A systematic approach to the plain radiographic evaluation of the young adult hip

Osteoarthritis of the hip: is radiography still needed?

Diagnosis of hip osteoarthritis (OA) is based on clinical arguments, and medical imaging is obtained to confirm the diagnosis and rule out other possible sources of pain. Conventional radiographs are recommended as the first line imaging modality to investigate chronic hip pain. They should be obtained in a rigorous technique that includes an antero-posterior (AP) radiograph of the pelvis. The choice of the appropriate lateral view depends on the clinical indication, Lequesne's false profile being valuable in the assessment of OA. Magnetic resonance imaging (MRI) is more sensitive to detect joint effusion/synovitis, cartilage, labral, and bone marrow lesions. However, structural joint changes are frequent in asymptomatic population and neither radiographs nor MRI have shown a good correlation with pain and functional impairment. MRI seems to be more suitable than radiographs as a biomarker for clinical trials addressing early OA. The absence of a validated MR biomarker of early OA, together with issues related to machine availability and MRI protocol repeatability, prevent the widespread use of MRI in clinical trials.

How Often Do Patients Presenting With Severe Adolescent Idiopathic Scoliosis Have Underlying Hip Dysplasia?

INTRODUCTION

Adolescent idiopathic scoliosis radiographic screening will often include the hips. The purpose of this study is to evaluate the prevalence of hip dysplasia by lateral center edge angle (LCEA) on scoliosis radiographs in patients presenting with severe range (>45 deg) idiopathic curves.

METHODS

We reviewed 200 consecutive patients (400 hips) with idiopathic scoliosis with major coronal curves ≥45 degrees between October 2009 and October 2022. The presenting scoliosis radiograph PA were reviewed for the following variables: major coronal curve direction, coronal balance, and lateral center edge angles. An LCEA value ≤18 was considered dysplastic. To assess potential measurement variability related to parallax of the scoliosis radiographs, the intermodality intraclass correlation coefficient (ICC) was measured from a subset of 20 hip LCEA values from patients with both scoliosis and pelvis radiographs.

RESULTS

A total of 200 patients [mean age: 13.6 (1.8) years; Female: 79%] were reviewed. The mean major curve (SD) was 58.6 degrees (11.4 deg). Overall 19% (37/200) patients or 11% (43/400) of hips had hip dysplasia. Of the dysplastic hips, 16% (6/43, P <0.001) were bilateral and 57% (21/43, P =0.04) were right sided. There was no association between dysplastic hip laterality and ipsilateral or contralateral coronal balance ( P =0.26) or curve direction ( P =0.49). The interobserver ICC for assessment of LCEA on scoliosis radiographs was 0.85, and the intermodality ICC between pelvic and scoliosis radiographs was 0.78.

CONCLUSION

Hip dysplasia was present in 19% of patients presenting with large major curves, and many of these patients had right sided hip dysplasia. There was no association between hip dysplasia laterality and the patient's major curve direction or coronal balance. There was good intermodality reliability (ICC=0.78) between LCEA values in patients who had both scoliosis and pelvis radiographs, and good inter-rater reliability between raters. Radiographic interpretation of adolescent idiopathic scoliosis should focus not only on the description of the curve and ruling out underlying segmentation anomalies but should also include critical assessment of the hips to exclude co-existing hip dysplasia.

LEVEL OF EVIDENCE

Therapeutic study-level IV.

Does hip muscle strength and functional performance differ between football players with and without hip dysplasia?

OBJECTIVE

To compare hip muscle strength and functional performance in football players with and without hip dysplasia and investigate if the relationships were modified by sex.

DESIGN

Cross-sectional study.

METHODS

This study compared football players with hip dysplasia (HD group) and without hip dysplasia (control group). Hip muscle strength (Nm/kg) and functional task performance were assessed in both groups. Linear regression with generalized estimating equations were used to assess differences between groups. Sex was assessed as a potential effect modifier.

RESULTS

101 football players were included (HD group, n = 50, control group, n = 51). There was no difference in hip muscle strength or functional performance between the HD group and the control group. Results ranged from hip extension strength (Estimate -0.13.95%CI: 0.29 to 0.02, P = 0.087) to hip external rotation strength (Estimate 0.00.95%CI: 0.05 to 0.05, P = 0.918). No relationships were modified by sex or age.

CONCLUSIONS

Similar levels of hip muscle strength and functional performance were found in active football players with and without hip dysplasia. These findings differ from other studies. This may be due to our cohort having less advanced hip dysplasia than the surgical populations that have been previously investigated, or due to a beneficial effect of football participation on muscle strength and functional performance in people with hip dysplasia.

Contemporary, non-navigation, cup orientation techniques improve accuracy and eliminate differences seen between the anterior and posterior approach in THA

BACKGROUND

This study aimed to: (1) Determine the ability to achieve the surgeons' desired cup orientation, without navigation, using contemporary measures with the anterior- (AA) and posterior- approaches (PA); and (2) assess whether surgical approach is associated with cup orientation accuracy, as previously reported, when contemporary measures are used.

METHODS

A prospective, 2-centre, multi-surgeon study of 400 THAs (200 AA; 200 PA) was performed. Intraoperative radiographs were obtained with the AA. A digital inclinometer and 3-point pelvic support were used with the PA. With the PA, intraoperative cup inclination at impaction was recorded. Radiographic inclination/anteversion (RI/RA) was measured from intraoperative radiographs (AA-only) and from postoperative radiographs for all cases. Optimum inclination/anteversion was defined as 40°/20° (±10°). The difference between intra- and postoperative orientations allowed for determination of the difference in pelvic position at impaction.

RESULTS

Optimum RI and RA were achieved in 91.3% (n = 365) and 92% (n = 368) of cases respectively. Optimum cup orientation was detected in 84% of cases (n = 336). There was equivalent ability to achieve cup orientation between approaches (AA: 82.5% vs. PA: 85.5%; p = 0.41). The use of an inclinometer in the PA was associated with a smaller variability of inclination at implantation (10° vs. 14°) and counteracted the greater difference in pelvic position (4.4° vs. 2.1°) seen with the PA.

CONCLUSIONS

Over 80% of cases can have optimum orientation without navigation, using simple, cheap contemporary measures. Such measures eliminate differences between approaches, related to patient position. Narrower implantation angles will further reduce variability in cup orientation achieved.

Acetabular Sector Angles in Asymptomatic and Dysplastic Hips: Defining Dysplasia and Thresholds to Guide Management

BACKGROUND

Radiographic evaluation plays an important role in detecting and grading hip dysplasia. Acetabular sector angles (ASAs) measure the degree of femoral head coverage provided by the acetabulum on computed tomographic (CT) scans. In this study, we aimed to determine ASA values at different axial levels in a control cohort with asymptomatic, high-functioning hips without underlying hip pathology and a study group with symptomatic, dysplastic hips that underwent periacetabular osteotomy (PAO), thereby defining the ASA thresholds for hip dysplasia.

METHODS

This was a cross-sectional study evaluating a control group of 51 patients (102 hips) and a study group of 66 patients (72 hips). The control group was high-functioning and asymptomatic, with an Oxford Hip Score of >43, did not have osteoarthritis (Tönnis grade ≤1), underwent a pelvic CT scan, had a mean age (and standard deviation) of 52.1 ± 5.5 years, and was 52.9% female. The study group had symptomatic hip dysplasia treated with PAO, had a mean age of 29.5 ± 7.3 years, and 83.3% was female. Anterior ASA (AASA) and posterior ASA (PASA) were measured at 3 axial CT levels to determine equatorial, intermediate, and proximal ASA. The thresholds for dysplasia were determined using receiver operating characteristic (ROC) curve analysis, including the area under the curve (AUC).

RESULTS

Patients with dysplasia had significantly smaller ASAs compared with the control group; the differences were most pronounced for proximal AASAs and proximal and intermediate PASAs. The control group had a mean proximal PASA of 162° ± 17°, yielding a threshold for dysplasia of 137° (AUC, 0.908). The mean intermediate PASA for the control group was 117° ± 11°, yielding a threshold of 107° (AUC, 0.904). The threshold for anterior dysplasia was 133° for proximal AASA (AUC, 0.859) and 57° for equatorial AASA (AUC, 0.868). The threshold for posterior dysplasia was 102° for intermediate PASA (AUC, 0.933).

CONCLUSIONS

Measurement of ASA is a reliable tool to identify focal acetabular deficiency with high accuracy, aiding diagnosis and management. A proximal PASA of <137° or an intermediate PASA of <107° should alert clinicians to the presence of dysplasia.

LEVEL OF EVIDENCE

Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Team Approach: Hip Preservation Surgery

The evaluation and treatment of adolescents and young adults with hip pain has seen tremendous growth over the past 20 years. Labral tears are well established as a common cause of hip pain but often occur because of underlying bony abnormalities. Femoroacetabular impingement (FAI) and acetabular dysplasia are now well-established causes of hip osteoarthritis and are increasingly treated in the prearthritic stage in hopes of improving symptoms and prolonging the longevity of the native hip. Beyond FAI and acetabular dysplasia, this patient population can present with a complex and variable group of underlying conditions that need to be taken into account. Expertise in the conservative management of this population, including physical therapy, is valuable to maximize the success. Preoperative, surgical, and postoperative decision-making and care in this population is complex and evolving. A comprehensive, multidisciplinary approach to the care of this patient population has been used for over 20 years by our institution with great success. The purpose of this article is to review the "team-based approach" necessary for successful management of the spectrum of adolescent and young adult hip disorders.

Football Players With Hip Dysplasia: The Relationship Between Muscle Strength, Functional Performance, Self-reported Sport and Recreation, Cartilage Defects, and Sex. A Cross-sectional Study

OBJECTIVE: In symptomatic football players with hip dysplasia, we aimed to explore the relationships between self-reported sport and recreation ability and (1) hip muscle strength, (2) functional performance, and investigate if these relationships were modified by sex or cartilage defects. METHODS: In this cross-sectional study, football players (n = 50) with longstanding (>6 months) hip and/or groin pain, a positive flexion/adduction/internal rotation test, and a lateral-center-edge angle <25° were included. Hip muscle strength and functional performance were assessed. Self-reported sport and recreation ability was quantified using the sports and recreational subscales from the International Hip Outcome Tool-33 (iHOT-Sport) and the Copenhagen Hip and Groin Outcome Score (HAGOS-Sport). Relationships were evaluated using regression models with sex and cartilage defects as potential effect modifiers. RESULTS: There was a positive linear relationship between the one-leg-rise test and the iHOT-Sport subscale (β = 0.61; 95% CI: 0.09, 1.14). A polynomial (concave) relationship was found between peak eccentric adduction strength and the HAGOS-Sport subscale (β = -30.88; 95% CI: -57.78, -3.99). Cartilage defects modified the relationship between peak isometric adduction strength and HAGOS-Sport, with those with cartilage defects having a polynomial (convex) relationship (β = 36.59; 95% CI: 12.74, 60.45), and those without cartilage defects having no relationship. CONCLUSION: One-leg-rise performance and adduction strength were associated with self-reported sport and recreation ability, indicating a possible relationship between physical function, hip joint structure, and sport and recreation ability in football players with hip dysplasia. J Orthop Sports Phys Ther 2023;53(10):1-8. Epub: 8 September 2023. doi:10.2519/jospt.2023.12026.

Deviation of Latitude Cut: A Simple Sign to Differentiate Total Hip Arthroplasty from Hemiarthroplasty in Radiography

This study aims to propose latitude cut deviation for differentiating hip arthroplasty types and evaluate its diagnostic utility in distinguishing total hip arthroplasty (THA) from hemiarthroplasty using radiography. After assessing various cup designs from top manufacturers for THA and hemiarthroplasty, we conducted a retrospective study on 40 patients (20 THA and 20 hemiarthroplasty). Three readers independently evaluated the radiographs, assessing acetabular sparing, cup-bone interface texture, and latitude cut deviation. Diagnostic performance and inter-observer agreement were compared using receiver operating characteristic curves and the Fleiss kappa coefficient. Latitude cut deviation measured on implant designs ranged from 19% to 42% in hemiarthroplasty and from -12% to 9% in THA. The sensitivity, specificity, and accuracy used to distinguish THA from hemiarthroplasty were 60-85%, 55-95%, and 62.5-77.5% for acetabular sparing; 100%, 50-80%, and 75-90% for cup-bone interface texture; and 100%, 90-100%, and 95-100% for latitude cut deviation. Inter-observer agreement for acetabular sparing, cup-bone interface texture, and latitude cut deviation ranged from moderate to excellent (κ = 0.499, 0.772, and 0.900, respectively). The latitude cut deviation exhibited excellent diagnostic performance and inter-reader agreement in distinguishing hemiarthroplasty from THA on radiographs, offering a concise way to identify hip arthroplasty type.

Clinical application of modified hip joint lateral position in femoral neck fracture

BACKGROUND

To show the femoral neck better in hip lateral view of X-ray, we design a modified hip lateral view and then investigate the value in femoral neck fractures.

METHODS

CT images of 10 normal hip joints for 3D reconstruction were selected, the Mimics Medical 21.0 was used, and rotating the proximal femur was to find the most suitable angle for showing the femoral neck well, designed the modified lateral view according to this angle. We collected 35 healthy cases and 35 femoral neck fractures as the normal and fracture group. And two groups were all taken hip anteroposterior view, cross-table lateral view and modified lateral view, which were analyzed by two radiologists to score the anatomical structures of the articular surface, femoral head, head neck junction, femoral neck, basal region and intertrochanteric region. Friedman test was used to analyze the score of femoral neck at different angles. T test and Wilcoxon signed-rank test were to compare inter-groups.

RESULTS

The modified lateral view was designed as follows: The subjects were supine, with the sagittal axis biased toward the healthy side at an angle of approximately 20° to the long axis of the examination table, the hip joint flexed at 45°, the lower extremity abducted at 40°, the centerline inclined 45° toward the head and the centerline aligned with the center of the groin. The modified lateral view showed the femoral head, head neck junction and femoral neck more clearly than the cross-table lateral view, but the cross-table lateral view showed the femoral neck basal and intertrochanteric region better. In addition, the time of taking the modified lateral view was significantly less than the cross-table lateral view (normal group: 0.789 min ± 0.223 vs 0.623 min ± 0.207, P < 0.001; fracture group: 1.131 min ± 0.362 vs 0.946 min ± 0.390, P < 0.001).

CONCLUSIONS

The modified lateral view can obtain a standard sagittal image of femoral neck, which can show the dislocation and angulation of the sagittal femoral neck fracture clearly, and improve the accuracy of diagnosis. And it is more convenient and easier for patients to cooperate, which is worthy promoting and applying in clinical work.

Progression of Osteoarthritis at Long-term Follow-up in Patients Treated for Symptomatic Femoroacetabular Impingement With Hip Arthroscopy Compared With Nonsurgically Treated Patients

BACKGROUND

Femoroacetabular impingement (FAI) is a common cause of hip pain, especially in young patients. When left untreated, it has been demonstrated to be a risk factor for the onset or progression of osteoarthritis (OA) and has been identified as one of the main contributors leading to the need for total hip arthroplasty (THA) at a young age. While the short-term therapeutic potential of hip arthroscopy is widely recognized, little is known regarding its potential mid- to long-term preventive effect on the progression of hip OA.

PURPOSE

To (1) report clinical outcomes of arthroscopically treated FAI syndrome with a minimum 5-year follow-up and compare the results to a cohort with FAI treated nonsurgically and (2) determine the influence of hip arthroscopy on the onset and progression of hip OA in patients diagnosed with FAI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who had hip pain and were diagnosed with FAI were included. Exclusion criteria were (1) previous or concomitant hip surgery, (2) <5 years of follow-up, and (3) insufficient radiographs. Patients treated with hip arthroscopy were compared with a cohort of patients with FAI who were treated nonsurgically. Kaplan-Meier estimates of failure (defined as conversion to THA) were performed. Bivariate analysis and Cox regression were used to identify factors associated with inferior clinical and radiographic outcomes.

RESULTS

A total of 957 patients (650 female, 307 male; 1114 hips) (mean age, 28.03 ± 8.9 years [range, 6.5-41.0 years]) with FAI were included. A total of 132 hips underwent hip arthroscopy and 982 hips were nonoperatively treated. The mean follow-up was 12.5 ± 4.7 years (range, 5.0-23.4 years). At the final follow-up, the rate of OA progression was 26.5% in the operative group and 35.2% in the nonoperative cohort (P < .01). Conversion to THA was performed in 6.8% of the surgical patients and 10.5% of the initially nonsurgical patients (P = .19). Additionally, there was no significant difference in the risk of failure between the operatively and nonoperatively treated patients. Male sex, increased age at initial diagnosis, presence of cam morphology, and increased initial Tönnis grade were risk factors for failure (male sex: hazard ratio [HR], 2.3; P < .01; per year of increased age: HR, 1.1; P < .01; presence of cam: HR, 3.5; P < .01; per Tönnis grade: HR, 4.0; P < .01).

CONCLUSION

At a mean follow-up of nearly 13 years, 7% of patients of the surgical group experienced progression to THA, compared with 11% of the nonoperative control group. While most of the operative group showed little to no OA at final follow-up, moderate OA (Tönnis grade 2) was present in 12% of the cohort compared with 22% of nonsurgical patients. Increased age at diagnosis, male sex, presence of a cam morphology, and presence of initial arthritic joint changes were found to be risk factors for failure. The results of this study demonstrated evidence for a preventive effect of hip arthroscopy on the development and progression of OA in young patients with FAI at mid- to long-term follow-up.

The Ambiguity of Names and Landmarks in Radiographs of the Pediatric Pelvis: Variations and a Historical Perspective

For over a century, the plain radiograph has been used to measure and predict the development of pediatric hip conditions. Classic measurements, such as the acetabular index, the center-edge angle, and the migration percentage, have stood the test of time and remain the default tools for any pediatric orthopaedic surgeons. However, in contemporary research, the terminology regarding these measurements has become markedly inconsistent. A substantial number of synonyms, acronyms, and similar, but not identical, terms are used to label measurements. This is perhaps unsurprising, considering decades of use and numerous suggested modifications. The results of treatment cannot be reliably compared if the measured parameters are not identical, and scientific analysis of disease requires consistent terminology. In this review, we aim both to provide historical definitions and identification of radiographic landmarks commonly used in three parameters of interest on pediatric AP radiographs and to examine the variability of landmarks and definitions in contemporary research.

Correlation between Femoral Head Lateralization and Bone Morphology in Primary Hip Osteoarthritis

Background

Osteoarthritis (OA) is the most common disease of the hip in adults, and its etiology is divided into two groups: primary and secondary. Although acetabular dysplasia is the most frequent reason for total hip arthroplasty (THA) in Japan, primary OA has increased recently. Although there are two types of femoral head migration in primary OA: superior and medial, there are some patients with prominent femoral head lateralization. This study aimed at evaluating the relationship between femoral head lateralization and bone morphology of the acetabulum and proximal femur using radiographic factors in primary OA of the hip.

Methods

A retrospective study was conducted between 2008 and 2017 to assess 1308 hips with OA who underwent primary THAs at our institute. The diagnostic criteria for primary OA were Crowe type 1, Sharp's angle <45°, and center-edge (CE) angle >25°. We classified patients with primary OA into two groups based on femoral head lateralization: group L with lateralization or group N without. Radiographic factors included Sharp's angle, CE angle, acetabular inclination, acetabular depth ratio (ADR), acetabular head index (AHI), and femoral neck-shaft angle (FNA), all examined on an anteroposterior pelvic radiograph. Femoral neck anteversion was calculated using computerized axial tomography.

Results

Primary OA was diagnosed in 210/1308 hips (16.1%) (group L: 112 hips (8.6%); group N: 98 (7.5%)). Patient demographics were not significantly different. Radiographic factors with observed significant differences between group L and group N were the average CE angle (33.0° vs. 35.1°, respectively, p = 0.009), ADR (251.6 vs. 273.4, p < 0.001), AHI (77.2 vs. 80.4, p < 0.001), and FNA (136.9° vs. 134.8°, p = 0.012).

Conclusions

This investigation suggests that primary OA with femoral head lateralization demonstrated specific identifiable radiographic characteristics in the acetabulum and proximal femur that might contribute to hip joint instability such as the dysplastic hip.

Developmental dysplasia of the hip is common in patients undergoing total hip arthroplasty under 50 years of age

INTRODUCTION

Developmental dysplasia of the hip (DDH) refers to congenital and/or developmental hip instability that can result in hip joint subluxation or dislocation. When detected neonatally, conservative treatment with hip bracing can restore normal hip anatomy. Missed detection of DDH in the neonatal period or late development of DDH often requires surgical intervention to correct the abnormal anatomy. Furthermore, despite surgical intervention, residual sequelae may persist leading to early osteoarthritis of the hip joint requiring joint replacement surgery.

AIM

This study investigates the prevalence of hip dysplasia in patients undergoing total hip arthroplasty (THA) under 50 years of age.

METHODS

The hip arthroplasty database at a national referral centre was investigated from January 2014 to December 2020. In patients under 50 years of age, those with an adequate pre-operative anteroposterior pelvic radiograph without previous hip arthroplasty were included, while those with inadequate radiographs were excluded. The following measurements were made on the contralateral non-operated hip: (1) lateral centre-edge angle (LCEA), (2) Tönnis angle, (3) acetabular version, (4) acetabular depth, (5) femoral head lateralisation, (6) femoral head extrusion index, and (7) acetabular depth-to-width ratio.

RESULTS

In total, 451 patients were included in this study. Twenty two percent of the patients had hip dysplasia, based on a LCEA of <25° and 42.6% of patients had hip dysplasia, based on a Tönnis angle of > 10°. The mean LCEA and Tönnis angle were 31.47 ± 9.64 and 9.82 ± 6.79°, respectively.

CONCLUSION

Hip dysplasia is common in patients undergoing THA under the age of 50 years with over 40% having dysplasia according to the Tönnis angle. Classification of primary and secondary osteoarthritis in the joint registries will benefit our knowledge on the prevalence of DDH in the adult population.

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

BACKGROUND

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.

PURPOSE

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.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

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).

RESULTS

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).

CONCLUSION

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.

Does pelvic tilt change with a peri-acetabular osteotomy?

Change in pelvic tilt (PT) during and after peri-acetabular osteotomy (PAO) is important for surgical planning. The aims of this study were to (i) determine how PT varies throughout the course of treatment in patients undergoing PAO, (ii) test what factors influence the change in PT and (iii) assess whether changes in PT influenced achieved correction. This is an retrospective, single-centre, consecutive case series of 111 patients treated with PAO for global (n = 79), posterior (n = 49) or anterior dysplasia (n = 6) (mean age: 27.3 ± 7.7 years; 85% females). PT was determined on supine, anteroposterior pelvic radiographs pre-, intra-, 1 day, 6 weeks and 1 year post-operatively, using the sacro-femoral-pubic (SFP) angle, a validated, surrogate marker of PT. An optimal acetabular correction was based on the lateral centre-edge angle (25°-40°), acetabular index (-5° to 10°) and cross-over ratio (<20%). There was a significant difference across pre- (70.1° ± 4.8°), 1-day (71.7° ± 4.3°; P < 0.001) and early post-operative SFP (70.6° ± 4.7°; P = 0.004). The difference in SPF between pre-operative and 1-year post-operative was -0.5° ± 3.1° (P = 0.043), with 9% of cases having a difference of >5°. The difference in SFP did not correlate with age, sex, body mass index, type of dysplasia or achievement of optimal acetabular correction (P = 0.1-0.9). In the early post-operative period, PT is reduced, leading to a relative appearance of acetabular retroversion, which gradually corrects and is restored by annual follow-up. The degree of change in PT during PAO did not adversely affect fragment orientation. PT does not significantly change in most patients undergoing PAO and therefore does not appear to be a compensatory mechanism.

Acetabular Rim Ossification Variants Are Found in Almost 20% of Patients Presenting With Hip Pain

Purpose

To determine the prevalence of 4 different types of acetabular rim ossifications, including partial labral ossification or punctate calcification, true os acetabuli, acetabular rim stress fracture, and complete labral ossification, and to determine whether different types of periacetabular ossifications are linked to demographic or radiological factors.

Methods

We retrospectively reviewed the medial records of patients presenting for hip-related complaints at 2 sports medicine practices from September 2007 to December 2009. An anteroposterior radiograph of both hips and a lateral radiograph of each hip was obtained for all patients and reviewed for findings of cam and pincer femoroacetabular impingement, degenerative changes (Tönnis grade), and periacetabular calcifications for both hips. These parameters were also evaluated with respect to symptoms, sex, and age.

Results

Four hundred ninety-one consecutive patients (982 hips) presented to 2 orthopaedic surgeons at 2 centers for "hip"-related complaints. There were 223 males and 268 females (age 39 ± 14 years). The overall prevalence of periacetabular calcifications in hips was 17.6%, with 56.6% of calcifications in the symptomatic hip and 43.4% in the contralateral hip. Four basic patterns of calcification were identified: punctuate calcifications within the labrum (8.0% hips), large rounded calcifications (os acetabuli) (4.2% hip), large fragments with a vertical line of the superior-lateral acetabular rim, consistent with healed or non-healed stress fracture (2.0% hips), and complete ossification of the labrum (3.4% hips). Overall, male sex (P = .002), increased lateral center-edge angle (P = .046), and higher Tönnis grade (P < .001) statistically predicted the presence of periacetabular ossification. Punctate calcifications were more prevalent in males (P = .002). Higher Tönnis grade (P = .029) and increased alpha angle (P = .046) were more prevalent with os acetabuli. Younger age (P = .001), male sex (P = .048), increased alpha angle (P = .012), and increased lateral center-edge angle (P < .001) were more prevalent in acetabular rim fractures. No factors were statistically significant at predicting the presence of an ossified labrum.

Conclusions

Periacetabular calcifications are not uncommon. Four particular patterns of calcification are identified: punctate labral calcifications (8%), larger rounded calcifications (i.e., os acetabuli) (4.2%), acetabular rim stress fractures (2%), and complete ossification of the labrum (3.4%) for a combined prevalence of 17.6% in patients presenting to an orthopaedic surgeon with "hip"-related complaints. Nearly half were in the asymptomatic hip. Male sex had a higher prevalence of periacetabular calcifications. An increased lateral center edge angle and higher Tönnis grade also had a higher prevalence of periacetabular calcifications. Younger male patients are more likely to have acetabular rim stress fractures. Patients with an increased alpha angle have a higher prevalence of os acetabuli and rim stress fractures.

Clinical Relevance

This study aims to identify, quantify, and categorize periacetabular calcifications about the hip. Their clinical relationships and relevance have been discussed, but no study has distinctly categorized the various types and their prevalence. This study provides a framework for identification and categorization.

Acetabular Rim Disorders: Epidemiology, Etiology, Management, and Outcomes

» Anatomic disorders of the acetabular rim are a common, correctable source of hip pain in younger patients.» Some common conditions of involving abnormal acetabular rim morphology include developmental dysplasia of the hip, pincer-type femoroacetabular impingement, acetabular protrusion, and acetabular retroversion.» Treatment option for these conditions were historically limited to open osteotomy and osteoplasty procedures; however, there is increasing use of arthroscopic intervention for these patients.» Arthroscopic intervention has demonstrated short-term success in a variety of focal acetabular rim disorders; however, further research is needed to determine the long-term outcomes of these procedures and their utility in more global pathology.

What Is Important to the Younger Person (≤50 Years) When Having a Total Hip Arthroplasty: A Systematic Literature Review

Total hip arthroplasties (THAs) are usually performed in older patients. Despite a growing number of THAs in younger adults, it is unclear whether they have similar priorities in recovery compared with their older counterparts. The purpose of this systematic review was to explore younger patients' priorities when undergoing a THA. Multiple databases were searched in September 2021 prioritizing qualitative data. This review was reported using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Of 14,495 articles screened, nine remained for analysis. Four common themes were discovered: improving function and mobility; pain; relationships; and patient expectations and education. However, there was insufficient information to clarify whether these themes could be attributed directly to younger adults undergoing a THA. The absence of research on THA patients younger than 50 years results in the loss of the voices of these patients. Further research is essential to ensure their needs are identified, addressed, and met.

Postoperative alpha angle seems to be important for the achievement of clinical significance at a minimum 5-year follow-up after primary hip arthroscopy

The purpose of the present study was to clarify whether there is an association of postoperative alpha value with functional scores or progression of osteoarthritis at X-rays at the midterm after arthroscopic treatment of femoroacetabular impingement (FAI) syndrome with femoral osteoplasty, labral repair or debridement and rim trimming. A retrospective review of prospectively gathered data from 2013 to 2017 was performed. All patients who underwent first-time unilateral hip arthroscopy for FAI resection with 5-year follow-up were included. Patient-reported outcomes included the modified Harris Hip Score (mHHS) and Visual Analog Scale for Pain (Pain VAS). The progression of osteoarthritis (Tönnis grade) and radiological parameters (alpha angle, lateral center-edge angle [LCEA] and head-neck offset) were evaluated. A receiver operating characteristic (ROC) analysis was used to evaluate the correlation between significant variables and achievement of patient-acceptable symptomatic state (PASS) and degree of osteoarthritis. We identified 52 patients with a minimum 5-year follow-up (average, 6.7 years). The average patient age was 33.9 ± 11.5 years. There were 19 (36.5%) female patients. The mHHS improved from 60.1 ± 13.4 before surgery to 86.8 ± 14 after surgery (P < 0.001). The Pain VAS decreased from 6.21 before surgery to 2 after surgery (P < 0.001). Overall, 69% achieved the PASS for mHHS. The ROC curve for postoperative alpha angle demonstrated acceptable discrimination between patients achieving a fifth-year PASS value and those who did not have an area under the curve of 0.72. Patients having a postoperative alpha angle of ≤48.3° achieved the fifth-year PASS value at a significantly higher rate than patients having a postoperative alpha angle of >48.3° (P = 0.002). The postoperative alpha angle is a predictor of the achievement of the fifth-year PASS value for the mHHS. A threshold of ≤48.3° had a sensitivity of 0.75 and a specificity of 0.69 to predict positivity. Level of evidence IV.

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.

Ten-Year Survivorship, Outcomes, and Sports Participation in Athletes After Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome

BACKGROUND

Hip arthroscopy is an effective treatment tool for athletes with femoroacetabular impingement (FAI) syndrome. However, long-term data are scarce.

PURPOSE

To assess survivorship, minimum 10-year patient-reported outcome measures (PROMs), and sports participation after primary hip arthroscopy for FAI syndrome in athletes and to perform a propensity-matched comparison between patients undergoing labral debridement and labral repair.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Athletes who underwent hip arthroscopy for FAI syndrome between February 2008 and December 2010 were eligible. Exclusion criteria were other ipsilateral hip condition, Tönnis grade ≥2, or no baseline PROMs. Survivorship was defined as no conversion to total hip arthroplasty. The Patient Acceptable Symptom State (PASS), minimal clinically important difference (MCID), maximum outcome improvement (MOI) satisfaction threshold, and sports participation were reported. A propensity-matched comparison between labral debridement and labral repair was performed. Two additional propensity-matched subanalyses were performed for capsular management and cartilage damage.

RESULTS

In total, 189 hips (177 patients) were included. The mean ± SD follow-up was 127.2 ± 6.0 months. Survivorship was 85.7%. Significant improvement in all PROMs was reported (P < .001). A total of 46 athletes with labral repair were propensity matched to 46 athletes with labral debridement. This subanalysis demonstrated significant and comparable improvement in all PROMs at minimum 10-year follow-up (P < .001). For the labral repair group, the PASS achievement rates were 88.9% for the modified Harris Hip Score (mHHS) and 80% for the Hip Outcome Score-Sport Specific Subscale (HOS-SSS); the MCID achievement rates were 80.6% for the mHHS and 84% for HOS-SSS; and for the MOI satisfaction threshold, rates were 77.8%, 80.6%, and 55.6% for the mHHS, Nonarthritic Hip Score, and visual analog scale, respectively. For the labral debridement group, the PASS achievement rates were 85.3% for the mHHS and 70.4% for the HOS-SSS; the MCID achievement rates were 81.8% for the mHHS and 74.1% for HOS-SSS; and for the MOI satisfaction threshold, rates were 72.7%, 81.8%, and 66.7% for the mHHS, Nonarthritic Hip Score, and visual analog scale. Total hip arthroplasty conversions occurred significantly sooner with labral debridement than labral repair (P = .048). Age was identified as a significant predictor of achieving the PASS.

CONCLUSION

Primary hip arthroscopy for FAI syndrome in athletes results in 85.7% survivorship and sustained PROM improvement at a minimum 10-year follow-up. A significant time delay to total hip arthroplasty conversion at 10-year follow-up was reported with labral repair over debridement, although this should be interpreted with caution, as the total number of conversions was small.

Acetabular deficiency in borderline hip dysplasia is underestimated by lateral center edge angle alone

INTRODUCTION

In hip preservation surgery, the term "borderline hip dysplasia" was used when the lateral center edge angle (LCEA), historically described by Wiberg, measured 18-25°. In recent years, several radiographic parameters have been described to assess the antero posterior coverage of the femoral head, for example, the anterior and posterior wall index (AWI and PWI). This allowed an increasingly comprehensive understanding of acetabular morphology and a questioning of the borderline definition.

MATERIAL AND METHODS

A retrospective review of 397 consecutive hips was performed, all treated with triple pelvic osteotomy (TPO) due to symptomatic hip dysplasia. On all preoperative pelvic radiographs with a LCEA of 18-25°, acetabular index (AI), AWI and PWI were measured. With these values, the hips were categorized into laterally, antero-laterally and postero-laterally dysplastic and stratified by gender. Intra- and interobserver correlation of the parameters was analyzed by intraclass correlation coefficient (ICC).

RESULTS

According to LCEA, 192 hips were identified as "borderline dysplastic". Based on AWI and PWI, the categorization resulted in 116 laterally dysplastic (60.4%), 33 antero-laterally (17.2%) and 43 postero-laterally dysplastic hips (22.4%). Gender stratification revealed that male acetabula seemed to be slightly more postero-laterally deficient than female (mean PWI 0.80 vs 0.89; p = 0.017). ICC confirmed highly accurate and reproducible readings of all parameters.

CONCLUSION

The rather high proportion of symptomatic hips labelled borderline dysplastic suggested, that there might be substantial acetabular deficiency not recognizable by LCEA. Comprehensive deformity analysis using LCEA, AI, AWI and PWI showed, that 40% of these hips were deficient either antero-laterally or postero-laterally. Male acetabula were more deficient postero-laterally than female.

Hip Pain and Movement Dysfunction Associated With Nonarthritic Hip Joint Pain: A Revision

The Academy of Orthopaedic Physical Therapy (AOPT), formerly the Orthopaedic Section of the American Physical Therapy Association (APTA), has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). This is an update to the 2014 Clinical Practice Guideline (CPG) for Hip Pain and Movement Dysfunction Associated with Nonarthritic Hip Joint Pain. The goals of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. This current CPG covers pathoanatomical features, clinical course, prognosis, diagnosis, examination, and physical therapy interventions in the management of nonarthritic hip joint pain. J Orthop Sports Phys Ther 2023;53(7):CPG1-CPG70. doi:10.2519/jospt.2023.0302.

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

PURPOSE

Insufficient 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.

METHODS

In 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.

RESULTS

Upon 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.

CONCLUSION

Anterior 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.

The Direct Anterior Approach (DAA) as a Standard Approach for Total Hip Arthroplasty (THA) in Coxa Profunda and Protrusio Acetabuli? A Radiographic Analysis of 188 Cases

INTRODUCTION

The direct anterior approach (DAA) represents a well-recognized soft tissue sparing technique for primary total hip arthroplasty (THA). The feasibility and suitability of the DAA in cases of complex acetabular deformities, namely coxa profunda (CP) and protrusio acetabuli (PA), remain to be determined.

METHODS

A total of 188 cases of CP (100 cases) and PA (88 cases) hips undergoing primary THA via the DAA were retrospectively analyzed. Surgical and radiographic parameters were evaluated and potential complications were assessed. Finally, successful implantation was defined if surgical and radiographic parameters were well within established values of non-complex primary THA.

RESULTS

In 159 hips, the medial border of the acetabular component was transferred laterally to the ilioischial line, corresponding to a fully treated acetabular protrusion. In 23 (12.23%) cases, mild, and in 5 (2.66%) cases, moderate residual acetabular protrusion remained after THA. Postoperatively, 11.40% (PA group) and 9.00% (CP group) had a leg length discrepancy (LLD) greater than 10 mm. The mean operative time was significantly less than 60 min. A linear relationship between the BMI and operative time was observed, with an additional 0.9 min of operative time per BMI unit. Overall, complications were rare and did not differ between the two groups.

CONCLUSION

The results of this study suggest that the DAA is a suitable approach for primary THA in patients with coxa profunda and acetabular protrusion if performed by experienced surgeons familiar with the DAA. Obese patients with acetabular protrusion may pose a significant limitation to the DAA and caution should be advised in cases of obesity.

Sagittal deformity of Garden type I and II geriatric femoral neck fractures is frequently misclassified by lateral radiographs

The objective of this study was to determine the validity and inter-rater reliability of radiographic assessment of sagittal deformity of femoral neck fractures.

Design

This is a retrospective cohort study.

Setting

Level 1 trauma center.

Patients/Participants

Thirty-one patients 65 years or older who sustained low-energy, Garden type I/II femoral neck fractures imaged with biplanar radiographs and either computed tomography or magnetic resonance imaging were included.

Main Outcome Measurements

Preoperative sagittal tilt was measured on lateral radiographs and compared with the tilt identified on advanced imaging. Fractures were defined as "high-risk" if posterior tilt was ≥20 degrees or anterior tilt was >10 degrees.

Results

Of 31 Garden type I/II femoral neck fractures, advanced imaging identified 10 high-risk fractures including 8 (25.8%) with posterior tilt ≥20 degrees and 2 (6.5%) with anterior tilt >10 degrees. Overall, there was no significant difference between sagittal tilt measured using lateral radiographs and advanced imaging (P = 0.84), and the 3 raters had good agreement between their measurements of sagittal tilt on lateral radiographs (interclass correlation coefficient 0.79, 95% confidence interval [0.65, 0.88], P < 0.01). However, for high-risk fractures, radiographic measurements from lateral radiographs alone resulted in greater variability and underestimation of tilt by 5.2 degrees (95% confidence interval [-18.68, 8.28]) when compared with computed tomography/magnetic resonance imaging. Owing to this underestimation of sagittal tilt, the raters misclassified high-risk fractures as "low-risk" in most cases (averaging 6.3 of 10, 63%, range 6 - 7) when using lateral radiographs while low-risk fractures were rarely misclassified as high-risk (averaging 1.7 of 21, 7.9%, range 1 - 3, P = 0.01).

Conclusions

Lateral radiographs frequently lead surgeons to misclassify high-risk sagittal tilt of low-energy femoral neck fractures as low-risk. Further research is necessary to improve the assessment of sagittal plane deformity for these injuries.

Level of Evidence

Level IV diagnostic study.

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.

Optimizing post-operative imaging: a retrospective cohort study comparing two methods of lateral hip radiography after cephalomedullary nail surgery

BACKGROUND

Currently, there is no consensus on the most appropriate technique for obtaining lateral hip radiographs after cephalomedullary nail (CMN) surgery. The aim of this study was to investigate the distribution of two commonly used postoperative lateral hip radiographic methods (classic lateral view and modified lateral view) and try to find out which one is better suited for this situation.

METHODS

A retrospective analysis was conducted on 146 patients who underwent surgical fixation for extracapsular hip fractures between January 2018 and June 2022. The main outcome measured was the angle between the straight part of the CMN and the lag screw/blade on hip lateral X-rays (CMNA). The lateral hip radiographs were categorized into two groups based on different lateral hip radiographic methods. CMNA, patient age, gender, fracture classification based on the 2018 AO classification, nail length (short/long), surgical side (left/right), height, weight, BMI, preoperative waiting time, postoperative imaging interval were collected and compared between the two groups.

RESULTS

The distribution trend of CMNA significantly differs between two types of hip joint lateral radiographic methods. Specifically, the classic lateral method exhibits a significantly bimodal and skewed distribution with a median (p25, p75) of -21.6° (-31.2°, -8°), whereas the modified lateral method presents a normal distribution with a mean ± SD of +7.57° ± 14.4°. The difference in the Mean Rank between the classic (47.10) and the modified (102.96) lateral methods is statistically significant (P < 0.001).

CONCLUSIONS

The CMNA method is an excellent tool for studying the lateral distribution.We recommend using the modified lateral view as the preferred option for obtaining lateral hip radiographs after CMN surgery due to its superior distribution of CMNA and greater patient-friendliness.

ACR Appropriateness Criteria® Chronic Hip Pain: 2022 Update

Chronic hip pain is a frequent chief complaint for adult patients who present for evaluation in a variety of clinical practice settings. Following a targeted history and physical examination, imaging plays a vital role in elucidating the etiologies of a patient's symptoms, as a wide spectrum of pathological entities may cause chronic hip pain. Radiography is usually the appropriate initial imaging test following a clinical examination. Depending on the clinical picture, advanced cross-sectional imaging may be subsequently performed for further evaluation. This documents provides best practice for the imaging workup of chronic hip pain in patients presenting with a variety of clinical scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Accuracy of digital templating in uncemented primary total hip arthroplasty: which factors are associated with accuracy of preoperative planning?

BACKGROUND

Preoperative planning is a fundamental step for successful total hip arthroplasty (THA). Studies have highlighted the accuracy of preoperative digital templating for estimating acetabular cup and stem size. Stem design such as single-wedge metadiaphyseal (Type 1 stem) versus mid-short stem (microplasty) and surgical approach (anterior, direct lateral or posterior) have not been well investigated as predictors of THA templating accuracy.

METHODS

204 patients (220 hips) who had undergone elective THA between November 2016 and December 2019 and presented a saved preoperative template were retrospectively reviewed. Templates from 5 different surgeons were involved in the analysis. 3 different approaches were used: direct lateral (DL), posterior (PA), direct anterior (DAA). 2 different stem designs were used: single-wedge metadiaphyseal and single-wedge mid-short (Biomet Taperloc Microplasty), while the acetabular component remained the same. Bivariate and multivariate regression analyses were performed to determine predictors of accuracy.

RESULTS

Femoral component size templating accuracy was significantly improved when using the single-wedge mid-short stem (Taperloc Microplasty) design when performing bivariate analysis. Although accuracy of cup sizing was not affected by approach, precision was significantly better in the PA group (p < 0.05). Accuracy of templating was found to be independent of BMI and gender but dependent on presence of calibration marker and stem design (p < 0.05).

CONCLUSIONS

When striving for improved templating accuracy, acetabular and femoral component accuracy were best achieved using a calibration marker and a metaphyseal short femoral stem design.

Borderline Dysplasia After Primary Hip Arthroscopy with Capsular Plication and Labral Preservation: Ten-Year Survivorship and Patient-Reported Outcomes

BACKGROUND

The arthroscopic management of borderline hip dysplasia (BHD) is controversial, and long-term follow-up data are scarce. The purpose of this study was to report prospectively collected survivorship and patient-reported outcome measures (PROMs) at a minimum 10-year follow-up following primary hip arthroscopy with capsular plication and labral preservation in patients with BHD.

METHODS

Data were prospectively collected on all patients who underwent primary hip arthroscopy between September 2008 and September 2011. Patients with BHD (defined by a lateral center-edge angle [LCEA] between 18° and 25°) were included. Preoperative and minimum 10-year follow-up scores for the modified Harris hip score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sports Specific Subscale (HOS-SSS), and visual analog scale (VAS) for pain were collected. Exclusion criteria were prior ipsilateral hip surgery, Workers' Compensation status, Tönnis grade of >1, previous hip conditions, or LCEA of <18°. Survivorship was defined as no conversion to total hip arthroplasty (THA). The risk factors for THA conversion were analyzed. The achievement rate for the minimal clinically important difference (MCID) was reported. A propensity-matched comparison with a control group without BHD was performed.

RESULTS

Forty-five (80%) of 56 eligible hips were included in this study: 38 hips (84%) of female patients and 7 hips (16%) of male patients. The mean patient age was 31.0 ± 12.9 years, and the mean patient body mass index (BMI) was 24.5 ± 5.4 kg/m2. The 10-year survivorship was 82.2%, and there was significant improvement in all PROMs and VAS pain from baseline to the minimum 10-year follow-up (p < 0.001). The odds of undergoing conversion to THA were 4.4 times higher for patients with a BMI of ≥23 kg/m2 and 7.1 times higher for patients who were ≥42 years of age. The MCID was achieved at high rates for the mHHS (79%), NAHS (79%), HOS-SSS (70%), and VAS pain (76%). The minimum 10-year survivorship, PROMs, and MCID achievement rates for the BHD group were comparable with those for the control group.

CONCLUSIONS

Patients with BHD who underwent primary hip arthroscopy with capsular plication and labral preservation demonstrated an overall survivorship of 82.2% and significant improvement in all PROMs and achieved the MCID at high rates at a minimum 10-year follow-up.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Standard radiographic values for the acetabulum in Japanese adolescents: a cross-sectional study

BACKGROUND

Most previous reports of normal acetabular radiographic values focused on adults or elderly people. Recent reports have described premature hip osteoarthritis in adolescents not caused by acetabular dysplasia. In addition, there is a certain failure rate of surgical treatment for young patients with borderline acetabular dysplasia. Accurate indices for treatment of adolescent hips are unclear because standard measurement values of the adolescent acetabulum have not been reported.

METHODS

This cross-sectional study involved 552 Japanese adolescents aged 12-18 years who had scoliosis or suspected scoliosis and asymptomatic hips. All persons underwent plain standing anteroposterior whole-spine radiography, and measurements were obtained using the pelvic part of the radiograph. We excluded persons who were unable to correctly perform measurements because of conditions such as pelvic rotation or lateral inclination and persons in whom closure of the triradiate cartilage or closure of the secondary ossification centers of the acetabulum had not yet occurred. In 1101 hips, we measured the lateral center-edge angle (LCEA), Tönnis angle, Sharp angle, acetabular head index (AHI), lateral subluxation (LS), vertical subluxation (VS), and peak-to-edge distance (PED). We evaluated the correlation coefficient and coefficient of determination between each parameter and age, height, body weight, and body mass index (BMI) and assessed the intra- and inter-rater reliability of each radiographic parameter.

RESULTS

Among all hips, the mean of each parameter was as follows: LCEA, 27.9° ± 4.8°; Tönnis angle, 5.0° ± 3.7°; Sharp angle, 44.1° ± 3.1°; AHI, 82.1% ± 5.5%; LS, 5.4 ± 1.4 mm; VS, 0.3 ± 1.2 mm; and PED, 14.0 ± 2.3 mm. The correlation between each parameter and age, height, body weight, and BMI was considerably low. Intra- and inter-rater reliability was moderate or good for almost all parameters.

CONCLUSIONS

The values for each radiographic parameter of the acetabulum in this study are considered standard for the adolescent acetabulum without age-related changes. Some parameters differ slightly from the normal values for adults or elderly people in previous reports; thus, we suggest careful evaluation of these parameters for adolescents.

An Interpretable Machine Learning Model for Predicting 10-Year Total Hip Arthroplasty Risk

BACKGROUND

As the demand for total hip arthroplasty (THA) rises, a predictive model for THA risk may aid patients and clinicians in augmenting shared decision-making. We aimed to develop and validate a model predicting THA within 10 years in patients using demographic, clinical, and deep learning (DL)-automated radiographic measurements.

METHODS

Patients enrolled in the Osteoarthritis Initiative were included. DL algorithms measuring osteoarthritis- and dysplasia-relevant parameters on baseline pelvis radiographs were developed. Demographic, clinical, and radiographic measurement variables were then used to train generalized additive models to predict THA within 10 years from baseline. A total of 4,796 patients were included (9,592 hips; 58% female; 230 THAs (2.4%)). Model performance using 1) baseline demographic and clinical variables 2) radiographic variables, and 3) all variables were compared.

RESULTS

Using 110 demographic and clinical variables, the model had a baseline area under the receiver operating curve (AUROC) of 0.68 and area under the precision recall curve (AUPRC) of 0.08. Using 26 DL-automated hip measurements, the AUROC was 0.77 and AUPRC was 0.22. Combining all variables, the model improved to an AUROC of 0.81 and AUPRC of 0.28. Three of the top five predictive features in the combined model were radiographic variables including minimum joint space along with hip pain and analgesic use. Partial dependency plots revealed predictive discontinuities for radiographic measurements consistent with literature thresholds of osteoarthritis progression and hip dysplasia.

CONCLUSION

A machine learning model predicting 10-year THA performed more accurately with DL radiographic measurements. The model weighted predictive variables in concordance with clinical THA-pathology assessments.

Dysplastic hips demonstrate increased joint translation at higher body mass index

OBJECTIVE

To determine which radiographic measures used to define the severity of hip dysplasia are associated with hip joint translation and to investigate relationships between position, body mass index, and joint translation.

MATERIALS AND METHODS

This is a cross-sectional retrospective study evaluating 10 validated radiographic measures of dysplasia on weight-bearing AP pelvis and supine 45-degree bilateral Dunn radiographs of 93 young adults with symptomatic hip dysplasia presenting to a single academic institution between October 2016 and May 2019. We determined the difference between standing and supine measurements for each hip and the correlation of each measure with the patient's body mass index.

RESULTS

Femoral head extrusion index was 2.49% lower on supine X-ray (p = 0.0020). Patients with higher body mass index had higher center gap distance (p = 0.0274), femoral head extrusion (p = 0.0170), and femoral head lateralization (p = 0.0028) when standing. They also had higher Tönnis angle (p_standing = 0.0076, p_supine = 0.0121) and lower lateral center-edge angle (p_standing = 0.0196, p_supine = 0.0410) in both positions. The difference in femoral head lateralization between standing and supine positions increased with higher body mass index (p = 0.0081).

CONCLUSION

Translation of the hip joint with position change is demonstrated by decreased femoral head extrusion index on supine X-ray. Patients with higher body mass index had more dysplastic hips, as measured by five of six radiographic outcomes of dysplasia, and experienced more translation with weight-bearing, reflected by increased femoral head lateralization.

Patients With Simple Posterior Hip Dislocations Have Higher Rates of Hip Dysplasia and Borderline Dysplasia

OBJECTIVES

To determine if patients suffering simple, posterior hip dislocations are more likely to display dysplastic characteristics of their acetabulum as compared with those suffering fracture dislocations.

DESIGN

Retrospective cohort study.

SETTING

Level 1 trauma center.

PATIENTS/PARTICIPANTS

Eighty-six patients suffering posterior, native hip dislocations over a 5-year period.

MAIN OUTCOME MEASUREMENT

The primary outcome was measurement of the lateral center edge angle (LCEA), acetabular index (AI), acetabular version, and femoro-epiphyseal acetabular roof (FEAR) index.

RESULTS

Eighteen patients (20.9%) sustained simple dislocations, whereas 68 patients (79.1%) suffered fracture dislocations. Patients with simple dislocations had decreased LCEA (25.7 vs. 34.3; P < 0.001), increased AI (7.4 vs. 5.8; P = 0.019), and decreased acetabular anteversion (14.02 vs. 18.45; P = 0.011). Additionally, patients with simple dislocations had higher rates of dysplasia and borderline dysplasia (61.1% vs. 7.3%; P < 0.001). Patients with fracture dislocations had higher rates of concomitant injuries (60.9% vs. 29.4%; P = 0.039) and higher injury severity scores (8.1 vs. 12.3; P = 0.022).

CONCLUSION

Patients who sustain simple hip dislocations are more likely to have undercoverage of the femoral head by the acetabulum as compared with patients suffering fracture dislocations. In addition, the simple dislocation group had a lower ISS and fewer concomitant injuries, which likely relates to a lower energy required for dislocation in the setting of lesser bony constraint. Surgeons treating these complicated injuries should consider measurements of LCE and AI when counseling patients on treatment strategies.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Radiographically successful periacetabular osteotomy does not achieve optimal contact mechanics in dysplastic hips

BACKGROUND

Optimal correction of hip dysplasia via periacetabular osteotomy may reduce osteoarthritis development by reducing damaging contact stress. The objective of this study was to computationally determine if patient-specific acetabular corrections that optimize contact mechanics can improve upon contact mechanics resulting from clinically successful, surgically achieved corrections.

METHODS

Preoperative and postoperative hip models were retrospectively created from CT scans of 20 dysplasia patients treated with periacetabular osteotomy. A digitally extracted acetabular fragment was computationally rotated in 2-degree increments around anteroposterior and oblique axes to simulate candidate acetabular reorientations. From discrete element analysis of each patient's set of candidate reorientation models, a mechanically optimal reorientation that minimized chronic contact stress exposure and a clinically optimal reorientation that balanced improving mechanics with surgically acceptable acetabular coverage angles was selected. Radiographic coverage, contact area, peak/mean contact stress, and peak/mean chronic exposure were compared between mechanically optimal, clinically optimal, and surgically achieved orientations.

FINDINGS

Compared to actual surgical corrections, computationally derived mechanically/clinically optimal reorientations had a median[IQR] 13[4-16]/8[3-12] degrees and 16[6-26]/10[3-16] degrees more lateral and anterior coverage, respectively. Mechanically/clinically optimal reorientations had 212[143-353]/217[111-280] mm2 more contact area and 8.2[5.8-11.1]/6.4[4.5-9.3] MPa lower peak contact stresses than surgical corrections. Chronic metrics demonstrated similar findings (p ≤ 0.003 for all comparisons).

INTERPRETATION

Computationally selected orientations achieved a greater mechanical improvement than surgically achieved corrections; however, many predicted corrections would be considered acetabular over-coverage. Identifying patient-specific corrections that balance optimizing mechanics with clinical constraints will be necessary to reduce the risk of osteoarthritis progression after periacetabular osteotomy.

Can an artificial intelligence powered software reliably assess pelvic radiographs?

PURPOSE

Despite advances of three-dimensional imaging pelvic radiographs remain the cornerstone in the evaluation of the hip joint. However, large inter- and intra-rater variabilities were reported due to subjective landmark setting. Artificial intelligence (AI)-powered software applications could improve the reproducibility of pelvic radiograph evaluation by providing standardized measurements. The aim of this study was to evaluate the reliability and agreement of a newly developed AI algorithm for the evaluation of pelvic radiographs.

METHODS

Three-hundred pelvic radiographs from 280 patients with different degrees of acetabular coverage and osteoarthritis (Tönnis Grade 0 to 3) were evaluated. Reliability and agreement between manual measurements and the outputs of the AI software were assessed for the lateral-center-edge (LCE) angle, neck-shaft angle, sharp angle, acetabular index, as well as the femoral head extrusion index.

RESULTS

The AI software provided reliable results in 94.3% (283/300). The ICC values ranged between 0.73 for the Acetabular Index to 0.80 for the LCE Angle. Agreement between readers and AI outputs, given by the standard error of measurement (SEM), was good for hips with normal coverage (LCE-SEM: 3.4°) and no osteoarthritis (LCE-SEM: 3.3°) and worse for hips with undercoverage (LCE-SEM: 5.2°) or severe osteoarthritis (LCE-SEM: 5.1°).

CONCLUSION

AI-powered applications are a reliable alternative to manual evaluation of pelvic radiographs. While being accurate for patients with normal acetabular coverage and mild signs of osteoarthritis, it needs improvement in the evaluation of patients with hip dysplasia and severe osteoarthritis.

John Charnley Award: A Quantitative Fluoroscopic Tool Improves Acetabular Fragment Positioning in Periacetabular Osteotomy

BACKGROUND

Radiographic assessment of acetabular fragment positioning during periacetabular osteotomy (PAO) has been linked to hip survivorship. Intraoperative plain radiographs are time and resource intensive, while fluoroscopy can introduce image distortion affecting measurement accuracy. Our purpose was to determine whether intraoperative fluoroscopy-based measurements with a distortion correcting fluoroscopic tool improved PAO measurement targets.

METHODS

We retrospectively reviewed 570 PAOs; 136 PAOs utilized a distortion correcting fluoroscopic tool, and 434 PAOs performed with routine fluoroscopy, prior to this technology. Lateral center-edge angle (LCEA), acetabular index (AI), posterior wall sign (PWS), and anterior center-edge angle (ACEA) were measured on preoperative standing radiographs, intraoperative fluoroscopic images, and postoperative standing radiographs. Defined target zones of correction were AI: 0-10^°, ACEA: 25-40^°, LCEA: 25-40^°, PWS: negative. Postoperative correction in zones and patient-reported outcomes were compared using chi-square tests and paired t-tests, respectively.

RESULTS

The average difference between postcorrection fluoroscopic measurements and 6-week postoperative radiographs was 0.21° for LCEA, 0.01° for ACEA, and -0.07° for AI (all P < .01). The PWS agreement was 92%. The percentages of hips meeting target goals overall improved with the new fluoroscopic tool: 74%-92% for LCEA (P < .01), 72%-85% for ACEA (P < .01), and 69 versus 74% for AI (P = .25), though there was no improvement in PWS (85 versus 85%, P = .92). All patient-reported outcomes except PROMIS Mental Health were significantly improved at most recent follow-up.

CONCLUSIONS

Our study demonstrated improved PAO measurements and target goals with the use of a distortion correcting quantitative fluoroscopic real-time measuring device. This value-additive tool gives reliable quantitative measurements of correction without interfering with surgical workflow.

Radiographic Predictors of Reoperation in Adolescents Undergoing Hip Preservation Surgery for Femoroacetabular Impingement

BACKGROUND

Femoroacetabular impingement (FAI) is a condition caused by repetitive abutment of a morphologically abnormal proximal femur and/or acetabulum that may result in chondral and labral pathology. An understanding of radiographic parameters associated with successful primary surgery has not been well established.

PURPOSE

To determine preoperative radiographic parameters that predict reoperation for FAI and correlate radiographic measurements with outcomes in these patients.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A prospectively collected institutional registry of adolescent patients (age, <19 years) who underwent surgery for FAI (arthroscopic/open) was reviewed. Preoperative standing anteroposterior pelvic radiographs were analyzed for femoroepiphyseal acetabular roof (FEAR) index, as well as lateral center-edge angle (LCEA) and alpha, Tönnis, and Sharp angles. Patient-reported outcomes (PROs) (modified Harris Hip Score, Hip disability and Osteoarthritis Outcome Score) were analyzed preoperatively and at 1- and 2-year followup. Radiographic indication of risk for reoperation was evaluated using receiver operating characteristic (ROC) analysis. Spearman correlation was calculated between radiographic measurements and PROs at 2 years postoperatively.

RESULTS

A total of 81 patients (91 hips) underwent primary surgery (57 surgical dislocations vs 34 arthroscopies) for FAI. The mean age at time of primary operation was 16.23 years (range, 10.4-19.6 years) (73.6% female). Eleven hips (12.1%) underwent reoperation at a mean of 20.6 months from primary surgery. The LCEA, FEAR index, Tönnis angle, and Sharp angle before index surgery were significantly different (P < .05) between patients who underwent reoperation and those who did not. ROC analysis indicated that LCEA <22°, FEAR index >-8.7°, Tönnis angle >6.0°, and Sharp angle >44° were predictors for increased risk of reoperation. Using the cutoff values from the ROC analysis in this series, 43% of patients with an LCEA ≤22° had a repeat procedure, while only 8% of those with an LCEA >22° had a repeat procedure. Similar trends were seen with the other aforementioned acetabular radiographic measurements (FEAR index, Tönnis angle, Sharp angle). Patients who did not require a reoperation demonstrated significant improvement in all PRO categories from their preoperative to 2-year postoperative visits (P < .0001).

CONCLUSION

In patients undergoing treatment for FAI, a reoperation was associated with radiographic signs of hip dysplasia, indicating that patients with a shallower acetabulum are at risk for a repeat operation.

How to perform correct templating in total hip replacement

Templating plays a key role in surgery that is often underestimated. There is a difference between planning and templating: in the first not only the hip is considered but involves the evaluation of the patient in its entirety. Templating instead consists of calculating the position of the implant in order to place it in the best possible position. Fundamental is a correct X-ray of the pelvis, which must follow certain standards. For traditional templating, drawings on appropriately enlarged transparent implants were provided by the prosthesis manufacturer. The implementation of digital software into clinical practice has improved the accuracy and reproducibility of templating, which in most surgical units is performed by standard 2D radiographic images. Thanks to digital preoperative templating in a digital radiology environment, the hip reconstructive surgeon can perform preoperative planning and implant sizing quickly, consistently, and affordably. Currently, 3D templating can also be performed by software used initially to create personalized stems for THA. Aim of the current review is to outline the essentials of correct templating in THA performance, and to report the updates since the introduction of digital and 3D technologies in this setting.

Patient-Reported Outcomes are Similar in the First Two Years after Staged versus Combined Hip Arthroscopy and Periacetabular Osteotomy for Hip Dysplasia

PURPOSE

The purpose of this study was to compare early patient reported outcomes after staged versus combined hip arthroscopy and periacetabular osteotomy for hip dysplasia.

METHODS

A prospective database was retrospectively reviewed to identify patients that underwent combined or staged hip arthroscopy and PAO from 2012-2020. Patients were excluded if they were >40 years of age, had prior ipsilateral hip surgery, or did not have at least 12-24 month postoperative PRO data. PROs included the Hip Outcomes Score (HOS) Activities of Daily Living (ADL) and Sports Subscale (SS), Non-Arthritic Hip Score (NAHS), and the Modified Harris Hip Score (mHHS). Paired t-tests were used to compare preoperative to postoperative scores for both groups. Outcomes were compared using linear regression adjusted for baseline characteristics including age, obesity, cartilage damage, acetabular index, and procedure timing (early vs. late practice).

RESULTS

Sixty-two hips were included in this analysis (39 combined, 23 staged). The average length of follow up was similar between the combined and staged groups (20.8 vs. 19.6 months, p=0.192). Both groups reported significant improvements in PROs at final follow up compared to preoperative scores (p<0.05 for all). There were no significant differences in HOS-ADL, HOS-SS, NAHS, or mHHS scores between groups preoperatively or at 3, 6, or 12 months postoperatively (p>0.05 for all). There was no significant difference in PROs between the combined and staged groups at the final postoperative time point: HOS-ADL (84.5 vs. 84.3, p=0.77), HOS-SS (76.0 vs. 79.2, p=0.68), NAHS (82.2 vs. 84.5, p=0.79), mHHS (71.0 vs. 71.0, p=0.75) respectively.

CONCLUSION

Staged hip arthroscopy and PAO for hip dysplasia leads to similar PROs at 12-24 months compared to combined procedures. This suggests that with careful and informed patient selection, staging these procedures is an acceptable option for these patients and does not change early outcomes.

LEVEL OF EVIDENCE

Level III Retrospective Comparative.

A history of eponym usage in hip and pelvis radiography part 2: the adult hip

Eponyms, while inherently flawed, remain a constant in medical vernacular, especially in orthopaedic surgery. It is essential to understand how these eponyms came to be named and for whom they were named after in order to understand their correct usage and definitions. In this second part of a 2-part review, we describe the history of eponym usage in the radiography of the adult hip; who, when, what, where, and how. We hope to provide a historical perspective of interest, resolve any controversies in semantic definitions, and create a comprehensive library of eponymous terms related to adult hip radiography.

High Survivorship and Comparable Patient-Reported Outcomes at a Minimum 5 Years After Hip Arthroscopic Surgery in Patients With Femoroacetabular Impingement, With and Without Lateral Rim Dysplasia

BACKGROUND

Femoroacetabular impingement (FAI) in patients with dysplasia presents a unique challenge to surgeons. Short-term outcomes are conflicting, while longer term follow-up data are only emerging.

PURPOSE

To quantify midterm (minimum 5-year follow-up) outcomes after the arthroscopic correction of FAI in the presence of lateral rim dysplasia compared with a matched control group with FAI with normal acetabular coverage.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Prospective outcome data, collected in a consecutive series of patients undergoing arthroscopic FAI correction with lateral rim dysplasia (lateral center-edge angle [LCEA] of 13°-25°), were reviewed (N = 75 cases). An age- and sex-matched control group of 120 cases was also formed (LCEA >25°). Survivorship was defined as the avoidance of total hip replacement and assessed using a Kaplan-Meier curve with the log-rank test. Survival rates and patient-reported outcome measure (PROM) scores (modified Harris Hip Score [mHHS], University of California, Los Angeles [UCLA], 36-Item Short Form Health Survey [SF-36], and Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] preoperatively and at 5 years postoperatively) were compared between the groups. The proportion of patients across groups achieving the minimal clinically important difference (MCID) was compared for each PROM. The dysplasia group was also analyzed independently to identify any factors that may indicate a less favorable outcome using regression analysis. The group was divided into 2 subgroups: borderline dysplasia (LCEA of 20°-25°) and severe dysplasia (LCEA <20°).

RESULTS

The survival rate in the dysplasia group was 97%. There was no statistical difference with respect to survival rates or any PROM scores (P > .05 for all) between the groups. There were similar rates of achieving the MCID between the groups for the mHHS, UCLA, and WOMAC. The FAI control group had a higher rate of achieving the MCID for the SF-36 (P = .012; effect size = 0.274 [small]). Subgroup analysis indicated a lower survival rate (78% vs 100%, respectively; P < .001) in female cases in the dysplasia group (n = 9) compared with male cases in the dysplasia group (n = 66). The UCLA score in female cases in the dysplasia group at 5 years was statistically lower compared with that in male cases in the dysplasia group (6 vs 10, respectively; P = .003; effect size = 0.378 [medium]), but no other outcome revealed any differences between the sexes. There were also no variables identified on regression analysis that accurately predicted a poorer outcome in the dysplasia group. When stratified by severity, there was no difference in survivorship or outcomes between those with severe dysplasia (LCEA <20°; n = 11) and those with borderline dysplasia (LCEA of 20°-25°; n = 64).

CONCLUSION

An arthroscopic intervention was a successful treatment option for FAI in the presence of lateral rim dysplasia at midterm follow-up. Irrespective of the severity of dysplasia, patients can expect similar improvements to those in patients with normal femoral head coverage.

Joint contact stress improves in dysplastic hips after periacetabular osteotomy but remains higher than in normal hips

AIM

The purpose of this study was to use computational modeling to determine if surgical correction of hip dysplasia restores hip contact mechanics to those of asymptomatic, radiographically normal hips.

METHODS

Discrete element analysis (DEA) was used to compute joint contact stresses during the stance phase of normal walking gait for 10 individuals with radiographically normal, asymptomatic hips and 10 age- and weight-matched patients with acetabular dysplasia who underwent periacetabular osteotomy (PAO).

RESULTS

Mean and peak contact stresses were higher (p < 0.001 and p = 0.036, respectively) in the dysplastic hips than in the matched normal hips. PAO normalised standard radiographic measurements and medialised the location of computed contact stress within the joint. Mean contact stress computed in dysplastic hips throughout the stance phase of gait (median 5.5 MPa, [IQR 3.9-6.1 MPa]) did not significantly decrease after PAO (3.7 MPa, [IQR 3.2-4.8]; p = 0.109) and remained significantly (p < 0.001) elevated compared to radiographically normal hips (2.4 MPa, [IQR 2.2-2.8 MPa]). Peak contact stress demonstrated a similar trend. Joint contact area during the stance phase of gait in the dysplastic hips increased significantly (p = 0.036) after PAO from 395 mm2 (IQR 378-496 mm2) to 595 mm2 (IQR 474-660 mm2), but remained significantly smaller (p = 0.001) than that for radiographically normal hips (median 1120 mm2, IQR 853-1444 mm2).

CONCLUSIONS

While contact mechanics in dysplastic hips more closely resembled those of normal hips after PAO, the elevated contact stresses and smaller contact areas remaining after PAO indicate ongoing mechanical abnormalities should be expected even after radiographically successful surgical correction.

Preoperative radiographs to predict component malposition in direct anterior approach total hip arthroplasty

INTRODUCTION

There is conflicting evidence as to whether or not patients undergoing total hip arthroplasty (THA) via the direct anterior approach (DAA) have increased risk of component malposition. The aim of this study was to investigate whether specific preoperative radiographic features were predictive of postoperative component malposition in DAA THA.

PATIENTS AND METHODS

We examined 204 THA operations performed for osteoarthritis via the DAA at a single institution. Preoperative radiographs were analysed with numerous pre-specified measurements and classifications being recorded. Postoperative radiographs were analysed to determine if any of these preoperative radiographic factors correlated with component malposition in regard to cup inclination, cup version, femoral stem coronal alignment, leg-length discrepancy (LLD) and femoral offset discrepancy.

RESULTS

Numerous preoperative factors were associated with component malposition. Coxa profunda was found to be a significant predictor of cup anteversion being outside of the target range (p = 0.0089) and an increased centre-edge angle was a significant predictor for a postoperative LLD (p = 0.0134). A decreased neck-shaft angle (p = 0.0007) and a lower preoperative LLD (p = 0.0019) were both predictive of femoral stem coronal malalignment.

CONCLUSIONS

Preoperative radiographs can be a valuable tool for surgeons in predicting patients at risk of component malposition in DAA THA.

High-Level Athletes With Borderline Hip Dysplasia Achieve Favorable Outcomes and Return to Sport Rates Following Primary Hip Arthroscopy: Minimum 5-Year Outcomes Comparison to a Propensity-Matched Control Group

PURPOSE

(1) To report minimum 5-year patient-reported outcomes (PROs) and return to sport (RTS) rates in high-level athletes with borderline hip dysplasia (BHD) following primary hip arthroscopy for labral pathology and femoroacetabular impingement syndrome and (2) to compare results to a propensity-matched control group of athletes with normal acetabular coverage.

METHODS

Data were reviewed for surgeries performed between February 2009 and February 2016. Patients were eligible if they underwent primary hip arthroscopy in the setting of BHD (lateral center-edge angle [LCEA] 18-25°) and competed in professional, collegiate, or high school sports. Inclusion criteria were preoperative and minimum 5-year follow-up scores for the modified Harris Hip Score (mHHS), Non-Arthritis Hip Score, Hip Outcome Score-Sport Specific Subscale (HOS-SSS), and visual analog scale for pain. Rates of achieving the minimal clinically importance difference (MCID), patient acceptable symptomatic state (PASS), and maximum outcome improvement satisfaction threshold (MOIST) were recorded in addition to RTS. BHD athletes were matched by age at the time of surgery, sex, body mass index, Tönnis grade, follow-up time, sport type, and competition level to a control group of 58 athletes with normal acetabular coverage (LCEA 25°-40°) for comparison.

RESULTS

A total of 34 BHD athletes were included with a mean follow-up of 73.6 ± 10.7 months. BHD athletes showed significant improvements in all PROs, demonstrated high RTS rates (90.0%), and achieved PASS/MCID/MOIST for mHHS (MCID: 80.0%, PASS: 93.3%, MOIST: 80.0%) and HOS-SSS (MCID: 76.7%, PASS: 73.3%) at high rates. When compared to a propensity-matched group with normal acetabular coverage, BHD athletes demonstrated similar postoperative PROs, rates of achieving psychometric thresholds, and RTS rates (P > .05). Additionally, by the latest follow-up, no athlete in either group required conversion to total hip arthroplasty.

CONCLUSIONS

High-level athletes with BHD undergoing primary hip arthroscopy for labral pathology and femoroacetabular impingement syndrome may expect favorable midterm outcomes and high RTS rates. These results were comparable to a control group of athletes with normal coverage.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Lateral to Medial Joint Space Ratio is Predictive of Survivorship After Primary Hip Arthroscopy

PURPOSE

To assess whether preoperative joint space measures would be predictive of survivorship in patients undergoing hip arthroscopy (HA) for femoroacetabular impingement (FAI).

METHODS

Data on consecutive patients who underwent hip arthroscopy between February 2008 and February 2018 were retrospectively reviewed. To be eligible for final analysis, patients were required to have preoperative radiographs for joint space measurements and data indicating conversion to a total hip arthroplasty (THA), hip resurfacing, or neither; at a minimum of 2 years after primary hip arthroscopy. Survivorship following HA was defined as remaining conversion free and served as the primary outcome. A multivariate logistic regression analysis and receiver operator curve (ROC) were used to evaluate the correlation between joint space measurements and survivorship following HA.

RESULTS

A total of 1,885 primary arthroscopy cases were included in this study. The multivariate regression analysis found preoperative lateral-to-medial joint space ratio (L/M ratio) to be the strongest predictive factor of survivorship after primary hip arthroscopy (OR = 2.084, CI_95% = 1.239-3.503; P = .006). The ROC curve for the model demonstrated acceptable discrimination with an area under the curve (AUC) of 0.792. Patients with an L/M ratio ≥0.75 had a survivorship rate of 91.7% compared to a rate of 75% for patients with an L/M ratio <0.75 (OR: 3.68).

CONCLUSIONS

This study found that, of the factors evaluated in this study, the most significant factor in predicting survivorship at 2 years after undergoing primary hip arthroscopy was a larger lateral-to-medial joint space ratio. This may suggest an initiation of primary arthritis at the edge-loading area of the lateral acetabulum. LEVEL OF EVIDENCE: III, retrospective comparative observation study.

Allograft reconstruction of acetabular labrum has comparable outcomes to labral refixation

The acetabular labrum plays an important role in hip stability, intra-articular fluid pressurization and force distribution. For irreparable labral pathology, labral reconstruction is an increasingly adopted technique shown to decrease hip pain and improve function. We evaluated survivorship and clinical outcomes of allograft labral reconstruction using the mini-open anterior surgical approach. Twelve patients who underwent labral reconstruction using a semitendinosus tendon allograft (reconstruction group) were matched 1:3 based on age, gender, body mass index, year of surgery, preoperative Tönnis grade, previous hip surgery, residual hip pathology and extent of acetabular chondral lesion to a control group of 36 patients who underwent direct labral repair with anchors (refixation group). At a minimum follow-up of 2 years, patient-reported outcomes, radiological findings and failure rates were compared. The average age was 31.3 years (±13.6) for reconstruction and 34.7 (±10.2) for refixation. Both groups had similar preoperative symptomatic periods (P = 0.3), prevalence of residual hip pathology (P = 1.0) and prevalence of prior hip surgeries (P = 1.0). both groups had a significant improvement of modified Harris Hip scores and 36-Item Short-Form Health Survey physical scores. There was no statistically significant difference in conversion rates to total hip arthroplasty (25% versus 8.3%, P = 0.2); however, time to conversion was significantly longer in the reconstruction group (3.58 years ±1.04) compared to the refixation group (1.20 years± 0.93; P = 0.04). In conclusion, at a minimum of 2 years of follow-up, mini-open labrum reconstruction for severe insufficiency of acetabular labrum demonstrated comparable improvements in functional outcomes and significantly longer survivorship compared to labral refixation.

Which hip morphology measures and patient factors are associated with age of onset and symptom severity in femoroacetabular impingement syndrome?

BACKGROUND

Bony morphology is central to the pathomechanism of femoroacetabular impingement syndrome (FAIS), however isolated radiographic measures poorly predict symptom onset and severity. More comprehensive morphology measurement considered together with patient factors may better predict symptom presentation. This study aimed to determine the morphological parameter(s) and patient factor(s) associated with symptom age of onset and severity in FAIS.

METHODS

99 participants (age 32.9 ± 10.5 years; body mass index (BMI 24.3 ± 3.1 kg/m²; 42% females) diagnosed with FAIS received standardised plain radiographs and magnetic resonance scans. Alpha angle in four radial planes (superior to anterior), acetabular version (AV), femoral torsion, lateral centre-edge, anterior centre-edge (ACEA) and femoral neck-shaft angles were measured. Age of symptom onset (age at presentation minus duration of symptoms), international Hip Outcome Tool-33 (iHOT-33) and modified UCLA activity scores were recorded. Backward stepwise regression assessed morphological parameters and patient factors (age, sex, BMI, symptom duration, annual income, private/public healthcare system accessed) to determine variables independently associated with onset age and iHOT-33 score.

RESULTS

Earlier symptom onset was associated with larger superoanterior alpha angle (p = 0.007), smaller AV (p = 0.023), lower BMI (p = 0.010) and public healthcare system access (p = 0.041) (r² = 0.320). Worse iHOT-33 score was associated with smaller ACEA (p = 0.034), female sex (p = 0.040), worse modified UCLA activity score (p = 0.010) and public healthcare system access (p < 0.001) (r² = 0.340).

CONCLUSIONS

Age of symptom onset was chiefly predicted by femoral and acetabular bony morphology measures, whereas symptom severity predominantly by patient factors. Factors measured explained a small amount of variance in the data; additional unmeasured factors may be more influential.