Anterior Center Edge Research Articles

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.

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.

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.

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.

Acetabular dysplasia and the risk of developing hip osteoarthritis at 2,5,8, and 10 years follow-up in a prospective nationwide cohort study (CHECK).

ObjectiveTo assess the relationship between acetabular dysplasia (AD) and the risk of incident and end-stage radiographic hip osteoarthritis (RHOA) over 2,5,8 and 10 years. DesignIndividuals (n = 1002) aged between 45 and 65 from the prospective Cohort Hip and Cohort Knee (CHECK) were studied. Anteroposterior pelvic radiographs were obtained at baseline and 2,5,8, and 10-years follow-up. False profile radiographs were obtained at baseline. AD was defined as a lateral center edge angle, an anterior center edge angle, or both <25° at baseline. The risk of developing RHOA was determined at each follow-up moment. Incident RHOA was defined by Kellgren & Lawrence (KL) grade ≥2 or total hip replacement (THR), end-stage RHOA by a KL grade ≥3 or THR. Associations were expressed in odds ratios (OR) using logistic regression with generalized estimating equations. ResultsAD was associated with the development of incident RHOA at 2 years follow-up (OR 2.46, 95% CI 1.00–6.04), 5 years follow-up (OR 2.28, 95% CI 1.20–4.31), and 8 years follow-up (OR 1.86, 95%CI 1.22–2.83). AD was only associated with end-stage RHOA at 5 years follow-up (OR 3.75, 95% CI 1.02–13.77). No statistically significant associations were observed between AD and RHOA at 10-years follow-up. ConclusionBaseline AD in individuals between 45 and 65 years is associated with an increased risk of developing RHOA within 2- and 5 years. However, this association seems to weaken after 8 years and disappears after 10 years.

Surgical Treatment of Acetabular Dysplasia With Labral Tears

Acetabular dysplasia results in abnormal forces across the hip joint and can result in both labral tears and cartilage degeneration. A continuum exists from classic dysplasia to normal acetabular morphology. Diagnosis is aided by several radiographic measurements and parameters including a lateral center edge angle of less than 20°, an anterior center edge angle of less than 20°, a Sharp's angle of greater than 42°, and a Tonnis angle of greater than 10°, or version abnormalities. When patients with acetabular dysplasia present with intra-articular hip pain, skeletal maturity, and preserved radiographic joint space, a periacetabular osteotomy (PAO) is considered as a surgical treatment option when conservative measures have failed. The Bernese PAO was developed in 1984 as a way for reorienting the acetabulumto restore more normal femoral head coverage and orientation. The long-term results of this procedure have been promising with 10-year and 20-year survivorships of approximately 85% and 60%, respectively. When dysplasia is coupled with a labral tear or other intra-articular pathology including focal chondral damage, ligamentum teres tears, or capsular defects, hip arthroscopy and PAO are performed. Although there is a paucity in the literature of the long-term evidence for the combined procedure, early results indicate improved patient reported outcome measures. Appropriate treatment of borderline hip dysplasia remains controversial.

Competitive Athletes with Femoroacetabular Impingement and Painful Internal Snapping Treated Arthroscopically with Intrabursal Iliopsoas Fractional Lengthening: High Rate of Return to Sport and Favorable Midterm Functional Outcomes

Background: Athletes with femoroacetabular impingement syndrome (FAIS) who undergo hip arthroscopy with iliopsoas fractional lengthening (IFL) in the context of painful internal snapping have demonstrated favorable patient–reported outcomes (PROs), return to sport (RTS), and resolution of internal snapping symptoms at short term follow–up. Midterm outcomes have not been established. Purposes: (1) To report minimum 5–year PROs and RTS rate in competitive athletes who underwent primary hip arthroscopy for FAIS and intra–bursal IFL for painful internal snapping and (2) to compare these clinical results with those of a propensity score–matched control group of competitive athletes who underwent primary hip arthroscopy without painful internal snapping and IFL. Study Design: Cohort study; Level of evidence, 3. Methods: Data were reviewed for consecutive surgeries performed by a single surgeon between February 2010 and December 2013. Patients were considered eligible if they were professional, collegiate, or high school athletes and received a primary hip arthroscopy for FAIS and intra–bursal IFL without extended capsulotomy for painful internal snapping. Indications for IFL were painful internal snapping on preoperative physical examination. Inclusion criteria were preoperative and minimum 5–year follow–up scores for the modified Harris Hip Score, Nonarthritic Hip Score, Hip Outcome Score–Sport Specific Subscale, and visual analog scale for pain. Rates of achieving the minimal clinically important difference were also reported. For comparison, athletes in the IFL group were propensity matched by age, sex, body mass index, lateral and anterior center–edge angles, and sports level to a control group of athletes without internal snapping who underwent primary hip arthroscopy for FAIS without IFL. Results: A total of 105 competitive athletes in the IFL group were included in the study with a follow–up of 66.8 ± 6.9 months (mean ± SD). The IFL cohort showed significant improvement in all recorded PROs at minimum 5–year follow–up (P < .001). Furthermore, they demonstrated favorable rates of achieving the minimal clinically important difference for the modified Harris Hip Score (82.0%), Nonarthritic Hip Score (85.4%), and Hip Outcome Score–Sport Specific Subscale (82.8%). Further, 89.5% of athletes in the IFL cohort successfully returned to sport. A total of 42 athletes in the IFL group were propensity matched to 54 control athletes. When groups were compared, they demonstrated similar improvement in PROs and rates of RTS, revision arthroscopy, and achieving psychometric thresholds. Conclusion: Competitive athletes undergoing primary hip arthroscopy and intra–bursal IFL in the context of FAIS and painful internal snapping demonstrated favorable PROs and RTS rate at minimum 5–year follow–up. These results were comparable with those of a control group of athletes not requiring IFL.

Hip Morphology in Periacetabular Osteotomy (PAO) Patients Treated for Developmental Dysplasia of the Hip (DDH) as Infants Compared With Those Without Infant Treatment.

A subset of patients successfully treated for developmental dysplasia of the hip (DDH) as infants have symptomatic acetabular dysplasia at skeletal maturity leading to periacetabular osteotomy (PAO). The purpose of this study was to compare femoral and acetabular morphology in PAO patients with late acetabular dysplasia after previous treatment for DDH with PAO patients who do not have a history of DDH treatment. A single surgeon's patients who underwent PAO between 2011 and 2021 were retrospectively reviewed. Patients previously treated for infantile DDH with a Pavlik harness, abduction brace, closed reduction and spica casting, or open reduction and spica casting were included. Patients with previous bony hip surgery were excluded. Preoperative radiographic measurements of each hip were recorded including lateral center edge angle, anterior center edge angle, and Femoro-Epiphyseal Acetabular Roof index. Computed tomography measurements included the coronal center edge angle, sagittal center edge angle, Tönnis angle, acetabular anteversion at 1, 2, and 3 o'clock, femoral neck-shaft angle, femoral version, and alpha angle. Control PAO cases without a history of DDH diagnosis or treatment were matched with the infantile DDH treatment group in a 2:1 ratio based on coronal center edge angle, age, and sex. There were 21 hips in 18 patients previously treated for infantile DDH (13 patients Pavlik harness, 3 abduction brace, 1 closed reduction, and 1 open reduction). The control PAO cohort was 42 hips in 42 patients who did not have previous DDH treatment. There was no statistically significant difference in any of the recorded measurements between patients previously treated for DDH and those without previous treatment including femoral version (P=0.494), anteversion at 1 o'clock (P=0.820), anteversion at 2 o'clock (P=0.584), anteversion at 3 o'clock (P=0.137), neck-shaft angle (P=0.612), lateral center edge angle (P=0.433), Femoro-Epiphyseal Acetabular Roof index (P=0.144), and alpha angle (P=0.156). Femoral and acetabular morphology is similar between PAO patients with persistent symptomatic acetabular dysplasia following DDH treatment and patients presenting after skeletal maturity with acetabular dysplasia and no previous history of DDH treatment. Level III-case-control, prognostic study.

Role of the Anterior Center-Edge Angle on Acetabular Stress Distribution in Borderline Development Dysplastic of Hip Determined by Finite Element Analysis.

Background: The joint with hip dysplasia is more likely to develop osteoarthritis because of the higher contact pressure, especially in the socket. The lateral center-edge angle (LCEA) is the major indicator for hip dysplasia via radiography. However, the pathological conditions of LCEA angles in the range of 18°–25° are still controversial, which challenges precise diagnosis and treatment decision-making. Objective: The purpose of this study is to investigate the influence of anterior center-edge angle (ACEA) on the mechanical stress distribution of the hip joint, via finite element analysis, to provide insights into the severity of the borderline development dysplasia. Methods: From 2017 to 2019, there were 116 patients with borderline developmental dysplasia of the hip (BDDH) enrolled in this research. Based on the inclusion criteria, nine patients were involved and categorized into three LCEA groups with the maximal ACEA differences. Patient-specific hip joint models were reconstructed from computed tomography scans, and the cartilages, including the labrum, were established via a modified numerical method. The finite element analysis was conducted to compare the stress distributions due to the different ACEA. Results: As ACEA decreased, the maximum stress of the acetabulum increased, and the high stress area developed toward the edge. Quantitative analysis showed that in the cases with lower ACEA, the area ratio of high stress increased, and the contact facies lunata area significantly affected the stress distribution. Conclusion: For patients with BDDH, both the ACEA and the area of facies lunata played essential roles in determining the severity of hip dysplasia and the mechanical mechanism preceding osteoarthritis.

Effect of Patient Positioning on Measurement of the Anterior Center-Edge Angle on False-Profile Radiographs and Its 3-Dimensional Mapping to the Acetabular Rim.

Background:The anterior center-edge angle (ACEA) is used to quantify anterior coverage of the femoral head by the acetabulum. However, its measurement has not been evaluated in a manner consistent with routine use, and the precise 3-dimensional (3D) anatomic location where it measures coverage is not known.Purpose:To determine the effect of patient positioning on ACEA measurement reliability, magnitude, and 3D location.Study Design:Descriptive laboratory study.Methods:Included were 18 adults; 7 participants had cam morphology and femoroacetabular impingement syndrome, and 11 participants had no radiographic evidence of hip abnormalities and no history of hip pain or injuries. Ultimately, 3D femur and pelvis models were generated from computed tomography images. Radiographs were generated with the models in different degrees of pelvic rotation, tilt, and obliquity relative to the standard false-profile view. The ACEA was measured by 2 raters by selecting the location of the bone edge on each radiograph. Selections were projected onto the pelvis model and expressed as a clockface location on the acetabular rim. The clockface was mirrored on left hips to allow a direct comparison of locations between hips. Interrater and intrarater reliability were quantified via the intraclass correlation coefficient (ICC). The effect of position on ACEA measurements and clockface locations was determined via linear regression.Results:Intrarater and interrater reliability were excellent (ICC ≥0.97 for all). For every degree increase in rotation, tilt, and obliquity, the ACEA changed by +0.53°, +0.93°, and –0.04°, respectively. The mean clockface location (hour:minute:second) in the false-profile view was 2:09:32 ± 0:12:00 and changed by +0:02:08, –0:00:35, and –0:00:05 for every degree increase in rotation, tilt, and obliquity, respectively.Conclusion:ACEA measurements were reliable even with differences in patient positioning. Rotation and tilt were associated with notable changes in ACEA measurements. ACEA bone edge measurements mapped to the anterosuperior acetabular rim, typically in proximity to the anterior inferior iliac spine. Mapped location was most sensitive to rotation.Clinical Relevance:Pelvic rotation and tilt affected ACEA measurements, which could alter the clinical classification and treatment of borderline abnormalities. Rotation in particular must be well controlled during patient imaging to preserve measurement reliability and accuracy and to describe coverage from the intended 3D rim location.

Combination of Anterior Acetabular Coverage and Femoral Head Shape Predicts Femoroacetabular Impingement After Periacetabular Osteotomy.

Femoroacetabular impingement (FAI) after periacetabular osteotomy (PAO) may be affected by both anterior acetabular coverage and femoral head shape. This study aimed to radiographically evaluate the relationship of the combination of acetabular coverage and femoral head shape with the occurrence of FAI after curved PAO. In this study, 76 hip joints from patients with symptomatic developmental dysplasia of the hip underwent curved PAO. The relationship between the combined postoperative anterior center-edge and alpha angles (ie, the combination angle) and the occurrence of postoperative FAI was evaluated. Clinical factors and the preoperative and postoperative 3-dimensional center-edge angles, acetabular versions, femoral versions, radiographic alpha angles of the femoral head, and the combination angle were measured and compared to clinical outcomes. The modified Harris Hip Scores, University of California, Los Angeles activity scores, and acetabular coverage angles were significantly improved following curved PAO. Receiver operator characteristic curve analysis demonstrated that the combination angle over 108° may be a predictive factor for the occurrence of FAI after curved PAO. Multivariate analysis demonstrated that an age <40 years (odds ratio 6.6, 95% confidence interval 1.2-36.4, P= .037) and a combination angle <108° (odds ratio 9.2, 95% confidence interval 1.7-50.0, P= .010) were significantly associated with modified Harris Hip Scores ≧90 points. A combination angle >108° may be a predictive factor for the occurrence of FAI after curved PAO and impaired clinical outcomes. To avoid postoperative FAI, we propose that osteochondroplasty of the femoral head should be performed for patients with preoperative combination angles >90°.

Anterior acetabular coverage and femoral head-neck measurements predict postoperative anterior impingement: A simulation study.

The aim of this simulation study was to evaluate the relationship of elements of anterior acetabular coverage and femoral head-neck shape with the occurrence of postoperative anterior impingement after curved periacetabular osteotomy (PAO). Sixty-two patients with symptomatic developmental dysplasia of the hip who had undergone curved PAO were selected. The likelihood of developing postoperative anterior impingement was explored through simulations of the range of motion by collision detection of the pelvis and femur. Postoperative anterior impingement was defined as impingement that occurred during postoperative bone flexion <105° or postoperative internal rotation <20° at 90° flexion. The three-dimensional center-edge (CE) angles, acetabular and femoral versions, radiographic alpha angles of the femoral head, combination angles of anterior CE and alpha angles, and combined anteversions of acetabular and femoral versions were compared between patients with postoperative anterior impingement and nonimpingement. A receiver operator characteristic (ROC) analysis was conducted to determine thresholds of the examined radiographic parameters and calculate their accuracy for predicting postoperative anterior impingement. A multivariate analysis was performed to test whether combined anteversion, anterior CE angle, and combination angle are associated with excellent modified Harris Hip Scores (mHHSs).ROC analysis demonstrated a combination angle ≥108° was predictive of the occurrence of postoperative anterior impingement after curved PAO, which can lead to impaired clinical outcomes. Conversely, a combination angle <108° was significantly associated with mHHS ≥ 90 points. To avoid postoperative anterior impingement, osteochondroplasty of the femoral head or anterior CE angle control should be performed for patients with preoperative combination angles ≥90°.

The anterior center edge angle has limited ability to predict three-dimensional coverage of the femoral head in patients with developmental dysplasia of the hip undergoing curved periacetabular osteotomy.

Femoral head coverage in patients with hip dysplasia (DDH) is typically quantified using 2D measurements of the lateral center edge angle (LCEA) and anterior center edge angle (ACEA). However, as the morphology of DDH is complex and varies between patients, 2D measurements may not predict the true 3D femoral head coverage. Herein, 2D and 3D coverage were quantified before and after curved periacetabular osteotomy (CPO) and their relationships were assessed. Forty-three hips that underwent CPO for DDH were analyzed. For 2D evaluation, LCEA was quantified from X-rays and CT images. The ACEA was measured from CT images (CT-ACEA) and digitally reconstructed radiographs generated from CT images (DRR-ACEA). Three-dimensional coverage was quantified from CT reconstructions of the hip and evaluated in the anterior, superior, posterior, and inferior regions of the femoral head. Two-dimensional measurements were correlated to 3D coverage to assess their relationships. The median preoperative 3D percent coverage was 17.7, 36.1, 56.1, and 14.6% for the anterior, superior, posterior, and inferior region, respectively. After CPO, all LCEAs and ACEAs increased significantly (all p < 0.001). For the 3D coverage, anterior and superior coverage significantly increased while the posterior and inferior coverage decreased (all p < 0.001). Moderate to strong correlations were detected between the two LCEAs and the 3D superior coverage in both the preoperative and postoperative period. For the correlation between 3D anterior coverage, no significant correlation was found between the CT-ACEA while a moderate correlation was found between the DRR-ACEA (rs = 0.41, p = 0.023). Our results indicate that the LCEA can be used to predict 3D coverage in the superior region of the femoral head. However, as the CT-ACEA or DRR-ACEA had no or only moderate correlation between the 3D anterior coverage, these measurements are not recommended for evaluating/estimating the 3D anterior coverage in patients with DDH.

Generalized Joint Laxity Is Associated With Dynamic Hip Ultrasonography Measures in Female Athlete Patients Who Are Not Hypermobile.

To investigate ultrasound (US) femoroacetabular translation measurements in female athlete patients. A prospective cross-sectional study was conducted in female athlete patients <50 years. Demographic data, Beighton score/hypermobility status, and sport participation were collected. Hip dysplasia was determined using radiographic measurements (lateral center edge angle, anterior center edge angle, Tönnis angle); femoral version angles were measured with CT or MR. Femoroacetabular translation US measures included neutral (N), neutral flexed (NF), extension external rotation/apprehension (EER) positions. Maximal difference (delta) between US measures was calculated. 206/349 female hips were analyzed (median age 21.2 years [range, 12-49.5]). The primary sport group was performing arts (45%, 92/206). Mean Beighton score was 5.2 (SD, 2.5) with 61% (129/206) of hips exhibiting hypermobility (Beighton score ≥5). For each additional unit of Beighton score, N US measurement increased by 0.7 mm (β=0.7; 95% confidence interval [CI]=0.22-1.25; P < .001), NF by 1 mm ( = 0.9; 95% CI=0.3-1.43; P=.002) and EER by 0.8 mm ( = 0.8; 95% CI=0.27-1.37; P < .001) when adjusting for age and dysplasia status. A positive correlation was detected between NF (r=0.19; 95% CI=0.05-0.33; P=.007) and EER (r=0.19; 95% CI=0.05-0.32; P=.01) with Tönnis angle and a negative correlation between the delta and femoral version (r=-0.20; 95% CI=-0.35 to 0.03; P=.02). No difference in US measures was detected across sport groups (N [P=.24], NF [P=.51], EER [P=.20], delta [P=.07]). Beighton score was independently associated with dynamic US measures in female athlete patients who are not hypermobile when controlling for other factors.

Use of Younger Patient Age and Greater Anterior Center-Edge Angle to Predict the Need for Bilateral Hip Arthroscopy in Patients With Bilateral Femoroacetabular Impingement–Related Hip Pain

Background: In patients with symptomatic femoroacetabular impingement syndrome, bilateral hip pain has been reported to occur in high frequency. However, not all patients require bilateral hip arthroscopy. Purpose: To determine the incidence, patient-specific variables, and postoperative outcomes in patients who presented with bilateral hip pain at the time of index hip arthroscopy and underwent subsequent contralateral arthroscopic hip surgery. Study Design: Case series; Level of evidence, 4. Methods: Patients who presented with bilateral hip pain, underwent primary hip arthroscopy between January 2012 and June 2018 for indication of femoroacetabular impingement syndrome, and had minimum 2-year follow-up were retrospectively analyzed. Baseline descriptive data, preoperative hip range of motion, and radiographic measurements were recorded with pre- and postoperative patient-reported outcomes (PROs). Independent samples t test was used to compare continuous variables, and chi-square test was used to compare categorical variables between patients undergoing unilateral and bilateral surgery. Bivariate correlations and a multivariable binary logistic regression were performed to determine factors predictive of the need for future contralateral hip arthroscopy. Results: In total, 108 patients were identified who reported bilateral hip pain during the index evaluation, underwent primary hip arthroscopy, and had 2-year follow-up. Among these, 42% (n = 45) elected to undergo hip arthroscopy on the contralateral hip at a mean of 6.0 months (range, 1-17 months) after the index surgery. Patients requiring bilateral surgery were significantly younger (P = .004) and had a larger preoperative anterior center-edge angle (ACEA; P = .038) when compared with patients who had unilateral surgery. There were no significant differences in alpha angle measurements between patients who had unilateral and bilateral surgery. On bivariate analysis, younger age at the time of the index surgery (r = −0.272; P = .005) and preoperative ACEA (r = 0.249; P = .016) were significantly correlated with the need for bilateral surgery. On multivariate analysis, younger age remained a significant predictor for bilateral surgery (odds ratio, 0.95; 95% CI, 0.91-0.99). Patients who underwent bilateral hip arthroscopy reported significant improvement in all PROs (P < .001), with a significantly greater mean Hip Outcome Score− Sports Specific Subscale score when compared with patients undergoing unilateral surgery (P = .037). Conclusion: Subsequent contralateral hip arthroscopy was performed in 42% of patients who presented with bilateral hip pain. Younger age at the time of the index surgery and greater ACEA were predictive of the need for contralateral surgery. Patients undergoing bilateral surgery reported significantly improvement in PROs at minimum 2-year follow-up.

Volume-based dysplasia severity index with the spheric cup method in the evaluation of adult and adolescent acetabular dysplasia

Introduction / Aim: Defining and treating adult and adolescent acetabular dysplasia before arthrosis develops is one of the basic principles of hip-preserving surgery. During the evaluation of cases with asymptomatic or mild symptoms, the severity of the acetabular covering deficiency directs the treatment. We attempted to find answers to two questions with our study: 1) Are the values revealed by the described measurement technique sufficient to detect acetabular dysplasia? 2) Do the criteria calculated by the current technique correlate with the well-known radiological criteria for acetabular dysplasia?&#x0D; &#x0D; Material and Method: Eighteen hips of patients who had undergone periacetabular osteotomy evaluated by computed tomography (CT) between June 2009 and February 2019 were included in the study (Group 1, dysplasia group). Eighteen patients of similar age and sex, who had tomography examination from the pelvic region, except for orthopedic reasons, were identified between the same dates (Group 2, control group). In the tomography examinations of the patients, the entrance area of the acetabulum was determined using the multiplanar reformation (MPR) technique. Acetabulum volume and femoral head volume was calculated according to the spheric cup measurement method. Acetabular index (AI), extrusion index (EI), Sharp angle (SA), lateral center edge angle (LCEA), and anterior center edge angle (ACEA) values were calculated from direct graphy and CT scanograms of the patients. &#x0D; &#x0D; Findings / Results: In the comparative analysis between the groups, a significant difference was observed in terms of acetabular volume, VBADSI, AI, EI, LCEA, SA, and ACEA values (p &lt; 0.05). &#x0D; &#x0D; Conclusion: Acetabular volume measured using the spheric cup method and the VBADSI proved to be criteria that could contribute to the diagnosis of acetabular dysplasia. It would be appropriate to measure the described method with a larger series to reveal values peculiar to specific communities.