An anatomic consideration of the femoral nerve during direct anterior hip approach: A cadaveric study.

PURPOSE: This study aimed to investigate the distance and correlation between the anatomy of the anterior side of the hip joint and the femoral nerve. METHODS: Using ten fresh-frozen cadavers with twenty hip joints. We dissected and marked the femoral nerve in the inguinal area. Employing the direct anterior approach, we identified and marked study points, including the superior and inferior points of the anterior rim of the acetabulum, » point, half point, and ¾ point along an imagined line connecting the formers, the inferomedial and mid aspect of the femoral neck, and the soft spot. Coronal plane measurements gauged the distance between these points and the femoral nerve. The collected data were analyzed to assess the distance and correlation. RESULTS: In the coronal plane, the median distance between the inferior point of the anterior rim of the acetabulum and the femoral nerve was 0 millimeters (interquartile range [IQR] 0-0). Likewise, the median distance between the mid aspect of the medial side of the femoral neck and the femoral nerve was 0 millimeters (IQR 0-0). Additionally, the mean distance between the soft spot and the femoral nerve was 1.18 cm (SD 0.63). CONCLUSION: Surgeons approaching the hip joint via the direct anterior approach should be cautious at the inferior point of the anterior rim of the acetabulum and the mid aspect of the femoral neck. The soft spot at the anterior rim of the acetabulum remains safe from direct injury when surgeons use the correct technique during anterior retractor insertion.

Anatomic variations of the hip joint in soldiers of different ages / Variaciones anatómicas de la articulación coxal en soldados de diferentes edades

SUMMARY: Anatomic variations in hip joint are one of the risk factors for the occurrence of osteoarthritis of that part of locomotor system. Due to different age structure and a special way of conducting physical activity in the army, it is justified to presume the presence of even other risk factors which relate to the aging process, carrying of oversize weight and performing higher amplitudes of movement under load. The objective of the study related to determining the existence of eventual anatomic variations in the hip joint in soldiers of different age. This cross-sectional study covers 240 soldiers of Montenegro Army, divided into 8 age groups. Gathered data for morphological measures hip width and hip circumference were processed using the basic statistics, multivariate and univariate of variance and Tukey's Honestly Significant Difference test-HSD. The differences were considered statistically significant for p≤0.05. It was determined that for both morphological measures there are differences between soldiers of certain age. This is confirmed also by drastic deviations between certain age groups obtained for the defined level of statistical significance. The most pronounced is the detection of the annual increase of hip width of soldiers which is higher for 0.38 mm compared to general population. Based on the obtained results the existence of anatomic variations in soldiers' hip joints is stated. The confirmed anatomic changes in conjunction with other risk factors may lead to hip osteoarthritis, i.e to soldiers' health condition impairment. It is necessary to conduct longitudinal studies on the same examinees with precise diagnostics.

RESUMEN: Las variaciones anatómicas en la articulación coxal son uno de los factores de riesgo de la osteoartritis de esa zona del sistema locomotor. Debido a la diferente estructura respecto a la de edad y una forma especial de realizar la actividad física en el ejército, se justifica presumir la presencia de otros factores de riesgo que se relacionan con el proceso de envejecimiento, el transporte de peso sobredimensionado y la realización de mayores amplitudes de movimiento bajo carga. El objetivo del estudio fue determinar la existencia de eventuales variaciones anatómicas en la articulación coxal en soldados de diferentes edades. Este estudio transversal incluyó 240 soldados del Ejército de Montenegro, divididos en 8 grupos de edad. Los datos recopilados para las medidas morfológicas del ancho y la circunferencia de la articulación coxal se procesaron utilizando las estadísticas básicas, la varianza multivariada y univariada y la prueba HSD de diferencia significativa de Tukey. Las diferencias fueron consideradas estadísticamente significativas para p≤0,05. Se determinó que para ambas medidas morfológicas existen diferencias entre soldados de cierta edad. Esto fue confirmado también por las desviaciones drásticas entre ciertos grupos de edad obtenidos para el nivel definido de significación estadística. El más pronunciado es la detección del aumento anual del ancho de cadera de los soldados, que es superior en 0,38 mm en comparación con la población general. En base a los resultados obtenidos se afirma la existencia de variaciones anatómicas en las articulaciones coxales de los soldados. Los cambios anatómicos confirmados junto con otros factores de riesgo pueden conducir a la osteoartritis de cadera, es decir, al deterioro del estado de salud de los soldados. Es necesario realizar estudios longitudinales en los mismos examinados con diagnósticos precisos.

Is hip morphology a risk factor for developing hip osteoarthritis? A systematic review with meta-analysis.

OBJECTIVE: To appraise the highest evidence on hip morphology as a risk factor for developing hip osteoarthritis (OA). DESIGN: We searched for studies evaluating the association between radiological hip morphology parameters and the prevalence, incidence or progression of hip OA (based on different radiographic and clinical criteria) in the MEDLINE, EMBASE, Web of Science, Scopus, Cochrane Library and PEDro databases from inception until June 2020. Prospective and cross-sectional studies were separately evaluated. Data are presented as odds ratios (OR) with 95% confidence intervals (CI). RESULTS: We included 9 prospective and 21 cross-sectional studies in the meta-analysis, and evaluated 42,831 hips from 25,898 individuals (mean age: 59 years). Prospective studies showed that, compared with control hips, hips with cam morphology (alpha angle >60°; OR = 2.52, 95% CI: 1.83 to 3.46, P < 0.001) or hip dysplasia (lateral center-edge angle (LCEA) <25°; OR = 2.38, 95% CI: 1.84 to 3.07, P < 0.001), but not hips with pincer morphology (LCEA >39°; OR = 1.08, 95% CI: 0.57 to 2.07, P = 0.810), were more likely to develop hip OA than hips without these morphologies. Cross-sectional studies showed a greater prevalence of pincer morphology (LCEA >39°, OR = 3.71, 95% CI: 2.98 to 4.61, P < 0.001) and acetabular retroversion (crossover sign; OR = 2.65, 95% CI: 1.17 to 6.03, P = 0.020) in hips with OA than in control hips. CONCLUSION: Cam morphology and hip dysplasia were consistently associated with the development of hip OA. Pincer morphology was associated with hip OA in cross-sectional but not in prospective studies. The heterogeneous quantification of pincer morphology on radiographs limits a clear conclusion on its association with hip OA.

Hip geometry in hip fracture patients in Greenland occurring over a 7.7-year period.

BACKGROUND: Hip geometry influences hip fracture risk. Hip fractures are common, and they are associated with pain, disability, premature death and marked costs on society. Osteoporotic fractures are frequent in Arctic populations and increase with advancing age in this society with a steep rise in life expectancy. Greenland Inuit is a distinct ethnic group, and data on hip geometry is missing. We thus aimed to describe hip geometry in 7.7 years of consecutive hip fracture patients in Greenland. METHODS: We evaluated collodiaphysial angle, femoral neck length, the outer and inner diameter of the femur at 2 and 5 centimetres below the centre of the lesser trochanter and the cortical thickness from pelvic and hip radiographs in all patients operated in Greenland over 7.7 years. We included all 84 patients with one non-fractured hip visible for geometric analysis. Analyses were conducted in duplicate. RESULTS: We found a collodiaphysial angle of 134.8/132.6o in men/women (p = 0.06) and a femoral neck length of 38.0/33.9 mm in men/women (p = 0.001). Cortical thickness was affected by sex in the adjusted analysis (p < 0.001). Cortical thickness index at 5 cm below the centre of the lesser trochanter decreased with age (p = 0.026) and may be influenced by height (2 cm below the centre of the lesser trochanter, p = 0.053). CONCLUSION: Our findings differed from European data and suggest a delicate balance in hip geometry in Arctic populations. Ethnic peculiarities influence the structure of the hip and may influence fracture risk. A focus on hip geometry and risk factors for osteoporotic fractures in Arctic populations is warranted.

Morphological consistency of bilateral hip joints in adults based on the X-ray and CT data.

PURPOSE: The application of the anatomical parameters of the contralateral hip joint to guide the preoperative template of the affected side relies on the bilateral hip symmetry. We investigated the bilateral hip symmetry and range of anatomical variations by measurement and comparison of bilateral hip anatomical parameters. METHODS: This study included 224 patients (448 hips) who were diagnosed with osteoarthritis (OA) and avascular necrosis (AVN) of the femur head, and underwent bilateral primary total hip arthroplasty (THA) in our hospital from January 2012 to August 2020. Imaging data included 224 patients X-ray and 30 CT data at the end of the cohort. Anatomical parameters, including the acetabular abduction angle and trochanteric height, were measured using the Noble method. Postoperative measurements included stem size, difference of leg length and offset. RESULTS: Except for the isthmus width, there were no significant differences in the anatomical morphology of the hip joint. Among the demographic factors, there was a correlation between body weight and NSA. Among various anatomical parameters, a correlation was present between medullary cavity widths of T + 20, T, and T - 20. The difference in the use of stem size is not due to the morphological difference of bilateral medullary cavity, but due to the different of 1- or 2-stage surgery. CONCLUSION: Bilateral symmetry was present among the patients with normal morphology of the hip medullary cavity, theoretically confirming the feasibility of structural reconstruction of the hip joint using the hip joint on the uninjured side. Additionally, the difference in the morphology of the hip medullary cavity is not present in a single plane but is synergistically affected by multiple adjacent planes.

Capsular Management Techniques and Hip Arthroscopy.

There has been an increased emphasis on capsular management during hip arthroscopy in the literature in recent years. The capsule plays a significant role in the hip joint stability and studies have demonstrated that capsular closure can restore the biomechanics of the hip back to the native state. Capsular management also affects functional outcomes with capsular repair resulting in better clinical outcomes in some studies. Management of the capsule has evolved in recent years with more surgeons performing routine capsular closure. Management techniques and degree of capsular closure, however, can be quite variable between surgeons. This review will discuss hip capsular anatomy, the importance of the capsule in hip biomechanics, management of the capsule during arthroscopy, and functional outcomes as it relates to the various capsular closure techniques versus leaving the capsulotomy unrepaired.

Why Does Hip Arthroscopy Fail? Indications and PEARLS for Revision Success.

The surgical treatment of femoroacetabular impingement has been shown to have successful early and mid-term clinical outcomes. Despite these favorable clinical outcomes that have been published in the literature, there is a subgroup of patients that present with continued or recurrent symptoms after surgical treatment. Not only has there been an increase in the number of hip arthroscopy procedures, but also there has been a corresponding increase in the number of revision hip arthroscopy and hip preservation surgeries. Previous studies have reported residual deformity to be the most common reason for revision hip arthroscopy. However, chondral, labral, and capsular considerations also are important when addressing patients not only in the primary but also, the revision setting. In this review, we outline the evaluation and treatment of the patient that presents with continued hip and groin pain after undergoing a hip.

Anatomía articular y parámetros radiográficos de la cadera como factor de riesgo de fractura: una mirada actualizada / Joint Anatomy and Radiographic Parameters of the Hip as Risk Factor for Fracture: An Updated Look

RESUMEN Introducción: Existe un aumento de la evidencia de que la estructura geométrica de la anatomía de la cadera juega un importante papel en la etiología de la fractura. Objetivo: Sistematizar los conocimientos más actuales referentes a las características anatómicas de los parámetros radiográficos de la articulación de la cadera, y su relación con la fractura. Métodos: Se realizó una investigación documental, con los artículos científicos publicados en las bases de datos médicas informáticas como PubMed, Ebsco y SciELo en los últimos 5 años. Resultados: La mayoría de las publicaciones analizan el ángulo cervicodiafisario y el eje de la cadera. Otras medidas analizadas son el eje femoral, la longitud y el ancho del cuello femoral, así como medidas acetabulares. No existe un consenso en la medida del largo del cuello femoral o del eje femoral, a pesar de ser un componente importante de la estructura. El conocimiento de las particularidades de la anatomía y de las características biomecánicas de la cadera permite establecer una base para la comprensión de los factores que afectan esta articulación. Conclusiones: Los estudios que se han realizado sobre las características de los componentes estructurales, demuestran que existe una asociación entre sus dimensiones y la ocurrencia de fractura de cadera, en algunos casos independientes de la densidad mineral ósea(AU)

ABSTRACT Introduction: There is increasing evidence that the geometric structure of the hip anatomy plays an important role in the etiology of the fracture. Objective: To systematize the most current knowledge regarding the anatomical characteristics of the radiographic parameters of the hip joint, and their relationship with the fracture. Methods: A documentary research was carried out, with the scientific articles published, in the last 5 years, in medical computer databases such as PubMed, Ebsco and SciELo. Results: Most of the publications analyze the cervicodiaphyseal angle and the axis of the hip. Other measurements analyzed are the femoral axis, the length and width of the femoral neck, as well as acetabular measurements. There is no consensus on the length of the femoral neck or the femoral shaft, despite being an important component of the structure. Knowledge of the particularities of the anatomy and biomechanical characteristics of the hip allows to establish basis for understanding the factors that affect this joint. Conclusions: The studies that have been carried out on the characteristics of the structural components show that there is association between their dimensions and the occurrence of hip fracture, in some cases independent of bone mineral density(AU)

Biomechanical comparison of standing posture and during trot between German shepherd and Labrador retriever dogs.

It is widely accepted that canine breeds stand and move differently. The prevalence of various musculoskeletal disorders such as hip and elbow dysplasia is also different between breeds. German shepherd dog (GSD) and Labrador retriever dog (LRD) are two large breeds with different conformations that have high prevalence of these disorders. This study quantifies the movement and standing posture of twelve healthy GSDs and twelve healthy LRDs to identify biomechanical similarities and differences that may be linked to sub-optimal hip and elbow mechanics. A pressure walkway and a motion capture system obtained measures of kinetics, kinematics and conformation during standing and trot. During standing, LRDs carry a greater percentage of the weight on the forelimbs (69%±5% vs. GSDs: 62%±2%, p<0.001) and their body Centre of Pressure (CoP) is located more cranially (p<0.001). GSDs had a greater pelvic tilt (79°±8 vs. 66°±9°, p = 0.004), more flexed stifles (44°±9° vs. LRDs: 34°±10°, p<0.05) and hocks (58°±11° vs. 26°±9°, p<0.01) and more extended hips (-10°±11° vs. 30°±12°, p<0.001). During trot, the GSDs' CoP had a longer anterior-posterior trajectory (151%±22% vs. LRDs: 93%±25% of the withers height, p<0.001). Stride parameters and loading of limbs were similar when normalised to the size and weight of the dog, respectively. The LRDs had a more extended thoracolumbar angle (p<0.001) and a less flexed lumbosacral angle (p<0.05). The LRDs' hip remained flexed during trot whereas the GSDs' hip joint was less flexed during swing (p<0.001) and more extended in late stance and early swing (p<0.001). In conclusion, the LRDs and GSDs differ in the way they stand and move and this would result in different loading pattern of the joints. Further investigation is required to determine the extent to which biomechanical differences are linked to musculoskeletal problems presented clinically.

Optimal Treatment of Cam Morphology May Change the Natural History of Femoroacetabular Impingement.

BACKGROUND: There is debate in the literature whether cam morphology is associated with increased risk for hip osteoarthritis. The capability of femoroplasty to alter the natural history of cam morphology is still in question. PURPOSE: To (1) investigate the correlation between cam morphology and damage to the articular cartilage and (2) assess whether correction of the cam morphology affects survivorship of the joint, progression to arthroplasty, and functional patient-reported outcome scores. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Data were prospectively collected for patients presenting for hip arthroscopy between February 2008 and April 2017. Cases were divided into 3 groups: control group with an alpha angle <50° pre- and postoperatively, treated group with an alpha angle >55° preoperatively and <50° postoperatively, and a group with an alpha angle >55° pre- and postoperatively. All patients had minimum 2-year postoperative follow-up for the modified Harris Hip Score, the Non-arthritic Hip Score, and visual analog scale for pain. Conversion to total hip arthroplasty was recorded. RESULTS: A 1:1:1 match successfully yielded 98 hips for each group. Follow-up time was 50.77 ± 24.60 months (mean ± SD). The pre- and postoperative mean alpha angles were 45.2°± 3.4° and 40.6°± 4.3° in the control group, respectively; 66.2°± 8.4° and 42.3°± 5.9° in the treated group; and 68.5°± 9.4° and 61.4°± 7.6° in the alpha >55° group. Intraoperatively, the alpha >55° and treated groups had greater acetabular cartilage damage than the control group (P = .0245 and P = .0036, acetabular labrum articular disruption, respectively; P = .0347 and P = .0211, acetabular Outerbridge). The alpha >55° group achieved the patient acceptable symptomatic state for the modified Harris Hip Score (58.2%) significantly less than the treated (75.5%; P = .0100) and control (73.5%; P = .0239) groups. Progression to arthroplasty was significantly higher in the alpha >55° group (n = 17) when compared with the control (n = 8) and treated (n = 10) groups (P = .0034 and P = .0338, respectively). CONCLUSION: Cam deformity was associated with higher-grade damage of the acetabular articular cartilage. An alpha angle >55° after surgery was associated with lower native hip joint survivability and less successful functional outcomes when compared with that of treated cam deformity as well as no deformity. These data suggest that correcting the cam deformity may positively affect the natural history of these patients.

Stepwise Safe Access in Hip Arthroscopy in the Supine Position: Tips and Pearls From A to Z.

Hip arthroscopy is rapidly growing as a treatment with good outcomes for pathologic conditions such as femoroacetabular impingement syndrome and labral tears. At the same time, it is one of the most technically challenging and demanding procedures in orthopaedics with a technically demanding skill. The first challenge is to safely access the joint, which requires accurate anatomical knowledge, a strong sense of spatial orientation, and repeated practice. Iatrogenic chondrolabral injury has been reported as the most common complication in hip arthroscopy and most frequently occurs during hip joint access. As such, basic foundations cannot be overstated. These complications can be minimized with adequate patient positioning, reproducible hip joint access techniques, and proper portals placement. Nonetheless, these three points are perhaps the greatest hurdles that orthopaedic surgeons face when entering the hip arthroscopy field. In this review, we outlined a stepwise approach for a safe access to hip arthroscopy.

No Differences in Hip Joint Space Measurements Between Weightbearing or Supine Anteroposterior Pelvic Radiographs.

PURPOSE: To to assess whether there are any significant differences in hip joint space width (JSW) between weight-bearing versus supine pelvic radiographs. METHODS: Standing and supine anteroposterior pelvic radiographs of 86 patients (146 hips) were included. Sample size was sufficiently powered to assess for equivalence between standing and supine films for JSW measurements made at the medial, lateral, and central aspects of the sourcil line. Measurements were made by 2 independent reviewers blinded to patient positioning. Each reviewer repeated a subset of the measurements to assess intra-rater reproducibility. Mean differences in joint space measurements between standing and supine radiographs were reported for each point of the sourcil. Intraclass correlation coefficients (ICCs) for inter and intra-rater reliability were also calculated. RESULTS: There were no significant differences between JSW measurements made on standing and supine pelvic radiographs (P = .468). Furthermore, equivalence testing demonstrated statistical equivalence between standing and supine JSW measurements made based on an equivalence threshold of ±0.5 mm. Inter-rater reliability demonstrated good agreement with an overall ICC of 0.775 (95% confidence interval [CI] 0.734-0.809). Intra-rater reliability also demonstrated good agreement with ICCs of 0.84 (95% CI 0.758-0.889) and 0.798 (95% CI 0.721-0.851) for the 2 reviewers, respectively. CONCLUSIONS: JSW measurements on standing and supine pelvic radiographs were not significantly different, and their inter-rater agreement and intra-rater reproducibility demonstrated good reliability and repeatability. Therefore, either may be used to assess JSW, including measurements that may impact treatment decisions for hip arthroscopy. LEVEL OF EVIDENCE: Level III; retrospective comparative study.

Distraction index measurement on the dog's hip joint using a dedicated software / [Medição do índice de distração da anca do cão usando um software especial]

The aim of this study was to test the accuracy of a new automated computer software tool for the assessment of passive hip laxity. The hip laxity was estimated using the dedicated computer software by two blinded evaluators, one previously trained and one without specific training for distraction index measurement, in two independent sessions using 230 hip joints from 115 dogs that underwent screening for passive hip laxity using the distraction view. Previously, all of these radiographs were sent to PennHIP Analysis Center for an official distraction index record. The measurement repeatability of the two sessions was adequate for both evaluators. The reproducibility of the official distraction index measurement, mean distraction index±standard deviation 0.44±0.15, was adequate (P>0.05) for the trained evaluator, 0.44±0.15, and non-adequate (P<0.05), for the non-trained evaluator 0.47±0.17. The distraction index measurement tool proposed can be used with confidence for hip laxity evaluation by trained evaluators, as it provided good repeatability and reproducibility of official reports. The simplicity of the process described leads to a less time-consuming and more affordable procedure.(AU)

O objetivo deste estudo foi testar a viabilidade de uma nova ferramenta de software informático para avaliação da lassitude articular passiva da articulação coxofemoral. A lassitude articular da articulação coxofemoral foi estimada usando-se um programa informático especial, desenvolvido para o efeito, por dois avaliadores, um com treino prévio e outro não treinado, na medição do índice de distração, em duas sessões independentes, utilizando-se 230 articulações coxofemorais de 115 cães, as quais efetuaram o rastreio de displasia coxofemoral realizando a projeção de distração da articulação coxofemoral. Previamente, todas as radiografias foram enviadas para o PennHIP Analysis Center, para se obter uma medida oficial do índice de distração. A repetibilidade das medições das duas sessões foi adequada para ambos os avaliadores. A reprodutibilidade do índice de distração oficial, média±desvio-padrão 0,44±0,15, foi adequada (P>0,05) para o avaliador treinado, 0,44±0,15, e não adequada (P>0,05) para o avaliador não treinado, 0,47±0,17. A ferramenta de medição do índice de distração proposta pode ser usada com segurança na medição do índice de distração por avaliadores treinados, uma vez que mostra uma adequada repetibilidade e reprodutibilidade das medições oficiais do índice de distração. A simplicidade do processo apresentado torna-o menos demorado e mais econômico.(AU)

Patients With a Hypotrophic Labrum Achieve Similar Outcomes After Primary Labral Repair Compared With Patients With a Normal-Sized Labrum: A Matched Cohort Analysis of 346 Patients With Femoroacetabular Impingement Syndrome.

PURPOSE: To compare patient functional scores and rates of achieving minimum clinically important differences (MCID) and patient acceptable symptomatic state (PASS) between patients with a hypotrophic labrum with those with a normal labrum width at a minimum 1-year follow-up from arthroscopic treatment of femoroacetabular impingement syndrome. METHODS: Data from consecutive patients who underwent primary hip arthroscopy between November 2015 and July 2018 for the treatment of femoroacetabular impingement syndrome were analyzed. Baseline demographic data, preoperative patient-reported outcome measures (PROMs), and minimum 1-year PROMs, including Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score, international Hip Outcome Tool 12 questions, and visual analog scale for pain and satisfaction were recorded. The labrum size was determined using an arthroscopic probe at the 12- to 2-o'clock position with a hypotrophic labrum being defined as <4 mm and normal labrum defined as having a width between 4 and 7 mm on the articular side. Patients with hypotrophic labrum were matched 1:1 by age and body mass index to patients with normal labrum width. RESULTS: A total of 346 patients were included in the study with an average age of 31.4 ± 11.9 and a majority being female (72.0%). There were 173 in each of the normal and hypotrophic groups. There were no significant differences seen in 1-year PROMs between the 2 groups (P > .05 for all). The normal labrum group achieved MCID at a rate of 75% to 84% and PASS at a rate of 51% to 70%. The hypotrophic labrum group achieved MCID at a rate of 70% to 85% and PASS at a rate of 57% to 71%. There were no significant differences in rates between each group (P > .05 for all). CONCLUSIONS: Patients with an intraoperative finding of labral hypotrophy achieve 1-year meaningful clinical outcome at the same rate as those with normal labral width following arthroscopic labral repair. LEVEL OF EVIDENCE: III, Case-control study.

Piezo2 expressed in proprioceptive neurons is essential for skeletal integrity.

In humans, mutations in the PIEZO2 gene, which encodes for a mechanosensitive ion channel, were found to result in skeletal abnormalities including scoliosis and hip dysplasia. Here, we show in mice that loss of Piezo2 expression in the proprioceptive system recapitulates several human skeletal abnormalities. While loss of Piezo2 in chondrogenic or osteogenic lineages does not lead to human-like skeletal abnormalities, its loss in proprioceptive neurons leads to spine malalignment and hip dysplasia. To validate the non-autonomous role of proprioception in hip joint morphogenesis, we studied this process in mice mutant for proprioceptive system regulators Runx3 or Egr3. Loss of Runx3 in the peripheral nervous system, but not in skeletal lineages, leads to similar joint abnormalities, as does Egr3 loss of function. These findings expand the range of known regulatory roles of the proprioception system on the skeleton and provide a central component of the underlying molecular mechanism, namely Piezo2.

MRI hip findings in asymptomatic professional rugby players, ballet dancers, and age-matched controls.

AIM: To investigate hip magnetic resonance imaging (MRI) findings in asymptomatic professional male rugby players and male ballet dancers compared to age-matched controls. MATERIALS AND METHODS: After ethics committee approval and consent from participants, 11 professional rugby players, 10 professional ballet dancers, and 10 controls completed activity and symptom questionnaires and underwent 3 T MRI of their self-declared dominant hip. Each scan was independently scored by two musculoskeletal radiologists for multiple features, including: joint morphology, acetabular labrum appearance, cartilage loss, and capsular thickness. Clinical and MRI features were assessed for variance by group using one-way analysis of variance (ANOVA) tests and Tukey post-hoc pairwise comparison of means. RESULTS: Labral tear prevalence was 87% with no significant difference between groups (p>0.05). Rates of paralabral cysts were significantly higher in ballet dancers (50%), compared to rugby players (0%) and controls (10%; p=0.01). Acetabular cartilage loss was present in 54% with no significant differences between groups. Superior capsular thickness was significantly greater in ballet dancers (5.3 mm) compared to rugby players (3.8 mm) and controls (3.8 mm; p=0.03). CONCLUSION: Despite the difference in type of activity between groups, there were equally high rates of labral tears and acetabular cartilage loss, questioning the role that sport plays in the development of these findings and their relationship to symptoms. The focally increased superior capsular thickness in ballet dancers may be an adaptive response to extreme ranges of movement.

Smaller Epiphyseal Tubercle and Larger Peripheral Cupping in Slipped Capital Femoral Epiphysis Compared with Healthy Hips: A 3-Dimensional Computed Tomography Study.

BACKGROUND: The inner surface of the capital femoral epiphysis is important for growth plate stability. However, abnormalities of epiphyseal morphology associated with the pathogenesis of slipped capital femoral epiphysis (SCFE) remain poorly understood. This study compares the 3-dimensional anatomy of the epiphyseal tubercle and peripheral cupping in hips with SCFE and normal hips. METHODS: We created 3-dimensional models of the capital femoral epiphysis with use of computed tomography (CT) imaging from 51 patients with SCFE and 80 subjects without hip symptoms who underwent CT because of abdominal pain. The height, width, and length of the epiphyseal tubercle and the peripheral cupping were measured and normalized by the epiphyseal diameter and presented as a percentage. We used analysis of variance for the comparison of the measurements between SCFE and control hips after adjusting for age and sex. RESULTS: Compared with normal hips, hips with mild SCFE had smaller mean epiphyseal tubercle height (0.9% ± 0.9% compared with 4.4% ± 0.4%; p = 0.006) and length (32.3% ± 1.8% compared with 43.7% ± 0.8%; p < 0.001). The mean epiphyseal tubercle height was also smaller in hips with moderate (0.6% ± 0.9%; p = 0.004) and severe SCFE (0.3% ± 0.8%; p < 0.001) compared with normal hips. No differences were observed for measurements of epiphyseal tubercle height and length between SCFE subgroups. The mean peripheral cupping was larger in hips with mild (16.3% ± 1.0%; p < 0.001), moderate (16.4% ± 1.1%; p < 0.001), and severe SCFE (18.9% ± 0.9%; p < 0.001) overall and when assessed individually in all regions compared with normal hips (10.6% ± 0.5%). CONCLUSIONS: Hips with SCFE have a smaller epiphyseal tubercle and larger peripheral cupping compared with healthy hips. A smaller epiphyseal tubercle may be a predisposing morphologic factor or a consequence of the increased shearing stress across the physis secondary to the slip. Increased peripheral growth may be an adaptive response to instability as other stabilizers (i.e., epiphyseal tubercle and anterior periosteum) become compromised with slip progression. Future studies are necessary to determine the biomechanical basis of our morphologic findings.

Translational relevance of the goat as a preclinical model of the human labrum and chondrolabral junction-histological study.

The purpose of this study was to evaluate the histologic features of the caprine labrum, with emphasis on the chondrolabral junction, with the goal of informing the feasibility of the goat as an animal model. The left hip joint of six adolescent Spanish goats (Capra pyrenaica) was harvested and subjected to anatomical and histological assessments. Human acetabular and femoral head samples, collected during total hip arthroplasty, served as comparison samples. The caprine labrum was found to consist of mostly type I collagen with uniform crimp, with an average crimp length of 20.8 µm. Upon histological assessment, acetabular articular chondrocytes were found to express substance-P, especially near or in the chondrolabral junction. And the majority of nonvascular cells expressed α-smooth muscle actin (SMA), with no notable elastin and laminin expression. Human labrum demonstrated similar staining patterns. Overall, the goat hip was found to be homologous to the human hip, demonstrating potential as a useful animal model for future studies. This is the first report of a crimped collagen structure in the labrum. Crimped type I collagen at the chondrolabral junction imparts an extension-recovery property which allows for toleration of stress without permanent deformation, underlying the importance of its preservation during surgery. The high expression of substance-P reflects the degree to which the labrum is innervated. Finally, the expression of α-SMA with contractile characteristics could indicate the potential for chondrocyte (i.e., myochondrocytes) modeling of the extracellular matrix. Statement of Clinical Significance: Establishment of a large animal model and deeper knowledge of the histological composition of the hip joint will enhance our study of the acetabular labrum, including repair techniques. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1070-1080, 2020.

An Anatomical Study of the Anterosuperior Capsular Attachment Site on the Acetabulum.

BACKGROUND: Despite the fact that many surgeons perform partial capsular detachment from the anterosuperior aspect of the acetabulum to correct acetabular deformities during hip arthroscopy, few studies have focused on whether these detachments influence hip joint stability. The aim of this study was to investigate the capsular attachment on the anterosuperior aspect of the acetabulum. We hypothesized that the attachment on the inferior aspect of the anterior inferior iliac spine (AIIS) is wide and fibrocartilaginous and might have a substantial role in hip joint stability. METHODS: Fifteen hips from 9 cadavers of Japanese donors were analyzed. Eleven hips were analyzed macroscopically, and the other 4 were analyzed histologically. In all specimens, the 3-dimensional morphology of the acetabulum and AIIS was examined using micro-computed tomography (micro-CT). RESULTS: Macroscopic analysis showed that the widths of the capsular attachments varied according to the location, and the attachment width on the inferior edge of the AIIS was significantly larger than that on the anterosuperior aspect of the acetabulum. Moreover, the capsular attachment on the inferior edge of the AIIS corresponded with the impression, which was identified by micro-CT. Histological analysis revealed that the hip joint capsule on the inferior edge of the AIIS attached to the acetabulum adjacent to the proximal margin of the labrum. In addition, the hip joint capsule attached to the inferior edge of the AIIS via the fibrocartilage. CONCLUSIONS: The capsular attachment on the inferior edge of the AIIS was characterized by an osseous impression, large attachment width, and distributed fibrocartilage. CLINICAL RELEVANCE: It appeared that the capsular attachment on the inferior edge of the AIIS was highly adaptive to mechanical stress, on the basis of its osseous impression, attachment width, and histological features. Anatomical knowledge of the capsular attachment on the inferior edge of the AIIS provides a better understanding of the pathological condition of hip joint instability.