MR imaging findings of acetabular dysplasia in adults

What Is the Influence of Femoral Version on Size, Tear Location, and Tear Pattern of the Acetabular Labrum in Patients With FAI?

BACKGROUND

Femoral version deformities have recently been identified as a major contributor to femoroacetabular impingement (FAI). An in-depth understanding of the specific labral damage patterns caused by femoral version deformities may help to understand the underlying pathomorphologies in symptomatic patients and select the appropriate surgical treatment.

QUESTIONS/PURPOSES

We asked: (1) Is there a correlation between femoral version and the mean cross-sectional area of the acetabular labrum? (2) Is there a difference in the location of lesions of the acetabular labrum between hips with increased femoral version and hips with decreased femoral version? (3) Is there a difference in the pattern of lesions of the acetabular labrum between hips with increased femoral version and hips with decreased femoral version?

METHODS

This was a retrospective, comparative study. Between November 2009 and September 2016, we evaluated 640 hips with FAI. We considered patients with complete diagnostic imaging including magnetic resonance arthrography (MRA) of the affected hip with radial slices of the proximal femur and axial imaging of the distal femoral condyles (allowing for calculation of femoral version) as eligible. Based on that, 97% (620 of 640 hips) were eligible; a further 77% (491 of 640 hips) were excluded because they had either normal femoral version (384 hips), incomplete imaging (20 hips), a lateral center-edge angle < 22° (43 hips) or > 39° (16 hips), age > 50 years (8 hips), or a history of pediatric hip disease (20 hips), leaving 20% (129 of 640 hips) of patients with a mean age of 27 ± 9 years for analysis, and 61% (79 of 129 hips) were female. Patients were assigned to either the increased (> 30°) or decreased (< 5°) femoral version group. The labral cross-sectional area was measured on radial MR images in all patients. The location-dependent labral cross-sectional area, presence of labral tears, and labral tear patterns were assessed using the acetabular clockface system and compared among groups.

RESULTS

In hips with increased femoral version, the labrum was normal in size (21 ± 6 mm 2 [95% confidence interval 20 to 23 mm 2 ]), whereas hips with decreased femoral version showed labral hypotrophy (14 ± 4 mm 2 [95% CI 13 to 15 mm 2 ]; p < 0.01). In hips with increased femoral version, labral tears were located more anteriorly (median 1:30 versus 12:00; p < 0.01). Hips with increased femoral version exhibited damage of the anterior labrum with more intrasubstance tears anterosuperiorly (17% [222 of 1322] versus 9% [93 of 1084]; p < 0.01) and partial tears anteroinferiorly (22% [36 of 165] versus 6% [8 of 126]; p < 0.01). Hips with decreased femoral version showed superior labral damage consisting primarily of partial labral tears.

CONCLUSION

In the evaluation of patients with FAI, the term "labral tear" is not accurate enough to describe labral pathology. Based on high-quality radial MR images, surgeons should always evaluate the combination of labral tear location and labral tear pattern, because these may provide insight into associated femoral version abnormalities, which can inform appropriate surgical treatment. Future studies should examine symptomatic patients with normal femoral version, as well as an asymptomatic control group, to describe the effect of femoral version on labral morphology across the entire spectrum of pathomorphologies.

LEVEL OF EVIDENCE

Level III, prognostic study.

Construction of a predictive nomogram for functional recovery after Bernese periacetabular osteotomy

Background and purpose

Surgical indications for Bernese periacetabular osteotomy (PAO) are well-established. However, the extent of postoperative functional recovery varies widely, as observed in clinical follow-ups. Thus, preoperative evaluation is crucial. This study aims to identify factors that influence functional recovery post-PAO and to develop a predictive nomogram.

Patients and methods

Retrospective data were collected between December 2016 and March 2022 at The First Affiliated Hospital of Shandong First Medical University. The dataset included demographic and imaging data of patients who underwent PAO. The least absolute shrinkage and selection operator (LASSO) regression was utilized to identify influencing factors, which were further analyzed using multivariate logistic regression to construct a predictive nomogram for post-PAO functional recovery.

Result

The analysis identified critical factors affecting functional recovery post-PAO, namely, the preoperative distance from the innermost surface of the femoral head to the ilioischial line, the surgical approach, preoperative acetabular depth, and the continuity of the preoperative Calve line. A nomogram was developed using these significant predictors. The model's validity was demonstrated by the receiver operating characteristic curve, with an area under the curve of 0.864. Additionally, the calibration curve confirmed the nomogram's accuracy, showing a strong correlation between observed and predicted probabilities, indicating high predictive accuracy.

Conclusion

This predictive nomogram effectively identifies patients most suitable for PAO, providing valuable guidance for selecting surgical candidates and determining the appropriate surgical approach.

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.

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.

The dimensions of the hip labrum can be reliably measured using magnetic resonance and computed tomography which can be used to develop a standardized definition of the hypoplastic labrum

PURPOSE

The purpose of this study was to examine the existing literature to determine the dimensions of the acetabular labrum, with a focus on hypotrophic labra, including the modalities and accuracy of measurement, factors associated with smaller labra, and any impacts on surgical management.

METHODS

Four databases (PubMed, Ovid [MEDLINE], Cochrane Database, and EMBASE) were searched from database inception to January 2020. Two reviewers screened the literature independently and in duplicate. Methodological quality of included papers was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria. Where possible, data on labral size were combined using a random effects model.

RESULTS

Twenty-one studies (5 level II, 9 level III, 7 level IV) were identified. This resulted in 6,159 patients (6,436 hips) with a mean age of 34.3 years (range 8.4-85). The patients were 67.3% female with an average follow-up of 57.3 months. There was no consistent definition of labral size quoted throughout the literature. The mean width on MRI/MRA was 7.3 mm (95% CI 6.9-7.8 mm), on computed tomography arthrography was 8.7 mm (95% CI 8.0-9.3), and during arthroscopy was 5.0 mm (95% CI 4.9-5.2). Inter-observer reliability was good to excellent in all modalities. Labral hypotrophy may be associated with increased acetabular coverage. Hypertrophic labra were highly associated with acetabular dysplasia (r = - 0.706, - 0.596, - 0.504, respectively; P < 0.001).

CONCLUSION

Labral width can reliably be measured utilizing imaging techniques including magnetic resonance and computed tomography. The pooled mean labral width was 6.2 mm, and height 4.6 mm. The establishment of a gold-standard of measurement on arthroscopy and advanced imaging would aid in clinical decision-making regarding treatment options for patients presenting with a painful hip, particularly those with hypoplastic labra, and provide radiological guidelines for standardized labrum size classifications.

LEVEL OF EVIDENCE

Level IV.

The utility of hip arthroscopy for patients with painful borderline hip dysplasia

PURPOSE

We measured the width of the acetabular labra in, and the clinical outcomes of, patients with borderline hip dysplasia (HD) who underwent arthroscopy.

METHODS

A total of 1436 patients who underwent hip arthroscopy to treat symptomatic, acetabular labral tears were enrolled. From this cohort, we extracted a borderline HD group (162 cases). Lateral labral widths were evaluated using preoperative magnetic resonance imaging scans. Clinical data including the modified Harris hip score (mHHS), non-arthritic hip score (NAHS), hip outcome score-activity of daily living (HOS-ADL) score, visual analog scale (VAS) pain score, and Tönnis grade were collected. In addition, patient satisfaction with arthroscopy outcomes was rated. All complications and reoperations were noted.

RESULTS

The mean follow-up time was 87.4 months. The lateral labral width was 7.64 mm in those with normal hips and 7.73 mm in borderline HD patients, respectively (p = 0.870). The Tönnis grade progressed mildly from 0.46 to 0.76 (p = 0.227). At the last follow-up, clinical outcome scores (mHHS, NAHS, and HOS-ADL scores) and the VAS score were improved (p < 0.001). The mean patient satisfaction was scored at 8.2. The reoperation rate was higher in those who underwent labral debridement (25.6%) than labral repair (4.1%).

CONCLUSIONS

The lateral labral width did not differ significantly between the borderline HD group and the nondysplastic control group. Arthroscopy relieved the symptoms of painful borderline HD and did not accelerate osteoarthritis. Therefore, if such patients do not respond to conservative treatment, hip arthroscopy can be considered for further treatment.

Larger Acetabular Labrum Is Associated With Hip Dysplasia, Joint Incongruence, and Clinical Symptoms

PURPOSE

To evaluate the association of labral length with acetabular morphology and clinical symptoms.

METHODS

Patients treated at our hip joint clinic between January 2015 and December 2018 were retrospectively enrolled in the study. Our sample included patients who received a diagnosis of one or more of the following: hip labral tear, femoroacetabular impingement (FAI), and developmental dysplasia of the hip. Patients with osteoarthritis and/or osteonecrosis were excluded. Bilateral labral length was measured as the distance from the acetabular rim to the edge of the labrum at the level of the central coronal T1-weighted magnetic resonance imaging scan cross-referenced to the axial plane (3- to 9-o'clock position). The lateral center-edge angle (LCEA) and acetabular roof obliquity (ARO) were evaluated with plain radiographs. An LCEA of 25° or less was defined as developmental dysplasia of the hip, whereas a positive crossover sign in the presence of an LCEA of 30° or greater, an LCEA greater than 40°, or acetabular inclination lower 0° was defined as pincer FAI. An alpha angle greater than 50° or head-neck offset lower 8 mm was considered cam FAI. The severity of hip symptoms was evaluated bilaterally using the Japanese Orthopaedic Association pain scale, on which hips scoring full points (i.e., a perfect score) were defined as asymptomatic whereas hips with all other scores were considered symptomatic. We used simple linear regression to examine the correlations of labral length with the LCEA and ARO. Labral length was also compared according to patient hip symptom status using the Mann-Whitney U test.

RESULTS

The study included 102 patients (14 with bilateral symptoms and 88 with unilateral symptoms). Labral length was strongly correlated with the LCEA (r = -0.612, P < .001) and ARO (r = 0.635, P < .001). Additionally, patients with symptomatic hips had significantly larger labra (9.5 ± 3.0 mm) than those with asymptomatic hips (7.9 ± 2.1 mm, P = .004).

CONCLUSIONS

Acetabular labral length is significantly greater in dysplastic, irregularly congruent, symptomatic hips.

LEVEL OF EVIDENCE

Level Ⅳ, retrospective cross-sectional study.

The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability

BACKGROUND

The acetabular labrum has been found to provide a significant contribution to the distractive stability of the hip. However, the influence of labral height on hip suction seal biomechanics is not known.

HYPOTHESIS

The smaller height of acetabular labrum is associated with decreased distractive stability.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 23 fresh-frozen cadaveric hemipelvises were used in this study. Hips with acetabular dysplasia or femoroacetabular impingement-related bony morphologic features, intra-articular pathology, or no measurable suction seal were excluded. Before testing, each specimen's hip capsule was removed, a pressure sensor was placed intra-articularly, and the hip was fixed in a heated saline bath. Labral size was measured by use of a digital caliper. Maximum distraction force, distance to suction seal rupture, and peak negative pressure were recorded while the hip underwent distraction at a rate of 0.5 mm/s. Correlations between factors were analyzed using the Spearman rho, and differences between groups were detected using Mann-Whitney U test.

RESULTS

Of 23 hips, 12 satisfied inclusion criteria. The maximum distraction force and peak negative pressure were significantly correlated (R = -0.83; P = .001). Labral height was largely correlated with all suction seal parameters (maximum distraction force, R = 0.69, P = .013; distance to suction seal rupture, R = 0.55, P = .063; peak negative pressure, R = -0.62, P = .031). Labral height less than 6 mm was observed in 5 hips, with a mean height of 6.48 mm (SD, 2.65 mm; range, 2.62-11.90 mm; 95% CI, 4.80-8.17 mm). Compared with the 7 hips with larger labra (>6 mm), the hips with smaller labra had significantly shorter distance to suction seal rupture (median, 2.3 vs 7.2 mm; P = .010) and significantly decreased peak negative pressure (median, -59.3 vs -66.9 kPa; P = .048).

CONCLUSION

Smaller height (<6 mm) of the acetabular labrum was significantly associated with decreased distance to suction seal rupture and decreased peak negative pressure. A new strategy to increase the size of the labrum, such as labral augmentation, could be justified for patients with smaller labra in order to optimize the hip suction seal.

CLINICAL RELEVANCE

The height of the acetabular labrum is correlated with hip suction seal biomechanics. Further studies are required to identify the clinical effects of labral height on hip stability.

Is Labral Size Predictive of Failure With Repair in Hip Arthroscopy?

PURPOSE

To assess whether labral size is predictive of labral repair failure or shows an association with patient outcomes after hip arthroscopy.

METHODS

We performed a retrospective chart review of patients who underwent arthroscopic hip labral repair. Labral size was measured in 4 quadrants with an arthroscopic probe. The average size across torn labral segments was assessed for failure as determined by the change in patient-reported outcomes, the rate at which subjects achieved the minimal clinically important difference and patient acceptable symptomatic state, and the need for additional surgery. Outcomes were evaluated for any continuous correlation as well as significant differences between the middle 50% of labral sizes and classes of labral sizes derived from upper and lower quartile and decile ranges. Included hips were those from patients aged between 18 and 55 years with 2-year postoperative follow-up and lateral center-edge angles between 25° and 40°.

RESULTS

The study included 571 hips. Labral width did not show a significant difference between hips requiring revision and those not requiring revision (P = .4054). No significant correlation was found between labral width and the change in the International Hip Outcome Tool 12 score (R² = 0.05780), modified Harris Hip Score (R² = 0.19826), or Nonarthritic Hip Score (R² = 0.23543) from preoperatively to 2 years postoperatively. Hips with labral sizes in the upper decile of our cohort showed significantly decreased improvement in the International Hip Outcome Tool 12 score (P = .0287) and Nonarthritic Hip Score (P = .0490) compared with the middle 50% of labral sizes. No statistically significant difference was found in the rate at which the groups achieved the minimal clinically important difference or patient acceptable symptomatic state.

CONCLUSIONS

Hypertrophic labra in the largest 10th percentile showed lower postoperative outcome scores. However, no detectable clinical benefit was found in terms of patient-perceived clinical difference or acceptable symptomatic state. For most patients, labral size does not appear to significantly alter patient outcomes or the need for arthroplasty.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Understanding Painful Hip in Young Adults: A Review Article

A wide number of disorders, including pathologies outside the hip, can cause and refer pain to hip. However, determining the cause of a painful hip can be a major challenge to orthopedic surgeons. Failure to diagnose and appropriately investigate pathologies of the hip in adults may result in delayed management and prolonged patient morbidity. A systematic approach to investigating the etiology of hip pain in adults (e.g., history, careful clinical and radiographic examination), will help identify the majority of clinically important pathologies which can cause hip pain. Conservative treatment and selective use of injection therapies has proven quite successful for the treatment of most causes of hip pain.

The CU PAO: A Minimally Invasive, 2-Incision, Interlocking Periacetabular Osteotomy: Technique and Early Results

BACKGROUND

The aims of this study were to describe a novel minimally invasive, interlocking periacetabular osteotomy (PAO) for the treatment of hip dysplasia that was developed at our institution and to report on its safety, complications, and early clinical outcomes.

METHODS

This was a prospective longitudinal study of the first 200 consecutive hips that underwent the CU (University of Colorado) PAO, an interlocking osteotomy combining the benefits of the Birmingham interlocking pelvic osteotomy (BIPO) and the Ganz PAO. The technique provides direct visualization of the sciatic nerve during the ischial osteotomy and allows for immediate weight-bearing postoperatively. Demographic characteristics, intraoperative and perioperative parameters, and functional outcomes were documented. All patients underwent hip arthroscopy 3 to 10 days prior to the PAO to address concomitant intra-articular pathology. Mechanical deep venous thrombosis (DVT) prophylaxis was used for 2 weeks postoperatively. Results were stratified to compare the first 100 and the second 100 cases.

RESULTS

A total of 161 patients (200 hips) underwent primary PAO; mean follow-up was 20 months (range, 3 to 33 months). The mean patient age at the time of surgery was 29.4 years (range, 13 to 55 years). Females accounted for 89% of the patients included in this study. The average length of stay was 4 days. A concomitant proximal femoral derotational osteotomy was performed in 19 hips. The lateral center-edge angle (LCEA) improved from a mean of 18.8° preoperatively to 31.5° postoperatively (p < 0.001). The mean Non-Arthritic Hip Score (NAHS) improved from 56.0 preoperatively to 89.4 at the 24-month follow-up (p < 0.0001). Paresthesias in the distribution of the lateral femoral cutaneous nerve were common (65% at 2 weeks postoperatively) but resolved in 85% of the patients within the first 6 months. There were no sciatic nerve-related complications, deep infections, or DVTs.

CONCLUSIONS

The CU PAO enables corrective realignment of symptomatic acetabular dysplasia with direct visualization of the sciatic nerve, early weight-bearing, cosmetic incisions, and good short-term outcomes.

LEVEL OF EVIDENCE

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

Labral hypertrophy correlates with borderline hip dysplasia and microinstability in femoroacetabular impingement: a matched case-control analysis

PURPOSE:

The goal of this study was to: (1) investigate the association between labral hypertrophy and radiographic and computed tomography (CT) imaging measurements of dysplasia in a femoroacetabular impingement (FAI) cohort; (2) evaluate the association between physical examination parameters suggestive of microinstability and labral hypertrophy.

METHODS:

A retrospective case-control study was performed. Labral hypertrophy was defined as intraoperative labral width measuring greater >4 mm. A control cohort (NL) was matched to the cases. Physical examination parameters and preoperative radiographic and CT imaging studies were reviewed.

RESULTS:

231 hip arthroscopies for FAI were reviewed from which 42 cases of labral hypertrophy were identified (LH). In the LH group there was significantly increased hip internal rotation at 90° hip flexion compared to normal controls (13.6° ± 1 0.7° LH vs. 9.3° ± 6.2° NL; p = 0.04). On plain radiographs, the mean lateral centre-edge angle was smaller in the LH group compared to the NL group (27.6° ± 6.00° LH vs. 31.6° ± 6.59° NL; p < 0.001) and the acetabular index was larger in the LH group compared to the NL group (6.61 ± 4.18 LH vs. 4.14 ± 6.13 NL; p = 0.04). On CT imaging coronal sagittal CEA was significantly lower in LH cases compared to NL control (31.8° ± 5.30° LH vs. 35.1° ± 7.67° NL; p = 0.01).

CONCLUSIONS:

We found that patients with labral hypertrophy have radiographic and CT measurements consistent with subtle but not absolute dysplasia and physical examination findings suggestive of microinstability. We propose that labral hypertrophy can be a useful clinical tool for identifying FAI patients on the dysplasia spectrum.

The 'low-volume acetabulum': dysplasia in disguise

Although there are well described radiological criteria for diagnosing DDH, our experience has highlighted that a new sub-category of hips exists in which the classic radiographic characteristics for DDH may be normal but the coverage of the femoral head is compromised. The purpose of this study was to validate a simple radiographic measurement method for calculating the depth of the acetabulum in order to detect individuals with 'low-volume' acetabuli and under-covered femoral heads. We identified 24 patients who were suspected of having low-volume acetabuli and compared their radiographs with those of 150 patients with non-dysplastic hips. The radiographic indices measured included the lateral center-edge (CE) angle, the anterior CE angle, the femoral neck-shaft angle, the extrusion index, integrity of the Shenton's line, the crossover sign, and ischial spine sign. We have developed a novel, but a simple method, named the 'coverage index' (CI) to identify the presence of a low-volume acetabulum on plain radiographs. Comparisons were made between the low-volume hips and the non-dysplastic hips. The radiographic parameters indicative of developmental dysplasia of the hip (DDH) were within normal limits in all patients with low-volume acetabuli and therefore these hips could not be classified as 'dysplastic' based on the traditional radiological parameters. There was no difference between the mean radius of the femoral head in two groups. The mean CI was significantly greater in the non-dysplastic group compared with the low-volume acetabula cohort (1.62 ± 0.117 in non-dysplastic group versus 1.07 ± 0.11 in low-volume hips) (P = 0.0001). Orthopaedic surgeons should be aware of a hip abnormality in which the femoral head coverage is deficient, yet all the conventional parameters for measuring coverage, including the center edge angle, are within normal limits. We have introduced a simple radiographic measurement method that may help surgeons identify these patients using the anteroposterior radiographs of the hip.

Biomechanics, anatomy, pathology, imaging and clinical evaluation of the acetabular labrum: current concepts

The labrum has been recognised to play an important role in the hip in regard to stability, fluid regulation, decreasing contact forces, proprioception and nociception. These functions are all important for normal joint homeostasis in a well-functioning hip and can be responsible for increasing joint pain, damage, instability and dysfunction when compromised. The labrum has been studied intently in the last few decades to better understand its role in the normal and the pathologic hip and how best to treat pathology that causes debilitating hip pain and dysfunction. This current concept review discusses and summarises the current literature on labral anatomy, biomechanics, pathology, clinical exam and imaging.

Prevalence and clinical significance of hypertrophic labrum in non-dysplastic hips

BACKGROUND

Hypertrophic labrum in dysplastic hip has been frequently reported and is known as limbus in developmental dysplasia of the hip. However, hypertrophic labrum without hip dysplasia has not been reported to date. The purpose of this study was to define hypertrophic labrum and to investigate the prevalence and clinical significance of an abnormally hypertrophic labrum in non-dysplastic hips.

METHODS

Between 2007 and 2014, direct CT arthrography was performed in 464 patients (470 hips) who had chronic groin pain and positive impingement or Faber test. There were 189 male (192 hips) and 275 female (278 hips) patients. The mean age was 46.8 years (range, 16-74 years). The hypertrophic labrum was defined as a labrum wider than two standard deviations away from the mean. Surgical correlation of hypertrophic labrum was obtained in cases with hip arthroscopy by a single surgeon.

RESULTS

Seventeen hips (3.6%) were found to have a hypertrophic labrum which had a mean width of 11.2 mm (±1.1) (range, 9.8-14.1 mm). The average width (±SD) of the labrum without hypertrophy was 5.5 mm (±2.4) (range, 2-9.8 mm). Arthroscopic findings of the hypertrophic labrum included fissure and longitudinal tear at the chondrolabral junction and they were associated with chondral abnormality adjacent to the lesion.

CONCLUSIONS

Hypertrophic labrum without hip dysplasia is not rare with a high incidence of tears. Care should be taken during arthroscopic access to the hip joint in patients with this morphologic variation as iatrogenic damage can occur more easily.

LEVEL OF EVIDENCE

Case Series; Level IV.

Lateral Acetabular Coverage Predicts the Size of the Hip Labrum

BACKGROUND

Bony morphological abnormalities of the hip joint are often accompanied by adaptive soft tissue changes. These adaptive changes, if better understood and characterized, may serve to inform clinical decision making.

PURPOSE

To investigate the correlation between the size of the hip labrum and lateral acetabular coverage in patients at our hip preservation clinic.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A cohort of 236 patients seen at a dedicated hip preservation service between June 2013 and June 2015 were retrospectively analyzed. Patients were grouped according to the degree of acetabular coverage, as measured by the lateral center-edge angle (LCEA): normal acetabular coverage (25°-39.9°), acetabular overcoverage (≥40°), borderline dysplasia (20°-24.9°), and frank dysplasia (<20°). Preoperative magnetic resonance imaging was utilized to measure the length of the labrum at 3 locations: laterally, anteriorly, and anteroinferiorly.

RESULTS

Frankly dysplastic and borderline dysplastic hips exhibited larger values of labral length at all locations when compared with hips with normal acetabular coverage (P < .001) or acetabular overcoverage (P < .001). Interestingly, mean labral length values in frank dysplasia were statistically similar to corresponding measurements in borderline dysplasia. In hips with frank dysplasia, borderline dysplasia, or normal acetabular coverage, labral length was consistently greatest at the lateral labrum and correspondingly lowest at the anteroinferior labrum (P < .001). In hips with acetabular overcoverage, labral length did not vary significantly between the lateral, anterior, and anteroinferior locations. Multivariate analyses confirmed LCEA to be the strongest predictor of labral length, irrespective of measurement location.

CONCLUSION

Patients with borderline dysplasia and frank dysplasia exhibited increased values of labral length in the weightbearing zone, potentially indicating a compensatory reaction to the lack of bony coverage. Labral length may serve as an instability marker and inform clinical decision making for patients with borderline dysplasia.

A Comparison of Supine and Lateral Decubitus Positions for Hip Arthroscopy: A Systematic Review of Outcomes and Complications

PURPOSE

This systematic review examines outcomes and risk profiles of the hip arthroscopy in the supine versus lateral decubitus positions to elucidate any superiority of one approach over the other.

METHODS

Three databases (Embase, PubMed, and Medline) were searched for studies that addressed hip arthroscopy performed in either position, and were subsequently screened by two reviewers with data abstracted in duplicate.

RESULTS

Similar outcomes were observed. Supine studies showed a greater mean postoperative improvement for modified Harris hip score (33.74), visual analog scale (-3.99), nonarthritic hip score (29.61), Harris hip score (35.73), and hip outcome score (31.4). Lateral decubitus studies showed greater improvement using the Western Ontario and McMaster University Osteoarthritis (14.76) score. Supine studies reported more neuropraxic injuries (2.06% v 0.47%), labral penetration (0.65% v 0%), and heterotopic ossification (0.21% v 0%). Lateral decubitus studies reported more fluid extravasation (0.21% v 0.05%) and missed loose bodies (0.08% v 0.01%). Similar rates of revision (1.8% lateral, 1.4% supine) and conversion to open procedures (2.6% in lateral, 2.0% in supine) were also identified.

CONCLUSIONS

Because of quality of evidence, direct comparisons are currently limited; however, the supine position is associated with more neuropraxic injuries, labral penetration, and heterotopic ossification, whereas lateral decubitus has increased risk of fluid extravasation and missed loose bodies. At this time, no evidence exists to establish superiority of one position.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II, III, and IV studies.

Lateral acetabular labral length is inversely related to acetabular coverage as measured by lateral center edge angle of Wiberg

Patients with developmental dysplasia of the hip often have compensatory labral hypertrophy, which presumably lends stability to an unstable joint. Conversely, patients with acetabular overcoverage may have small or ossified labra. The purpose of this study is to explore the interaction of labral length with the degree of acetabular hip coverage. A retrospective cohort of patients with hip pain presenting to a hip preservation center, who had undergone hip magnetic resonance imaging and AP pelvis radiographs were studied. General linear multivariate models were used to assess the association between three measures of labral length (lateral, anterior and anterior inferior locations along the acetabular rim) and the X-ray derived lateral center edge angle (LCEA) of Wiberg. Of the three acetabular labral locations measured, only the lateral labrum was associated with LCEA Wiberg (P = 0.0008). Lateral labral length increases as LCEA of Wiberg decreases. The anterior and anterior inferior labral locations did not show a predictable increase in labral length as LCEA Wiberg decreased.

Does Labral Size Correlate With Degree of Acetabular Dysplasia?

BACKGROUND

Hip dysplasia has been shown to be a cause of early arthritis. The decrease in bony coverage has shown increased stress on the acetabular labrum as it shares an increased load.

PURPOSE/HYPOTHESIS

The purpose of this study was to divide a cohort of patients by radiographic measures of dysplastic and nondysplastic hips for comparison with regard to labral size at 4 anatomic locations. The hypothesis was that dysplastic hips will have significantly larger labral size compared with nondysplastic hips.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A prospective study was conducted at a single institution. A total of 130 patients underwent hip arthroscopy during the study period from September 2011 to February 2012. Intraoperatively, arthroscopic measurements were taken at 4 quadrants on the acetabular clockface: anterosuperior (12-3 o'clock), anteroinferior (3-6 o'clock), posterosuperior (9-12 o'clock), and posteroinferior (6-9 o'clock). Three radiographic parameters for dysplasia were used to substratify the study population base: lateral center-edge angle (LCEA) ≤25° and LCEA >25°, acetabular inclination (AI) ≤10° and AI >10°, and anterior center-edge angle (ACEA) ≤20° and ACEA >20°.

RESULTS

For the LCEA ≤25° group, there were 28 hips with mean LCEA of 20.96° ± 3.40°. Patients with LCEA ≤25° had larger labral width in all 4 quadrants (P < .05). For AI >10°, there were 12 hips with the mean AI 12.92° ± 2.50°. Patients with AI >10° had larger labral size in the posteroinferior quadrant only (P < .05). For ACEA ≤20°, there were 4 hips with a mean ACEA of 11.25° ± 5.19°. The anteroinferior and posteroinferior quadrants had a significant increase in labral size when substratified by ACEA ≤20° (P < .05).

CONCLUSION

Labral size was significantly larger in dysplastic hips compared with nondysplastic hips. The posteroinferior quadrant labrum was larger in size in dysplastic hips, as measured by any of the 3 radiographic measurements of dysplasia. Hips with LCEA ≤25° had larger labra in all 4 quadrants.

Evaluation of Labral Pathology and Hip Articular Cartilage in Patients with Femoroacetabular Impingement (FAI): Comparison of Multidetector CT Arthrography and MR Arthrography

Background

To compare the multidetector computed tomography (MDCT) arthrography (CTa) and magnetic resonance (MR) arthrography (MRa) findings with surgical findings in patients with femoroacetabular impingement (FAI) and to evaluate the diagnostic performance of these methods.

Material/Methods

Labral pathology and articular cartilage were prospectively evaluated with MRa and CTa in 14 hips of 14 patients. The findings were evaluated by two musculoskeletal radiologists with 10 and 20 years of experience, respectively. Sensitivity, specificity, accuracy, and positive predictive value were determined using surgical findings as the standard of reference.

Results

While the disagreement between observers was recorded in two cases of labral tearing with MRa, there was a complete consensus with CTa. Disagreement between observers was found in four cases of femoral cartilage loss with both MRa and CTa. Disagreement was also recorded in only one case of acetabular cartilage loss with both methods. The percent sensitivity, specificity, and accuracy for correctly assessing the labral tearing were as follows for MRa/CTa, respectively: 100/100, 50/100, 86/100 (p<0.05). The same values for acetabular cartilage assessment were 89/56, 40/60, 71/71 (p>0.05) and for femoral cartilage assessment were 100/75, 90/70, 86/71 (p>0.05). Inter-observer reliability value showed excellent agreement for labral tearing with CTa (κ=1.0). Inter-observer agreement was substantial to excellent with regard to acetabular cartilage assessment with MRa and CTa (κ=0.76 for MRa and κ=0.86 for CTa)

Conclusions

Inter-observer reliability with CTa is excellent for labral tearing assessment. CTa seems to have an equal sensitivity and a higher specificity than MRa for the detection of labral pathology. MRa is better, but not statistically significantly, in demonstrating acetabular and femoral cartilage pathology.

Imaging evaluation of developmental hip dysplasia in the young adult

OBJECTIVE

The purpose of this article is to review the clinical and imaging features as well as the potential complications of hip dysplasia in the young adult. Hip dysplasia is an important cause of secondary osteoarthrosis, which accounts for a significant proportion of patients requiring total hip arthroplasty. The radiographic diagnosis of mild hip dysplasia in the young adult may be subtle and is primarily based on the detection of deficient coverage of the femoral head by the acetabulum.

CONCLUSION

Cross-sectional imaging, including CT and MRI, afford improved detection and characterization by providing morphologic information about acetabular deficiency. MRI also allows evaluation of potential associated injuries to the articular cartilage, the labrum, and the ligamentum teres. Familiarity with the radiographic and cross-sectional imaging findings of mild hip dysplasia in the young adult may allow a timely diagnosis and implementation of treatment strategies, which may prevent or delay the development of early osteoarthritis.

The biomechanical case for labral débridement

BACKGROUND

Labral repair is increasingly performed in conjunction with open and arthroscopic surgical procedures used to treat patients with mechanically related hip pain. The current rationale for labral repair is based on restoring the suction-seal function and clinical reports suggesting improved clinical outcome scores when acetabular rim trimming is accompanied by labral repair. However, it is unclear whether available scientific evidence supports routine labral repair.

QUESTIONS/PURPOSES

The questions raised in this review were: (1) does labral repair restore normal histologic structure, tissue permeability, hip hydrodynamics, load transfer, and in vivo kinematics; and (2) does labral repair favorably alter the natural course of femoroacetabular impingement (FAI) treatment or age-related degeneration of the acetabular labrum?

METHODS

An electronic literature search for the keywords acetabular labrum was performed. Three hundred fifty-five abstracts were reviewed and 52 selected for full-text review that described information concerning pertinent aspects of labral formation, development, degeneration, biomechanics, and clinical results of labral repair or resection.

RESULTS

Several clinical studies support labral repair when performed in conjunction with acetabular rim trimming. Little data support or refute the use of routine labral repair for all patients with symptomatic labral damage associated with FAI. It is not known whether or how labral repair affects the natural course of FAI.

CONCLUSIONS

Based on the current understanding of labral degenerative changes associated with mechanical hip abnormalities, the low biologic likelihood of restoring normal tissue characteristics, and mechanical data suggesting minimal consequence from small labral resections, routine labral repair over labral débridement is not supported.

Anterior impingement test for labral lesions has high positive predictive value

BACKGROUND

The anterior impingement test is intended to detect anterosuperior acetabular labral lesions. In patients treated for labral lesions its sensitivity is reportedly 95% to 100%, and in a small group of patients undergoing periacetabular osteotomy, its sensitivity was 59% and specificity 100%. However, the sensitivity, specificity, positive predictive value, and negative predict value of this test to detect these labral lesions in unselected patients with hip pain are unknown.

QUESTIONS/PURPOSES

We investigated these four parameters (1) in unselected patients with hip pain, and (2) in three subgroups of patients with dysplasia, femoroacetabular impingement (FAI), and with an intact joint space.

METHODS

We prospectively studied 69 patients (15 men and 54 women) with a mean age of 57.2 years (range, 27-81 years). One observer performed the anterior impingement test in all patients. We determined the presence or absence of an anterosuperior labral lesion with radial MRI in 107 hips (38 patients in both hips: 14 with pain, and 24 without pain). We also investigated the parameters in the three subgroups which consisted of 60 cases of dysplasia, 27 cases of FAI, and 80 cases with intact joint space; the third subgroup partially overlapped the first and second subgroups.

RESULTS

The four parameters in all hips were 50.6% (45/89), 88.9% (16/18), 95.7% (45/47), and 26.7% (16/60), respectively. Parameters in the three subgroups were similar to those of all cases.

CONCLUSIONS

Although the sensitivity of the anterior impingement test did not reach a sufficient level for detecting anterosuperior labral lesions, we believe the high positive predictive value makes the test useful.

LEVEL OF EVIDENCE

Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Fovea alta on MR images: is it a marker of hip dysplasia in young adults?

OBJECTIVE

The objective of our study was to investigate the association between high fovea capitis (fovea alta) and hip dysplasia in young adults.

MATERIALS AND METHODS

In a retrospective study, blinded observers reviewed 82 pelvic radiographic and hip MRI studies of three groups of patients: those with developmental dysplasia of the hip (DDH) (center-edge angle, ≤20°), those with borderline DDH (center-edge angle, 21°-25°), and control patients (center-edge angle, >25°). The center-edge angle and coxa valga (femoral neck-shaft angle, >135°) were assessed on pelvic radiographs, and fovea alta was assessed on MR images (delta angle, ≤10°). The Mann-Whitney and Fisher exact tests were used to correlate fovea alta with DDH and with coxa valga, respectively. Interobserver agreement for center-edge and delta angles and the diagnostic performance of fovea alta as a marker of DDH were calculated.

RESULTS

Thirty-one patients with DDH, 23 with borderline DDH, and 28 without DDH were included. Excellent interobserver agreement was found for center-edge angle (concordance correlation coefficient, 0.94) and for delta angle (concordance correlation coefficient, 0.91). Fovea alta had a significant association with DDH (p<0.001) but no association with coxa valga (p>0.57). A significant difference (p<0.001) was found between patients with DDH (3.4°) and those without DDH (21.7°) with respect to mean delta angle measurements. Fovea alta had 69.4% sensitivity, 82.1% specificity, 67.2% positive predictive value, 81.0% negative predictive value, and 75.6% overall accuracy as an indicator of DDH.

CONCLUSION

Fovea alta shows promise as a strong MRI marker of DDH.

Cyst-like lesion of the acetabular roof - an abnormal finding or an anatomical variant?

Cyst-like lesions are frequently found in the area of the acetabulum on MRI scans. However, their presence is not always abnormal. We report four patients with such lesions found on MRI where, during hip arthroscopy, an area resembling a horseshoe-like extension of the cotyloid fossa was found. Clinicians must be aware that not all cystic acetabular lesions are pathological and may simply represent a normal anatomical or developmental variant of the hip joint. They do not always represent an indication for hip arthroscopic surgery.

The role of multidetector CT arthrography in the investigation of suspected intra-articular hip pathology

The aim of this study was to evaluate the role of multidetector CT (MDCT) arthrography in the diagnosis of intra-articular hip pathology. A retrospective review of 96 patients who had undergone CT hip arthrography was performed. Data regarding the presence of a labral tear, paralabral cyst, chondral loss, acetabular version, femoral morphology and fibrocystic change were collected. We detected 28 labral tears (24 anterior, 2 anterolateral, 1 lateral and 1 posterolateral). An abnormal labral-chondral transitional zone was seen in 9 patients and 4 patients had surface labral fraying. We identified three paralabral cysts. Acetabular cartilage loss was detected in 45 and femoral cartilage loss in 9 patients. An abnormal anterior femoral head and neck junction was present in 18 hips and fibrocystic change in 8. Acetabular retroversion was present in 11 hips. 63 sets of patient notes were reviewed, of which 49 were in-patients with abnormal MDCT arthrogram findings. Surgical correlation was available in 27 patients. There was a discrepancy between the findings of a labral tear in one patient (false negative, 90% sensitivity and 100% specificity) and the presence of acetabular cartilage loss (88% sensitivity and 100% specificity) and femoral cartilage loss (94% sensitivity and 100% specificity) in three patients. MDCT arthrography affords accurate detection of intra-articular hip pathology.

[Radiological diagnosis of femoroacetabular impingement]

Femoroacetabular impingements (FAI) are due to an anatomical disproportion between the proximal femur and the acetabulum which causes premature wear of the joint surfaces. An operation is often necessary in order to relieve symptoms such as limited movement and pain as well as to prevent or slow down the degenerative process. The result is dependent on the preoperative status of the joint with poor results for advanced arthritis of the hip joint. This explains the necessity for an accurate diagnosis in order to recognize early stages of damage to the joint. The diagnosis of FAI includes clinical examination, X-ray examination and magnetic resonance imaging (MRI). The standard X-radiological examination for FAI is carried out using two X-ray images, an anterior-posterior view of the pelvis and a lateral view of the proximal femur, such as the cross-table lateral or Lauenstein projections. It is necessary that positioning criteria are adhered to in order to avoid distortion artifacts. MRI permits an examination of the pelvis on three levels and should also include radial planned sequences for improved representation of peripheral structures, such as the labrum and peripheral cartilage. The use of contrast medium for a direct MR arthrogram has proved to be advantageous particularly for representation of labrum damage. The data with respect to cartilage imaging are still unclear. Further developments in technology, such as biochemical-sensitive MRI applications, will be able to improve the diagnosis of the pelvis in the near future.

Relationships among measurements obtained by use of computed tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs

OBJECTIVE

To evaluate correlations among measurements on radiographic and computed tomography (CT) images with articular cartilage microdamage in lax hip joints of dogs.

ANIMALS

12 adult mixed-breed hounds.

PROCEDURES

Pelvic CT and radiography were performed. Hip joints were harvested following euthanasia. Orthopedic Foundation for Animals (OFA) and PennHIP radiograph reports were obtained. Norberg angle (NA) and radiographic percentage femoral head coverage (RPC) were determined. Center-edge angle (CEA), horizontal toit externe angle (HTEA), ventral acetabular sector angle (VASA), dorsal acetabular sector angle (DASA), horizontal acetabular sector angle (HASA), acetabular index (AI), and CT percentage femoral head coverage (CPC) were measured on 2-dimensional CT images. Femoral head-acetabular shelf percentage was measured on sagittal 3-dimensional CT (SCT) and transverse 3-dimensional CT (TCT) images. Light microscopy was used to score joint cartilage. Relationships of OFA confirmation and PennHIP osteoarthritis scores with radiography, CT, and cartilage variables and relationships of cartilage scores with radiography and CT measurements were evaluated with Spearman rank correlations. Pearson correlation was used for relationships of distraction index (DI) with radiography, CT, and cartilage variables.

RESULTS

Significant relationships included PennHIP osteoarthritis score with cartilage score, CEA, HTEA, DASA, AI, CPC, and TCT; OFA confirmation score with cartilage score, NA, RPC, CEA, HTEA, DASA, AI, CPC, and TCT; cartilage score with NA, RPC, CEA, HTEA, DASA, HASA, AI, and TCT; and DI with cartilage score, CEA, HTEA, DASA, HASA, AI, and CPC.

CONCLUSIONS AND CLINICAL RELEVANCE

CT appeared to be a valuable imaging modality for predicting cartilage microdamage in canine hip joints.