Impact of combined lumbar spine fusion and total hip arthroplasty on spine, pelvis, and hip kinematics during a sit to stand task.

Lumbar fusion is a risk factor for hip dislocation following total hip arthroplasty (THA). The objective was to compare joint/segment angles during sit-stand-sit in participants that had a THA with and without a lumbar fusion. The secondary objective was to compare pain, physical function, disability, and quality of life. This cross-sectional study includes participants that had THA and lumbar fusion (THA-fusion; n = 12) or THA only (THA-only; n = 12). Participants completed sit-stand-sit trials. Joint/segment angles were measured using electromagnetic motion capture. Angle characteristics were determined using principal component analysis. Hierarchical linear models examined relationships between angle characteristics and groups. Pain, physical function, and disability were compared using Mann-Whitney U tests. Upper lumbar spine was more extended during sit-stand-sit in the THA-fusion group (b = 42.41, P = 0.04). The pelvis was more posteriorly and anteriorly tilted during down and end sit-stand-sit phases, respectively, in the THA-fusion group (b = 12.21, P = 0.03). There were no significant associations between group and other angles. THA-fusion group had worse pain, physical function, disability, and quality of life. Although differences in spine joint, pelvis segment, and hip joint angles existed, these findings are unlikely to account for the increased incidence of hip dislocation after total hip arthroplasty in patients that had spine fusion.

A rare soccer-related injury: Traumatic posterior hip fracture-dislocation - Case series and overview of the literature.

BACKGROUND: Soccer is one of the most popular sports with millions of active professional and non-professional players worldwide. Traumatic hip dislocations are rare in soccer but can lead to major sequelae both physically and psychologically. The aim of this review was to obtain insight into the outcomes after surgerically repaired hip fracture-dislocation in soccer players as well as rehabilitation and prevention. METHODS: Two cases of a posterior hip fracture-dislocation that occurred during an amateur soccer match are presented and mechanism of injury, complications and rehabilitation were analysed. Follow-up of both patients was at least one year after surgery. Questionnaires and physical examinations were obtained to quantify and qualify outcome. RESULTS: In both cases the hip-dislocations were reduced within 3 h after injury. Semi-elective open reduction and internal fixation was performed within seven days. In one case, there was a concomitant Pipkin fracture and sciatic nerve neuropathy. There were no postoperative complications. Follow-up showed full of range of motion and normal hip functionality in both cases. However, both patients indicated a reduced quality of life and anxiety related to the accident. CONCLUSION: Traumatic hip fracture-dislocations during soccer practice are extremely rare. Despite uncomplicated fracture healing after surgery and return of hip function, both patients still suffer from psychological problems resulting in a decreased quality of life. Further research is required to enhance psychological outcomes, as well as to facilitate return to pre-injury levels of participation and engagement in sports following traumatic hip fracture-dislocations related to soccer.

Acetabular "Fleck" Sign: Outcomes of Surgical Repair.

BACKGROUND: Traumatic, posterior hip dislocations in the pediatric population are typically managed by closed reduction to achieve a concentric hip joint. The presence of an acetabular "fleck" sign, despite concentric reduction, has been shown to signify significant hip pathology. The purpose of this study was to evaluate the outcomes of open labral repair through a surgical hip dislocation (SHD) in a consecutive series of patients with an acetabular "fleck" sign associated with a traumatic hip dislocation/subluxation. METHODS: A retrospective review of patients between 2008 and 2022 who presented to a single, level 1 pediatric trauma center with a traumatic posterior hip dislocation/subluxation was performed. Patients were included if they had an acetabular "fleck" sign on advanced imaging and underwent open labral repair through SHD. Medical records were reviewed for sex, age, laterality, mechanism of injury (MOI), and associated orthopaedic injuries. The modified Harris hip score (mHHS) was utilized as the primary clinical outcomes measure. Patients were assessed for the presence of heterotopic ossification (HO) and complications, including implant issues, infection, avascular necrosis (AVN), and post-traumatic dysplasia. RESULTS: Twenty-nine patients (23 male, average age: 13.0±2.7 y; range: 5.2 to 17.3) were identified. Eighteen injuries were sports related, 9 caused by motor vehicle accidents, and 1 pedestrian struck. All patients were found to have an acetabular "fleck" sign on CT (26 patients) or MRI (5 patients). Associated injuries included: femoral head fracture (n=6), pelvic ring injury (n=3), ipsilateral femur fracture (n=2), and ipsilateral PCL avulsion (n=1). At the latest follow-up (2.2±1.4 y), all patients had returned to preinjury activity/sport. Three patients developed asymptomatic, grade 1 HO in the greater trochanter region. There was no incidence of AVN. One patient developed post-traumatic acetabular dysplasia due to early triradiate closure. mHHS scores showed excellent outcomes (n=21, 94.9±7.4, range: 81 to 100.1). CONCLUSIONS: The acetabular "fleck" sign indicates a consistent pattern of osteochondral avulsion of the posterior/superior labrum. Restoring native hip anatomy and stability is likely to improve outcomes. SHD with open labral repair in these patients produces excellent clinical outcomes, with no reported cases of AVN. LEVEL OF EVIDENCE: Level IV-therapeutic.

Does Size Really Matter? Incidence of Periprosthetic Fractures After Femoral Osteotomy in Patients With Cerebral Palsy.

OBJECTIVE: Of children, 30% to 35% with cerebral palsy (CP) develop hip subluxation or dislocation and often require reconstructive hip surgery, including varus derotation osteotomy (VDRO). A recent literature review identified postoperative fractures as the most common complication (9.4%) of VDROs. This study aimed to assess risk factors for periprosthetic fracture after VDRO in children with CP. METHODS: A total of 347 patients (644 hips, 526 bilateral hips) with CP and hip subluxation or dislocation (129 females; mean age at index VDRO: 8.6 y, SD 3.4, range: 1.5 to 17.7; 2 Gross Motor Function Classification System (GMFCS) I, 35 GMFCS II, 39 GMFCS III, 119 GMFCS IV, 133 GMFCS V, 21 unavailable) were included in this retrospective, single-group intervention (VDRO) study at a tertiary referral center. Imaging and clinical documentation for patients age 18 years or younger at index surgery, treated with VDRO were reviewed to determine demographic data, GMFCS level, surgeon, type of hardware implanted, use of anticonvulsants and steroids, type of postoperative immobilization, presence of periprosthetic fractures, fracture location and mechanism, and time from surgery to fracture. Potential determinants of periprosthetic fractures were assessed using mixed effects logistic regression. RESULTS: Of 644 hips, 14 (2.2%, 95% CI: 1.3%, 3.6%) sustained a periprosthetic fracture, at a median of 2.1 years postoperatively (interquartile range: 4.6 y, range: 1.2 mo to 7.8 y). Patients with a fracture had a median age at index surgery of 7.3 years (interquartile range: 4.3, range: 2.8 to 17.8; 1 GMFCS II, 6 GMFCS IV, 7 GMFCS V). Periprosthetic fractures were not significantly related to age at index surgery ( P = 0.18), sex ( P = 0.30), body mass index percentile ( P = 0.87), surgery side ( P = 0.16), anticonvulsant use ( P = 0.35), type of postoperative immobilization ( P = 0.40), GMFCS level ( P = 0.31), or blade plate size ( P = 0.17). Only surgeon volume significantly related to periprosthetic fracture (odds ratio = 5.03, 95% CI: 1.53, 16.56, P = 0.008), with the highest-volume surgeon also using smaller blade plates ( P < 0.01). CONCLUSIONS: Periprosthetic fractures after VDRO surgery in children with CP are uncommon, and routine hardware removal appears unnecessary. The data suggest that the common dogma of putting in the largest blade plate possible to maximize fixation may increase the risk of periprosthetic fracture. Due to the overall low fracture rate, especially when contextualized relative to the risk of hardware removal, a reactive approach to hardware removal appears warranted. LEVEL OF EVIDENCE: Level III-retrospective study (targeting varus derotational osteotomies in children with cerebral palsy).

Closed reduction of dislocated hip prosthesis using a traction table.

This article describes three cases in which a dislocated hip prosthesis was reduced by a new reduction technique - that we previously described - using traction table. The dissociation of a prosthesis is a rare but serious complication of closed reduction manoeuvre. The new reduction manoeuvre using a traction table may be a good option to avoid dissociation of the prosthesis during closed reduction for treatment of dislocation after total hip arthroplasty.

Unveiling the learning curve of periacetabular osteotomy.

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 (ß = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p < 0.001), learning curve procedure phase of 26 procedures (ß = 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 (ß = 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.

Application of deep learning for automated diagnosis and classification of hip dysplasia on plain radiographs.

BACKGROUND: Hip dysplasia is a condition where the acetabulum is too shallow to support the femoral head and is commonly considered a risk factor for hip osteoarthritis. The objective of this study was to develop a deep learning model to diagnose hip dysplasia from plain radiographs and classify dysplastic hips based on their severity. METHODS: We collected pelvic radiographs of 571 patients from two single-center cohorts and one multicenter cohort. The radiographs were split in half to create hip radiographs (n = 1022). One orthopaedic surgeon and one resident assessed the radiographs for hip dysplasia on either side. We used the center edge (CE) angle as the primary diagnostic criteria. Hips with a CE angle < 20°, 20° to 25°, and > 25° were labeled as dysplastic, borderline, and normal, respectively. The dysplastic hips were also classified with both Crowe and Hartofilakidis classification of dysplasia. The dataset was divided into train, validation, and test subsets using 80:10:10 split-ratio that were used to train two deep learning models to classify images into normal, borderline and (1) Crowe grade 1-4 or (2) Hartofilakidis grade 1-3. A pre-trained on Imagenet VGG16 convolutional neural network (CNN) was utilized by performing layer-wise fine-turning. RESULTS: Both models struggled with distinguishing between normal and borderline hips. However, achieved high accuracy (Model 1: 92.2% and Model 2: 83.3%) in distinguishing between normal/borderline vs. dysplastic hips. The overall accuracy of Model 1 was 68% and for Model 2 73.5%. Most misclassifications for the Crowe and Hartofilakidis classifications were +/- 1 class from the correct class. CONCLUSIONS: This pilot study shows promising results that a deep learning model distinguish between normal and dysplastic hips with high accuracy. Future research and external validation are warranted regarding the ability of deep learning models to perform complex tasks such as identifying and classifying disorders using plain radiographs. LEVEL OF EVIDENCE: Diagnostic level IV.

Replacing hip precautions after hemiarthroplasty with a pose avoidance protocol.

AIMS: After hip arthroplasty surgery, hip precautions are often implemented to minimise the risk of dislocation, although existing evidence does not support their effectiveness. At our institution, we replaced post-operative precautions with a novel pose avoidance protocol in patients undergoing hip hemiarthroplasty for neck of femur fracture. The objectives of our study were to validate this new protocol by assessing the incidence of dislocation before and after its introduction and evaluating its impact on the length of hospital stay. METHODS: Between 20th September 2021 and 19th March 2023, 200 patients underwent 203 hip hemiarthroplasties. Hip precautions were replaced with the new pose avoidance protocol on 20th June 2022. Data were retrospectively collected and included patient demographics, Abbreviated Mental Test Score, American Society of Anaesthesiologists grade, surgical approach, prosthesis, dislocation, and mortality. RESULTS: The incidence of dislocation within 90 days after hip hemiarthroplasty decreased from seven out of 98 cases (7.1%) before 20th June 2022 to one out of 105 cases (1.0%), p-value 0.030. However, there was no significant difference in the length of stay, with a median (interquartile range) of 19 (10 - 29) days before 20th June 2022, and 16 (11 - 22) days thereafter, p-value 0.242. A multivariate logistic regression confirmed the pose avoidance protocol and the anterolateral approach to be independent negative predictors of dislocation, p-value 0.030 (Odds Ratio [OR] 0.077) and p-value 0.005 (OR 0.022), respectively. CONCLUSIONS: Hip precautions are unnecessary and potentially detrimental to patient outcomes following hemiarthroplasty. Replacing these precautions with our new pose avoidance protocol may have led to a significant reduction in dislocation rates and saved on the cost of adaptive equipment. We advocate for the anterolateral over the posterior approach in hip hemiarthroplasty to further mitigate the risk of dislocation. LEVEL OF EVIDENCE: IV.

Functional and radiological outcomes of periacetabular osteotomy for hip dysplasia in patients under fifty years using a minimally invasive approach-a single surgeon series with a minimum follow up of two years.

PURPOSE: We conducted a retrospective analysis of prospectively collected data to evaluate (1) the extent of surgical correction following minimally invasive periacetabular osteotomy, (2) improvements in functional outcomes and any potential predictors for favourable outcome, and (3) complications after minimally invasive periacetabular osteotomy. METHODS: A total of 352 minimally invasive periacetabular osteotomy procedures were performed on 312 hip dysplasia patients between 2013 and 2020. Radiological parameters such as lateral centre edge angle, acetabular index, and Tönnis grade of arthritis were calculated. Patients also completed a range of patient reported outcome measures. Wilcoxon signed-rank tests were performed to assess for differences between patient reported outcome measures and radiological outcomes across the follow-up periods. Univariate linear regression and logistic regression were used to assess for predictors of change in functional outcome. RESULTS: Patients had a significant correction in mean lateral centre edge angle from 17.2° to 35.3° (p < 0.001) and mean acetabular index from 13.2° to - 0.82°. At one year follow-up all patient reported outcome measures were significantly greater than their baseline measurements and this improvement was maintained at two years. Changes in patient reported outcome measures were independent of radiological parameters such as change in the lateral centre edge angle and acetabular index, pre-operative Tönnis grade, and patient factors such as age and sex. A total of 5.11% of patients developed post-operative complications, with four requiring posterior column fixation. Four patients (1.12%) needed a total hip replacement. CONCLUSION: Minimally invasive periacetabular osteotomy is a safe procedure that provides significant functional outcome improvements following surgery at six months which is maintained at two years. More than three-fourths of patients achieved improvement of iHOT-12 score beyond the minimal clinically important difference and more than half of the patients achieved substantial clinical benefit for iHOT-12 score.

Periacetabular osteotomy: an analysis of social media to determine the most common questions asked by the periacetabular osteotomy population.

BACKGROUND: The Bernese Periacetabular Osteotomy (PAO) has become a popular surgery for fixing development dysplasia of the hip, yet the most common concerns of the PAO population remains ambiguous. The aim of this study was to investigate Facebook, Instagram and Twitter to further understand what the most common preoperative and postoperative questions patients undergoing PAO are asking. We hypothesized most questions would be asked by patients in the preoperative timeframe with regards to education surrounding PAO surgery. METHODS: Facebook, Instagram and Twitter were queried consecutively from February 1, 2023 to November 23, 2011. Facebook was searched for the two most populated interest groups; "Periacetabular Osteotomy (PAO)" and "Periacetabular Osteotomy Australia". Instagram and Twitter were queried for the most popular hashtags: "#PAOwarrior", "#PAOsurgery", "#periacetabularosteotomy", "#periacetabularosteotomyrecovery", and "#paorecovery". Patient questions were categorized according to preoperative and postoperative questions. Questions were further placed into specific themes in their respective preoperative or postoperative question types. RESULTS: Two thousand five hundred and fifty-nine posts were collected, with 849 (33%) posts containing 966 questions. Of the 966 questions, 443 (45.9%) and 523 (54.1%) were preoperative and postoperative questions, respectively. The majority of questions were postoperative complication related (23%) and symptom management (21%). Other postoperative questions included recovery/rehabilitation (21%), and general postoperative questions (18%). The most common preoperative questions were related to PAO education (23%). Rehabilitation (19%), hip dysplasia education (17%), and surgeon selection (12%) were other preoperative questions topics included. Most questions came from Facebook posts. Of 1,054 Facebook posts, 76% were either preoperative or postoperative questions and from the perspective of the patient (87%). CONCLUSION: The majority of patients in the PAO population sought advice on postoperative complications and symptom management. Some patients asked about education surrounding PAO surgery. Understanding the most common concerns and questions patients have can help providers educate patients and focus on more patient-relevant perioperative conversations.

Incorporating patient-specific hip orientation from weightbearing computed tomography affects discrete element analysis-computed regional joint contact mechanics in individuals treated with periacetabular osteotomy for hip dysplasia.

Computational models of the hip often omit patient-specific functional orientation when placing imaging-derived bony geometry into anatomic landmark-based coordinate systems for application of joint loading schemes. The purpose of this study was to determine if this omission meaningfully alters computed contact mechanics. Discrete element analysis models were created from non-weightbearing (NWB) clinical CT scans of 10 hip dysplasia patients (11 hips) and oriented in the International Society of Biomechanics (ISB) coordinate system (NWB-ISB). Three additional models were generated for each hip by adding patient-specific stance information obtained via weightbearing CT (WBCT) to each ISB-oriented model: (1) patient-specific sagittal tilt added (WBCT-sagittal), (2) coronal and axial rotation from optical motion capture added to (1; WBCT-combo), and (3) WBCT-derived axial, sagittal, and coronal rotation added to (1; WBCT-original). Identical gait cycle loading was applied to all models for a given hip, and computed contact stress and contact area were compared between model initialization techniques. Addition of sagittal tilt did not significantly change whole-joint peak (p = 0.922) or mean (p = 0.871) contact stress or contact area (p = 0.638). Inclusion of motion-captured coronal and axial rotation (WBCT-combo) decreased peak contact stress (p = 0.014) and slightly increased average contact area (p = 0.071) from WBCT-sagittal models. Including all WBCT-derived rotations (WBCT-original) further reduced computed peak contact stress (p = 0.001) and significantly increased contact area (p = 0.001). Variably significant differences (p = 0.001-1.0) in patient-specific acetabular subregion mechanics indicate the importance of functional orientation incorporation for modeling applications in which local contact mechanics are of interest.

Editorial Commentary: Borderline Hip Dysplasia Combined With Increased Anteversion and Ligamentum Teres Disruption Is a Recipe for Hip Microinstability.

The ligamentum teres (LT) is known to play a role as a secondary stabilizer of the hip joint. LT tears can be associated with hip instability. In patients with borderline developmental dysplasia of the hip (BDDH), the correlation between LT tears and microinstability is even more pronounced because of the increased mechanical stress placed on the ligament. This relationship may lead certain surgeons to consider new indications for LT reconstructions. However, caution is warranted regarding the potential role of LT reconstruction in these patients, particularly since the primary deficiency in BDDH is bony undercoverage. Addressing this bony undercoverage should be a primary consideration that may be supplemented with other procedures, which may include addressing soft-tissue injuries around the hip such as LT tears. This is especially the case in those patients with persistent symptoms after management of labral tears or LT disruption.

Editorial Commentary: Arthroscopy With Labral Preservation or Reconstruction Plus Capsular Closure Shows Excellent Outcome in Patients With Borderline Hip Dysplasia and is Less Invasive Than Periacetabular Osteotomy.

Borderline developmental dysplasia of the hip (BDDH), or borderline hip dysplasia (BHD), traditionally characterized by a relatively low lateral center-edge angle (LCEA), presents a complex challenge in treatment due to its multifaceted etiology involving instability, femoroacetabular impingement (FAI), or a combination thereof. The optimal approach to managing adult BDDH remains a subject of significant debate. Periacetabular osteotomy (PAO) is considered the preferred treatment for addressing severe acetabular under-coverage, as it rectifies the underlying bony deficiency and promotes stability. However, the treatment of BDDH is less straightforward, particularly with the advancement of hip arthroscopy techniques, specifically labral preservation and capsular management. Given the minimally invasive and rapid postoperative rehabilitation advantage for arthroscopic procedures over open surgeries, numerous attempts have been undertaken in this context. Research has revealed favorable patient-reported outcomes (PROs), low failure rates, and a significant proportion of returning to sports (RTS) after arthroscopic management for patients with BDDH. Although we might in the right direction, Level I evidence studies are needed to comprehensively compare long-term PROs, failure rates, and rates of RTS between arthroscopy and PAO in the treatment of BDDH.

Editorial Commentary: Concomitant Hip Arthroscopy and Periacetabular Osteotomy Treat Both the Cause and the Effects of Hip Dysplasia: The Best of Both Worlds.

In the management of true hip dysplasia, the bony deformity is nearly always accompanied by, and often causal of, intra-articular pathology. It is strongly recommended to conduct a comprehensive preoperative evaluation as well as arthroscopic evaluation and treatment of coexisting hip joint conditions prior to performing an open Bernese periacetabular osteotomy. The osteotomy improves coverage of the femoral head and corrects the abnormal joint mechanics and loading patterns, which result in cartilage damage and subsequent osteoarthritis. Arthroscopy allows treatment of the intra-articular pathology. Combining the hip arthroscopy and periacetabular osteotomy procedures into a single surgical intervention, performed by either a single surgeon or a collaborative surgical team, allows us to address both the cause and the effects of dysplasia. This once-controversial combined technique has become a standard practice in the field with widespread adoption.

Instability in Patients With Lumbar Spine Disease Undergoing Posterior Approach and Lateral Approach Primary Total Hip Arthroplasty.

INTRODUCTION: Dislocation rates in patients who have fixed spinopelvic motion have been reported up to 20%. Few studies have directly compared dislocation rates in patients who have spine pathology undergoing total hip arthroplasty (THA) through different surgical approaches. This study compared postoperative dislocation rates in patients who had lumbar spine disease and underwent primary THA using a posterior or direct lateral approach. METHODS: Between 2011 and 2017, consecutive cohorts of primary THAs were retrospectively reviewed. One surgeon routinely used a posterior approach, while the other used a direct lateral approach. Chart and radiographic review were conducted to identify patients who had lumbar spine disease. Dislocations among cohorts with and without lumbar spine disease were compared by posterior and direct lateral approaches. RESULTS: The overall dislocation rate was 1.3% (15/1,198). The top four predictors of dislocation were presence of lumbar spine disease (odds ratio [OR] 5.0; P = 0.014), posterior surgical approach (OR, 6.5; P = 0.074), cases performed for fracture (OR, 4.4; P = 0.035), and women (OR, 4.6; P = 0.050). Dislocation rates among direct lateral approach patients who had lumbar spine pathology were significantly lower than posterior approach patients who had lumbar spine pathology (0.0% versus 3.6%; P = 0.011). DISCUSSION: Although dislocation rates were low in both groups, study results suggest that a direct lateral approach for primary THA may reduce postoperative dislocations for patients who have limited spinopelvic motion due to lumbar spine pathology. Furthermore, surgeons using the posterior approach might consider optimizing the femoral head to acetabular cup ratio in patients who have lumbar spine disease.

Current concepts in the diagnosis and management of Os Acetabuli.

PURPOSE: The aim of this review is to appraise the current evidence on the epidemiology, pathophysiology, diagnosis and management of os acetabuli. METHODS: A scoping review was conducted according to the Joanna Briggs Institute guidelines. A systematic search was performed on Medline (PubMed), Embase and Cochrane Library. Inclusion criteria comprised observational and interventional studies and review articles published in the English language that focused on patients with os acetabuli according to the PRISMA extension of scoping reviews checklist using the terms 'Os Acetabuli' or 'os acetabula' or 'acetabular ossicles'. A narrative synthesis of results was undertaken, and the included articles were divided into (i) definition, (ii) aetiology, (iii) diagnosis and imaging and (iv) management of os acetabuli. RESULTS: 107 articles were screened, with 22 meeting the eligibility criteria. A total of 8836 patients were considered, of which 604 had os acetabuli. The mean age was 32.8 years. The prevalence of os acetabuli ranged from 3.4 to 7.7%, with a higher prevalence in males compared to females. True os acetabuli was defined as an unfused secondary ossification centre along the acetabular rim. The aetiology of os acetabuli is thought to be secondary to acetabular dysplasia and/or femoroacetabular impingement. Standard of care for management of symptomatic os acetabuli is considered to be arthroscopic excision unless the excision results in acetabular undercoverage and/or instability, in which case, fixation is recommended. CONCLUSIONS: Successful management of os acetabuli depends on understanding the pathology and treating the underlying cause rather than treating the os acetabuli in isolation. Future work needs to focus on establishing clear diagnostic criteria, consensus on definition and an evidence-based treatment algorithm.

Gait pattern analysis before and after periacetabular osteotomy in unilaterally affected dysplastic patients.

BACKGROUND: Patients with acetabular dysplasia have an abnormal acetabular geometry which results in insufficient coverage of the femoral head. This coverage deficiency reduces contact surfaces within the joint, accelerating the wear of the articular cartilage and predisposing patients to early osteoarthritis. Periacetabular osteotomy is a surgical treatment of acetabular dysplasia that aims to reorient the acetabulum relative to the femoral head, increasing coverage. METHODS: Pelvic kinematics and lower limbs joint kinematics and kinetics during the stance phase of gait were recorded using a 3D motion capture system and force plates, then compared pre- to post- and between limbs with a repeated measures 2-way ANOVA. Radiographic measurements and gait parameters were compared pre- to post-surgery using a t-test for dependant samples. To identify predictors of pelvic symmetry improvements during gait, a multivariate analysis was performed using a forward stepwise linear regression. FINDINGS: Radiographic measurements improved for all participants while gait parameters remained unchanged. Hip flexion symmetry was improved following surgery. The external rotation moment of the healthy hip was reduced after surgery (-29%) resulting in increased asymmetry. Pelvic tilt was significantly greater on the affected side (+0.5°) during the loading response, and the difference tended to be greater after surgery (+0.8°). INTERPRETATION: Unilaterally affected dysplastic patients have an asymmetrical gait pattern that is only partially corrected by periacetabular osteotomy even when radiographic and clinical targets are met. Differences between the limbs could be explained in part by a learned antalgic pattern and muscle weaknesses leading to complex compensation mechanisms.