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

Introduction. The patient's perspective is important in determining contemporary quality measures. Hip surgery may be much more disruptive on patient and family than many surgeons appreciate. We sought to investigate the character of the periacetabular osteotomy(PAO) experience from the patient's point of view. We hypothesized that interviewing this largely female population, treated in their very active years, would yield unique insights. Methods. We carried out an internet-based survey using a Google Forms platform posted on the PAO Facebook page and the Yahoo Hip Women group, comprising more than 1300 members. In a ten day enrollment period, 154 respondents completed the survey, which consisted of demographic information, plus multiple specific and open-ended questions. Results. 96% female, mean age 33y at surgery. 8.4y mean time from pain onset to PAO, >4y mean time from dx dysplasia to PAO. 30% not informed of PAO at dx of dysplasia. 18% connected with a “Hip Buddy” preop—all felt it strongly positive. Postop constipation severe problem>90%. All felt postop physical therapy important but 62% felt surgeon and PT team did not communicate well. Major emotional issues post discharge: depression/isolation 67%; emotionally unprepared for surgery 6%. Frequent mention of major negative impact on marriage/relationships/personal life/work/finances. Only 4/154 met with a mental health professional preoperatively. 88% did not regret having PAO. 73% felt PAO adequately corrected pain. Conclusion. The perioperative and postoperative experience of the PAO patient is far from universally positive. Learning the patient's perspective offers a previously-underappreciated important opportunity to improve outcomes. For any tables or figures, please contact the authors directly

Aims. Social media is a popular resource for patients seeking medical information and sharing experiences. periacetabular osteotomy (PAO) is the gold-standard treatment for symptomatic acetabular dysplasia with good long-term outcomes. However, little is known regarding the perceived outcomes of PAO on social media. The aims of this study were to describe the perceived outcomes following PAO using three social media platforms: Facebook, Instagram, and X (formerly known as Twitter). Methods. Facebook, Instagram, and X posts were retrospectively collected from 1 February 2023. Facebook posts were collected from the two most populated interest groups: “periacetabular osteotomy” and “PAO Australia.” Instagram and X posts were queried using the most popular hashtags: #PAOwarrior, #periacetabularosteotomy, #periacetabularosteotomyrecovery, #PAOsurgery, and #PAOrecovery. Posts were assessed for demographic data (sex, race, location), perspective (patient, physician, professional organization, industry), timing (preoperative vs postoperative), and perceived outcome (positive, negative, neutral). Results. A total of 1,054 Facebook posts, 1,003 Instagram posts, and 502 X posts were consecutively assessed from 887 unique authors. The majority (63.3%) of these posts were from patients in the postoperative period, with a median of 84 days postoperatively (interquartile range 20 to 275). The longest follow-up timeframe postoperatively was 20 years. Regarding perceived outcomes, 52.8% expressed satisfaction, 39.7% held neutral opinions, and 7.5% were dissatisfied. Most dissatisfied patients (50.9%) reported pain (chronic or uncontrolled acute) as an attributing factor. Conclusion. Most PAO-perceived surgical outcomes on social media had a positive tone. Findings also indicate that a small percentage of patients reported negative perceived outcomes. However, dissatisfaction with PAO primarily stemmed from postoperative pain. Social media posts from other sources (physicians, hospitals, professional organizations, etc.) trend towards neutrality. Healthcare providers must consider the social media narratives of patients following PAO, as they may reveal additional outcome expectations and help improve patient-centred care, create informed decision-making, and optimize treatment outcomes. Cite this article: Bone Jt Open 2024;5(1):53–59

Aims. Periacetabular osteotomy (PAO) is well established for acetabular reorientation and has shown successful improvement in patient-reported outcome measures (PROMs). Nevertheless, studies focusing on postoperative outcomes related to patient individual factors are still underrepresented. Therefore, this study aimed to analyze the functional outcome and activity level in relation to patient sex with a minimum follow-up of two years after PAO for mild to severe hip dysplasia. Methods. A single-centre study was conducted, enrolling patients undergoing PAO and completing a preoperative and postoperative radiological and clinical outcome assessment. The PROMs were assessed using the modified Harris Hip Score (mHHS), the Hip disability and Osteoarthritis Outcome Score (HOOS) with the subscales for pain, sport, activities of daily living (ADL), and quality of life (QoL), and the University of California, Los Angeles (UCLA) activity score. Kendall’s tau were calculated for correlation analyses. Results. In total, 145 patients (28 male, 117 female) were included. The PROMs improved significantly across males and females at the latest follow-up. Female patients had significantly lower preoperative PROMs: mHHS (47 vs 57.4; p = 0.002); HOOS pain (44.9 vs 60; p = 0.003), sport (47 vs 57.4; p = 0.002), ADL (58.9 vs 69.3; p = 0.032), and QoL (26.8 vs 39.3; p = 0.009); and UCLA (5.6 vs 6.7, p = 0.042) scores. Males showed higher postoperative UCLA scores (7.5 vs 6.7; p = 0.03). Kendall’s tau showed significant negative correlation between BMI and UCLA scores in females and males (-0.21 to -0.29; p = 0.002/0.048), while BMI and HOOS sport (-0.16; p = 0.015) and ADL (-0.2; p = 0.003), as well as QoL (-0.14; p = 0.031) and preoperative acetabular inclination (-0.13; p = 0.049) were only significantly negatively correlated in females. Conclusion. Patient sex affects PROMs before and after PAO. Female patients experience higher improvement in hip function and activity level, due to poorer preoperative PROMs than males. Thus, these data are particularly interesting in providing preoperative guidance regarding postoperative outcome expectations. Cite this article: Bone Jt Open 2024;6(1):35–42

The Bernese periacetabular osteotomy (PAO) described by Ganz, et al. is a commonly used surgical intervention in hip dysplasia. PAO is being performed more frequently and is a viable alternative to hip arthroplasty for younger and more physically active patients. The procedure is challenging because pelvic anatomy is prohibitive to visibility and open access and requires four X-ray guided blind cuts around the acetabulum to free it from the hemi-pelvis. The crucial step is the re-orientation of the freed acetabulum to correct the inadequate coverage of the femoral head by idealy rotating the freed acetabular fragment. Diagnosis and the decision for surgical intervention is currently based upon patient symptoms, use of two-dimensional (2D) radiographic measurements, and the intrinsic experience of the surgeon. With the advent of new technologies allowing three-dimensional reconstructions of hip anatomy, previous two-dimensional X-ray definitions have created much debate in standardizing numerical representations of hip dysplasia. Recent work done by groups such as Arminger et al. have combined and expanded two-dimensional measurements such as Center-Edge (CE) angle of Wiberg, Vertical-Center-Anterior margin (VCA) angle, Acetabular Anteversion (AcetAV) and applied them to three-dimensional CT rendering of hip anatomy. Further, variability in pelvic tilt is a confounding factor and has further impeded measurement translatability. Computer assisted surgery (CAS) and navigation also called image-guided surgery (IGS) has been used in clinical cases of PAO with mixed results. The first appearing study of CAS/IGS in PAO was conducted by Langlotz, et. al 1997 and reported no clinical benefit to using CAS/IGS. However, they did conclude that the use of CAS/IGS is undoubtedly useful for surgeons starting this technically demanding procedure. This is supported by a more recent study done by Hsieh, et. al 2006 who conducted a two year randomised study of CAS/IGS in PAO and concluded its feasibility to facilitate PAO, but there was not an additional benefit when conventional PAO is done by an experienced surgeon. A study done by Peters, et. Al 2006 studying the learning curve necessary to become proficient at PAO found that “The occurrence of complications demonstrates a substantial learning curve” and thus makes a compelling argument for the use of CAS/IGS. A major obstacle to navigation and CAS/IGS revolves around consistency, intra-operative time and ease of use. Custom made guides and implants may help circumvent these limitations. The use of CAS/CAM in developing custom made guides has been proven very successful in areas of oral maxillofacial surgery, hip arthroplasty, and knee replacement surgeries. Additionally, a significant study in the development of rapid prototyping guides in the treatment of dysplastic hip joints was done by Radermacher et. al 1998. They describe a process of using CAS/CAM within the operational theatre using a desktop planning station and a manufacturing unit to develop what they termed as “templates” to carry out a triple osteotomy. Our group is evaluating and developing strategies in PAO using CAS/IGS and more recently using CAS and computer aided modeling (CAM) to develop custom made guides for acetabular positioning. Our first study (Burch et al.) focused on CAS/IGS in PAO using cadavers and yielded small mean cut (1.97± 0.73mm) and CE angle (4.9± 6.0) errors. Our recent study used full sized high-resolution foam pelvis models (Sawbones. ®. , Vashon, Washington) and used CAS/IGS to carry out the pelvic cuts and CAS/CAM to develop a acetabular positioning guide (APG) by rapid prototyping. The CAS/IGS pelvic cuts results were good (mean error of 3.18 mm ± 1.35) and support our and other studies done using CAS/IGS in PAO. The APG yielded high accuracy and was analysed using four angles with an overall mean angular error of 1.81 (0.55. 0. )and individual angulation was as follows: CE 0.83° ± 0.53, S-AC 0.28° ± 0.19, AcetAV 0.41° ± 0.37, and VCA 0.68° ± 0.27. To our knowledge this is the first developed APG for PAO. The APG we developed was to demonstrate the concept of using a positioning guide to obtain accurate rotation of the acetabular fragment. For a clinical application a refined and sleeker design would be required. Further, because working space within the pelvis is extraordinary constrained, once fitted the APG would need to remain and serve as an implantable cage capable of holding bone graft. A potential material is polyetheretherketone (PEEK). Customised PEEK implants and cages have been established in the literature and is a potential option for PAO. The benefits of an implant not only serve to constrain the acetabular fragment in the ideal position based upon the pre-operative plan, but may also provide the structural support for rotations not other wise possible. Though CAS/IGS is a proven viable option, we envision a potentially simpler method for PAO, the use of a cut guide and an acetabular positioning implant. Using customized guides and implants could potentially circumvent the need for specialised intra-operative equipment and the associated learning curves, by providing guides that incorporate the pre-operational plan within the guide, constraining the surgeon to the desired outcome

Aims

Avascular femoral head necrosis in the context of gymnastics is a rare but serious complication, appearing similar to Perthes’ disease but occurring later during adolescence. Based on 3D CT animations, we propose repetitive impact between the main supplying vessels on the posterolateral femoral neck and the posterior acetabular wall in hyperextension and external rotation as a possible cause of direct vascular damage, and subsequent femoral head necrosis in three adolescent female gymnasts we are reporting on.

Aims. We assessed the long-term outcomes of a large cohort of patients who have undergone a periacetabular osteotomy (PAO), and sought to validate a patient satisfaction questionnaire for use in a PAO cohort. Methods. All patients who had undergone a PAO from July 1998 to February 2013 were surveyed, with several patient-reported outcome measures (PROMs) and radiological measurements of preoperative acetabular dysplasia and postoperative correction also recorded. Patients were asked to rate their level of satisfaction with their operation in achieving pain relief, restoration of activities of daily living, ability to perform recreational activity, and their overall level of satisfaction with the procedure. Results. A total of 143 PAOs were performed between 1998 and 2013. Of those, 90 postoperative surveys were returned. Only 65 patients (73 hips) had both pre- and postoperative radiographs available for measurement. The mean time to follow-up was 15 years (6.5 to 20). Most patients were female (91%), with a mean age of 26.4 years (14.9 to 48.3) at the time of their surgery. A statistically significant improvement in radiological correction was detected in all hips (p < 0.001). A total of 67 patients (92.3%) remained either very satisfied or satisfied with their PAO. The internal consistency of the patient satisfaction questionnaire, measured using Cronbach’s α, ranged from 0.89 to 0.94 indicating ‘good’ to ‘excellent’ reliability. Conclusion. Outcomes of importance to patients undergoing a PAO include several key domains: pain relief, improve activities of daily living, and improve recreational ability. Our study demonstrates high rates of long-term patient satisfaction in all domains, and found the patient satisfaction questionnaire to be a valid and reliable instrument for use in this cohort. Cite this article: Bone Jt Open 2023;4(12):964–969

Introduction. Symptomatic hip dysplasia is often treated with periacetabular osteotomy (PAO). Studies investigating the effect of PAO have primarily focused on radiographic measurements, pain-related outcomes, and hip survival whereas evidence related to sport participation is limited. Methods. All patients in our institutional database were deemed eligible for this cohort study if they underwent PAO and had answered at least one question related to sport participation. Patients were asked if they were playing sport preoperatively, 6 months after PAO as well as 2, 5, 10, 15 and 20 years after. In addition, patients were asked if they were able to play their preferred sport, what type and at what level they were playing sport, and if surgery had improved their sport performance. Results. Among 2398 patients surveyed, 1926 (80%) were included and 56% were playing sport 6 months after PAO. This number was 61% two years after PAO, and remained around that for the following years, before dropping 15 years after PAO. Between 56% and 71% of patients felt that their sporting performance improved following PAO at the different time points. Between 39% (6 months after PAO) and 63% (15 years after PAO) were able to participate in their preferred sport. Conclusion. The majority of patients undergoing PAO due to hip dysplasia will return to, and maintain, sport after PAO. More than half of patients undergoing PAO believe that the surgery improved their sports performance, and long after the surgery more than half of patients undergoing PAO are able to play their preferred sport

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

It has been reported that 60-85% of patients who undergo PAO have concomitant intraarticular pathology that cannot be addressed with PAO alone. Currently, there are limited diagnostic tools to determine which patients would benefit from hip arthroscopy at the time of PAO to address intra-articular pathology. This study aims to see if preoperative PROMs scores measured by IHOT-33 scores have predictive value in whether intra-articular pathology is addressed during PAO + scope. The secondary aim is to see how often surgeons at high-volume hip preservation centers address intra-articular pathology if a scope is performed during the same anesthesia event. A randomized, prospective Multicenter trial was performed on patients who underwent PAO and hip arthroscopy to treat hip dysplasia from 2019 to 2020. Preoperative PROMs and intraoperative findings and procedures were recorded and analyzed. A total of 75 patients, 84% Female, and 16% male, with an average age of 27 years old, were included in the study. Patients were randomized to have PAO alone 34 patients vs. PAO + arthroscopy 41 patients during the same anesthesia event. The procedures performed, including types of labral procedures and chondroplasty procedures, were recorded. Additionally, a two-sided student T-test was used to evaluate the difference in means of preoperative IHOT score among patients for whom a labral procedure was performed versus no labral procedure. A total of 82% of patients had an intra-articular procedure performed at the time of hip arthroscopy. 68% of patients who had PAO + arthroscopy had a labral procedure performed. The most common labral procedure was a labral refixation which was performed in 78% of patients who had a labral procedure performed. Femoral head-neck junction chondroplasty was performed in 51% of patients who had an intra-articular procedure performed. The mean IHOT score was 29.3 in patients who had a labral procedure performed and 33.63 in those who did not have a labral procedure performed P- value=0.24. Our findings demonstrate preoperative IHOT-33 scores were not predictive in determining whether intra-articular labral pathology was addressed at the time of surgery. Additionally, we found that if labral pathology was addressed, labral refixation was the most common repair performed. This study also provides valuable information on what procedures high-volume hip preservation centers are performing when performing PAO + arthroscopy

Pelvic osteotomies for hip dysplasia results can be variable and depend on the amount of preexisting arthritis. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a technique designed to measure early arthritis, and could be used to select hips that would benefit from a joint-preserving reconstructive procedure. Our objective was to investigate the role of preoperative dGEMRIC in predicting the success of PAO in patients 40 and above. We hypothesized that patients who failed had lower preoperative dGEMRIC index compared to those who did not. Following IRB approval, patients 40 or older who underwent PAO between 1990–2013 and had preoperative dGEMRIC scan and minimum follow-up of 4 years were identified. Patients with prior hip surgeries or any pathologies were removed leading to a total of 70 patients (Age: 44.2 ± 2.9 years old, BMI: 25.7 ± 4.5 Kg/m. 2. ). We only included the first hip undergoing PAO for those with bilateral PAO. Out of 70, 19 had failure defined by the need for total hip replacement or WOMAC pain score of 10 and above within 10 years after index PAO surgery. Articular cartilage was segmented on the 3D pre-operative dGEMRIC scan. The average thickness and dGEMRIC index across the whole articular surface were analyzed. Failed hips had a lower dGEMRIC index by 115 ± 20 ms (P<0.001). All but one failed hips had a dGMERIC index of 400 or less (range: 313 – 479 ms), while all survived hips had a dGMERIC index of greater than 400 (range: 403 – 691 ms). Similar trends were observed when comparing the dGEMRIC index within the 6 subgroups (P<0.01). There were no differences in cartilage thickness (combined femoral head and acetabular cartilage) between the failed and survived hips (p>0.2). Patients with a high dGMERIC index (indicating high GAG content) may have a higher chance of successful outcomes following PAO. Current efforts are underway to develop a multi-modal predictive model to evaluate risk of failure after PAO

Aims. Psychological status may be an important predictor of outcome after periacetabular osteotomy (PAO). The aim of this study was to investigate the influence of psychological distress on postoperative health-related quality of life, joint function, self-assessed pain, and sports ability in patients undergoing PAO. Methods. In all, 202 consecutive patients who underwent PAO for developmental dysplasia of the hip (DDH) at our institution from 2015 to 2017 were included and followed up at 63 months (SD 10) postoperatively. Of these, 101 with complete data sets entered final analysis. Patients were assessed by questionnaire. Psychological status was measured by Brief Symptom Inventory (BSI-18), health-related quality of life was raised with 36-Item Short Form Survey (SF-36), hip functionality was measured by the short version 0f the International Hip Outcome Tool (iHOT-12), Subjective Hip Value (SHV), and Hip Disability and Outcome Score (HOS). Surgery satisfaction and pain were assessed. Dependent variables (endpoints) were postoperative quality of life (SF-36, HOS quality of life (QoL)), joint function (iHOT-12, SHV, HOS), patient satisfaction, and pain. Psychological distress was assessed by the Global Severity Index (GSI), somatization (BSI Soma), depression (BSI Depr), and anxiety (BSI Anx). Influence of psychological status was assessed by means of univariate and multiple multivariate regression analysis. Results. In multiple multivariate regression, postoperative GSI, BSI Soma, and BSI Depr had a negative effect on postoperative SF-36 (e -2.07, -3.05, and -2.67, respectively; p < 0.001), iHOT-12 (e -1.35 and -4.65, respectively; p < 0.001), SHV (e -1.20 and -2.71, respectively; p < 0.001), HOS QoL (e -2.09 and -4.79, respectively; p < 0.001), HOS Function (e -1.00 and -3.94, respectively; p < 0.001), and HOS Sport (e -1.44 and -5.29, respectively; p < 0.001), and had an effect on postoperative pain (e 0.13 and 0.37, respectively; p < 0.001). Conclusion. Psychological distress, depression, and somatization disorders affect health-related quality of life, perceived joint function, and sports ability. Pain perception is significantly increased by somatization. However, patient satisfaction with surgery is not affected. Cite this article: Bone Jt Open 2023;4(10):758–765

Periacetabular osteotomy (PAO) is the preferred treatment for symptomatic acetabular dysplasia in adolescents and young adults. There remains a lack of consensus regarding whether intra-articular work such as labral repair or improvement of femoral offset should be performed at the time of PAO or addressed subsequent to PAO if symptoms warrant. The purpose was to determine the rate of subsequent hip arthroscopy (HA) in a contemporary PAO cohort with no intra-articular work performed at the time of PAO. From June 2012 to March 2022, 368 rectus sparing PAOs were performed and followed for a minimum of one year (mean 5.9 years). The average age was 24 (range 14–46) and 89% were female. Patients were evaluated at last follow-up for patient-reported outcomes (PROMs). Clinical records were reviewed for complications or subsequent surgery. Radiographs were reviewed for the following acetabular parameters: LCEA, ACEA, AI, and the alpha-angle (AA). Patients were cross-referenced from the two largest hospital systems in our area to determine if subsequent HA was performed. Descriptive statistics were used to analyze risk factors for HA. 16 hips (15 patients) (4.4%) underwent subsequent HA with labral repair and femoral osteochondroplasty most common. For those with a minimum of two years of follow-up, 5.3% underwent subsequent HA. No hips underwent THA; one revision PAO was performed. 14 hips experienced a complication and 99 underwent hardware removal. All PROMs improved significantly post-operatively. Radiographically 80% of hips were in goal for acetabular correction parameters with no significant differences between those who underwent subsequent HA and those who did not. Rectus sparing PAO is associated with a low rate of subsequent HA for intra-articular pathology at 5-year follow-up. Acetabular correction alone may be sufficient as the primary intervention for the majority of patients with symptomatic acetabular dysplasia

Aims. Developmental dysplasia of the hip (DDH) describes a pathological relationship between the femoral head and acetabulum. Periacetabular osteotomy (PAO) may be used to treat this condition. The aim of this study was to evaluate the results of PAO in adolescents and adults with persistent DDH. Methods. Patients were divided into four groups: A, adolescents who had not undergone surgery for DDH in childhood (25 hips); B, adolescents who had undergone surgery for DDH in childhood (20 hips); C, adults with DDH who had not undergone previous surgery (80 hips); and D, a control group of patients with healthy hips (70 hips). The radiological evaluation of digital anteroposterior views of hips included the Wiberg angle (centre-edge angle (CEA)), femoral head cover (FHC), medialization, distalization, and the ilioischial angle. Clinical assessment involved the Harris Hip Score (HHS) and gluteal muscle performance assessment. Results. Significant improvements in radiological parameters were achieved in all measurements in all groups (p < 0.05). The greatest improvement was in CEA (mean of 19° (17.2° to 22.3°) in Group B), medialization (mean of 3 mm (0.9 to 5.2) in Group C), distalization (mean of 6 mm (3.5 to 8.2) in Group B), FHC (mean of 17% (12.7% to 21.2%) in Group B), and ilioischial angle (mean of 5° (2.3° to 8.1°) in Group B). There were significant improvements in the mean HHS and gluteal muscle performance scores postoperatively in all three groups. Conclusion. The greatest correction of radiological parameters and clinical outcomes was found in patients who had undergone hip surgery in childhood. Although the surgical treatment of DDH in childhood makes subsequent hip surgery more difficult due to scarring, adhesions, and altered anatomy, it requires less correction of the deformity and has a beneficial effect on the outcome of PAO in adolescence and early adulthood. Cite this article: Bone Joint J 2022;104-B(7):775–780

The periacetabular osteotomy(PAO) is an effective common hip-preserving procedure to treat symptomatic acetabular dysplasia of the hip (DDH). The literature regarding truly long-term patient outcomes after PAO remains limited. We sought to evaluate our patient cohort treated by PAO 25 to 33 years ago to identify factors positively and negatively associated with durable therapeutic success. 219 dysplastic hips (183 patients) underwent PAO between August 1991 and December 1999 by a single surgeon. 164 hips in 134 patients were retrospectively evaluated at minimum of 25 years and maximum of 33 years post-operatively. Hips were evaluated using the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) postoperatively. Osteotomy failure was defined as WOMAC pain score of >/=10 or the need for total hip arthroplasty (THA). 7 patients (7 hips) had died - none of whom had THR. 142/176 remaining patients were located. All patients returned questionnaires; some were seen in person with images. Of patients analyzed to date, 109 hips (63%) were asymptomatic/mildly symptomatic with a preserved hip. 58 hips (33%) had undergone THA. 7 preserved hips (5%) were symptomatic (WOMAC>10). Patients with THA were slightly older than asymptomatic patients (54 ± 8 years vs. 50 ± 11 years; p=0.08), as they had been at time of PAO. Most patients were female (83%), with 89% of hip replacement patients being female. 4/58 replaced hips had been revised - 3 for instability and 1 for acetabular loosening. Data collection is ongoing as more patients are located and reviewed. Long-term follow-up of patients is challenging. Review after minimum of 25 years of the Boston cohort treated with PAO after minimum of 25 years dysplasia reveals that most at long-term follow-up report high levels of function, whether or not they had required arthroplasty, although 33% had required interim treatment with THA

Finite element analysis (FEA) has been applied for the biomechanical analysis of acetabular dysplasia, but not for biomechanical studies of periacetabular osteotomy (PAO) or those performing analysis taking into consideration the severity of acetabular dysplasia. This study aimed to perform biomechanical evaluation of changes in stress distribution following PAO and to determine the effect of the severity of developmental dysplasia of the hip (DDH) using three-dimensional FEA. A normal model was designed with a 25° center-edge (CE) angle and a 25° vertical-center-anterior margin (VCA) angle. DDH models were designed with CE and VCA angles each of 10, 0, or −10°. Post-PAO models were created by separating each DDH model and rotating the acetabular bone fragment in the anterolateral direction so that the femoral head was covered by the acetabular bone fragment, with CE and VCA angles each at 25°. Compared to the normal hip joint model, the DDH models showed stress concentration in the acetabular edge and contacting femoral head, and higher stress values; stress increased with decreasing CE and VCA angles. Compared to the DDH models, the post-PAO models showed near-normal patterns of stress distribution in the acetabulum and femoral head, with stress concentration areas shifted from the lateral to medial sides. Stress dispersion was especially apparent in the severe acetabular dysplasia models. PAO provided greater decreases in the maximum values of von Mises stress in the load-bearing area of the acetabulum and femoral head when applied to the DDH models of higher degrees of severity, although the values increased with increasing severity of DDH. PAO is expected to provide biomechanical improvement of the hip joint, although the results also suggest a limitation in the applicability of PAO for the patients with severe acetabular dysplasia

The influence of patient age on functional outcomes after periacetabular osteotomy (PAO) for acetabular dysplasia remains unclear, with previous studies utilising scores developed for older, arthritic patients. The purpose of this study is to assess the influence of patient age on International Hip Outcome Tool (iHOT-12) scores, two years after PAO. Eighty-six patients (72 female, 14 male; mean age 26.9 years) who underwent PAO by a single surgeon and had completed a minimum of two years follow up were identified. Patients were categorised into three groups according to age at the time of surgery: adolescent (11–20 years; n=29), young adult (21–30 years; n=29), and mature (≥31 years; n=28). The three groups were compared with respect to baseline variables and functional outcomes (iHOT-12, EQ-5D quality of life score, University of California Los Angeles (UCLA) activity score, pain visual analogue score (VAS)). Multivariate regression was undertaken to assess for independent predictors of two-year iHOT-12 score. The adolescent group demonstrated a lower BMI (p=0.004) while the mature group had a greater American Society of Anaesthesiology (ASA) score (p=0.049). There were otherwise no significant differences in baseline variables between the three groups (all p>0.05). The three groups demonstrated significant post-operative improvements across all functional outcome measures. There were no significant differences in two-year iHOT-12, EQ-5D, UCLA score or pain VAS between the three groups (all p>0.05). Regression modelling found that patient age at the time of surgery did not have an independent effect on two-year iHOT-12 score (p=0.878). We found that patient age at the time of surgery did not influence functional outcomes two years after PAO. Our results suggest that patient age should not be considered in isolation as an indication or contraindication for PAO

Mixed Reality has the potential to improve accuracy and reduce required dissection for the performance of peri-acetabular osteotomy. The current work assesses initial proof of concept of MR guidance for PAO. A PAO planning module, based on preoperative computed tomography (CT) imaging, allows for the planning of PAO cut planes and repositioning of the acetabular fragment. 3D files (holograms) of the cut planes and native and planned acetabulum positions are exported with the associated spatial information. The files are then displayed on mixed reality head mounted device (HoloLens2, Microsoft) following intraoperative registration using an FDA-cleared mixed reality application designed primary for hip arthroplasty (HipInsight). PAO was performed on both sides of a bone model (Pacific Research). The osteotomies and acetabular reposition were performed in accordance with the displayed holograms. Post-op CT imaging was performed for analysis. Cutting plane-accuracy was evaluated using a best-fit plane and 2D angles (°) between the planned and achieved supra (SA)- and retroacetabular (RA) osteotomy and retroacetabular and ischial osteotomies (IO) were measured. To evaluate the accuracy of acetabular reorientation, we digitized the acetabular rim and calculated the acetabular opening plane. Absolute errors of planned and achieved operative inclination and anteversion (°) of the acetabular fragment, as well as 3D lateral-center-edge (LCE) angles were calculated. The mean absolute difference between the planned and performed osteotomy angles was 3 ± 3°. The mean absolute error between planned and achieved operative anteversion and inclination was 1 ± 0° and 0 ± 0° respectively. Mean absolute error between planned and achieved 3D LCE angle was 0.5 ± 0.7°. Mixed-reality guidance for the performance of pelvic osteotomies and acetabular fragment reorientation was feasible and highly accurate. This solution may improve the current standard of care by enabling reliable and precise reproduction of the desired acetabular realignment

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