Normal values of Wiberg's lateral center-edge angle and Lequesne's acetabular index--a coxometric update

Prevalence of Acetabular Dysplasia at a Mean age of 18 Years After Treatment for Neonatal hip Instability

BACKGROUND

The long-term radiological outcomes after the treatment of neonatal hip instability (NHI) in developmental dysplasia of the hip are unclear. Therefore, the prevalence of acetabular dysplasia at a mean age of 18 years after treatment was investigated. The relationship between acetabular dysplasia and hip discomfort has also been poorly established. Therefore, the differences in pain, hip-related quality of life (QOL), and hip impingement tests in hips with and without acetabular dysplasia were assessed.

METHODS

All 127 patients treated for NHI from 1995 to 2001 at the study hospital and meeting the inclusion criteria were invited to participate in this population-based follow-up. Of these individuals, 88 (69.3%) participated. The lateral center-edge angle (LCEA), Sharp's angle (SA), and acetabular head index (AHI) were calculated for both hips from pelvic anterior-posterior radiographs. The Copenhagen Hip and Groin Outcome Score (HAGOS) questionnaire was completed for both hips separately; the total score, pain, and QOL subscores were calculated; and the impingement test was performed.

RESULTS

The prevalence of acetabular dysplasia, defined as an LCEA <20°, was 3.4%. Only the mean AHI (81.1%, SD 5.3) differed (-5.08, 95% CI -5.77 to -4.38, P <0.001) from previously described gender-specific and side-specific means, whereas the mean LCEA and SA did not. The odds ratio for a positive hip impingement test was 2.8 (95% CI: 1.11-7.05, P = 0.029) for hips with an LCEA <25° compared to hips with LCEA ≥25°. The hips with an SA ≥45° had a mean of 7.8 points lower for the HAGOS pain subscore (95% CI: 4.2-11.4, P <0.001) and a mean of 6.1 points lower for the HAGOS QOL subscore (95% CI: 2.1-10.2, P = 0.003) compared with hips with an SA <45°.

CONCLUSIONS

The prevalence of acetabular dysplasia was low after treatment for NHI. Acetabular dysplasia seems to be as common in the general population as for those treated for NHI based on the LCEA. Only an SA ≥45° resulted in slightly more pain and lower hip-related QOL.

Birmingham Royal Orthopaedic Hospital (BROH) Femoral Offset-An Ancillary Measure of Adult Dysplasia of the Hip

Introduction  Adult dysplasia of the hip (ADH) is a disorder of abnormal development of the hip joint resulting in a shallow acetabulum and uncovering of the femoral head. Several radiological measurements such as the Tönnis angle (acetabular index), lateral center edge angle of Wiberg, and cross-sectional imaging parameters exist to calculate hip dysplasia. Aims  The aim of this article was to describe a new ancillary linear measure of ADH on cross-sectional imaging, the Birmingham Royal Orthopaedic Hospital (BROH) Femoral offset. Patients and Methods  Anteroposterior radiographs of the pelvis and computed tomography imaging of 100 consecutive patients with suspected hip dysplasia were reviewed. Demographic details and clinical indications were recorded. Tönnis angle was utilized to measure hip slope on radiographs and the BROH femoral offset was calculated for each patient. Student's t -test and one-way analysis of variance (ANOVA) were performed. Intraclass correlation coefficient analysis was evaluated to assess the reliability between observers. Results  There was a total of 100 patients (128 hips) included in the study (60 with normal Tönnis angle, 53 had dysplasia, and 15 had decreased Tönnis angle). The average BROH femoral offset in the dysplastic cohort was increased in comparison to the normal cohort with a statistically significant p -Value of 0.0001. The p -value was 0.00031 on ANOVA. The BROH femoral offset calculation revealed good intra- and interobserver reliability of 0.9 and 0.9, respectively. Conclusion  The BROH femoral offset can be an additional index for measuring ADH that is easier to calculate, and reproducible with good intra- and inter-observer reliability on cross-sectional imaging.

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.

Development of acetabular retroversion in LCPD hips-an observational radiographic study from early stage to healing

BACKGROUND

Acetabular retroversion is observed frequently in healed Legg-Calvé-Perthes disease (LCPD). Currently, it is unknown at which stage and with what prevalence retroversion occurs because in non-ossified hips, retroversion cannot be measured with standard radiographic parameters.

METHODS

In a retrospective, observational study; we examined pelvic radiographs in children with LCPD the time point of occurrence of acetabular retroversion and calculated predictive factors for retroversion. Between 2004 and 2017, we included 55 children with a mean age of 5.7 ± 2.4 years at diagnosis. The mean radiographic follow-up was 7.0 ± 4.4 years. We used two new radiographic parameters which allow assessment of acetabular version in non-ossified hips: the pelvic width index and the ilioischial angle. They are based on the fact that the pelvic morphology differs depending on the acetabular version. These parameters were compared among the four Waldenström stages and to the contralateral side. Logistic regression analysis was performed to determine predictive factors for acetabular retroversion.

RESULTS

Both parameters differed significantly among the stages of Waldenström (p < 0.003 und 0.038, respectively). A more retroverted acetabulum was found in stage II and III (prevalence ranging from 54 to 56%) compared to stage I and IV (prevalence ranging from 23 to 39%). In hips of the contralateral side without LCPD, the prevalence of acetabular retroversion was 0% in all stages for both parameters. Predictive factors for retroversion were younger age at stage II and IV, collapse of the lateral pillar in stage II or a non-dysplastic hip.

CONCLUSIONS

This is the first study evaluating acetabular version in children with LCPD from early stage to healing. In the developing hip, LCPD may result in acetabular retroversion and is most prevalent in the fragmentation (stage II) and early healing stage (stage III). Partial correction of acetabular retroversion can occur after healing. This has a potential clinical impact on the timing and type of surgical correction, especially in pelvic osteotomies for correction of acetabular version.

LEVEL OF EVIDENCE

Level III, retrospective observational study.

Acetabular index and acetabular depth ratio in newborns and infants aged 6 months or less with the healthy development of hips: A retrospective cross-sectional study

Radiographic assessment of the hip may render critical in the diagnosis of developmental dysplasia of the hip (DDH) in newborns and infants aged ≤6 months. There is no complete dataset on the acetabular index (AI) and acetabular depth ratio (ADR) values in this age group. The objective of this study was to assess the AI and ADR values in newborns and infants aged ≤6 months with healthy development. A retrospective analysis was performed on pelvic radiographs of newborns and infants (≤6 months) between August 2020 and September 2021. There were 3000 children with pelvic radiographic imaging. Normal sonographic findings and radiographs without any structural deformity of the hip were inclusion criteria. A total of 1132 newborns and infants (2264 hips) were analyzed. Measurements of AI and ADR (ischium and pubic bone as landmarks for acetabular depth ratio A [ADR-A] and acetabular depth ratio B [ADR-B]) were performed. Correlation and intraclass correlation coefficient (ICC) values were calculated. Left-sided AI values were significantly higher than the right-sided AI values, except in infants aged 4 to ≤5 months (P < .05). ADR-B values differed significantly between male and female newborns and infants both in terms of the side of the hip measured and age (P < .05). AI values were fairly correlated with age (r = -0.286 for left and r = -0.254 for right) in the negative direction and with ADR-A (r = 0.449 and r = 0.469 for left and right) and ADR-B (r = 0.545 and r = 0.592 for left and right) in the positive direction. Inter-observer ICC was 0.845 to 0.989 (excellent) for AI, 0.534 and 0.904 (moderate to excellent) for ADR-A, and -0.014 and 0.774 (slightly good to good) for ADR-B. Intra-observer ICC was 0.811 to 0.996 (excellent) for AI, 0.575 to 0.98 (moderate to excellent) for ADR-A, and 0.023 to 0.954 (slightly good to excellent) for ADR-B. This study features the first complete data set of AI and ADR measurements, which are essential for pelvic radiographic imaging of hip dysplasia, in newborns and infants aged ≤6 months.

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.

Efficient cascaded V-net optimization for lower extremity CT segmentation validated using bone morphology assessment

Semantic segmentation of bone from lower extremity computerized tomography (CT) scans can improve and accelerate the visualization, diagnosis, and surgical planning in orthopaedics. However, the large field of view of these scans makes automatic segmentation using deep learning based methods challenging, slow and graphical processing unit (GPU) memory intensive. We investigated methods to more efficiently represent anatomical context for accurate and fast segmentation and compared these with state-of-the-art methodology. Six lower extremity bones from patients of two different datasets were manually segmented from CT scans, and used to train and optimize a cascaded deep learning approach. We varied the number of resolution levels, receptive fields, patch sizes, and number of V-net blocks. The best performing network used a multi-stage, cascaded V-net approach with 128³ -64³ -32³ voxel patches as input. The average Dice coefficient over all bones was 0.98 ± 0.01, the mean surface distance was 0.26 ± 0.12 mm and the 95th percentile Hausdorff distance 0.65 ± 0.28 mm. This was a significant improvement over the results of the state-of-the-art nnU-net, with only approximately 1/12th of training time, 1/3th of inference time and 1/4th of GPU memory required. Comparison of the morphometric measurements performed on automatic and manual segmentations showed good correlation (Intraclass Correlation Coefficient [ICC] >0.8) for the alpha angle and excellent correlation (ICC >0.95) for the hip-knee-ankle angle, femoral inclination, femoral version, acetabular version, Lateral Centre-Edge angle, acetabular coverage. The segmentations were generally of sufficient quality for the tested clinical applications and were performed accurately and quickly compared to state-of-the-art methodology from the literature.

Defining trapezial dysplasia - analysis of trapezial inclination in a normal population

We assess the distribution of trapezial inclination in a young population in order to propose a threshold for trapezial dysplasia. One hundred peritrapezial views were reconstructed from wrist computed tomography scan datasets to measure trapezial inclination. Seventy peritrapezial views were constructed from 10 datasets to assess the influence of radiograph rotation. Mean trapezial inclination in our population was 8° (range 0.2-17.9). Fifteen degrees of radiographic pronation or supination did not alter trapezial inclination significantly. Intra-rater consistency and absolute agreement had an interclass correlation (ICC) of 0.95. Inter-rater consistency and absolute agreement had an ICC of 0.88. Trapezial inclination is a reliable measurement for trapezial dysplasia with an excellent intra-rater and good inter-rater reliability and does not change significantly with 15° of radiographic pronation or supination. These normal values can be used to propose a threshold for trapezial dysplasia in the management of trapeziometacarpal joint instability in the younger population.Level of evidence: IV.

Prone Apprehension Relocation Test significantly correlates with radiological instability scores of the hip

Recently, there was a debate about whether borderline dysplastic hips should be treated surgically with hip arthroscopy or periacetabular osteotomy (PAO). Current studies recommend a classification into stable and unstable hips. Therefore, radiological scores have been described in recent years. Likewise, a new clinical stability test with the Prone Apprehension Relocation Test (PART) has been described. However, there has been no correlation between the modern radiological scores and the PART. We prospectively studied a consecutive group of patients who presented to our clinic. The PART and radiological scores were assessed in these patients. We divided the patients into a PART-positive and a PART-negative group and analyzed the associated clinical and radiological findings. Out of 126 patients (126 hips) included, 36 hips (29%) were evaluated as PART positive. There were significantly more females in the PART positive group (P = 0.005). Comparing the PART groups, significant differences (P < 0.0001) were found for the lateral center edge angle (LCEA), Femoro-Epiphyseal Acetabular Roof (FEAR) index, Gothic arch angle (GAA), anterior wall index (AWI), the occurrence of the upsloping lateral sourcil (ULS) and signs of acetabular retroversion. The correlation analysis showed an association between LCEA, FEAR index, GAA, AWI, ULS and the PART. A chi-square automatic interaction detection algorithm revealed that the strongest predictor of positive PART was the GAA. In conclusion, a high correlation between the PART and known radiological instability parameters was found. Consequently, a combination of clinical instability testing and radiological instability parameters should be applied to detect unstable hips.

The Inverse Relationship Between Labral Size and Acetabular Coverage: Does It Protect the Cartilage in the Dysplastic Hip?

PURPOSE

The aims of this study were to confirm the relationship between osseous coverage and labral size and to investigate the severity of intra-articular damage in borderline dysplastic hips in correlation to labral size.

METHODS

Patients treated with primary hip arthroscopy for symptomatic labral tears between 2010 and 2018 were considered for this study. Patients were included if they had preoperative radiographic measures and intraoperative assessments of the labra and cartilage. The study group was divided into borderline dysplastic and nondysplastic groups via 3 measurements: lateral center edge angle (LCEA), acetabular index (Ax), and anterior center edge angle (ACEA). Undercoverage was defined as LCEA ≤ 25°, Ax ≥ 10°, and ACEA ≤ 20°. The labrum was measured in four quadrants: anterosuperior (AS), anteroinferior (AI), posterosuperior (PS), and posteroinferior (PI). Additionally, to assess cartilage damage in borderline dysplastic hips, hips with average labral size in the top quartile were compared to hips with average labral size in the bottom quartile.

RESULTS

A total of 1765 hips (1589 patients) were included in the study. The mean LCEA, Ax, and ACEA between the borderline dysplastic and nondysplastic groups were significantly different (P < .001). According to the Ax classification, there was significant evidence that borderline dysplastic hips had larger labra (P < .05). Among the dysplastic group, there was significantly more cartilage damage according to the Outerbridge classifications along both the acetabulum and femoral head in hips with labra in the upper quartile (P =.011 and .005, respectively).

CONCLUSION

An inverse relationship may exist between acetabular depth and labral size. Additionally, specifically in borderline dysplastic hips, a relatively large labrum correlates with worse intra-articular damage compared to borderline dysplastic hips with a relatively small labrum. Larger labral size may indicate a higher degree of instability in patients with borderline dysplasia.

LEVEL OF EVIDENCE

Level III, case-control study.

Comparing Hip Dysplasia in Dogs and Humans: A Review

Hip dysplasia (HD) is common in both humans and dogs. This interconnection is because humans and dogs descended from a common ancestor and therefore have a similar anatomy at micro- and macroscopic levels. Furthermore, dogs are the animals of choice for testing new treatments for human hip dysplasia and orthopedic surgery in general. However, little literature exists comparing HD between the two species. Therefore, the aim of this review is to describe the anatomy, etiology, pathogenesis, diagnostics, and treatment of HD in humans and dogs. HD as an orthopedic condition has many common characteristics in terms of etiology and pathogenesis and most of the differences can be explained by the evolutionary differences between dogs and humans. Likewise, the treatment of HD shows many commonalities between humans and dogs. Conservative treatment and surgical interventions such as femoral osteotomy, pelvic osteotomy and total hip arthroplasty are very similar between humans and dogs. Therefore, future integration of knowledge and experiences for HD between dogs and humans could be beneficial for both species.

The unstable hip in children with cerebral palsy: does an acetabuloplasty add midterm stability?

PURPOSE

This study addresses whether an additional pelvic procedure is superior to a varus derotation osteotomy femur (VDRO) alone in unstable hips in children with cerebral palsy (CP).

METHODS

All patients had unstable hips utilising the Melbourne Cerebral Palsy Hip Classification System (MCPHCS). We compared one group that underwent VDRO alone with one that had a combination of VDRO and Dega osteotomy (VDRO+). Measurements were taken before surgery, postoperatively, two years after surgery and at latest follow-up. Generalised estimating equations were used to account for known and unknown correlations between hips from bilateral cases.

RESULTS

In total, 74 hips in 57 children fulfilled the inclusion criteria. There was no outcome difference between Gross Motor Function Classification System levels III, IV and V. Age at time of operation ranged from three to 16 years (mean 9.8 years). Mean follow-up was 49.1 months. In the VDRO group (28 hips) migration percentage (MP) changed from 61% preoperative to a final value of 35.7%. In the VDRO+ group (46 hips) the MP changed from 64.4% to 19.3%. At final follow-up 15 hips (54%) were stable in the VDRO group, 37 hips (83%) in the VDRO+ group. The odds ratio (OR) of hip stability at final follow-up was 3.5-times higher in the VDRO+ group versus the VDRO group (OR = 3.9; 95% confidence interval = 1.5 to 9.7; p = 0.004).

CONCLUSION

Reconstruction of unstable hips via VDRO + Dega in children with CP provides a higher likelihood of long-term stability than an isolated VDRO.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Residual Acetabular Dysplasia in the Reduced Hip

BACKGROUND

Residual acetabular dysplasia occurs in up to a third of patients treated successfully for developmental dysplasia of the hip (DDH) and has been found to be a significant risk factor for early hip osteoarthritis (OA).

DISCUSSION

Age at the time of initial reduction and the initial severity of DDH have been linked to residual acetabular dysplasia. An anteroposterior pelvic radiograph is the main diagnostic modality, but MRI also provides valuable information, particularly in equivocal cases. The literature supports intervening when significant residual acetabular dysplasia persists at 4-5 years of age, and common surgical indications include acetabular index (AI) > 25°-30°, lateral center-edge angle (LCEA) < 8°-10°, and a broken Shenton's line on radiographs; and a cartilaginous acetabular angle (CAI) > 18°, cartilaginous center-edge angle (CCE) < 13°, and/or the presence of high-signal intensity areas on MRI. Surgical options include redirectional pelvic osteotomies and reshaping acetabuloplasties, which provide comparable radiographic and clinical results.

CONCLUSION

RAD is common after treatment of DDH and requires regular follow-up for diagnosis and appropriate management to decrease the long-term risk of OA. Long-term outcomes of patients treated with pelvic osteotomies are generally favorable, and the risk of OA can be decreased, although the risk of total hip replacement in the long-term remains.

Periacetabular osteotomy for acetabular retroversion: A systematic review and meta-analysis

INTRODUCTION

The evidence for periacetabular osteotomy (PAO) when used in the management of acetabular retroversion remain limited. The review aims to answer the following questions: (1) What are the indications for an anteverting PAO for acetabular retroversion? (2) When are other concomitant procedures required when performing anteverting PAO for acetabular retroversion? (3) To what extent is an anteverting PAO able to correct acetabular retroversion? (4) What are the clinical outcomes for an anteverting PAO when used in acetabular retroversion? (5) What is the estimated survival for anteverting PAO when used in the treatment of acetabular retroversion, before other procedures need to be performed? (6) What are the complications and the complication rates when an anteverting PAO is performed? (7) How do the outcomes of an anteverting PAO compare to other surgical procedures used in the management of acetabular retroversion?

MATERIAL AND METHODS

The systematic review was conducted using the PRISMA guidelines. The search was conducted using PubMed Medical Literature Analysis and Retrieval System Online (MEDLINE) and Cumulative Index to Nursing and Allied Health Literature (CINAHL) from inception through 1 May 2020. The keywords used were "periacetabular osteotomy". All studies that reported the outcomes of periacetabular osteotomy for acetabular retroversion were included. Each study's data was then retrieved individually. The study design, surgical technique, indications, outcomes and complications of each study were analysed.

RESULTS

Seven studies with 225 hips were included. The pooled odds ratio (OR) for a positive crossover sign and posterior wall sign preoperatively as compared to postoperatively were 456.31 (95% CI: 99.57 to 2091.28) and 53.45 (95% CI: 23.05 to 123.93) respectively. The pooled weighted mean difference (WMD) for studies with their mean preoperative LCEA and AI in the dysplastic range were 12.61 (95% CI: 6.54 to 18.68) and-15.0 (95% CI: -19.40 to -11.80) respectively, while the pooled WMD for studies with their mean preoperative LCEA and AI in the normal range were 3.43 (95% CI: 1.08 to 5.77) and -3.56 (95% CI: -5.29 to -1.83) respectively. Other indicators for acetabular retroversion correction, hip dysplasia correction, functional outcomes and range of motion were also significantly improved and sustained up till 11 years postoperatively. Only 7.1% of the hips required subsequent surgical procedures for impingement symptoms or progression of osteoarthritis, and the mean estimate for survival time across the studies was 123.90 months (95% CI: 119.94 to 127.86). The complication rates for low-grade complication were 31.6% while the rate for high-grade complications was 12.0%.

DISCUSSION

Anteverting PAO is indicated for symptomatic acetabular retroversion, and when performed, leads to good deformity correction for both acetabular retroversion and hip dysplasia, positive improvement in clinical outcomes sustainable till 11 years postoperatively and a mean estimated survival time of more than 10 years.

LEVEL OF EVIDENCE

IV; Systematic review and meta-analysis.

The accuracy of digital templating in cementless total hip arthroplasty in dysplastic hips

Background

Total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH) is a complex procedure due to associated anatomical abnormalities. We studied the extent to which preoperative digital templating is reliable when performing cementless THA in patients with DDH.

Methods

We templated and compared the pre- and postoperative sizes of the acetabular and femoral components and the center of rotation (COR), and analysed the postoperative cup coverage, leg length discrepancy (LLD), and stem alignment in 50 patients (56 hips) with DDH treated with THA.

Results

The implant size exactly matched the template size in 42.9% of cases for the acetabular component and in 38.2% of cases for the femoral component, whereas the templated ±1 size was used in 80.4 and 81.8% of cases for the acetabular and femoral components, respectively. There were no statistically significant differences between templated and used component sizes among different DDH severity levels (acetabular cup: p = 0.30 under the Crowe classification and p = 0.94 under the Hartofilakidis classification; femoral stem: p = 0.98 and p = 0.74, respectively). There were no statistically significant differences between the planned and postoperative COR (p = 0.14 horizontally and p = 0.52 vertically). The median postoperative LLD was 7 (range 0–37) mm.

Conclusion

Digital preoperative templating is reliable in the planning of cementless THA in patients with DDH.

Hip dysplasia is not uncommon but frequently overlooked: a cross-sectional study based on radiographic examination of 1,870 adults

Background and purpose - Hip dysplasia in adults is a deformity in which the acetabulum inadequately covers the femoral head. The prevalence is sparingly described in the literature. We investigated the prevalence in Malmö (Sweden) and assessed whether the condition was recognized in the radiology reports.Subjects and methods - All pelvic radiographs performed in Malmö during 2007-2008 on subjects aged 20-70 years with a Swedish personal identity number were assessed. 1,870 digital radiographs were eligible for analysis. The lateral center-edge angle (LCEA) and acetabular index angle (AIA) were measured. Hip dysplasia was defined as an LCEA ≤ 20°. Intraclass correlation coefficients (ICC) for intra-observer measurements ranged from 0.87 (AIA, 95% CI 0.78-0.93) to 0.98 (LCEA, CI 0.97-0.99).Results - The prevalence of hip dysplasia (LCEA ≤ 20°) was 5.2% (CI 4.3-6.3), (98/1,870). There was no statistically significant difference between the sexes for either prevalence of hip dysplasia or mean LCEA. The mean AIA was 0.9° (CI 0.3-1.3) higher in men (4.1 SD 5.5) compared with women (3.2 SD 5.4). The radiologists had reported hip dysplasia in 7 of the 98 cases.Interpretation - The prevalence of hip dysplasia in Malmö (Sweden) is similar to previously reported data from Copenhagen (Denmark) and Bergen (Norway). Our results indicate that hip dysplasia is often overlooked by radiologists, which may influence patient treatment.

Total Hip Arthroplasty in a Patient with Mucopolysaccharidosis Type IVB

Introduction. Morquio syndrome or mucopolysaccharidosis (MPS) type IV is a rare autosomal recessive lysosomal storage disease, characterized by abnormal metabolism of glycosaminoglycans associated with specific skeletal deformities, also known as dysostosis multiplex. Case Presentation. We present the case of a 23-year-old patient with advanced osteonecrosis of the femoral head (ONFH) on both sides due to Morquio syndrome. A diagnosis of mucopolysaccharidosis type IVB was made after extensive genetic profiling. The patient had the condition for a long time. At 7 years old, the patient was treated with bilateral pelvic Salter's osteotomy. Afterward, the patient was able to walk freely but could never take part in sports. At 22 years old, pain in the hip increased, and magnetic resonance imaging showed a bilateral femur head necrosis. Hence, the patient underwent cementless total hip arthroplasty (THA). Intraoperatively, a periprosthetic fracture occurred. Therefore, revision surgery with internal fixation was performed on the next day. Postoperatively, a weight-bearing restriction of 20 kg on the left leg was imposed for 6 weeks. The patient made a full recovery and was able to move without residual complaints. Annual orthopedic evaluation in patients treated with surgical intervention is recommended. Discussion. Orthopedic challenges for mucopolysaccharidoses and corresponding bone alterations, known as dysostosis multiplex, involving trunk and limbs with typical radiological findings have been well described. The hip is invariably involved, with dysplasia affecting the femoral neck (coxa valga), femoral epiphysis (loss of sphericity, osteonecrosis), and a flared hypoplastic iliac wing. Symptomatic therapy consists, on the one hand, of a surgical procedure and, on the other hand, a variety of supportive measures. However, the management of joint replacement in lysosomal storage diseases has not been well reported. All patients with MPS should be considered at high risk for surgical intervention requiring anesthesia because of airway and cardiac disease manifestations. In the case of a need for THA, we recommend cemented stem fixation because of the overall poor bone quality in patients with Morquio syndrome.

Functional improvement in hip pathology is related to improvement in anxiety, depression, and pain catastrophizing: an intricate link between physical and mental well-being

Background

Pain catastrophizing, anxiety, and depression are risk factors for poor functional outcomes and worse post-treatment pain that can be treated alongside physical care given to orthopedic patients. While these factors have been shown to be common in patients with hip pathology, there is limited literature that follows these conditions throughout treatment. The purpose of this study was to track psychological factors in patients with various hip pathology to determine if they improved alongside functional measures following treatment.

Methods

Patients presenting to a specialist hip clinic were prospectively evaluated for outcomes of pain catastrophizing, anxiety, depression, and hip function. Pre- and post-treatment assessments were undertaken: Pain Catastrophizing Scale, the Hospital Anxiety Depression Scale, the Hip Outcome Survey, and Hip Disability and Osteoarthritis Outcome Score (HOOS). Patient characteristics were recorded. A correlation analysis, using the Spearman partial correlation coefficient (r_s), was conducted to evaluate the relationship between change in psychological factors with change in functional outcomes.

Results

A total of 201 patients (78 male, 123 female) with a mean age of 53.75 ± 18.97 years were included, with diagnoses of hip dysplasia (n = 35), femoroacetabular impingement (n = 35), lateral trochanteric pain syndrome (n = 9), osteoarthrosis (n = 109), and avascular necrosis of the hip (n = 13). Statistical analysis revealed a significant negative relationship between change in function level (as measured by HOOS ADL) and change in pain catastrophizing (r_s = − 0.373, p < 0.0001), depression (r_s = − 0.363, p < 0.0001), and anxiety (r_s = − 0.264, p = 0.0002). Pain catastrophizing, depression, and anxiety improved with function. Spearman correlation coefficients also revealed that pain catastrophizing, HADS anxiety, and HADS depression improved with improvement in other patient-reported functional outcomes.

Conclusions

Patients with hip pathology often exhibit pain catastrophizing, anxiety, and depression, but improvements in hip functionality are associated with decreased severity of these psychological comorbidities. Exploring this connection demonstrates the correlation between musculoskeletal impairment and psychosocial outcomes and mental health. Perioperative multidisciplinary assessment may be a beneficial part of comprehensive orthopaedic hip care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04001-5.

The Lisbon Agreement on femoroacetabular impingement imaging-part 2: general issues, parameters, and reporting

OBJECTIVES

Imaging assessment for the clinical management of femoroacetabular impingement (FAI) is controversial because of a paucity of evidence-based guidance and notable variability among practitioners. Hence, expert consensus is needed because standardised imaging assessment is critical for clinical practice and research. We aimed to establish expert-based statements on FAI imaging by using formal methods of consensus building.

METHODS

The Delphi method was used to formally derive consensus among 30 panel members from 13 countries. Forty-four questions were agreed upon, and relevant seminal literature was circulated and classified in major topics to produce answering statements. The level of evidence was noted for all statements, and panel members were asked to score their level of agreement (0-10). This is the second part of a three-part consensus series and focuses on 'General issues' and 'Parameters and reporting'.

RESULTS

Forty-seven statements were generated and group consensus was reached for 45. Twenty-five statements pertaining to 'General issues' (9 addressing diagnosis, differential diagnosis, and postoperative imaging) and 'Parameters and reporting' (16 addressing femoral/acetabular parameters) were produced.

CONCLUSIONS

The available evidence was reviewed critically, recommended criteria for diagnostic imaging highlighted, and the roles/values of different imaging parameters assessed. Radiographic evaluation (AP pelvis and a Dunn 45° view) is the cornerstone of hip-imaging assessment and the minimum imaging study that should be performed when evaluating adult patients for FAI. In most cases, cross-sectional imaging is warranted because MRI is the 'gold standard' imaging modality for the comprehensive evaluation, differential diagnosis assessment, and FAI surgical planning.

KEY POINTS

• Diagnostic imaging for FAI is not standardised due to scarce evidence-based guidance on which imaging modalities and diagnostic criteria/parameters should be used. • Radiographic evaluation is the cornerstone of hip assessment and the minimum study that should be performed when assessing suspected FAI. Cross-sectional imaging is justified in most cases because MRI is the 'gold standard' modality for comprehensive FAI evaluation. • For acetabular morphology, coverage (Wiberg's angle and acetabular index) and version (crossover, posterior wall, and ischial spine signs) should be assessed routinely. On the femoral side, the head-neck junction morphology (α° and offset), neck morphology (NSA), and torsion should be assessed.

The Lisbon Agreement on Femoroacetabular Impingement Imaging-part 1: overview

OBJECTIVES

Imaging assessment for the clinical management of femoroacetabular impingement (FAI) syndrome remains controversial because of a paucity of evidence-based guidance and notable variability in clinical practice, ultimately requiring expert consensus. The purpose of this agreement is to establish expert-based statements on FAI imaging, using formal techniques of consensus building.

METHODS

A validated Delphi method and peer-reviewed literature were used to formally derive consensus among 30 panel members (21 musculoskeletal radiologists and 9 orthopaedic surgeons) from 13 countries. Forty-four questions were agreed on, and recent relevant seminal literature was circulated and classified in five major topics ('General issues', 'Parameters and reporting', 'Radiographic assessment', 'MRI' and 'Ultrasound') in order to produce answering statements. The level of evidence was noted for all statements, and panel members were asked to score their level of agreement with each statement (0 to 10) during iterative rounds. Either 'consensus', 'agreement' or 'no agreement' was achieved.

RESULTS

Forty-seven statements were generated, and group consensus was reached for 45 (95.7%). Seventeen of these statements were selected as most important for dissemination in advance. There was no agreement for the two statements pertaining to 'Ultrasound'.

CONCLUSION

Radiographic evaluation is the cornerstone of hip evaluation. An anteroposterior pelvis radiograph and a Dunn 45° view are recommended for the initial assessment of FAI although MRI with a dedicated protocol is the gold standard imaging technique in this setting. The resulting consensus can serve as a tool to reduce variability in clinical practices and guide further research for the clinical management of FAI.

KEY POINTS

• FAI imaging literature is extensive although often of low level of evidence. • Radiographic evaluation with a reproducible technique is the cornerstone of hip imaging assessment. • MRI with a dedicated protocol is the gold standard imaging technique for FAI assessment.

Can EOS Imaging Substitute for Conventional Radiography in Measurement of Acetabular Morphology in the Young Dysplastic Hip?

BACKGROUND

EOS imaging offers a low-radiation alternative to conventional radiography (CR) and has little to no magnification effects. However, it is unclear how radiographic measures may be affected using EOS. The present study aims to determine the reproducibility of measures of acetabular morphology on EOS images as compared with CR, and to directly compare the 2 imaging modalities.

METHODS

A total of 21 consecutive patients (66.7% female; 14.4±4.7 y) indicated for an open hip preservation procedure with both an anterior-posterior pelvis radiograph and EOS image performed preoperatively were included. Three orthopaedic surgeons measured Tönnis angle, lateral center edge angle (LCEA), acetabular depth-width ratio (ADR), and extrusion index (EI). Measurements were performed twice, 2 weeks apart. Reliability between observers and time points was measured using intraclass correlation coefficients, and agreement between time points and modalities was measured using Bland-Altman analysis.

RESULTS

On EOS images, inter-rater reliability was 0.86 for Tönnis angle, 0.86 for LCEA, 0.74 for ADR, and 0.93 for EI. On CR, inter-rater reliability was 0.86 for Tönnis anlge, 0.90 for LCEA, 0.82 for ADR, and 0.84 for EI. In the agreement analysis, biases between imaging modalities were observed. On average, raters measured Tönnis angle and EI higher on EOS images than CR (2.22 degrees, 1.09%, respectively); and LCEA and ADR lower on EOS images than CR (1.54 degrees, 1.14% respectively). Limits of agreement (LOA) between modalities were similar to that of LOA observed in intra-rater analysis.

CONCLUSIONS

Measures of acetabular morphology performed on EOS images have similarly high intra-rater and inter-rater reliability compared with CR. Measures performed on EOS also have similar intra-rater agreement as compared with CR. Intermodality agreement had similar LOA as intra-rater agreement on either individual imaging modality. Small biases between imaging modalities were detected.

LEVELS OF EVIDENCE

Level I-diagnostic study: investigating a diagnostic test.

The borderline dysplastic hip: when and how is it abnormal?

Borderline acetabular dysplasia refers to mildly sub-normal patterns of acetabular shape and coverage that might predispose children to mechanical dysfunction and instability. Borderline dysplasia generally includes children with a lateral center edge angle (CEA) of 18-24°. Some children with borderline radiographic measurements have normal joint mechanics and function while others benefit from acetabular reorienting surgery. Although radiographic findings of borderline dysplasia might suggest instability, the ultimate diagnosis is based on history and physical exam in addition to imaging. Children with borderline acetabular dysplasia sometimes benefit from other cross-sectional imaging studies such as MR imaging to evaluate for secondary evidence of instability, including damage along the acetabular rim, or labral degeneration and hypertrophy. CT is also helpful for depiction of 3-D acetabular morphology for preoperative assessment and planning. Pediatric radiologists are often the first to identify borderline or mild dysplasia on radiographs. It is imperative that pediatric radiologists serve as effective consultants and offer appropriate recommendations as part of a cohesive multidisciplinary approach to this complex patient population.

Does Pelvic Rotation Alter Radiologic Measurement of Anterior and Lateral Acetabular Coverage?

PURPOSE

The purpose of this study was to determine the radiologic tolerance of the lateral center edge angle (LCEA) and anterior center edge angle (ACEA) to pelvic rotation.

METHODS

Eleven dry cadaveric pelvises from an osteological collection were reconstructed and placed in anatomic position with corresponding bilateral proximal femurs. Conventional anteroposterior (AP) and false-profile (FP) pelvic radiographs were taken at 5° increments with fluoroscopy from 0° to 25° of rotation. LCEA and ACEA were measured for conventional and rotated AP and FP fluoroscopic views, respectively. Statistical analysis was conducted to determine the error in ACEA and LCEA with pelvic rotation.

RESULTS

The mean LCEA was 29.1° (95% confidence interval [CI], 25.5°-32.7°). Mean ACEA was 38.9° (95% CI, 34.1°-43.8°). There was significant change in the LCEA past 10° of rotation (P = .041). There was significant change in the ACEA with 5^o or more of rotation (P < .001). The FP view rotated 40° from an AP view produced 6.8° (95% CI, 4.7-8.9) of error, whereas one rotated 90° from an AP view produced 13.2° (95% CI, 11.2°-15.3°) of error in the ACEA. An AP view rotated 25° toward the x-ray beam produced 2.3° (95% CI, 1.1°-3.4°) error, whereas one rotated 25° away from the beam produced 2.6° (95% CI, 1.5°-3.8°) of error.

CONCLUSIONS

Rotation of AP and FP radiographs significantly affects the measured values of the LCEA and ACEA, respectively. The ACEA experiences more dramatic changes with rotation of the FP view compared with the LCEA with the same amount of rotation of an AP view. This study illustrates the importance of verifying the quality of the FP radiograph when using ACEA to guide therapy for hip pathology.

CLINICAL RELEVANCE

This study emphasizes the importance of evaluating pelvic rotation when using the center edge angle to assess femoral head coverage.

Correlation of radiographic variables to guide safe implant positioning during acetabular surgery and hip replacement: a retrospective observational study

Background

Knowledge of periacetabular anatomy is crucial for prosthetic cup placement in total hip arthroplasty and for screw placement in anterior fixation with acetabular fractures. It is known that degree of hip dysplasia correlates with medial bone stock and that medial bone stock shows a weak correlation to Lequesne’s acetabular index (AI). Aim of this study was to investigate a possible correlation between AI and the newly proposed medial safe zone.

Methods

AI and the medial save zone were measured on 419 hips using a computed-tomography scan of the pelvis. AI was assessed on a 2D reconstructed anterior-posterior view of the pelvis using VOXAR™. Correlation was measured using the Pearson correlation coefficient.

Results

Mean AI was 4.2 degrees (SD 4.9 degrees). Mean medial safe zone was 8.1 mm (SD 1.9 mm). There was a significant correlation between AI and medial save space with a Pearson correlation coefficient r = 0.33 (p = .001).

Conclusion

There is a weak correlation between AI and medial safe zone. AI should not be used to predict medial safe zone. Due to the weakness in correlation AI is not suited for predicting medial safe zone. However, a low or negative AI can be a warning sign for less medial safe zone, prompting surgeons to take care when reaming in THA or placing periacetabular screws.

What Are the Reference Values and Associated Factors for Center-edge Angle and Alpha Angle? A Population-based Study

BACKGROUND

The available evidence regarding normal ranges for the center-edge angle and the alpha angle derives from a few small studies, and associated factors such as sex and anthropometric factors have not been well evaluated. Knowing more about normal values for these parameters is critical, because this can inform decisions about when to perform elective hip preservation surgery. Population-level studies would provide considerable clarity on these issues, but to our knowledge, no such studies are available.

QUESTIONS/PURPOSES

The purposes of this study were (1) to use MRI in patients of a population-based study to establish normal values for the alpha and center-edge angles in the normal adult hip; and (2) to determine whether age, sex, or anthropometric variables were associated with differences in these values.

METHODS

We used MRI images (1.5 T) of 3226 participants of the Study of Health in Pomerania (SHIP). SHIP is a population-based study that started with 4308 participants in 1997. Participants were recruited randomly from official inhabitant data files as a stratified cluster sample of the population from a defined region in northeastern Germany. To ensure a representative epidemiologic cohort, stratification variables were sex, age, and city of residence. Between 2008 and 2012, 1094 of these participants underwent whole-body MRI with pelvic sequences in the second followup. In parallel, the next cohort, SHIP-Trend, started with the same protocol in which 2132 participants underwent MRI examination. Reference values were calculated by quantile regressions for the 2.5 and 97.5 percentiles. Associations with the demographic features sex, age, weight, height, body mass index (BMI), and waist circumference were analyzed by bivariate linear regression models.

RESULTS

The mean center-edge angle was 31° (± 7°) with a corresponding calculated normal range of 17° to 45°. The mean alpha angle was 55° (± 8°) with a corresponding calculated normal range between 39° and 71°. Men (30° ± 7°) had a lower center-edge angle than women (32° ± 8°) (p < 0.001, β = 1.4°; 95% confidence interval [CI], 0.9°-1.9°) and a higher alpha angle (57° ± 8° versus 52° ± 7°, p < 0.001, β = 5.7°; 95% CI, 5.2°-6.3°). Moreover, a higher center-edge angle for the left side was found (33° ± 8° versus 30° ± 8°, p < 0.001, β =3.2°; 95% CI, 3.0°-3.4°). In addition to sex, we found that age, height, waist circumference, and BMI affected both center-edge angle and alpha angle. Weight was associated with the alpha angle as well. Because of these associations, age- and sex-adjusted reference values with belonging formulas were calculated.

CONCLUSIONS

The range of normal center-edge and alpha angles is quite wide. Therefore, only markedly abnormal angles may be associated with pathology. Moreover, center-edge angle and alpha angle are associated with age, sex, and anthropometric factors, which have to be taken into account for better interpretation.

CLINICAL RELEVANCE

The association of abnormal radiographic values with true clinical hip pathology is tenuous at best. Assuming that a patient with an abnormal radiograph requires treatment is unwise. The clinical picture has to be substantial for therapeutic decisions.

[Modified Salter innominate osteotomy in adults]

OBJECTIVE

The dysplastic acetabulum is shifted three-dimensionally outwards and forwards.

INDICATIONS

Symptomatic residual hip dysplasias and hip subluxations in skeletally mature patients up to the age of 50 years. Sharp's acetabular up to 60°, as an exception above 60°.

CONTRAINDICATIONS

Acetabular retroversion. Radiographic joint space at the lateral acetabular edge that is less than half the normal thickness for the patient's age. Relative contraindication: Elongated leg on the affected side.

SURGICAL TECHNIQUE

Ilioinguinal approach in a supine position. Division of the innominate bone. Pivoting the distal osteotomy fragment outwards and forwards with the aid of the Salter maneuver. Fixing the fragments with a guide wire. Final correction of the osteotomy fragments. Force fitting of a dovetail grooved, wedge-shaped bone graft. Insertion of a cannulated compression screw and two further threaded rods. Wound closure.

POSTOPERATIVE MANAGEMENT

Unloaded 3‑point walking for 4 weeks. Increasing weight bearing from week 4. Full weight bearing from week 10-12.

RESULTS

A total of 45 consecutive patients (7 men, 38 women, 49 hips) underwent surgery. Average age at surgery was 27.6 years. The Sharp acetabular angle improved from preoperatively 45.7° ± 4.2° by 13.8° to 32.0° ± 6.4°; the Wiberg (LCE) angle increased from 15.4° ± 9.3° by 19.5° to 34.9° ± 10° postoperatively. The anterior center edge (ACE) angle increased from 28.9° ± 10.4° by 8.6° ± 2.3° to 37.5° ± 8.1°. Complications requiring surgical intervention occurred in 7 patients.

Sub-elite Football Players With Hip-Related Groin Pain and a Positive Flexion, Adduction, and Internal Rotation Test Exhibit Distinct Biomechanical Differences Compared With the Asymptomatic Side

Background Hip-related groin pain is common in sub-elite football players and may be associated with altered hip biomechanics. Objectives To compare the hip biomechanics, bony hip morphology associated with femoroacetabular impingement (FAI) syndrome, and hip strength and range of motion (ROM) between the symptomatic and asymptomatic limbs of sub-elite football players with unilateral hip-related groin pain and a positive flexion, adduction, and internal rotation (FADIR) test. Methods Fifteen sub-elite football (soccer) players with unilateral hip-related groin pain and a positive FADIR test were recruited for this observational cross-sectional study. Three-dimensional motion analysis and ground reaction force data were recorded for walking and a single-leg drop-jump (SLDJ) task. Participants also underwent a standard anterior-posterior hip radiograph and hip strength and ROM assessment. Between-limb differences were assessed using paired t tests or Wilcoxon signed-rank tests. Results The symptomatic limb displayed a smaller peak hip extension angle (P = .01) and a lower peak hip adduction moment (P = .03) compared with the asymptomatic limb during the stance phase of walking. Additionally, during the SLDJ, the symptomatic limb demonstrated less total sagittal plane ROM (P = .04). The symptomatic limb also demonstrated less external rotation ROM (P = .03). However, no differences were found between limbs for bony hip morphology associated with FAI syndrome or hip strength. Conclusion This study found between-limb asymmetries in low- and high-impact functional tasks, such as walking and an SLDJ, in football players with unilateral hip-related groin pain. Despite unilateral pain, bony morphology associated with FAI syndrome did not differ between limbs. J Orthop Sports Phys Ther 2018;48(7):584-593. Epub 8 May 2018. doi:10.2519/jospt.2018.7910.

Secure corridor for infraacetabular screws in acetabular fracture fixation-a 3-D radiomorphometric analysis of 124 pelvic CT datasets

Background

Acetabular fracture surgery is directed toward anatomical reduction and stable fixation to allow for the early functional rehabilitation of an injured hip joint. Recent biomechanical investigations have shown the superiority of using an additional screw in the infraacetabular (IA) region, thereby transfixing the separated columns to strengthen the construct by closing the periacetabular fixation frame. However, the inter-individual existence and variance concerning secure IA screw corridors are poorly understood.

Methods

This computer-aided 3-D radiomorphometric study examined 124 CT Digital Imaging and Communications in Medicine (DICOM) datasets of intact human pelves (248 acetabula) to visualize the spatial IA corridors as the sum of all intraosseous screw positions. DICOM files were pre-processed using the Amira® 4.2 visualization software. Final corridor computation was accomplished using a custom-made software algorithm. The volumetric measurement data of each corridor were calculated for further statistical analyses. Correlations between the volumetric values and the biometric data were investigated. Furthermore, the influence of hip dysplasia on the IA corridor configuration was analyzed.

Results

The IA corridors consistently showed a double-cone shape with the isthmus located at the acetabular fovea. In 97% of male and 91% of female acetabula, a corridor for a 3.5-mm screw could be found. The number of IA corridors was significantly lower in females for screw diameters ≥ 4.5 mm. The mean 3.5-mm screw corridor volume was 16 cm³ in males and 9.2 cm³ in female pelves. Corridor volumes were significantly positively correlated with body height and weight and with the diameter of Köhler’s teardrop on standard AP pelvic X-rays. No correlation was observed between hip dysplasia and the IA corridor extent.

Conclusion

IA corridors are consistently smaller in females. However, 3.5-mm small fragment screws may still be used as the standard implant because sex-specific differences are significant only with screw diameters ≥ 4.5 mm. Congenital hip dysplasia does not affect secure IA screw insertion. The described method allows 3-D shape analyses with highly reliable results. The visualization of secure IA corridors may support the spatial awareness of surgeons. Volumetric data allow the reliable assessment of individual IA corridors using standard AP X-ray views, which aids preoperative planning.

Soft Tissue Structures Differ in Patients With Prearthritic Hip Disease

BACKGROUND

Clinically, understanding how the soft tissue envelope adapts to various forms of hip dysfunction could enhance both surgical and nonsurgical management. Very few studies have looked at soft tissue structures as preoperative discriminators between varying underlying etiologies of hip conditions.

PURPOSE

To demonstrate that the magnetic resonance arthrography assessment of soft tissue structures of the hip will preoperatively differ in patients with different underlying hip joint diseases.

METHODS

Fifty-seven patients who underwent preoperative magnetic resonance arthrography and corrective hip surgery were retrospectively identified yielding 3 groups: 17 with developmental dysplasia of the hip (DDH) (11 F, 6 M; mean age 35.1 years, range 19.6-53.6); 20 with isolated labral tears (LTs) (17 F, 3 M; mean age 38.4 years, range 15.2-62.1), and 20 with cam-type femoroacetabular impingement (FAI) (11 F, 9 M; mean age 38.8 years, range 18.9-51.2). Measurements of the hip labral length, capsule thickness, and psoas, rectus femoris, and gluteal muscle dimensions were performed, with normalization of the values for statistical analysis.

RESULTS

The superior labral length was significantly greater in the DDH group [normalized value (NV): 0.30] compared with the FAI group (NV: 0.25, P < 0.05). In addition, the superior (12 o'clock) capsular thickness (NV: 0.24) was significantly greater compared with the LT group (NV: 0.15, P < 0.05) and the FAI group (NV: 0.16, P < 0.05). The DDH group also had a significantly greater anterior (3 o'clock) capsular thickness (NV: 0.18) compared with the LT group (NV: 0.13, P < 0.05). The transverse dimension of the rectus femoris was larger in the DDH group (NV: 1.39) compared with the FAI group (NV: 1.14, P < 0.05).

CONCLUSION

An enlarged rectus femoris and thicker hip capsule as well as an enlarged labrum are characteristic findings in hip dysplasia.

LEVEL OF EVIDENCE

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

Hip shape is symmetric, non-dependent on limb dominance and gender-specific: implications for femoroacetabular impingement. A 3D CT analysis in asymptomatic subjects

OBJECTIVE

To determine the reference intervals (RefInt) of the quantitative morphometric parameters of femoroacetabular impingement (FAI) in asymptomatic hips with computed tomography (CT) and determine their dependence on age, side, limb dominance and sex.

METHODS

We prospectively included 590 patients and evaluated 1111 hips with semi-automated CT analysis. We calculated overall, side- and sex-specific parameters for imaging signs of cam [omega and alpha angle (α°)] and pincer-type morphology [acetabular version (ACvers), lateral centre-edge angle (LCEA) and cranio-caudal coverage].

RESULTS

Hip shape was symmetrical and did not depend on limb dominance. The 95% RefInt limits were sex-different for all cam-type parameters and extended beyond current abnormal thresholds. Specifically, the upper limits of RefInt for α° at 12:00, 1:30 and 3:00 o'clock positions were 56°, 70° and 58°, respectively, and 45° for LCEA. Acetabular morphology varied between age groups, with a trend toward an LCEA/ACvers increase over time.

CONCLUSION

Our morphometric measurements can be used to estimate normal hip morphology in asymptomatic individuals. Notably they extended beyond current thresholds used for FAI imaging diagnosis, which was most pronounced for cam-type parameters. We suggest the need to reassess α° RefInt and consider a 60° threshold for the 12:00/3:00 positions and 65-70° for other antero-superior positions.

KEY POINTS

• Hip shape is symmetrical regardless of limb dominance. • Pincer/cam morphology is frequent in asymptomatic subjects (20 and 71%, respectively). • LCEA and acetabular version increases with age (5-7° between opposite age groups). • Femoral morphology is stable after physeal closure (in the absence of pathology). • Alpha and omega angle thresholds should be set according to sex.

The Human Pelvis: Variation in Structure and Function During Gait

The shift to habitual bipedalism 4-6 million years ago in the hominin lineage created a morphologically and functionally different human pelvis compared to our closest living relatives, the chimpanzees. Evolutionary changes to the shape of the pelvis were necessary for the transition to habitual bipedalism in humans. These changes in the bony anatomy resulted in an altered role of muscle function, influencing bipedal gait. Additionally, there are normal sex-specific variations in the pelvis as well as abnormal variations in the acetabulum. During gait, the pelvis moves in the three planes to produce smooth and efficient motion. Subtle sex-specific differences in these motions may facilitate economical gait despite differences in pelvic structure. The motions of the pelvis and hip may also be altered in the presence of abnormal acetabular structure, especially with acetabular dysplasia. Anat Rec, 300:633-642, 2017. © 2017 Wiley Periodicals, Inc.

The fate of hips that are conservatively treated in multiple epiphyseal dysplasia

We reviewed the radiologic and clinical outcomes of hip joints affected by multiple epiphyseal dysplasia in 40 patients. The average patient age was 9.6 years. All patients were followed up for an average of 7.2 years. No patient underwent surgical treatment. The variances of the center-edge angle and femoral head coverage had the greatest tendency to increase with conservative treatment and follow-up (P=0.011 and 0.015, respectively). The acetabular angle and the acetabular depth index at the first visit and the latest follow-up were statistically significantly different (P=0.046 and 0.027, respectively). According to the Stulberg classification, the severity of hip deformity became less severe with age, but this was not statistically significant (P=0.090). Larger improvements in Harris hip scores were identified after conservative treatment (P=0.003). Favorable midterm outcomes were obtained for the treatment of hip deformity in multiple epiphyseal dysplasia patients by conservative treatment.

Decreased Synovial Inflammation in Atraumatic Hip Microinstability Compared With Femoroacetabular Impingement

PURPOSE

To compare the inflammatory profile of hip synovial tissue in those with atraumatic microinstability to patients with femoroacetabular impingement (FAI).

METHODS

Patients with cam and mixed-type FAI (FAI group) and patients with hip instability underwent sampling of the anterolateral synovium. Demographic data, intraoperative measurements, and functional outcome scores (International Hip Outcomes Tool and Short Form-12) were recorded. Cryosections were stained and examined under light microscopy as well as confocal fluorescent microscopy for anti-CD45 (common leukocyte antigen), anti-CD31 (endothelial), and anti-CD68 (macrophage) cell surface markers. A grading system was used to quantify synovitis under light microscopy whereas digital image analysis was used to quantify immunofluorescence staining area. Comparison were made with Student t test, Mann-Whitney U, χ², and regression analysis.

RESULTS

There were 12 patients in the FAI group and 5 in the instability group. Mean age was not significantly different (P > .05), but there was a significantly greater proportion of females in the instability group versus the FAI group (P < .001). There was a significant correlation (r = 0.653; P = .005) between number of turns needed for 10 mm of distraction and increased synovitis. Synovitis scores also were increased significantly in patients with cam morphology and articular cartilage damage (P = .024) versus those without. Immunohistochemistry did not reveal differences (P > .082) between the instability and FAI groups, but CD68 staining was significantly greater in those with cam morphology and cartilage damage (P < .045). CD45+/CD68- cells were noted in the perivascular area while CD45+/CD68+ cells were noted within the synovial lining in both groups.

CONCLUSIONS

Increased synovial inflammation was associated with an increased number of turns to achieve joint distraction. Both instability and FAI groups demonstrated baseline levels of synovial inflammation. Synovitis scores also were increased in patients with cartilage damage.

CLINICAL RELEVANCE

An understanding of the molecular and cellular mechanisms behind both hip instability and FAI may lead to novel therapeutic anti-inflammatory therapy, which may serve as an adjunct to treatment of mechanical abnormalities in this conditions.

Higher medially-directed joint reaction forces are a characteristic of dysplastic hips: A comparative study using subject-specific musculoskeletal models

Acetabular dysplasia is a known cause of hip osteoarthritis. In addition to abnormal anatomy, changes in kinematics, joint reaction forces (JRFs), and muscle forces could cause tissue damage to the cartilage and labrum, and may contribute to pain and fatigue. The objective of this study was to compare lower extremity joint angles, moments, hip JRFs and muscle forces during gait between patients with symptomatic acetabular dysplasia and healthy controls. Marker trajectories and ground reaction forces were measured in 10 dysplasia patients and 10 typically developing control subjects. A musculoskeletal model was scaled in OpenSim to each subject and subject-specific hip joint centers were determined using reconstructions from CT images. Joint kinematics and moments were calculated using inverse kinematics and inverse dynamics, respectively. Muscle forces and hip JRFs were estimated with static optimization. Inter-group differences were tested for statistical significance (p≤0.05) and large effect sizes (d≥0.8). Results demonstrated that dysplasia patients had higher medially directed JRFs. Joint angles and moments were mostly similar between the groups, but large inter-group effect sizes suggested some restriction in range of motion by patients at the hip and ankle. Higher medially-directed JRFs and inter-group differences in hip muscle forces likely stem from lateralization of the hip joint center in dysplastic patients. Joint force differences, combined with reductions in range of motion at the hip and ankle may also indicate compensatory strategies by patients with dysplasia to maintain joint stability.

Morphologic Changes and Outcomes After Arthroscopic Acetabular Labral Repair Evaluated Using Postoperative Computed Tomography Arthrography

PURPOSE

To investigate smaller sized labra after acetabular labral repair comparing preoperative and postoperative computed tomography arthrography (CTA) and to assess the correlation between the anatomic changes and clinical outcomes.

METHODS

The design and protocol of this retrospective study were approved by the institutional review board of our hospital. The inclusion criteria included age older than 18 years and hip pain associated with mechanical symptoms. Patients with previous hip surgery, avascular necrosis, rheumatologic disorders, or advanced arthritis were excluded. All tears with femoroacetabular impingement were treated with bumpectomy or acetabuloplasty and repaired using arthroscopic suture anchors. We evaluated clinical outcomes using the modified Harris Hip Score (mHHS) and the morphologic changes and radiologic outcomes (labral retear and leakage of dye) using CTA at a minimum 2-year follow-up. The paired t test was performed to detect changes in labral height, labral width, and mHHS.

RESULTS

Forty labral tears in 40 patients (mean age, 32.1 ± 9.2 years) underwent labral repair, with femoroplasty in 20 hips and acetabuloplasty in 17 hips, and no patients required capsular repair after capsulotomy. No leakage of contrast dye was detected during the follow-up CTA procedure. No labral retears were observed after labral refixation at the postoperative CTA evaluation. However, the mean width and height of the labrum changed from 8.1 mm and 4.9 mm, respectively, preoperatively to 6.7 mm and 4.4 mm, respectively, at the postoperative follow-up (decreasing by 19% and 11%, respectively; both P < .001). In addition, the mean mHHS for the 36 patients in the complete repair group improved from 61 ± 16.0 to 90 ± 9.6 (P = .01). Four hips showed incomplete repairs.

CONCLUSIONS

Repaired labra are well maintained after capsulotomy based on follow-up CTA after arthroscopic labral repair. In addition, decreased height and width of the labra do not affect the clinical outcomes.

LEVEL OF EVIDENCE

Level IV, therapeutic study (case series [no, or historical, control group]).

Cyclists Have Greater Chondromalacia Index Than Age-Matched Controls at the Time of Hip Arthroscopy

PURPOSE

To evaluate the clinical symptoms and intraoperative pathology associated with hip pain in the cyclist compared with a matched hip arthroscopy surgical group.

METHODS

In an institutional review board-approved study, we retrospectively reviewed a prospective database of 1,200 consecutive hip arthroscopy patients from 2008 to 2015. Adult patients were identified who reported cycling as a major component of their activity. Patients were age, gender, and body mass index matched to a control, noncycling group. Pain symptoms, preoperative examinations, radiographic and operative findings were compared. Primary outcome variables included the femoral and acetabular Outerbridge chondromalacia grade. Additional outcome measurements included the involved area and the chondromalacia index (CMI; the product of the Outerbridge chondromalacia grade and surface area [mm² × severity]).

RESULTS

A total of 167 noncyclists were matched to the cycling group (n = 16). Cyclists had significantly greater femoral head chondromalacia grade (2.0 [95% confidence interval (CI), 1.5-2.5] v 1.4 [95% CI, 1.3-1.6], P = .043), femoral head chondromalacia area (242 mm² [95% CI, 191-293 mm²] v 128 mm² [95% CI, 113-141 mm²], P < .001), and femoral head CMI (486 [95% CI, 358-615] v 247 [95% CI, 208-286], P = .001) assessed intraoperatively. Hip pain in cyclists positively correlated with an increased acetabular center-edge angle (R = 0.261, P < .001) and an increased Tonnis grade (R = 0.305, P < .001). Cyclists were also more likely to have a coxalgic gait on physical examination (R = 0.250, P = .006).

CONCLUSIONS

Cyclists had a greater degree of femoral chondromalacia than a matched group of noncyclists. Cycling activity positively correlated with the presence of femoral chondromalacia with clinically significant gait alterations. These data support the hypothesis that cyclists with hip pain have more chondral pathology than a similar group of other patients with hip pain. Ultimately, cyclists with hip pain should be identified as higher risk for more advanced chondral damage.

LEVEL OF EVIDENCE

Level III, case-control study, therapeutic.

Treatment Algorithm for Patients with Non-arthritic Hip Pain, Suspect for an Intraarticular Pathology

Background:

The amount of patients referred with longstanding, non-arthritic hip pain is increasing, as are the treatment options. Left untreated hip dysplasia, acetabular retroversion and femoroacetabular impingement (FAI) may lead to osteoarthritis (OA). Finding the right treatment option for the right patient can be challenging in patients with non-arthritic hip pain.

Purpose:

The purpose of this study was to categorize the radiographic findings seen in patients with longstanding hip pain, suspect for an intraarticular pathology, and provide a treatment algorithm allocating a specific treatment option for each clinical condition.

Material and Methods:

A review of the literature was performed using Public Medline searches of MeSH terms combined with synonyms for femoroacetabular impingement, acetabular retroversion, periacetabular osteotomy and hip arthroscopy.

Results:

Radiographic findings associated with acetabular retroversion described in the literature were the crossover sign, the posterior wall sign and the ischial spine sign, while Wiberg’s lateral center-edge angle (CE-angle) together with Leqeusne’s acetabular index indicate hip dysplasia. A Tönnis index >2 indicates osteoarthritis, however unsatisfying results are documented following joint preserving surgery with a Tönnis index >1. Furthermore, ischial spine sign in combination with the posterior wall sign indicates total acetabular retroversion prone to periacetabular osteotomy in contrast to focal retroversion prone to hip arthroscopy. These findings were used creating a treatment algorithm for intraarticular pathologies in patients with longstanding hip pain.

Conclusion:

Based on the radiographic findings, the algorithm presented in this study can be a helpful tool in the decision-making for the treatment of patients with non-arthritic hip pain, suspect for intraarticular pathologies.

Progression of Hip Displacement during Radiographic Surveillance in Patients with Cerebral Palsy

Progression of hip displacement is common in patients with cerebral palsy (CP). We aimed to investigate the rate of progression of hip displacement in patients with CP by assessing changes in radiographic indices according to Gross Motor Function Classification System (GMFCS) level during hip surveillance. We analyzed the medical records of patients with CP aged < 20 years who underwent at least 6 months interval of serial hip radiographs before any surgical hip intervention, including reconstructive surgery. After panel consensus and reliability testing, radiographic measurements of migration percentage (MP), neck-shaft angle (NSA), acetabular index (AI), and pelvic obliquity (PO) were obtained during hip surveillance. For each GMFCS level, annual changes in radiographic indices were analyzed and adjusted for affecting factors, such as sex, laterality, and type of CP. A total of 197 patients were included in this study, and 1,097 radiographs were evaluated. GMFCS classifications were as follows: 100 patients were level I-III, 48 were level IV, and 49 were level V. MP increased significantly over the duration of hip surveillance in patients with GMFCS levels I-III, IV, and V by 0.3%/year (P < 0.001), 1.9%/year (P < 0.001), and 6.2%/year (P < 0.001), respectively. In patients with GMFCS level IV, NSA increased significantly by 3.4°/year (P < 0.001). Our results suggest that periodic monitoring and radiographic hip surveillance is warranted for patients with CP, especially those with GMFCS level IV or V. Furthermore, physicians can predict and inform parents or caregivers regarding the progression of hip displacement in patients with CP.

Osteoarthritic changes rather than age predict outcome following arthroscopic treatment of femoroacetabular impingement in middle-aged patients

BACKGROUND

Our purpose was to evaluate outcome following arthroscopic treatment of femoroacetabular impingement (FAI) in middle-aged patients and to define risk factors for conversion to total hip arthroplasty (THA).

METHODS

This was a retrospective case series of 79 consecutive patients (40 to 65 years) undergoing arthroscopic treatment of FAI (follow-up ≥12 months). Outcome at follow-up was assessed using Hip outcome score (HOS). Alpha angle, Kellgren Lawrence grade (K-L grade), joint space width (JS), lateral center edge (LCE) angle, caput-collum-diaphysis (CCD) angle and acetabular index (AI) were analysed retrospectively. THA group and Non-THA group were compared.

RESULTS

Seventy-nine patients (mean age 48.6 years, mean follow-up 32 months) were included. 18 patients (22.8 %) were converted to THA. Mean HOS score in the Non-THA group at time point of follow-up was 80.2. Non-THA group and THA group showed no significant differences for mean age (48.2 years vs. 49.9 years, p = 0.278), alpha angel (p = 0.541), LCE (p = 0.294), CCD (p = 0.101) and AI (p = 0.661) in contrast to differences for JS (p = <0.001) and K-L grade (p = <0.001). Risk of conversion to THA was higher for patients with K-L grade 3 (p = 0.003) or joint space less or equal 2 mm (p = 0.001).

CONCLUSIONS

One fifth of the middle-aged patients required early conversion to THA. Advanced JS narrowing and K-L grade rather than age alone can be considered as risk factor for conversion to THA.

Hip morphology influences the pattern of articular cartilage damage

PURPOSE

The aim of this study was to obtain data on chondral damage and compare the damage patterns of various hip disorders.

METHODS

Data were collected at 100 consecutive arthroscopies, and chondral lesions were recorded on anatomic articular maps divided into different anatomical zones. This geographic zone method made it possible to analyze the ICRS grade and location in relation to the hip morphology.

RESULTS

The distribution and degree of the chondral defects showed a hip morphology-specific pattern. On the acetabular side, there were high incidences of full-thickness defects in the anterior-superior zone and the middle superior zone in patients with femoroacetabular impingement (FAI) (zone 2: 25.4 % grade 3, 35.5 % grade 4; zone 3: 20.3 % grade 3, 37.2 % grade 4) and borderline dysplasia (zone 2: 31.2 % grade 3, 12.5 % grade 4; zone 3: 18.7 % grade 3, 25 % grade 4). However, in patients with joint laxity, partial-thickness defects were dominant (zone 2: 50 % grade 1, 15 % grade 2; zone 3: 40 % grade 1). In patients with acetabular dysplasia, full-thickness defects extended even to the posterior superior zone (zone 4: 80 % grade 4). On the femoral head side, the incidence of full-thickness cartilage injuries was high in patients with FAI and borderline dysplasia compared to those with joint laxity and acetabular dysplasia.

CONCLUSION

Evaluation of chondral damage using the geographic zone method showed that the pattern of cartilage damage was influenced by hip morphology. Understanding of hip disorder-specific chondral damage patterns may be useful for the development of arthroscopic classification of hip disorders and may lead to the establishment of treatment guidelines.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Femoroacetabular Impingement: Prevalent and Often Asymptomatic in Older Men: The Osteoporotic Fractures in Men Study

BACKGROUND

The epidemiology of femoroacetabular impingement (FAI) is important but incompletely understood, because most reports arise from symptomatic populations. Investigating the prevalence of FAI in a community-based cohort could help us better understand its epidemiology and in particular the degree to which it might or might not be associated with hip pain.

QUESTIONS/PURPOSES

The purposes of this study were (1) to evaluate the proportion of older (≥65 years of age) men with morphologic abnormalities consistent with FAI; and (2) to assess the association of the morphologic abnormalities with prevalent radiographic hip osteoarthritis (OA) and hip pain.

METHODS

Anteroposterior radiographs were obtained in 4140 subjects (mean age±SD, 77±5 years) from the Osteoporotic Fractures in Men study. We assessed each hip for cam, pincer, and mixed FAI types using validated radiographic definitions. Both intra- and interobserver reproducibility were >0.9. Radiographic hip OA was assessed by an expert reader (intraobserver reproducibility, 0.7-0.8) using validated methods, and summary grades of 2 or greater (on a scale from 0 to 4) were used to define radiographic hip OA. Covariates including hip pain in the last 30 days were collected by questionnaires that were answered by all patients included in this report. Logistic regressions with generalized estimating equations were performed to evaluate the association of radiographic features of FAI and arthrosis.

RESULTS

Pincer, cam, or mixed types of radiographic FAI had a prevalence of 57% (1748 of 3053), 29% (886 of 3053), and 14% (419 of 3053), respectively, in this group of older men. Both pincer and mixed types of FAI were associated with arthrosis but not with hip pain (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.25-2.13; p<0.001 for pincer and OR, 2.49; 95% CI, 1.65-3.76; p<0.001 for mixed type). Patients with hips characterized by cam-type FAI had slightly reduced hip pain without the presence of arthrosis compared with hips without FAI (OR, 0.82; 95% CI, 0.68-0.99; p=0.037). A center-edge angle>39° and a caput-collum-diaphyseal angle<125° were associated with arthrosis (OR, 1.53; 95% CI, 1.22-1.94; p<0.001 and OR, 2.09; 95% CI, 1.24-3.51; p=0.006, respectively), but not with hip pain (OR, 0.89; 95% CI, 0.77-1.03; p<0.108 and OR, 0.99; 95% CI, 0.67-1.45; p=0.945, respectively). An impingement angle<70° was associated with less hip pain compared with hips with an impingement angle≥70° (OR, 0.76; 95% CI, 0.61-0.95; p=0.015).

CONCLUSIONS

FAI is common in older men and represents more of an anatomic variant rather than a symptomatic disease. This finding should raise questions on how age, activities, and this anatomic variant each contribute to result in symptomatic disease.

LEVEL OF EVIDENCE

Level III, prognostic study.

What are the radiographic reference values for acetabular under- and overcoverage?

BACKGROUND

Both acetabular undercoverage (hip dysplasia) and overcoverage (pincer-type femoroacetabular impingement) can result in hip osteoarthritis. In contrast to undercoverage, there is a lack of information on radiographic reference values for excessive acetabular coverage.

QUESTIONS/PURPOSES

(1) How do common radiographic hip parameters differ in hips with a deficient or an excessive acetabulum in relation to a control group; and (2) what are the reference values determined from these data for acetabular under- and overcoverage?

METHODS

We retrospectively compared 11 radiographic parameters describing the radiographic acetabular anatomy among hip dysplasia (26 hips undergoing periacetabular osteotomy), control hips (21 hips, requiring no rim trimming during surgical hip dislocation), hips with overcoverage (14 hips, requiring rim trimming during surgical hip dislocation), and hips with severe overcoverage (25 hips, defined as having acetabular protrusio). The hips were selected from a patient cohort of a total of 593 hips. Radiographic parameters were assessed with computerized methods on anteroposterior pelvic radiographs and corrected for neutral pelvic orientation with the help of a true lateral radiograph.

RESULTS

All parameters except the crossover sign differed among the four study groups. From dysplasia through control and overcoverage, the lateral center-edge angle, acetabular arc, and anteroposterior/craniocaudal coverage increased. In contrast, the medial center-edge angle, extrusion/acetabular index, Sharp angle, and prevalence of the posterior wall sign decreased. The following reference values were found: lateral center-edge angle 23° to 33°, medial center-edge angle 35° to 44°, acetabular arc 61° to 65°, extrusion index 17% to 27%, acetabular index 3° to 13°, Sharp angle 38° to 42°, negative crossover sign, positive posterior wall sign, anterior femoral head coverage 15% to 26%, posterior femoral head coverage 36% to 47%, and craniocaudal coverage 70% to 83%.

CONCLUSIONS

These acetabular reference values define excessive and deficient coverage. They may be used for radiographic evaluation of symptomatic hips, may offer possible predictors for surgical outcomes, and serve to guide clinical decision-making.

Femoral Neck Stress Fractures and Imaging Features of Femoroacetabular Impingement

BACKGROUND

Prior literature has suggested an association between the radiographic signs of femoroacetabular impingement (FAI) and femoral neck stress fractures (FNSF) or femoral neck stress reactions (FNSR). At the time of the writing of this article, no study has described the association of FAI and FNSF/FNSR along with the need for surgical intervention and outcomes.

OBJECTIVE

To determine the prevalence of radiographic features of FAI in patients diagnosed with FNSF.

DESIGN

Retrospective case series.

SETTING

Tertiary care, institutional setting.

PATIENTS

A medical records search program (Stanford Translational Research Integrated Database Environment, Stanford University, California) was used to retrospectively search for patients 18-40 years old with a history of FNSF or FNSR. The records were obtained from the period July 25, 2003, to September 23, 2011.

METHODS

For assessment of risk factors, plain radiographs and magnetic resonance imaging studies were reviewed for features of cam or pincer FAI. Medical records were reviewed to determine whether patients required operative intervention.

MAIN OUTCOME MEASURES

Incidence of abnormal alpha (α) angle, abnormal anterior offset ratio, abnormal femoral head-neck junction, coxa profunda, positive crossover sign, and abnormal lateral center-to-edge angle.

RESULTS

Twenty-one female and 3 male participants (mean age 27 years, range 19-39 years) were identified with magnetic resonance imaging evidence of femoral neck stress injury. Cam morphology was seen in 10 patients (42%). Pincer morphology could be assessed in 18 patients, with coxa profunda in 14 (78%) and acetabular retroversion in 6 (14%). Features of combined pincer and cam impingement were observed in 4 patients (17%). Seven patients (29%) had operative intervention, with 3 (12%) requiring internal fixation of their femoral neck fractures, and all had radiographic evidence of fracture union after surgery. Four patients (17%) had persistent symptoms after healing of their FNSF with conservative treatment and eventually required surgery for FAI, 3 had no pain at final follow-up 1 year post-surgery, and one patient was lost to follow-up.

CONCLUSION

The results of the current study suggest that patients in the general population with femoral neck stress injuries have a higher incidence of bony abnormalities associated with pincer impingement, including coxa profunda and acetabular retroversion, although it is unclear whether pincer FAI is a true risk factor in the development of FNSF.

Arthroscopic surgery for global versus focal pincer femoroacetabular impingement: are the outcomes different?

To determine outcomes from arthroscopic surgery for global pincer femoroacetabular impingement (FAI), a large multicenter prospective study investigating arthroscopic surgical outcomes was performed with minimum 2-year follow-up. Global (center-edge angle 40+ degrees) and Focal (center-edge angle 25-39 degrees) cohorts were based on pre-operative radiographs. Pre-operative and intra-operative findings, surgical procedures, post-operative nonarthritic hip score (NAHS) and satisfaction (5-point Likert scale), complications and conversion arthroplasties were compared. A nested case-control study was also performed. The Global cohort consisted of 15 patients (18 hips) of mean age 37.2 years. Pre-operative NAHS was 51.5 and 74.1 at 24+ months post-surgery. The change in NAHS was significant (P = 0.01). Mean satisfaction was 4.2. There was one total hip arthroplasty (THA) conversion (5.6%), no revision surgeries or complications. The Focal cohort consisted of 125 patients (129 hips) of mean age 39.8 years. Pre-operative NAHS was 54.8 and 77.8 at 24+ months post-surgery. The change in NAHS was significant (P < 0.0001). Mean satisfaction was 4.2. There were eight THA conversions (6.2%), three complications (2.3%) and two revision surgeries (1.5%). Cohort comparisons revealed no statistically significant difference in NAHS (P = 0.30), satisfaction (P = 0.92) or THA conversion rate (P = 0.91). The nested case-control study found mean post-operative change in NAHS was +22.2 and +20.4, respectively, at 24+ months (P = 0.76). Arthroscopic treatment of global pincer FAI is a safe and effective procedure. With outcomes comparable to those observed in the arthroscopic treatment of lesser focal deformities, arthroscopic surgery provides a less invasive option for the treatment of global pincer FAI.

Recognition of minor adult hip dysplasia: which anatomical indices are important?

The rise in popularity of hip arthroscopy has led to a renewed interest in mild hip dysplasia. There is a lack of clarity in the literature regarding both the diagnosis and management of such patients. The aim of this study was to analyse the relative importance of and the inter-relationship between the classically described anatomical indices of dysplasia.One hundred and fifty hips with varying degrees of hip dysplasia were studied. The following were measured: centre-edge (CE), Sharp's and Tönnis angles, acetabular head index (AHI), and acetabular index of depth to width (AIDW). Spearman's correlation coefficient was calculated.Using the CE angle 82 hips were classified as normal and 68 dysplastic. Of the 82 patients with a normal CE angle, 20-39% were dysplastic on at least one other variable. The CE angle did not have a significant correlation to other variables. The remaining four variables showed inter-correlations between 0.26 and 0.54. Overall the Tönnis angle showed the strongest correlation with the other variables. In the patient group with CE angles 21o to 25o (minor dysplasia) 72% of hips had Tönnis angles greater than 10o and 28% had angles greater than or equal to 15o indicating the great variability in the level of dysplasia within this group.In patients with mild dysplasia we have shown that measurement of a single anatomical variable may lead to under-diagnosis. We recommend the measurement the CE angle combined with at least one other variable and suggest the use of the Tönnis angle.