Anterior Center-edge Angle Research Articles

Acetabular rim syndrome revisited.

There has been limited literature regarding outcomes of acetabular rim syndrome (ARS) with persistent acetabular os in the setting of acetabular dysplasia. The purpose of this study was to characterize a cohort of adolescent and young adult patients with ARS with persistent os and compare their radiological and clinical outcomes to patients with acetabular dysplasia without an os. We reviewed a prospective database of patients undergoing periacetabular osteotomy (PAO) for symptomatic acetabular dysplasia between January 1999 and December 2021 to identify hips with preoperative os acetabuli, defined as a closed triradiate cartilage but persistence of a superolateral os acetabulum. A total of 14 hips in 12 patients with persistent os acetabuli (ARS cohort) were compared to 50 randomly selected 'control' hips without persistent os acetabuli. Preoperative and postoperative radiographs were measured for markers of dysplasia: lateral centre-edge angle, anterior centre-edge angle, acetabular inclination, and migration index. Union of the os was determined in patients with ≥ six months' follow-up. Patient-reported outcome measures (PROMs) included the University of California, Los Angeles (UCLA) activity score and modified Harris Hip Score (mHHS, maximum score 80) completed at one year postoperatively. There was no significant difference between the ARS and control cohorts with regard to sex distribution (p = 0.270), age at surgery (p = 0.186), or BMI (p = 0.442). Preoperatively, the ARS cohort had more severe dysplasia, including lower lateral centre-edge angle (-9.3° (SD 12.5°) vs 7.6° (SD 10.7°); p < 0.001) and greater acetabular inclination (33.9° (SD 8.2°) vs 21.8° (SD 8.7°); p < 0.001). Postoperatively, 6/13 (46%) hips with ≥ six months of radiological follow up demonstrated union of the os. There was no difference between the ARS and control cohorts at one year in UCLA score (9.1 (SD 1.5) vs 8.2 (SD 1.9); p = 0.167) or mHHS (73.4 (SD 9.5) vs 69.9 (SD 8.8); p = 0.312). ARS with persistent acetabular os may occur in more severe dysplasia. Union occurs in 50% cases following corrective PAO.

Radiographic Outcome Following Treatment of Residual Hip Dysplasia with Pemberton Versus Salter Osteotomy: Comparison of Results in Patients Followed to Skeletal Maturity.

Salter osteotomy (SO) and Pemberton acetabuloplasty (PA) are procedures to treat skeletally immature patients with developmental dysplasia of the hip (DDH). The purpose of this study was to compare the radiographic results and rate of residual dysplasia (RD) after treatment with SO and with PA. This was a retrospective analysis of pediatric patients treated with either SO or PA for DDH between 1980 and 2013 who were skeletally mature at the time of follow-up. The preoperative and postoperative acetabular index (AI) and postoperative lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) were collected. RD was defined as an LCEA or ACEA of <20° or an acetabular inclination (AIn) of >15° at skeletal maturity. Continuous variables were compared between treatment groups with 2-sample t tests, and categorical variables were compared using chi-square tests. Multivariable analysis was used to identify risk factors for RD with p < 0.05. The study included 113 hips in 102 patients with a mean follow-up of 10.5 years. The SO group had 73 hips treated at a mean patient age of 5.4 years, and the PA group had 40 hips treated at a mean age of 5.3 years. The preoperative AI did not differ between the treatment groups (32.2° versus 31.3°, p = 0.658), nor did the immediate postoperative AI (20.0° versus 20.2°, p = 0.459). At the time of final follow-up, the SO group had a significantly smaller AIn (8.6° versus 13.2°, p = 0.001), a trend toward a greater LCEA (26.2° versus 21.6°, p = 0.056), and a similar ACEA (24.1° versus 26.1°, p = 0.808). By the abovementioned definition, 36 hips (31.9%) had evidence of RD, with a lower rate in the SO group (26.0% versus 42.5%, p = 0.07). Patients who had a positive family history of hip dysplasia were more likely to have RD (odds ratio = 4.311, 95% confidence interval = 1.125 to 16.528). Patients with RD could be effectively treated with either SO or PA, with overall good radiographic outcomes. However, SO achieved a better AI and may thus yield better long-term health of the affected hip. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Radiographically Apparent Acetabular Sourcil Landmarks Are Created by Comparable Regions of the Pelvis With Extraarticular Bone Variably Confounding Estimates of Joint Coverage.

The severity of hip dysplasia is characterized by radiographic measurements that require user definition of the acetabular sourcil edge, a bony landmark for which the corresponding three-dimensional (3D) anatomy is not well defined in any imaging plane. To use digitally reconstructed radiographs to determine: (1) What 3D anatomy is contributing to the "acetabular sourcil" location used to make lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) measurements in standing AP and false-profile radiographic views, respectively? (2) How do intraobserver and interobserver agreement in LCEA and ACEA translate into agreement of the 3D anatomy being evaluated? (3) How distinct are regions around the acetabular rim circumference that are evaluated by LCEA and ACEA measurements on radiographs? Between January 2018 and May 2019, 72 patients were indicated for periacetabular osteotomy to treat hip dysplasia or acetabular retroversion at our institution. From these patients, a series of 10 patients were identified of the first 12 patients in 2018 who were treated with periacetabular osteotomy, excluding two with missing or low-quality clinical imaging. A second series of 10 patients was identified of the first 11 patients in 2019 who were treated with periacetabular osteotomy and concurrent hip arthroscopy, excluding one who was missing clinical imaging. Pelvis and femoral bone surface models were generated from CT scans of these two series of 10 patients. There were 15 female and five male patients, with a median patient age of 18 years (IQR 17 to 23 years), a preoperative LCEA of 22° (IQR 18° to 24°), and a preoperative ACEA of 23° (IQR 18° to 27°). Exclusion criteria included missing preoperative CT or standard clinical radiographic imaging or severe joint incongruity. To address our first study question, digitally reconstructed radiographs matching each patient's standing AP and false-profile clinical radiographs were created from the segmented CT volumes. A board-certified orthopaedic surgeon and three trained researchers measured LCEA and ACEA on the digitally reconstructed radiographs, and the selected sourcil points were projected back into coordinates in the 3D anatomic space. To address our second study question, intraobserver and interobserver agreement in radiographic coverage angles were related to variations in 3D coordinates of the selected bony anatomy. Lastly, to address our third study question, 3D locations around the acetabular rim identified as contributing to the lateral and anterior sourcil points were summarized across patients in a clockface coordinate system, and statistical analysis of the "time" separating the 3D acetabular contributions of the sourcil edges was performed. The 3D anatomy contributing to the lateral sourcil was a variable length (27 mm [IQR 15 to 34 mm]) span of the laterosuperior acetabular edges, with contributions by the anterior inferior iliac spine in 35% (7 of 20) of hips. The anterior sourcil reflected a 28-mm (IQR 25 to 31 mm) span of bone from the medial ilium (posterior-medial to the anterior-inferior iliac spine and anterior-lateral to the arcuate line) to the anterior and lateral edges of the acetabulum. Interobserver variability was good for LCEA (intraclass correlation coefficient [ICC] 0.82 to 0.83) and moderate to good for ACEA (ICC 0.73 to 0.79), whereas the agreement in identified 3D sourcil locations varied widely (ICC 0.32 to 0.95). The acetabular edge of the 3D anatomy contributing to the anterior sourcil overlapped the circumferential range of the acetabular rim contributing to the lateral sourcil. Projection of two-dimensional radiographic landmarks contributing to the diagnosis of structural hip deformity into 3D allowed for the identification of the overlapping bony anatomy contributing to radiographically visible anterior and lateral sourcil edges. This work leveraging digitally reconstructed radiographs and 3D pelvis anatomy has found that bone outside the joint contributes to the radiographic appearance of the sourcil and may variably confound estimates of joint coverage. Furthermore, the substantial overlap between the acetabular bone contributing to measurement of the LCEA and ACEA would indicate that these angles measure similar acetabular deformity, and that additional measures are needed to assess anterior coverage independent of lateral coverage.

False-Profile Radiograph Sourcil-Edge and Bone-Edge Measurements Correlate to Different Weightbearing Regions of the Acetabulum: A 3-Dimensional Analysis

Background: The acetabular sourcil is commonly interpreted as a reliable radiographic representation of the weightbearing dome of the acetabulum, despite limited modern data. Assessment of weightbearing acetabular coverage has been described using both the sourcil edge and bone edge as anatomic landmarks, leading to confusion and potential misguidance in surgical decision-making and thus compromised patient outcomes. Purpose/Hypothesis: The purpose of this study was to characterize the 3-dimensional (3D) anatomic correlates of the sourcil-edge and bone-edge radiographic measurements on false-profile radiographs. It was hypothesized that the sourcil edge would represent anterolateral coverage and the bone edge would represent anterior coverage. Study Design: Descriptive laboratory study. Methods: A total of 80 hips were grouped by large or small differences between bone-edge and sourcil-edge anterior center-edge angles, based on upper and lower quartiles of discrepancy. Three-dimensional surface mesh models and digitally reconstructed radiographs were generated from hip computed tomography scans. Sourcil-edge and bone-edge anterior center-edge angles were identified on digitally reconstructed radiographs and registered to the 3D models with fiducial markers. Intersections of bone-edge and sourcil-edge projection lines with the acetabular rim were obtained from the 3D models. Results: The bone-edge and sourcil-edge projections intersected the acetabular rim at clockface means of 2:05 ± 0:22 and 1:12 ± 0:25, respectively. The 3D models consistently demonstrated that, in both large- and small-discrepancy groups, the sourcil edge corresponded to the acetabular area just posterior to the anterior inferior iliac spine (AIIS) projection, and the bone edge corresponded to the weightbearing region inferior to the AIIS. Additionally, in large-discrepancy hips, the bone edge corresponded to more prominent acetabular coverage in the region inferomedial to the AIIS when compared with the small-discrepancy hips. Conclusion: On false-profile radiographs, the sourcil edge corresponds to superior femoral head coverage, and the bone edge corresponds to anterosuperior coverage. Radiographs with a large discrepancy between sourcil-edge and bone-edge measurements demonstrate acetabular rim prominence in the region of the AIIS. Clinical Relevance: Characterizing the anatomic weightbearing regions of the acetabulum represented on false-profile radiographs facilitates improved clinical and intraoperative decision-making in hip preservation surgery, including acetabuloplasty and periacetabular osteotomy.

Combined assessment of acetabular coverage and femoral head-neck shapes predicts osteoarthritis progression after periacetabular osteotomy.

Postoperative osteoarthritis (OA) progression is a major determinant of failure after curved periacetabular osteotomy (CPO). A large postoperative combination angle, i.e., the combination of computed tomography-based anterior center edge and alpha angles, is associated with femoroacetabular impingement after CPO, but its association with postoperative OA progression is unclear. We aimed to identify the anatomical parameters that can lead to OA progression after CPO and the impact of the combination angle on the same. We included 90 hips that were subjected to CPO at our center between March 2013 and March 2018. Seventeen hips showed OA progression with an increase in the Tönnis classification after surgery; 73 hips showed no progression. Radiographic anatomical parameters, including the lateral and anterior center edge angles, femoral and acetabular anteversion, and combination angle, and clinical outcomes, including modified Harris Hip Scores (mHHSs), postoperative anterior impingement, and range of motion, were compared between the two groups. Statistical significance was set at P < 0.05. Postoperative OA progression was significantly affected by preoperative OA evidence (P = 0.017), acetabular anteversion < 5.0° (P = 0.003), and a combination angle > 107.0° (P = 0.025). Patients with radiographic OA progression were associated with poor mHHSs (P = 0.017) and high frequencies of anterior impingement with a limited hip flexion and internal rotation angle. OA progression after CPO may be associated with preoperative evidence of OA and postoperative acetabular retroversion as well as a large combination angle. Surgeons should focus on the potential effects of preoperative OA grades, postoperative reduction in acetabular anteversion, and postoperative combination angle.

Poster 181: Hip Arthroscopy with Concomitant Periacetabular Osteotomy Demonstrates Excellent Outcomes and Survivorship at Minimum 10-Year Follow-Up

Objectives: Multiple studies have shown that hip arthroscopy with concomitant periacetabular osteotomy (PAO) is a safe and effective treatment option for patients presenting with Symptomatic acetabular dysplasia and intra-articular pathology. While excellent short- and mid-term outcomes have been previously reported, there exists a paucity of literature investigating long-term outcomes of hip arthroscopy with concomitant PAO. The purpose of this study was to report minimum 10-year follow-up results and survivorship of hip arthroscopy with concomitant PAO to treat acetabular dysplasia and intraarticular pathologies such as femoroacetabular impingement (FAI) and labral tears. Methods: Data from October 2010 to December 2012 was prospectively collected and retrospectively reviewed to identify patients undergoing hip arthroscopy with concomitant PAO. Patients were included in the present analysis if they had preoperative and minimum 10-year patient reported outcomes (PROs) documented for the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Scored Sports-Specific Subscale (HOS-SSS), and pain on a visual analog scale (VAS), as well as the International Hip Outcome Tool (iHOT-12) and patient satisfaction score on a 0-10 scale. Results: Fifteen patients were eligible for analysis and 12 had complete minimum 10-year follow-up (80.0%) at mean 10.2 years postoperation. There were 10 females (83.3%) and 2 males (16.7%) included in the study with a mean age and BMI of 24.4 years and 24.5 kg/m2, respectively. The mean lateral center-edge angle (LCEA) of all included hips in the analysis increased from 13.8° to 29.8° postoperatively ( P&lt;0.05) and the anterior center-edge angle (ACEA) increased from 14° to 28.8° postoperatively ( P&lt;0.05). Additionally, the Tönnis angle of acetabular inclination decreased from 17.9° to 7.3° postoperatively ( P&lt;0.05) and the alpha angle decreased from 56.5° to 52.1° postoperatively ( P&lt;0.05). There was significant improvement in all PROs from baseline to minimum 10-year follow-up (mHHS; NAHS; HOS-SSS, P&lt; 0.05). All patients achieved high rates of MCID for mHHS, NAHS, and HOS-SSS, as well as high rates of PASS for mHHS and VAS. The 10-year survivorship for all patients included in the analysis was 83.3% with 2 patients (16.7%) progressing to total hip arthroplasty (THA) at mean 58.0 months postoperatively. Additionally, 2 patients (16.7%) underwent subsequent ipsilateral revision hip arthroscopy at mean 79.5 months postoperatively. Conclusions: Patients with dysplasia and intra-articular pathology such as labral tears and FAI can be safely treated using hip arthroscopy with concomitant PAO. These patients can achieve excellent long-term outcomes and high rates of survivorship at minimum 10 years postoperation.

Staged Hip Arthroscopy With Labral Repair, Femoroplasty, and Capsular Plication Followed by Periacetabular Osteotomy for Hip Dysplasia Results in Improved Outcomes and 100% Survivorship at Minimum 2-Year Follow-Up

PurposeTo assess patient-reported outcomes (PROs), clinically significant outcomes (CSOs), and survivorship following staged hip arthroscopy with labral repair, femoroplasty, and capsular plication followed by periacetabular osteotomy (PAO) for the management of femoroacetabular impingement syndrome (FAIS) and hip dysplasia (lateral center edge angle ≤25°). MethodsA prospectively maintained database was queried to retrospectively identify patients who underwent staged primary hip arthroscopy and PAO between 1/2018–10/2021 and had a minimum 2-year follow-up. PROs collected included, Hip Outcome Score Activities of Daily Living/Sports Subscale (HOS-ADL/SS), international Hip Outcome Tool-12 item questionnaire (iHOT-12), and Visual Analog Scale for Pain (VAS Pain). CSO achievement for minimal clinical important difference (MCID) and patient acceptable symptom state (PASS) were determined through cohort specific thresholds. Rates of reoperation, including, revision hip arthroscopy and conversion to total hip arthroplasty (THA) were evaluated to determine short-term survivorship. ResultsThirty-nine hips met criteria for inclusion, of which 35 hips had minimum 2-year follow up (89.7% compliance). Mean age was 25±9.1 years and 91.7% of patients were female. Respective pre- and postoperative radiographic outcomes were: Alpha angle 59.8±5.9 to 39.7±2.6°, Tönnis angle 14.6±5.6° to -1.0±2.9°, lateral center-edge angle 16.6±5.5° to 36.6±4.6°, and anterior center-edge angle 15.6±9.1° to 36.1±3.8°, with statistically significant differences pre- to postoperatively for all (P<0.001). Patients demonstrated significant improvement in all PROs pre- to postoperatively (P ≤0.004). MCID and PASS achievement rates for any PRO were 93.9% and 78.8%, respectively. There were no revision hip surgeries or conversion to THA at a mean 2.7±1.0-year follow-up. Four patients (11.1%) underwent hardware removal. One patient (2.8%) experienced a postoperative infection treated with incision and drainage. ConclusionsStaged hip arthroscopy and PAO for the management of hip dysplasia demonstrated improvement in PROs, high CSO achievement rates, and 100% survivorship at minimum 2-year follow-up.

The incidence of subsequent hip arthroscopy after rectus-sparing periacetabular osteotomy.

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 procedures 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 cohort of patients, who underwent PAO in isolation without any intra-articular procedures. From June 2012 to March 2022, 349 rectus-sparing PAOs were performed and followed for a minimum of one year (mean 6.2 years (1 to 11)). The mean age was 24 years (14 to 46) and 88.8% were female (n = 310). Patients were evaluated at final follow-up for patient-reported outcome measures (PROMs). Clinical records were reviewed for complications or subsequent surgery. Radiographs were reviewed for the following acetabular parameters: lateral centre-edge angle, anterior centre-edge angle, acetabular index, 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. A total of 16 hips (15 patients; 4.6%) underwent subsequent HA with labral repair and femoral osteochondroplasty, the most common interventions. For those with a minimum of two years of follow-up, 5.3% (n = 14) underwent subsequent HA. No hips underwent total hip arthroplasty and one revision PAO was performed. Overall, 17 hips (4.9%) experienced a complication and 99 (26.9%) underwent hardware removal. All PROMs improved significantly postoperatively. Radiologically, 80% of hips (n = 279) reached the goal for acetabular correction (77% for acetbular index and 93% for LCEA), 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 a mean of 6.2 years' follow-up (1 to 11). Acetabular correction alone may be sufficient as the primary intervention for the majority of patients with symptomatic acetabular dysplasia.

The Three-Dimensional Criteria of Developmental Dysplasia of the Hip Using the Functional Pelvic Plane Is More Useful Than That Using the Anterior Pelvic Plane.

Background: This retrospective cross-sectional study investigated the cutoff values (COVs) for developmental dysplasia of the hip (DDH) using a three-dimensional (3D) pelvic model reconstructed using computed tomography (CT). We included 107 healthy Japanese participants and 73 patients who had undergone curved periacetabular osteotomy (CPO) for DDH between 2012 and 2017. Methods: The hip CT images were adjusted to the anterior pelvic plane (APP), functional pelvic plane (FPP), sagittal anterior center-edge angle (ACEA), and sagittal posterior center-edge angle (PCEA). The lateral center-edge angle (LCEA), acetabular roof obliquity (ARO), anterior acetabular sector angle (AASA), and posterior acetabular sector angle (PASA) were measured. Receiver operating characteristic (ROC) curves were used to calculate the COVs, and the association between the parameters was analyzed using multiple logistic regression. Results: The ARO (≥10.2°) and LCEA (≤22.2°) were independent influencing factors for the APP, whereas the AASA (≤53.1°) and LCEA (≤24.5°) were independent influencing factors for the FPP. Conclusions: The 3D criteria for the diagnosis of DDH in Japanese individuals can identify DDH with insufficient anterior coverage, which anteroposterior plain radiographs cannot visualize, and can help determine indications for acetabular osteotomy.

Pincer Morphology Is Not Associated With Hip Osteoarthritis Unless Hip Pain Is Present: Follow-Up Data From a Prospective Cohort Study.

The objective of this study was to assess the relationship between pincer morphology and radiographic hip osteoarthritis (RHOA) over 2, 5, 8, and 10 years' follow-up and to study the interaction between pincer morphology and pain. Individuals from the prospective Cohort Hip and Cohort Knee study were drawn. Anteroposterior pelvic and false profile radiographs were obtained. Hips free of definite RHOA (Kellgren and Lawrence [KL] grade 0 or 1) at baseline were included. Pincer morphology was defined as a lateral or anterior center edge angle or both ≥40° at baseline. Incident RHOA was defined as KL ≥ 2 or total hip replacement at follow-up. Multivariable logistic regression with generalized estimating equations estimated the associations at follow-up. Associations were expressed as unadjusted odds ratios (ORs) and adjusted ORs with 95% confidence intervals (CIs). An interaction term was added to investigate whether pincer morphology had a different effect on symptomatic hips. Incident RHOA developed in 69 hips (5%) at2 years' follow-up, in 178 hips (14%) at 5 years' follow-up, in 279 hips (24%) at 8 years' follow-up, and in 495 hips (42%) at 10 years' follow-up. No significant associations were found between pincer morphology and incident RHOA (adjusted OR 0.35 [95% CI 0.06-2.15]; adjusted OR 1.50 [95% CI 0.94-2.38]). Significant interactions between pain and anterior pincer morphology in predicting incident RHOA were found at 5, 8, and 10 years' follow-up (OR 1.97 [95% CI 1.03-3.78]; OR 3.41 [95% CI 1.35-8.61]). No associations were found between radiographic pincer morphology and incident RHOA at any follow-up moment. Anteriorly located pincer morphology with hip pain, however, was significantly associated with incident RHOA. This highlights the importance of studying symptoms and hip morphology simultaneously.

The correlation between hip alpha angle and acetabular labral tear location and size: A cross-sectional study.

Explore the correlation between hip morphology and labral tear location/size. This retrospective study analyzed patients with hip pain who received magnetic resonance (MR) arthrography at our institution, between January 2017 and December 2020. Imaging analysis includes labral tear location and size, and hip morphology measurement with alpha angle, lateral center-edge (CE) angle, anterior CE angle, and femoral neck version. The correlation between hip morphology angles and labral tear location/size was evaluated using multiple regression, followed by stratification analysis with Chi-square test to investigate interactions between the variables. A total of 103 patients (105 hips) with hip pain who received MR arthrography (mean age, 50 years ± 15 [SD]) were included, with mean alpha angle of 57.7° ± 9.9° [SD], mean lateral CE angle of 32.6° ± 6.8° [SD], mean anterior CE angle of 58.2° ± 8.1° [SD], mean femoral neck version of 17.1° ± 8.2° [SD]. Large alpha angle (>57°) and older age were both correlated with superior and posterosuperior labral tear incidence ( p < 0.05) and larger tear size ( p < 0.05). Furthermore, alpha angle is significantly correlated with superior labral tear incidence in young-age subgroup (age <45 years) ( p < 0.05), also significantly correlated with posterosuperior labral tear incidence and larger tear size in middle-age subgroup (45 ≤ age ≤ 60 years) ( p < 0.05). A large alpha angle (>57°) is significantly correlated with increased incidence of superior and posterosuperior labral tear, and larger tear size in patients with hip pain, and the relationships depend on age.

The favorable outcome of Bernese periacetabular osteotomy for the hip osteoarthritis in multiple epiphyseal dysplasia

BackgroundMultiple epiphyseal dysplasia (MED) is a rare congenital bone dysplasia. Patients with MED develop secondary hip osteoarthritis as early as the third to the fourth decade. Currently, there is no consensus on the prevention of the progressive hip osteoarthritis secondary to MED. The Bernese periacetabular osteotomy (PAO) is a joint-preserving surgery to reshape acetabulum and extend femoral head coverage. However, there is no documentary evidence for the effect of the procedure on MED hips.Patients and methodsWe analyzed the preliminary outcomes following the Bernese PAO in 6 MED hips. The average age at the time of surgery was 14.3 years (range from 11.4 to 17.2 years). For our study interest of time efficiency, radiographic parameters were analyzed preoperatively and 1 year postoperatively. The hip function was evaluated by the Harris Hip Score (HHS) before and after surgery.ResultsThe mean follow-up time was 1.7 years. The mean lateral center–edge angle increased from 3.8° to 47.1° (p = 0.02), anterior center–edge angle increased from 7.3° to 35.1° (p = 0.02), and acetabulum index decreased from 27.8° to 14.6° (p = 0.04). The femoral head coverage ratio increased from 66.8% to 100% (p = 0.02). The post-operative anteroposterior pelvic radiograph demonstrated all preoperative broken Shenton lines were reversed. The mean HHS improved from 67.3 to 86.7 (p = 0.05).ConclusionBernese PAO is a feasible treatment for hip disorders in MED patients. It reshapes acetabular and femoral morphology efficiently. In our study, the preliminary results showed the procedure not only improved radiographic outcomes but also hip function.

Defining the Borderline Dysplastic Hip: High Variability in Acetabular Coverage and Femoral Morphology on Low-Dose Computed Tomography.

Borderline acetabular dysplasia is commonly radiographically defined as a lateral center-edge angle (LCEA) of 20° to 25°. While the variability of plain radiographic assessment of this population has been reported, an understanding of the variability of 3-dimensional (3D) hip morphology remains to be better defined. To investigate the variability of 3D hip morphology present on low-dose computed tomography (CT) in the setting of symptomatic borderline acetabular dysplasia and to determine if plain radiographic parameters correlate with 3D coverage. Cohort study (diagnosis); Level of evidence, 2. A total of 70 consecutive hips with borderline acetabular dysplasia undergoing hip preservation surgery were included in the current study. Plain radiographic evaluation included LCEA, acetabular inclination, anterior center-edge angle (ACEA), anterior wall index (AWI), posterior wall index (PWI), and alpha angles on anteroposterior, 45° Dunn, and frog-leg views. All patients underwent low-dose pelvic CT for preoperative planning, which allowed detailed characterization of 3D morphology relative to normative data. Acetabular morphology was assessed with radial acetabular coverage (RAC) calculated according to standardized clockface positions from 8:00 (posterior) to 4:00 (anterior). Coverages at 10:00, 12:00, and 2:00 were classified as normal, undercoverage, or overcoverage relative to 1 SD from the mean of normative RAC values. Femoral morphology was assessed with femoral version, alpha angle (measured at 1:00 increments), and maximum alpha angle. Correlation was assessed with the Pearson correlation coefficient (r). Lateral coverage (12:00 RAC) was deficient in 74.1% of hips with borderline dysplasia. Anterior coverage (2:00 RAC) was highly variable, with 17.1% undercoverage, 72.9% normal, and 10.0% overcoverage. Posterior coverage (10:00 RAC) was also highly variable, with 30.0% undercoverage, 62.9% normal, and 7.1% overcoverage. The 3 most common patterns of coverage were isolated lateral undercoverage (31.4%), normal coverage (18.6%), and combined lateral and posterior undercoverage (17.1%). The mean femoral version was 19.7°± 10.6° (range, -4° to 59°), with 47.1% of hips having increased femoral version (>20°). The mean maximum alpha angle was 57.2° (range, 43°-81°), with 48.6% of hips having an alpha angle ≥ 55°. The ACEA and AWI were poorly correlated with radial anterior coverage (r = 0.059 and 0.311, respectively), while the PWI was strongly correlated with radial posterior coverage (r = 0.774). Patients with borderline acetabular dysplasia demonstrate highly variable 3D deformities, including anterior, lateral, and posterior acetabular coverage; femoral version; and alpha angle. Plain radiographic assessments of anterior coverage are poorly correlated with anterior 3D coverage on low-dose CT.

Poster 118: False Profile Radiograph Sourcil-Edge and Bone-Edge Measurements Both Correlate to Different Weight-Bearing Regions of the Acetabulum: A Three-Dimensional Analysis

Objectives: The acetabular sourcil has been thought of as the radiographic representation of the weightbearing dome of the acetabulum; however, there are limited modern data to support this supposition. In the literature, assessment of weightbearing acetabular coverage has been described using both the sourcil-edge and bone-edge as anatomic landmarks, leading to confusion and controversy in classification of hip dysplasia, indications for hip preservation surgery, and intraoperative coverage assessment. The purpose of this study was to localize the three-dimensional (3D) anatomic correlates of the sourcil-edge and bone-edge radiographic position on false profile radiographs. The authors hypothesized that the sourcil-edge on the false profile represents anterolateral coverage while the bone-edge represents anterior coverage. Methods: Forty hips were grouped by large or small differences between bone-edge and sourcil-edge anterior center edge angles (ACEA). The small difference group comprised the lowest quartile of sourcil-edge to bone-edge difference of an initial cohort of 80 hips, while the large difference group comprised the highest quartile of difference. 3D surface mesh models and digitally reconstructed radiographs (DRRs) were generated from hip computed tomography scans using the 3D Slicer Image Computing Platform (Figures 1 &amp; 3). Sourcil-edge, bone-edge, and ACEAs were identified on DRRs and registered to the 3D models with fiducial markers. Intersection of bone-edge and sourcil-edge projection lines with the acetabular rim were obtained from the 3D models (Figures 2 &amp; 4). 3D Anterior acetabular rim morphology was correlated with ACEA difference. Results: The bone-edge and sourcil-edge projections intersected the acetabular rim at a mean of 2:08 ± 0:25 and 1:20 ± 0:24 o’clock, respectively. The 3D models consistently demonstrated that, in both large and small discrepancy groups, the sourcil-edge corresponded to an area just posterior to the AIIS projection while the bone-edge corresponded to the weight-bearing region inferior to the AIIS (Figures 2 &amp; 4). Additionally, in large discrepancy hips, the bone-edge corresponded to a more prominent acetabular coverage in the region of the AIIS than when compared to the small discrepancy hips. Conclusions: This study demonstrates that both the sourcil-edge and bone-edge projections on false profile radiographs correlate with differing weightbearing regions of the acetabulum. The sourcil-edge ACEA represents coverage at 1:20 o’clock on the acetabular rim and is consistently posterior to the AIIS, while the bone-edge measurement represents the region of the acetabular rim at 2:08 o’clock and is consistently inferior to the AIIS. In hips with a large discrepancy between bone-edge and sourcil-edge (highest quartile), ACEA measurement differs by a mean of 19.7 degrees based on the selection of these radiographic landmarks. These findings have substantial implications for hip preservation surgery technique and clinical decision making. A comprehensive understanding of femoral head coverage is essential for the treatment of young adult hip pathology. Although the sourcil and bone edge are two of the most important radiographic landmarks for assessment of acetabular dysplasia, descriptions of these landmarks are often over simplified. Some authors have advocated for greater utilization of measurements of coverage to the bone edge as it can be more consistently identified. Other authors have advocated for utilizing the sourcil-edge measurement as this is more representative of the “weight bearing dome”. These descriptions are limited as they do not improve our understanding of the anatomic and radiographic structure of the anterior acetabular rim. Although the concept of the “weight bearing dome” is classically described, it lacks anatomic precision. The present study clarifies the anatomic features of the acetabular rim that correspond to these radiographic features. Increased difference between the sourcil-edge and bone edge is generated by the differences in undulation of the anterosuperior acetabular rim. Acetabuli that have maximal anterior rim prominence at or near the superior-most aspect of the acetabulum (generally counterclockwise from the AIIS) tend to demonstrate smaller discrepancy between the bone-edge and sourcil-edge (Figure 4). Acetabuli that have maximal rim prominence medial and anterior to the superior-most aspect of the acetabulum generally demonstrate larger discrepancy (Figure 2). The present anatomic description can be utilized by the hip arthroscopist to better determine which areas of the anterior rim may cause impingement. Similarly, while conducting a periacetabular osteotomy, the surgeon may use this information to better understand how acetabular rotation is contributing to both anterior and anterolateral coverage. In conclusion, on false profile radiographs, the sourcil-edge corresponds to superior femoral head coverage, while the bone-edge corresponds to anterosuperior coverage. False profile radiographs with a large discrepancy between sourcil-edge and bone-edge measurements demonstrate a prominent weight bearing surface in the region of the AIIS. These data regarding the radiographic phenomena of the acetabular rim can aid in clinical decision-making and intraoperative technique.

Can we determine anterior hip coverage from pelvic anteroposterior radiographs? A study of patients with hip dysplasia

PurposeInsufficient coverage causes hip joint instability and results in hip pain. Anterior hip coverage can be determined on both pelvic anteroposterior (AP) radiographs and false profile (FP) radiographs. Four parameters are commonly used to determine the anterior coverage on pelvic AP radiographs: the crossover index, crossover sign, anterior wall index (AWI), and rule of thirds. This study aims to clarify the relationship between these 4 parameters on AP radiographs and the anterior center edge angle (ACEA) on FP radiographs.MethodsIn this study, 53 patients who underwent periacetabular osteotomy for hip dysplasia at our center between July 2020 and October 2020 were retrospectively reviewed. Four parameters on AP radiographs and the ACEA on FP radiographs before surgery and 6 months after surgery were measured and compared for each hip.ResultsUpon examining the 53 hips in this study, there was no correlation between either the crossover index and the ACEA (P = 0.66) or the crossover sign before surgery. The postoperative correlation between the crossover index and the ACEA was weak (r = 0.36, P = 0.007), and that between the crossover sign and the ACEA was moderate (r = 0.41, P = 0.003). There was a weak correlation between the AWI and ACEA both before (r = 0.288, P = 0.036) and after (r = 0.349, P = 0.011) the operation. Evaluation of the anterior coverage by the rule of thirds was also not consistent when determining the anterior coverage with the ACEA.ConclusionAnterior coverage on AP radiographs is largely inconsistent with ACEA on FP radiographs, especially before the surgery. It is recommended to take FP radiographs routinely for determining anterior hip coverage.

Anterior Center-Edge Angle Is Less Reliable Than Anterior Wall Index to Predict Anterior Coverage of the Femoral Head

Background: No consensus is available regarding which radiographic measurement most accurately correlates with anterior coverage of the femoral head. Purpose: (1) To determine the correlation between 2 measurements of anterior wall coverage: total anterior coverage (TAC) calculated from radiographs and equatorial anterior acetabular sector angle (eAASA) calculated from computed tomography (CT) scans; (2) to define the correlation between anterior center-edge angle (ACEA) and anterior wall index (AWI) with TAC and eAASA; and (3) to investigate what other radiographic metrics may help predict anterior coverage. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: The authors retrospectively reviewed 77 hips (48 patients) for which radiographs and CT scans were obtained for reasons other than hip-related pain. Mean age of the population was 62 ± 22 years; 48 (62%) hips were from female patients. Two observers measured lateral center-edge angle (LCEA), AWI, Tönnis angle, ACEA, CT-based pelvic tilt, and CT-based acetabular version, with all Bland-Altman plots within 95% agreement. Correlation between intermethod measurements was estimated with a Pearson coefficient. Linear regression was used to test the ability of baseline radiographic measurements to predict both TAC and eAASA. Results: Pearson coefficients were r = 0.164 (ACEA vs TAC; P = .155), r = 0.170 (ACEA vs eAASA; P = .140), r = 0.58 (AWI vs TAC; P = .0001), and r = 0.693 (AWI vs eAASA; P < .0001). Multiple linear regression model 1 showed that AWI (β = 17.8; 95% CI, 5.7 to 29.9; P = .004), CT acetabular version (β = −0.45; 95% CI, −0.71 to −0.22; P = .001), and LCEA (β = 0.33; 95% CI, 0.19 to 0.47; P = .001) were useful to predict TAC. Multiple linear regression model 2 revealed that AWI (β = 25; 95% CI, 15.67 to 34.4; P = .001), CT acetabular version (β = −0.48; 95% CI, −0.67 to −0.29; P = .001), CT pelvic tilt (β = 0.26; 95% CI, 0.12 to 0.4; P = .001), and LCEA (β = 0.21; 95% CI, 0.1 to 0.3; P = .001) accurately predicted eAASA. Model-based estimates and 95% CIs using 2000 bootstrap samples from the original data were 6.16 to 28.6 for AWI in model 1 and 15.1 to 34.26 for AWI in model 2. Conclusion: There was a moderate to strong correlation between AWI and both TAC and eAASA, whereas ACEA correlated weakly with the former measurements, thus not being useful to quantify anterior acetabular coverage. Other variables such as LCEA, acetabular version, and pelvic tilt may also help predict anterior coverage in asymptomatic hips.

Evaluation of the anterior acetabular coverage with a false profile radiograph considering appropriate range of positioning

This study aimed to (1) set a reference value for anterior center edge angle (ACEA) for preoperative planning of periacetabular osteotomy (PAO), (2) investigate the effects of pelvic rotation and inclination from false profile (FP) radiographs on the measured ACEA, and (3) determine the “appropriate range of positioning” for FP radiograph. This single-centered, retrospective study analyzed 61 patients (61 hips) who underwent PAO from April 2018 and May 2021. ACEA was measured in each digitally reconstructed radiography (DRR) image of the FP radiograph reconstructed in different degrees of pelvic rotation. Detailed simulations were performed to determine the “appropriate range of positioning” (0.67 < ratio of the distance between the femoral heads to the diameter of the femoral head < 1.0). The vertical-center-anterior (VCA) angle was measured on the CT sagittal plane considering the patient-specific standing positions, and its correlation with the ACEA was investigated. The reference value of ACEA was determined by receiver operating characteristic (ROC) curve analysis. The ACEA measurement increased by 0.35° for every 1° pelvic rotation approaching the true lateral view. The pelvic rotation with the “appropriate range of positioning” was found at 5.0° (63.3–68.3°). The ACEA on the FP radiographs showed a good correlation with the VCA angle. The ROC curve revealed that an ACEA < 13.6° was associated with inadequate anterior coverage (VCA < 32°). Our findings suggest that during preoperative PAO planning, an ACEA < 13.6° on FP radiographs indicates insufficient anterior acetabular coverage. Images with the “appropriate positioning” can also have a measurement error of 1.7° due to the pelvic rotation.

Progress in diagnosis and hip arthroscopic treatment of borderline developmental dysplasia of hip with Cam-type femoroacetabular impingement

To summarize the biomechanical characteristics, diagnosis, and hip arthroscopic treatment of borderline developmental dysplasia of hip (BDDH) with Cam-type femoroacetabular impingement (Cam FAI). The literature on BDDH with Cam FAI at home and abroad in recent years was extensively reviewed and analyzed. In patients with BDDH and Cam FAI, the femoral neck anteversion angle and femoral neck shaft angle increase, the pelvis tilts, and the acetabulum rotates, resulting in instability of the hip joint. In order to maintain the stability of the hip joint, the direction of biomechanical action of the hip joint has changed, which further affects the anatomical structures such as the proximal femur and acetabular morphology. BDDH with Cam FAI can be diagnosed clinically by combining lateral center edge angle, anterior center edge angle, and acetabular index. BDDH with Cam FAI can be effectively treated through arthroscopic polishing of the edges of the acetabular proliferative bone, excision of Cam malformations, and minimally invasive repair of the glenoid lip and cartilage of the hip joint. Currently, there is no unified standard for the diagnosis and treatment of BDDH with Cam FAI. Minimally invasive treatment of the hip under arthroscopy can achieve good early- and medium-term effectiveness, and has certain advantages in repairing and maintaining the integrity of the glenoid lip and suturing/compression joint capsule. However, the long-term effectiveness needs to be further followed up to determine. The timing of surgery, intraoperative bone edge depth polishing, and joint capsule suturing/compression techniques also need to be further explored.

Evaluation of lateral and anterior center-edge angles according to sex and anterior pelvic plane tilt angle: a three-dimensional quantitative analysis

BackgroundThis study aimed to quantitatively evaluate lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) according to sex and the anterior pelvic plane (APP) tilt angle and analyze the correlation between these measurements and acetabular coverage.MethodsComputed tomography scans of 71 adults (38 men and 33 women) with normal hip joints were obtained. LCEA, anterior ACEA, and acetabular coverage were measured with APP tilt every 5° from − 30° to + 30° and were compared between the sexes. The correlation between acetabular coverage and LCEA/ACEA was also analyzed.Results(1) LCEA, ACEA, and acetabular coverage were statistically larger in men than in women at all APP tilt angles (with the exception of acetabular coverage ≥ 25°). (2) LCEA, ACEA, and acetabular coverage differed according to APP tilt angle. LCEA and acetabular coverage showed maximum values at 10°. ACEA showed a tendency to increase by an average of 3.6° for every 5° increase in the APP tilt angle. LCEA demonstrated strong and very strong associations across all APP tilting angles, whereas ACEA showed a moderate association at angles ≥ 15° in men and ≥ 30° in women.ConclusionsThe LCEA and ACEA are adequate measurement methods that reflect actual acetabular coverage unless the pelvis is tilted excessively anteriorly. While pelvic tilting does not need to be considered for LCEA within the physiologic range, it should always be taken into account for ACEA, as it increases by an average of 3.6° for every 5° increase in APP tilt angle.Level of evidenceLevel III: retrospective cohort study.

Periacetabular osteotomy for Tönnis grade 2 osteoarthritis secondary to hip dysplasia.

To investigate the clinical outcomes of periacetabular osteotomy (PAO) for Tönnis grade 2 osteoarthritis secondary to hip dysplasia. Forty-nine patients (51 hips) with Tönnis grade 2 osteoarthritis secondary to hip dysplasia, followed by a mean of 52.3months (range: 24.1 to 95.2months), were reviewed. As a control group, 51 patients (51 hips) with Tönnis grade 1 osteoarthritis were matched for age, surgery date, and follow-up period. All patients were evaluated clinically with the use of modified Harris hip score (mHHS) questionnaire, WOMAC score, and the 12-item International Hip Outcome Tool (iHot-12). Radiographic measurements included the lateral centre-edge angle (LCEA), Tönnis angle, and anterior centre-edge angle (ACEA). Kaplan-Meier survivorship analysis was performed to predict a fiveyear survival rate of no osteoarthritis progression. All functional scores and radiographic measurements of the two groups significantly improved at the final follow-up. There were no significant differences between the two groups either in functional scores or radiographic measurements. The fiveyear survival rate of no osteoarthritis progression was 86.2% in Tönnis grade 2 group and 93.1% in Tönnis grade 1 group, respectively. In the Tönnis grade 2 group, the osteoarthritis progressed in six hips. Of which, four hips had an ACEA of < 25°. No osteoarthritis progression was found in hips with an ACEA > 40°. PAO yielded similar results for patients with Tönnis grade 2 and grade 1 osteoarthritis secondary to hip dysplasia. The majority of hips can be preserved without progression of osteoarthritis at fiveyears postoperatively. The slight overcorrection anteriorly may be helpful in preventing osteoarthritis progression.