-up in all patients were to a period of two years. The American Shoulder and Elbow Surgeons (ASES) Shoulder Score was used for patient-reported functional and pain outcomes. The average age of the patients at the time of RTSA was 71 years old, with six female patients and one male patient. The indication for RTSA was primarily rotator cuff arthropathy. Possible correlation between Cobb angle and humeral retroversion was noted, whereby, Cobb angle greater than 40° matched with humeral retroversion greater than 30°, and resulted in significantly higher ASES scores. Two patients with mean Cobb angle of 50° and mean humeral retroversion 37.5° had mean ASES scores of 92.5. Five patients who received mean humeral retroversion of 30° had mean lower ASES scores of 63.7 (p < 0 .05). There was no significant correlation with glenosphere size or position, baseplate size, degree of inferior tilting or lateralization. Patient-reported outcomes have not been reported in RTSA patients with TH. In this case series, we observed that humeral stem retroversion greater than 30° may be correlated with less post-operative pain and greater patient satisfaction in patients with TH. Further clinical studies are needed to understanding the biomechanical relationship between RTSA, humeral retroversion and TH to optimize patient outcomes

This paper presents an ongoing review of the use of a wedge-shaped porous metal augments in the shoulder to address glenoid retroversion as part of anatomical total shoulder arthroplasty (aTSA). Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42 to 85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients received either a 15º or 30º PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Standardized Shoulder Assessment Form [ASES], visual analogue scale [VAS] pain scores and forward elevation [FE]) preoperatively, at three, six, and 12 months, and yearly thereafter, with similar radiological surveillance. Forty-nine consecutive series shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24–87 months). Median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90º to 140º). Four patients died, but no others were lost to follow-up. Apart from one infection at 18 months postoperatively and one minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency or posterior re-subluxations. Radiographs showed good incorporation of the wedge augment with correction of glenoid retroversion from median 22º (13º to 46º) to 4º. All but four glenoids were corrected to within the target range (less than 10º retroversion). The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure

Introduction. Peri-acetabular-osteotomy (PAO) was initially described for the correction of acetabular dysplasia. Anteverting PAO is an established treatment for acetabular retroversion. By reviewing a large cohort, we aimed to (1) Test whether PAO outcome is equivalent in different types of deformity (classic dysplasia vs. retroversion) and (2) Determine whether outcome in acetabular retroversion is different between impinging-only hip and hips with combined pathology (impingement & dysplasia). Methods. A single-centre, retrospective cohort study was performed on a group of patients (n=183) with acetabular retroversion (n=90) or lateral-under-coverage dysplasia (n=93) treated with PAO. Acetabular deformity was defined on pelvic radiographs and 3-D CTs using a number of parameters. Hips with retroversion, were sub-divided into combined pathology - retroversion with dysplasia (lateral centre-edge [LCEA] < 25°), or retroversion-only (LCEA≥25°). The mean age at time of the procedure was 29+/−7 years and most hips were in females (n=171). Complication (as per Dindo-Clavien)-, re-operation-, hip preservation rates and patient-reported-outcome measures were measured using the Non-Arthroplasty-Hip-Score (NAHS). Results. At 2±1 years of follow-up, 5 hips underwent THA (2 dysplastics; 3 retroversion). Major complication rate was 2% for dysplastics and 5% for retroversions (p=0.9). Similar re-operation rates were seen (4% Vs. 8%, p=0.1). Better NAHS was seen in dysplastics compared to retroversions post-operatively (83Vs.73; p=0.001) but not pre-operatively (59 vs 57; p=0.2). ΔNAHS was inferior in retroversions (25 Vs.16, p=0.02). No difference in complications (p=0.1), re-operations (p=0.4) nor post-operative NAHS (76Vs71; p=0.3) were identified between retroversion-only and retroversion-combined pathology cases. Conclusion. A PAO is as safe for retroversion as it is for dysplasia. This is the case for retroverted acetabulae showing either features of combined pathology or impingement-only. However, the pre-operative NAHS was inferior in retroversion and the improvement was not as great as dysplastic hips, illustarting that the impingement process has a detrimental effect on outcome

Abstract. Objective. To assess the prevalence of acetabular retroversion in patients presenting with Slipped Upper Femoral Epiphysis using both validated radiological signs and CT-angle measurements. Methods. A retrospective review of all cases involving surgical management for acute SUFE presenting to the Royal Children's Hospital, Melbourne were assessed from 2012–2018. Pre-operative plain radiographs were assessed for slip angle, validated radiological signs of retroversion (post wall/crossover/ischial spine sign) and standardised post-operative CT Scans were used to assess cranial and mid-acetabular version. Results. 116 SUFEs presented in 107 patients who underwent surgical intervention; 47 females and 60 boys, with an average age of 12.7 years (range 7.5–16.6 years). Complete radiological data was available for 91 patients (99 hips) with adequate axial CT imaging of both hips. 82% patients underwent pinning in situ (PIS) with subcapital realignment surgery (SRS) performed in 18% (slip angles >75°). Contralateral prophylactic hip PIS was performed in 72 patients (87%). On the slip side, 68% of patients had 1 or more radiological signs of retroversion in the slipped hip, with 60% on the contralateral side. The mean cranial and mid-acetabular version measurements were −8°(range −30 – 8°) and 10.5°(range −10 – 25°), respectively. Conclusions. Acetabular retroversion is rare in the normal population with studies reports ranging from 0–7%. This study showed an increased prevalence of 68% in SUFE patients, which is likely to be a primary anatomical abnormality, subsequently increasing the shear forces across the proximal femoral growth plate due to superior over-coverage. The resulting CAM lesion from SUFE in combination with the pincer lesion due to retroversion can lead to premature hip impingement and degeneration. Further larger studies are required to assess if acetabular retroversion is a true risk factor, and its role in helping guide management including prophylactic pinning. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aims. Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients. Methods. A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method). Results. Mean impingement-free flexion of patients with mixed-type FAI (110° (SD 8°)) and patients with pincer-type FAI (112° (SD 8°)) was significantly (p < 0.001) lower compared to the control group (125° (SD 13°)). The frequency of extra-articular subspine impingement was significantly (p < 0.001) increased in patients with pincer-type FAI (57%) compared to cam-type FAI (22%) in 125° flexion. Bony impingement in maximal flexion was located anterior-inferior at femoral four and five o’clock position in patients with cam-type FAI (63% (10 of 16 hips) and 37% (6 of 10 hips)), and did not involve the cam deformity. The cam deformity did not cause impingement in maximal flexion. Conclusion. Femoral impingement in maximal flexion was located anterior-inferior distal to the cam deformity. This differs to previous studies, a finding which could be important for FAI patients in order to avoid exacerbation of hip pain in deep flexion (e.g. during squats) and for hip arthroscopy (hip-preservation surgery) for planning of bone resection. Hip impingement in flexion has implications for daily activities (e.g. putting on shoes), sports, and sex. Cite this article: Bone Joint Res 2023;12(1):22–32

Introduction. The Walch Type B2 glenoid has the hallmark features of posteroinferior glenoid erosion, retroversion, and posterior humeral head subluxation. Although our understanding of the pathoanatomy of bone loss and its evolution in Type B's has improved, the etiology remains unclear. Furthermore, the morphology of the humerus in Walch B types has not been studied. The purpose of this imaging based anthropometric study was to examine the humeral torsion in Walch Type B2 shoulders. We hypothesized that there would be a compensatory decrease in humeral retroversion in Walch B2 glenoids. Methods. Three-dimensional models of the full length humerus were generated from computed tomography data of normal cadaveric (n = 59) and Walch Type B shoulders (n = 59). An anatomical coordinate system referencing the medial and lateral epicondyles was created for each model. A simulated humeral head osteotomy plane was created and used to determine humeral version relative to the epicondylar axis and the head-neck angle. Measurements were repeated by two experienced fellowship-trained shoulder surgeons to determine inter-rater reliability. Glenoid parameters (version, inclination and 2D critical shoulder angle) and posterior humeral head subluxation were calculated in the Type B group to determine the pathologic glenohumeral relationship. Two-way ANOVAs compared group and sex within humeral version and head-neck angle, and intra-class correlation coefficients (ICCs) with a 2-way random effects model and absolute agreement were used for inter-rater reliability. Results. There were statistically significant differences in humeral version between normal and Type B shoulders (p < .001) and between males and females within the normal group (p = .043). Normal shoulders had a humeral retroversion of 36±12°, while the Walch Type B group had a humeral retroversion of 14±9° relative to the epicondylar axis. For head-neck angle, there were no significant differences between sexes (p = .854), or between normal and Type B shoulders when grouped by sex (p = .433). In the Type B group, the mean glenoid version was 22±7°, glenoid inclination was 8±6°, 2D critical shoulder angle was 30±5° and humeral head subluxation was 80±9%. Inter-rater reliability showed fair agreement between the two experienced observers for head-neck angle (ICC = .562; 95% CI: -.28 to .809) and excellent agreement for humeral version (ICC = .962;.913 to .983). Although only fair agreement was found between observers in head-neck angle ICC, the difference in mean angle was only 2°. Discussion. Although much time and effort has been spent understanding and managing Type B2 glenoids, little attention has been paid to investigating associated humeral contributions to the Type B shoulder. Our results indicate that the humeral retroversion in Type B shoulders is significantly lower than in normals. These findings have several implications, including, helping to understanding the etiology of the B2, the unknown effects of arbitrarily selecting higher version angles for the humeral component, and the unknown effects of altered version on glenohumeral joint stability, loading and implant survivorship post-arthroplasty. Our results also raise an important question, whether it is best to reconstruct Type B humeral component version to pathologic version or to non-pathologic population means

Introduction & Background. Clinical outcome after reverse total shoulder arthroplasty (RTSA) can be influenced by technical and implant-related factors, so the purpose of this study was to investigate whether individualizing humeral retroversion and subscapularis repair affect the clinical outcomes after RTSA. Material & Method. Authors retrospectively analyzed the prospectively collected data from 80 patients who underwent RTSA from January 2007 to January 2015 using same implant (Biomet Comprehensive. ®. Reverse Shoulder System, Warsaw, Indiana). The mean follow up was 23.3 ± 1.7 (range, 12 ∼ 70) months. The retroversion of humeral component was decided according to native version estimated using shoulder CT in Group I (n=52), and fixed in 20° retroversion in Group II (n=28). Group I was subdivided into Group Ia (n=21, mean 19.3°), less than 20° of retroversion, and Group Ib (n=31, mean 31.9°), more than 20°. Intraoperative tenotomized subscapularis was repaired in 40 patients in Group I, and could not be repaired due to massive tear including subscapularis in remaining 12 patients. Clinical outcomes were evaluated with range of motion (ROM) and several clinical outcome scores. Results. Group I showed significantly better ROM and clinical scores compared to Group II at the final follow up (all p < 0.05). There were no significant differences in ROM and clinical scores between Group Ia and Ib. Group Ia showed better ROM and pain VAS than Group II (all p < 0.05), and Group Ib also demonstrated significantly better ROM and clinical outcome scores than Group II (all p < 0.05). With respect to subscapularis repair, there were no differences in ROM and clinical scores between two groups. No complications such as infection or dislocation were detected according to subscapularis repair. Conclusion. Individualizing humeral retroversion can obtain superior clinical outcomes than fixed 20° retroversion. Subscapularis repair would not be essential for the better clinical outcome in patients with the lateralized RTSA

Introduction. Acetabular retroversion is an accepted cause of Pincer-type femoroacetabular impingement. There is increasing evidence that acetabular retroversion is rather a rotational abnormality of the pelvis than an overgrowth of the acetabular wall or even a dysplasia of the posterior wall. Initially, patients with a retroverted acetabulum were treated with an open rim trimming through a surgical hip dislocation (SHD) based on the early understanding of the pathomorphology. Theoretically, the reduction of the anterior wall can decrease the already small joint contact area in retroverted hips to a critical size. Based on the most recent literature, anteverting periacetabular osteotomy (PAO) seems to be the more appropriate surgical treatment. With this technique, the anterior impingement conflict can be treated efficiently without compromising the joint contact area. However, it is unknown whether this theoretical advantage in turn results in better mid term results of treatment. Objectives. We asked if anteverting PAO results in better clinical and radiographical mid term results compared to rim trimming through a surgical hip dislocation. Methods. We performed a retrospective comparative study based on 257 hips (221 patients) with symptomatic femoroacetabular impingement due to acetabular retroversion. Acetabular retroversion was defined by a cross-over sign, a posterior wall sign, and a positive ischial spine sign. We then formed two matched groups consisting of 73 hips undergoing open acetabular rim trimming and 54 hips with an anteverting periacetabular osteotomy. Patients with incomplete radiographic documentation, previous surgery, and hip dysplasia (LCE < 20°) were excluded. Some patients were excluded due to a matching process (Fig. 1). Patients were generally followed clinically and radiographically after two, five and ten years. A Kaplan-Meier survivorship analysis was performed using the following endpoints: a low clinical score, radiographic progression of osteoarthritis, and/or the conversion to total hip arthroplasty. The Log Rank Score was used to compare the two survivorship curves. Results. Patients undergoing anteverting PAO for acetabular retroversion had a significantly increased survivorship (82%, 95% confidence interval, 72–91%) at seven years in comparison to open surgical rim trimming (63%, 95%CI, 49–76%, p<0.0001). The two survivorship curves are comparable for the first four years with a substantial drop for the rim trimming group after year five (Fig. 2). Conclusion. This study proofs for the first time that the theoretical advantages of anteverting periacetabular osteotomy in hips with symptomatic acetabular retroversion results in an increased survivorship at mid term follow-up in comparison to open rim trimming. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

INTRODUCTION:. Acetabular retroversion has been implicated as a risk factor for the development of early hip osteoarthritis. In clinical practice standard osseous signs such as the cross-over sign (COS) and the posterior wall sign (PWS) are widely used to establish the diagnosis of acetabular retroversion on plain radiographs. Despite standardized radiological evaluation protocols, an increased pelvic tilt can lead to a misdiagnosis of acetabular retroversion in AP radiographs and 2D MR or CT scans. Previous studies have shown that the elimination of observer bias using a standardized methodology based on 3D-CT models and the anterior pelvic plane (APP) for the assessment of COS and PWS results in greater diagnostic accuracy. Using this method a prevalence of 28% for COS and 24% for PWS has been found in a cohort of patients with symptoms indicative of FAI, however the prevalence of both signs in asymptomatic adults remains unknown. This study therefore sought to establish the prevalence of the COS and PWS in relation to the APP in an asymptomatic population using a reliable and accurate 3 D-CT based assessment. METHODS:. A large pool of consecutive CT scans of the pelvis undertaken in our department for conditions unrelated to disorders of the hip was available for analysis. Scans in subjects with a Harris hip score of less than 90 points were excluded leaving a sample of 100 asymptomatic subjects (200 hips) for this study. A previously established 3D analysis method designed to eliminate errors resulting from variations in the position and orientation of the pelvis during CT imaging was applied to determine in order to assess the prevalence of the COS and PWS in relation to the APP. Here, the acetabuli were defined as retroverted if either the COS, PWS or both were positive. RESULTS:. From the total of 200 hips a positive COS was identified in 24% (48/200) and a positive PWS was detected in 6.5% (13/200) relative to the APP using the CT data. A. In male adults a COS was observed in 25.4% (29/114) and a PWS in 10.5% (12/114). In female adults a COS were observed in 22.1% (19/86) and a PWS in 1.2% (1/86). DISCUSSION:. The high incidence of acetabular retroversion observed using an accurate 3D-CT based methodology shows that this anatomic configuration might not differ in frequency between asymptomatic individuals and patients with symptomatic FAI. Patients presenting with hip pain and evidence of FAI should therefore be subjected to strict diagnostic scrutiny, as the presence of a COS and/or PWS shows a poor correlation with the presence of symptomatic disease. In our collective of asymptomatic adults the COS showed a higher incidence than the PWS. Additionally a deficiency of the posterior acetabular wall was rare in asymptomatic adults compared to FAI patients. Therefore, the question whether an abnormal acetabular version does indeed lead to the development of osteoarthritis in all patients warrants further study. Although an association between osteoarthritis and femuro-acetabular impingement is believed to exist, long-term epidemiological studies are needed to establish the natural history of these anatomical configurations

Introduction: Restoration of original humeral head geometry in shoulder arthroplasty is a necessary requirement and may have a bearing on the longevity of the implant. Modern, adaptable, prosthetic components are believed to allow restoration of the individual’s proximal humeral anatomy, provided a precise osteotomy of the humeral head at the level of the anatomical neck is performed. The osteotomy and reconstruction of the humeral head is based on the assumption that the resected articular segment corresponds to a segment of a sphere oriented, identically, in inclination and retroversion to the original humeral head. Resection, along the mid-anterior portion of the cartilage/calcar border, is understood to create a surface that enables a prosthetic component to be mounted, retroverted and inclinated to the same degree as the original head geometry. The objective of this study was to determine the degree of variation in humeral head retroversion relative to the superior and inferior borders of the proximal humeral articular surface. Methods: Twenty-eight fresh frozen human cadaveric full arms were dissected free of soft tissue to expose the proximal humerus. The distal end of the humeral shaft was potted in PMMA and fixed rigidly in a custom–built jig. The following points and lines were identified and marked on each specimen:. the circumference of the anatomical neck;. (H) as the most superior point of the articular surface at the insertion of the supraspinatus tendon, (L) as the corresponding lowest point of the articular surface at the cartilage/calcar interface;. The medial (MC) and lateral (LC) humeral condyles were exposed and delineated with k-wires. A Microscribe 3D-X digitizer was used to digitize the points and lines. The data for each humerus were imported into Rhinoceros NURBS modelling software and graphically represented. The constructed graphical model was used to divide the articular portion of the humeral head into six equal sections in the axial plane. The retroversion angle, relative to the epicondyles, was calculated for each section. Results: A linear decrease in retroversion angle was noted from the most superior to most inferior point on the proximal humeral articular surface. The retroversion angle was greatest at the level of the insertion of the supraspinatus tendon (34.2deg +/−13.7deg) and least at the inferior cartilage/calcar interface (24.3deg +/−10.2deg). Discussion: Accurate recovery of humeral head geometry is a requirement in order to achieve good function. The variability in retroversion, as it relates to its point of measurement, may effect the accuracy of pre-operative assessment of a patient’s humeral head geometry as well as the osteotomy during shoulder arthroplasty, and, thus, may impact on joint range of motion and stability post-operatively. Further investigation is warranted

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

Introduction Shoulder arthroplasty is a difficult procedure which, for success, is dependant on many factors as correct retroversion of the humeral implant. An experimental set up was therefore devised, using a model to determine the actual accuracy of the retroversion obtained under ideal in vitro conditions in two different situations, one in which the proximal humerus was intact such as that encountered in osteoarthritis or P.A.R. and the other where most usual landmarks were missing such as that seen in the four-part fracture situation. Materials and methods 106 prostheses were inserted into 106 arms (plastic bone). 54 bones were cut at the level of the surgical collar as in complex fractures and 54 were untouched as in omarthrosis. The first series was done without any guide (52 implants). Every operator has to put 3 prostheses with 30 degree retroversion according to his particular chosen method of mark, either the bicondylar line, or according to the position of the forearm. The second one was done with a jig (Neer 3) indicating 25 degrees of retroversion (54 implants). The degree of retroversion of prostheses put is measured according to the angle between the axis passing by the previous face of the condyles of the ulna and the axis passing by the mark taken on the prosthesis (perpendicularly in the axis of the humerus). The humeral axis, the condylar axis, the prosthesis plane and the cutting plane were determined. 3 barycentres of humeral sections determined the humeral axis. The condylar axis is determined from the 2 barycentres of the digitalized points on the anterior articular condylar surfaces. These 2 axes determine the frontal plane on which a reference mark R(x, y, z) is attached with Z lined up with the humeral shaft and X lined up on the condyles. Discussion and results All these results show that with or without guide, the prosthesis is not inserted in the right way. Only one third of the P.T.E. ( 33 on 106) were put with a correct angle of retroversion, or between 20 and 40 °, with a maximum of 67,7 ° and a minimum of 4,4 ° (standard deviation 12, 8 !). Shoulder prosthesis, a difficult technique, may need computer help for the positioning especially for the retroversion angle