Abnormal extension of the femoral head epiphysis as a cause of cam impingement

Cam-type hip morphology in asymptomatic patients

BACKGROUND

The alpha angle has been widely used in the assessment of cam-type of impingement, but recent studies have shown that this angle may also be high in asymptomatic patients. The aim of this study is to report the prevalence of cam-type morphology in asymptomatic volunteers and explore its correlation with hip clinical and radiological parameters.

METHODS

This single-centre prospective study included 48 asymptomatic male volunteers (96 hips). All candidates fulfilled the inclusion and exclusion criteria. Physical examination and 1.5 -T MRI imaging were done for bilateral hips on the same day. Alpha angle measurements were obtained from 4 different positions and cam-type morphology was considered positive using 2 different cut points >55° and >60°. Descriptive statistics were analysed and correlations were performed where appropriate and p-value < 0.05 was considered to be significant.

RESULTS

The prevalence of cam-type morphology using alpha angle >55° was 68.8%, 87.5%, 50% and 34.4% in the 12, 1, 2 and 3 o'clock positions respectively. While it was 38.5%, 69.8%, 26% and 12.5% in the 12, 1, 2 and 3 o'clock positions of the studied hips respectively using alpha angle >60°. The maximum alpha angle was more frequently prevalent at the 1 o'clock position in 71 (74%). Labral tear was detected in 26 (27.1%) hips and impingement test was positive in 12 (12.5%) hips. There was no correlation between the presence of cam-type morphology and range of motion of the hip, presence of positive impingement test nor labral tears.

CONCLUSIONS

Cam-type morphology prevalence is high among asymptomatic males, and mostly pronounced at the 1 o'clock position. A correlation between high alpha angle and positive impingement test or labral tear was not found in our cohort. Future studies are required to determine the natural history of asymptomatic cam-type morphology and risk of hip derangement.

Lost in research translation: Female athletes are not male athletes, especially at the hip

Altered shape of the proximal femur (cam morphology) or acetabulum (pincer morphology) is indicative of femoroacetabular impingement, which can result in hip pain and osteoarthritis of the hip. As mechanical load during growth affects the resulting bone shape, there is strong evidence in males that cam morphology develops during skeletal growth while physes are open, rather than as an adaptation after growth plates are closed (skeletal maturity). This adaptation is particularly evident in athletes who participate at elite levels prior to skeletal maturity. The research providing this evidence, however, has primarily focused on male athletes. Despite the lack of inclusion in the research, females consistently comprise two thirds of the clinical and surgical populations with structural hip pain or pathology. Knowledge gained from male-dominated cohorts may not appropriately transfer to female athletes, especially at the hip. This perspectives article briefly reviews differences between females and males in femoral and acetabular structure, hormones, timing of puberty/maturation, hypermobility, activity level and movement control-factors which affect hip structure development and loading. Without female-focused research, the application of research findings from male athletes to female athletes may lead to ineffective or even inappropriate recommendations and treatments. Thus, there is a critical need for investment in research to promote life-long hip health for females.

Arthroscopic and Radiographic Features Distinguish Femoral Head Deformity from Idiopathic Cam, Slipped Capital Femoral Epiphysis, and Recurrent Cam After Slipped Epiphysis

Introduction

Hip impingement from slipped epiphysis and idiopathic cam is well known but not fully differentiated. Idiopathic cam can be a result of an undiagnosed slip. The mechanism of remodeling of slipped epiphysis deformity has also been controversial. The causes of recurrent femoral head deformity and new impingement beyond progression of the slip have not been studied.

Materials and Methods

A consecutive series of hips treated by arthroscopic femoral neck osteoplasty for impingement from slipped epiphysis were compared with a series of hips treated for idiopathic cam impingement. Demographics and clinical, radiographic, and arthroscopic features were retrospectively retrieved. The same parameters were studied in another consecutive series of hips treated for slipped epiphysis and developed recurrent pain from impingement. The deformity was analyzed to understand the causes of recurrence in these hips. The medial most point where the femoral head sphericity ended was called the Alpha point and the tissue covering the bone at the Alpha point was identified.

Results

Children with idiopathic cam were older, had less pain and limp, and less clinical deformity compared to those with slipped epiphysis. The damage pattern was chondrolabral separation and acetabular cartilage debonding from the subchondral bone by an articular cartilage covered bump in idiopathic cam impingement, while it was labral crushing and labral and cartilage abrasion by metaphyseal bone in slip impingement. Recurrent cam deformities after initial slips were from epiphyseal extension similar to the idiopathic cam deformity in 7 out of 9 hips.

Discussion

Slipped epiphysis and idiopathic cam seem to be distinct entities at the time of presentation. They were different in all findings except for having pain with flexion and internal rotation in both groups. Remodeling of slip deformity seems to occur by wear of the metaphyseal prominence on the acetabulum. Recurrence or worsening of cam deformity in slips occurred by growth of the epiphysis on to the neck anteriorly which can appear as a decrease in the posterior slip. The relationship of the Alpha point to the physeal scar and the tissue covering the femoral head at the Alpha point help differentiate between epiphyseal and metaphyseal cam deformities.

Level of Evidence

Level 3 retrospective comparative study.

Soft Tissue Cam Impingement in Adolescents: MRI Reveals Impingement Lesions Underappreciated on Radiographs

BACKGROUND

Femoroacetabular impingement (FAI) has been described as repetitive and abnormal contact between a structurally abnormal proximal femur (cam) and/or acetabulum (pincer), occurring during the terminal range of motion of the hip. While cam and pincer lesions have traditionally been defined as osseous abnormalities, there may be a subset of adolescent patients whose impingement is primarily soft tissue (nonosseous). The existence of a nonosseous cam lesion in adolescents with FAI has not been well described.

PURPOSE

To identify and characterize a series of adolescent patients with nonosseous (soft cam) FAI identified on magnetic resonance imaging (MRI) and compare these patients' clinical presentation and outcome with those of a cohort with primary osseous cam FAI in the same age group.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A prospective institutional registry of patients with symptomatic FAI was reviewed. Patients were included if they had an MRI scan and a lateral radiograph of the hip (45° Dunn or frog) at a baseline visit. On MRI, the anterolateral femoral head was evaluated using radial, coronal, sagittal, or axial oblique sequences. A soft cam lesion was identified by the presence of soft tissue thickening of ≥2 mm at the anterolateral femoral head-neck junction. An alpha angle was measured on MRI scans and radiographs when a lesion was identified. The cohort with soft cam lesions was reviewed and findings and outcomes were compared with those of a cohort with osseous cam lesions. Continuous variables were first examined for normality, and then nonparametric tests-such as the Kruskal-Wallis test-were considered. The change between pre- and postoperative patient-reported outcomes (PROs) was described by mean and standard deviation and evaluated with an independent-samples t test.

RESULTS

A total of 31 (9.3%) of 332 hips (mean age, 16.4 years [range 13.1-19.6 years]; women, 83.9%) were identified with a soft tissue impingment lesion on MRI at the femoral head-neck junction between the 12 and 3 o'clock positions. These lesions demonstrated a thickened perichondral ring (71%), periosteal thickening (26%), or a cartilaginous epiphyseal extension (3%). The mean alpha angle on MRI was greater than on radiographs (63.5°± 7.9° vs 51.3°± 7.9°; P < .0001). A total of 22 patients (71%) with soft impingement underwent hip preservation surgery. When compared with patients in the osseous cohort who also underwent surgical management, both groups showed similar significant improvements from pre- to postoperatively (soft: modified Harris Hip Score [mHHS], 26.9 ± 18.2; Hip disability and Osteoarthritis Outcome Score [HOOS], 31.4 ± 22.9; osseous: mHHS, 22.8 ± 20.8; HOOS, 27.4 ± 20.1; P < .0001), with a mean follow-up of 3.4 years (range, 1-7 years) in the soft cam cohort and 3 years (1-10.1 years) in the osseous cam cohort.

CONCLUSION

Clinicians should be aware of nonosseous or soft cam lesions that cause impingement in adolescent patients without an obvious osseous cam on radiographs. MRI is required to detect these soft cam lesions. When nonoperative treatment fails, the PROs in these patients after operative management are comparable with those in patients with osseous cam lesions. Further research is needed to determine whether the soft cam precedes an osseous cam or whether it is a separate entity.

[Clinical aspects of imaging the hip in infants, children and adolescents]

When a child with a hip problem is clinically evaluated, it is usually possible to make a presumptive diagnosis which is subsequently confirmed. The most important tool for confirmation in pediatric hip disorders is radiological imaging. Vice versa changes on sonogram, native X‑ray or magnetic resonance images (MRI) can often only be interpreted when the history and current clinical findings are known. In this constellation, it is desirable that all colleagues who are confronted with a child's hip problem know the most common and important pediatric hip disorders and use the same terminology. The aim of this article is to present a short outline of the pathogenesis and clinical aspects of congenital and neurogenic hip dysplasia, coxitis fugax, septic coxitis, Perthes' disease, infantile and adolescent femoroacetabular impingement, apophysiolyses, and slipped capital femoral epiphysis.

Hip Osteoarthritis: Bench to Bedside Perspective

Osteoarthritis is a major source of pain, disability, and economic cost worldwide. For nearly a century, there has been a debate about the causes of hip osteoarthritis and the role that structural abnormalities may play as a causative factor. Recent advances in open and minimally invasive techniques such as the periacetabular osteotomy, surgical hip dislocation and arthroscopic approaches have allowed us safe access into the joint to not only improve the abnormal bony structure and repair damaged tissue but also to gain clinical insights into the cause of joint damage. At present, structural abnormalities such as acetabular dysplasia and CAM deformities of the proximal femur are thought to be a major factor causing premature hip OA. Over the past 30 years, our understanding of the function and biology of articular cartilage has evolved from a relatively acellular lubricating cushion to a metabolically active tissue that can modulate its tissue composition in response to mechanical loading. Using advanced biochemical MR imaging technique called delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC), it has been shown that alteration in the mechanical environment of the hip with a pelvic osteotomy in acetabular dysplasia can alter the articular cartilage composition. This further demonstrates the importance of mechanics in development of joint damage and the potential for surgical correction to prevent or slow down the progression of OA.

A combination of acetabular coverage and femoral head-neck measurements can help diagnose femoroacetabular impingement

This study aimed to evaluate the relationship between the radiographical features of combination of the acetabular coverage and the femoral head-neck shape and the occurrence of femoroacetabular impingement (FAI). In this study, 114 patients who had FAI with or without labral tear and mild osteoarthritis were analyzed. Plain radiographs and computed tomography (CT) were taken for evaluation of acetabular coverage and femoral head-neck measurements. The relationship between the combination angle of acetabular coverage and femoral head-neck measurements and the occurrence of FAI was evaluated. The prevalence of FAI patients with the combination angle of CT-anterior CE + α angle ≥100° was 6.1% (7/114 patients). Receiver operator characteristic curve analysis demonstrated a higher area under the curve for combination of CT-anterior center edge angle (ACEA) with the α angle at 0.94 (CT-ACEA +α angle). A threshold for the occurrence of FAI was determined using the combination CT-ACEA + α angle at 100°. The frequency of FAI surgery was significantly higher in patients with a combination angle ≥100° than in those with a smaller angle. The average modified Harris hip score was significantly lower in patients with a combination angle ≥100° than in those with a smaller angle. We suggest that the combination of lateral center edge angle ≥40°, α angle ≥50° and combined angles of CT-ACEA and α angle ≥100° may help diagnosis of FAI. Level of evidence III: retrospective cohort study.

Open and arthroscopic management of femoroacetabular impingement: a review of current concepts

Femoroacetabular impingement (FAI) is a common femoral and/or acetabular abnormality that can cause progressive damage to the hip and osteoarthritis. FAI can be the result of femoral head/neck overgrowth, acetabular overgrowth or both femoral and acetabular abnormalities, resulting in a loss of native hip biomechanics and pain upon hip flexion and rotation. Radiographic evidence can include loss of sphericity of the femoral neck (cam impingement) and/or acetabular retroversion with focal or global overcoverage (pincer impingement). Operative intervention is indicated in symptomatic patients after failed conservative management with radiographic evidence of impingement and minimal arthritic changes of the hip, with the goal of restoring normal hip biomechanics and reducing pain. This is done by correcting the femoral head-neck relationship to the acetabulum through femoral and/or acetabular osteoplasty and treatment of concomitant hip pathology. In pincer impingement cases with small lunate surfaces, reverse periacetabular osteotomy is indicated as acetabular osteoplasty can decrease an already small articular surface. While surgical dislocation is regarded as the traditional gold standard, hip arthroscopy has become widely utilized in recent years. Studies comparing both open surgery and arthroscopy have shown comparable long-term pain reduction and improvements in clinical measures of hip function, as well as similar conversion rates to total hip arthroplasty. However, arthroscopy has trended toward earlier improvement, quicker recovery and faster return to sports. The purpose of this study was to review the recent literature on open and arthroscopic management of FAI.

Slipped Capital Femoral Epiphysis Associated With Athletic Activity

BACKGROUND

Little data exist regarding the association of slipped capital femoral epiphysis (SCFE) and sporting activities.

HYPOTHESIS

There is no association between SCFE and sporting activities.

STUDY DESIGN

Retrospective review of all SCFE cases at our institution from 2010 through March 2021.

LEVEL OF EVIDENCE

Level 3.

METHODS

All patients with idiopathic SCFE were reviewed looking for the presence/absence of sporting activities and symptom onset. Also collected were the age, symptom duration, and weight/height of the patient, sex, race, and stable/unstable nature of the SCFE. The severity of the SCFE was measured using the lateral epiphyseal-shaft angle.

RESULTS

There were 193 children (110 boys, 83 girls) with idiopathic SCFEs. The SCFE was stable in 147, unstable in 45, and unknown in 1. The average age was 12.1 ± 1.8 years, average SCFE angle 38° ± 20° and symptom duration 4.0 ± 5.1 months. An association with a sporting activity was present in 64 (33%). The sporting activity was basketball (18), football (11), baseball/softball (10), and others (23). Football, basketball, and soccer predominated in boys, baseball and running sports were equal between boys and girls, and cheerleading/gymnastics/dancing predominated in girls. Differences showed that those involved in sports had a slightly lower body mass index (BMI) (88th percentile vs 95th percentile, P = 0.00). There were no differences between those involved and those not those involved in sporting activities for symptom duration, SCFE severity, sex, race, or stable/unstable SCFE type.

CONCLUSION

Sporting activities are associated with the onset of symptoms in 1 of 3 of patients with SCFE, refuting the null hypothesis.

CLINICAL RELEVANCE

A high level of suspicion for SCFE should be given when any peripubertal athlete presents with hip or knee pain regardless of BMI/obesity status, and appropriate imaging performed.

[Femoroacetabular impingement syndrome in adolescents-How to adivse? How to treat?]

Hintergrund

Das Femoroazetabuläre Impingement-Syndrom (FAIS) ist eine relevante Ursache für Leistenschmerzen beim Jugendlichen. Insbesondere sind Sportler betroffen.

Ziel der Arbeit

Die Arbeit soll einen evidenzbasierten Hintergrund für Beratung und Therapie des FAIS beim Adoleszenten bieten.

Material und Methoden

Anhand der aktuellen Literatur wurde eine Übersicht zu Prävalenz und Pathogenese, Abklärung und Diagnostik sowie therapeutischen Empfehlung des FAIS beim Adoleszenten erarbeitet.

Ergebnisse und Diskussion

Das FAIS beim Jugendlichen betrifft vor allem sportlich aktive Patienten. Bestimmte Sportarten begünstigen die Entstehung eines FAIS. Cam-Impingement, Pincer-Impingement und kombiniertes FAIS sind die häufigsten Entitäten in dieser Altersgruppe. Die Cam-Morphologie entsteht kurz vor Schluss der proximalen Femurwachstumsfuge. Beim Cam-Impingement muss die Epiphyseolysis capitis femoris (ECF) von der primären Cam-Morphologie unterschieden werden. Die ECF verlangt eine rasche operative Versorgung mit Stabilisierung der Epiphyse, während das primäre Cam-Impingement elektiv abgeklärt werden kann und ein konservativer Behandlungsversuch sinnvoll ist. Schäden an Labrum und Knorpel werden regelhaft beobachtet. Eine systematische radiologische Abklärung mittels Projektionsröntgen und MRT ist obligat, um einen adäquaten Therapieplan zu entwickeln. Bei jugendlichen Patienten mit FAIS sollte immer ein konservativer Therapieversuch erfolgen. Ist dieser nicht erfolgreich, ist die operative Sanierung mit Hüftarthroskopie indiziert. Die postoperativen Ergebnisse zeigen bei Jugendlichen sehr gute Erfolge mit rascher Besserung der Beschwerden, geringen Komplikationen und einer hohen „Return-to-sport“-Rate.

The Response of Hip Joint Cartilage to Exercise in Children: An MRI Study Using T2-Mapping

OBJECTIVE

The aim of this study was to determine the effects of activity and cam morphology on cartilage composition during adolescence and investigate the development of cartilage composition with age.

DESIGN

Cross-sectional observational cohort study of individuals from football club academies and an age-matched control population, aged 9 to 18 years. Assessments included questionnaires and T2-mapping of hips. Primary imaging outcome measures were T2 relaxation time of acetabular and femoral cartilage, average alpha angle, and lateral epiphyseal extension.

RESULTS

The cohort consisted of 109 elite male footballers, 49 male controls, and 51 female controls. Elite male footballers had an acetabular cartilage T2 value 4.85 ms greater than male controls (P < 0.001). A significant positive correlation existed between Physical Activity Questionnaire Score and acetabular cartilage T2 value (coefficient 1.07, P < 0.001) and femoral cartilage T2 value (coefficient 0.66, P = 0.032). Individuals with a closed physis had an acetabular cartilage T2 value 7.86 ms less than individuals with an open physis. Acetabular cartilage T2 values decreased with age in elite footballers. No correlation existed between alpha angle and anterosuperior acetabular cartilage T2 value and no difference in T2 value existed between individuals with and without cam morphology.

CONCLUSIONS

This study demonstrates that high activity levels may significantly affect acetabular cartilage composition during adolescence, but cam morphology may not detrimentally affect cartilage composition until after adolescence.

Measuring 3D growth plate shape: Methodology and application to cam morphology

Physeal changes corresponding to cam morphology are currently measured using two-dimensional (2D) methods. These methods are limited by definitions of the femoral neck axis and head center that are dependent on the radiographic plane of view. To address these limitations, we developed three-dimensional (3D) methods for analyzing continuous growth plate shape using magnetic resonance imaging scans. These new methods rely on a single definition of the femoral neck axis and head center that are both nondependent on the radiographic plane of view and allow for analysis of growth plate shape across the growth plate surface (performed using statistical parametric mapping). Using our 3D method, we analyzed the position of the growth plate in the femoral head (relative to a plane tangent to the femoral head) and the curvature of the growth plate (relative to a plane through the center of the growth plate) in 9-16-year-old males at risk for cam morphology and their recreationally active peers (n = 17/cohort). These two measurements provide an avenue to separately analyze the effects of these variables in the overall growth plate shape. We detected differences in growth plate shape with age in recreationally active adolescents but did not detect differences between at risk and recreationally adolescents.

Acetabular retroversion after triple pelvic osteotomy for Legg-Calvé-Perthes disease and its impact on the femoroacetabular impingement: a case/control study at 15 years of follow-up

The objective of this study was to compare the effect of triple pelvic osteotomy (TPO) in Legg-Calvé-Perthes disease (LCPD) on acetabular version in a group of patients who developed a femoroacetabular impingement (FAI) and a control group without FAI. Patients who received a TPO for unilateral LCPD were retrospectively included. Patients with bilateral LCPDs, requiring TPO with femoral procedures, or with incomplete imaging were excluded. Seven patients with FAI (FAI+) and eight patients without FAI (FAI-) were evaluated at a mean follow-up of 14.8 years. The two groups were comparable in demographic data, age at diagnosis, Herring score, and BMI. We measured anatomical acetabular version on computed tomography scans, the difference (delta) of acetabular version between the operated hip and the healthy hip, the McKibbin (femoral version + acetabular version), Stulberg, and Tönnis scoring system. The two groups were not statistically different on the Stulberg and Tönnis scores. All operated hip acetabula were retroverted, FAI+: -8.41° (range, -44 to 10.5), FAI-: -3.38° (range, -37.3 to 11.5) (P = 0.61). The average delta was FAI+: 23.79° (range, 1.5-59.5), FAI-: 20.14° (range, 5-45.3) (P = 0.68). All seven patients of the FAI+ group have pathologic McKibbin index (<30°) versus only four of the FAI- group (P = 0.03). TPO induces acetabular retroversion in patients with LCPD. This retroversion, assessed in a static benchmark (anterior pelvic plane), does not in itself explain the FAI.

A longitudinal cohort study of adolescent elite footballers and controls investigating the development of cam morphology

Cam morphology describes an asphericity of the femoral head that develops during adolescence, is highly prevalent in athletes, and predisposes individuals to future osteoarthritis. However, it’s aetiology remains poorly understood. The aim of this study was to perform 3-year longitudinal follow-up of a control population and football club academy cohort to compare the change in hip and growth plate anatomy between athletes and controls. MRI and questionnaires were used to characterise change in hip and growth plate anatomy and quantify activity levels. 121 male academy footballers and 107 male and female controls participated at baseline. Footballers experienced significantly greater increases in femoral head asphericity (4.83 degrees (95% CI: 2.84 to 6.82), p < 0.001) than controls. A positive correlation existed between activity levels and change in femoral head morphology (coefficient 0.79, p  ≤  0.001). Greatest morphological change occurred in individuals aged 11–12 years at baseline, with no significant change in individuals aged 14 years and older at baseline. Cam morphology development was secondary to soft tissue hypertrophy and lateral growth plate extension. In conclusion, excessive loading of the hip joint through exercise prior to 14 years of age may result in growth plate adaptations causing cam morphology. Potential interventions may include training type and load modification in young adolescent football players.

Patient-Reported Outcomes in Athletes Following Hip Arthroscopy for Femoroacetabular Impingement With Subanalysis on Return to Sport and Performance Level: A Systematic Review

PURPOSE

To identify present trends in demographics, surgical indications, preoperative findings, and surgical treatment of athletes undergoing hip arthroscopy for femoroacetabular impingement and (2) to investigate the outcomes in this patient population, including patient-reported outcome scores (PROS), return-to-sport, complications, and reoperation data at minimum 2-year follow-up in the athletic population.

METHODS

Cochrane, Embase, and PubMed databases were searched according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines to distinguish articles that reported PROS after hip arthroscopy in athletes. Athletes were defined as anyone who played a sport for minimum 2 years at any level. The standardized mean difference was calculated to compare the effect size of hip arthroscopy on various PROS.

RESULTS

Eighteen studies, with 904 athlete hips and a collective study period of January 1993 to April 2017, were included in this systematic review. Across all studies, the mean age and body mass index ranged from 15.7-36.7 years and 20.3-26.3, respectively. The follow-up range was 24-240 months. Mean preoperative alpha angle ranged from 57.7° to 80.0°. Athletes most commonly underwent femoroplasty and labral management. At latest follow-up, the modified Harris Hip Score were excellent in 6 studies (range, 92.1-98), good in 10 studies (range, 84.2-88.5), and fair in 1 study (77.1). Each studies' individual athletic cohort showed significant improvement on the modified Harris Hip Score, Nonarthritic Hip Score, the Hip Outcome Score-Activities of Daily Living, the Hip Outcome Score-Sport-Specific Subscale, visual analog scale for pain, and International Hip Outcome Tool at latest follow-up (P < .05). The return-to-sport rate ranged from 72.7% to 100%, with 74.2-100% of these athletes returning to preinjury or greater level.

CONCLUSIONS

Athletes undergoing arthroscopic hip surgery in the setting of femoroacetabular impingement, not only exhibit significant functional improvement, but also have a high rate of return to sport at the same or greater competition level compared with preinjury level.

LEVEL OF EVIDENCE

IV, systematic review of Level III and IV studies.

How does the cam morphology develop in athletes? A systematic review and meta-analysis

OBJECTIVE

A higher prevalence of cam morphology has been reported in the athletic population but the development of the cam morphology is not fully understood. The purpose of this systematic review is to establish the timing of development of the cam morphology in athletes, the proximal femoral morphologies associated with its development, and other associated factors.

DESIGN

Embase, MEDLINE and the Cochrane Library were searched for articles related to development of the cam morphology, and PRISMA guidelines were followed. Data was pooled using random effects meta-analysis. Study quality was assessed using the Downs and Black criteria and evidence quality using the GRADE framework.

RESULTS

This search identified 16 articles involving 2,028 participants. In males, alpha angle was higher in athletes with closed physes than open physes (SMD 0.71; 95% CI 0.23, 1.19). Prevalence of cam morphology was associated with age during adolescence when measured per hip (β 0.055; 95% CI 0.020, 0.091) and per individual (β 0.049; 95% CI 0.034, 0.064). Lateral extension of the epiphysis was associated with an increased alpha angle (r 0.68; 95% CI 0.63, 0.73). A dose-response relationship was frequently reported between sporting frequency and cam morphology. There was a paucity of data regarding the development of cam morphology in females.

CONCLUSIONS

Very low and low quality evidence suggests that in the majority of adolescent male athletes, osseous cam morphology developed during skeletal immaturity, and that prevalence increases with age. Very low quality evidence suggests that osseous cam morphology development was related to lateral extension of the proximal femoral epiphysis.

Primary cam morphology; bump, burden or bog-standard? A concept analysis

BACKGROUND

Cam morphology, a distinct bony morphology of the hip, is prevalent in many athletes, and a risk factor for hip-related pain and osteoarthritis. Secondary cam morphology, due to existing or previous hip disease (eg, Legg-Calve-Perthes disease), is well-described. Cam morphology not clearly associated with a disease is a challenging concept for clinicians, scientists and patients. We propose this morphology, which likely develops during skeletal maturation as a physiological response to load, should be referred to as primary cam morphology. The aim of this study was to introduce and clarify the concept of primary cam morphology.

DESIGN

We conducted a concept analysis of primary cam morphology using articles that reported risk factors associated with primary cam morphology; we excluded articles on secondary cam morphology. The concept analysis method is a rigorous eight-step process designed to clarify complex 'concepts'; the end product is a precise definition that supports the theoretical basis of the chosen concept.

RESULTS

We propose five defining attributes of primary cam morphology-tissue type, size, site, shape and ownership-in a new conceptual and operational definition. Primary cam morphology is a cartilage or bony prominence (bump) of varying size at the femoral head-neck junction, which changes the shape of the femoral head from spherical to aspherical. It often occurs in asymptomatic male athletes in both hips. The cartilage or bone alpha angle (calculated from radiographs, CT or MRI) is the most common method to measure cam morphology. We found inconsistent reporting of primary cam morphology taxonomy, terminology, and how the morphology is operationalised.

CONCLUSION

We introduce and clarify primary cam morphology, and propose a new conceptual and operational definition. Several elements of the concept of primary cam morphology remain unclear and contested. Experts need to agree on the new taxonomy, terminology and definition that better reflect the primary cam morphology landscape-a bog-standard bump in most athletic hips, and a possible hip disease burden in a selected few.

Arthroscopic Fixation of Os Acetabuli and Labral Repair: Suture-on-Screw Technique

Os acetabuli is thought to be the result of an unfused ossification center or an acetabular rim fracture in the setting of femoral-sided femoroacetabular impingement syndrome. Historically, patients with symptomatic hips have been treated with resection alone; however, in patients with large bone fragments or with reduced acetabular coverage prior to surgical intervention, iatrogenic dysplasia and structural instability may develop after resection. Therefore, for patients with an acetabular os, labral tearing, and cam-type femoroacetabular impingement, internal fixation of the os acetabuli, femoral osteochondroplasty, and labral repair have been described. We propose a "suture-on-screw" arthroscopic technique to simultaneously address both the labral tear and os acetabuli, thereby reducing the number of suture anchors required for labral fixation, leading to an efficient and cost-effective approach for the treatment of these patients.

A Cam Morphology Develops in the Early Phase of the Final Growth Spurt in Adolescent Ice Hockey Players: Results of a Prospective MRI-based Study

BACKGROUND

Cam morphologies seem to develop with an increased prevalence in adolescent boys performing high-impact sports. The crucial question is at what age the cam morphology actually develops and whether there is an association with an aberration of the shape of the growth plate at the cam morphology site.

QUESTIONS/PURPOSES

(1) What is the frequency of cam morphologies in adolescent ice hockey players, and when do they appear? (2) Is there an association between an extension of the physeal growth plate and the development of a cam morphology? (3) How often do these players demonstrate clinical findings like pain and lack of internal rotation?

METHODS

A prospective, longitudinal MRI study was done to monitor the proximal femoral development and to define the appearance of cam morphologies in adolescent ice hockey players during the final growth spurt. Young ice hockey players from the local boys' league up to the age of 13 years (mean age 12 ± 0.5 years) were invited to participate. From 35 players performing on the highest national level, 25 boys and their parents consented to participate. None of these 25 players had to be excluded for known disease or previous surgery or hip trauma. At baseline examination as well as 1.5 and 3 years later, we performed a prospective noncontrast MRI scan and a clinical examination. The three-dimensional morphology of the proximal femur was assessed by one of the authors using radial images of the hip in a clockwise manner. The two validated parameters were: (1) the alpha angle for head asphericity (abnormal > 60°) and (2) the epiphyseal extension for detecting an abnormality in the shape of the capital physis and a potential correlation at the site of the cam morphology. The clinical examination was performed by one of the authors evaluating (1) internal rotation in 90° of hip and knee flexion and (2) hip pain during the anterior impingement test.

RESULTS

Cam morphologies were most apparent at the 1.5-year follow-up interval (10 of 25; baseline versus 1.5-year follow-up: p = 0.007) and a few more occurred between 1.5 and 3 years (12 of 23; 1.5-year versus 3-year follow-up: p = 0.14). At 3-year follow-up, there was a positive correlation between increased epiphyseal extension and a high alpha angle at the anterosuperior quadrant (1 o'clock to 3 o'clock) (Spearman correlation coefficient = 0.341; p < 0.003). The prevalence of pain on the impingement test and/or restricted internal rotation less than 20° increased most between 1.5-year (1 of 25) and the 3-year follow-up (6 of 22; 1.5-year versus 3-year follow-up: p = 0.02).

CONCLUSION

Our data suggest that a cam morphology develops early during the final growth spurt of the femoral head in adolescent ice hockey players predominantly between 13 to 16 years of age. A correlation between an increased extension of the growth plate and an increased alpha angle at the site of the cam morphology suggests a potential underlying growth disturbance. This should be further followed by high-resolution or biochemical MRI methods. Considering the high number of cam morphologies that correlated with abnormal clinical findings, we propose that adolescents performing high-impact sports should be screened for signs of cam impingement, such as by asking about hip pain and/or examining the patient for limited internal hip rotation.

LEVEL OF EVIDENCE

Level I, prognostic study.

Does the Capital Femoral Physis Bony MorphologyDiffer in Children with Symptomatic Cam-type Femoroacetabular Impingement

BACKGROUND

The epiphyseal tubercle, the corresponding metaphyseal fossa, and peripheral cupping are key stabilizers of the femoral head-neck junction. Abnormal development of these features in the setting of supraphysiologic physeal stress under high forces (for example, forces that occur during sports activity) may result in a cam morphology. Although most previous studies on cam-type femoroacetabular impingement (FAI) have mainly focused on overgrowth of the peripheral cupping, little is known about detailed morphologic changes of the epiphyseal and metaphyseal bony surfaces in patients with cam morphology.

QUESTIONS/PURPOSES

(1) Does the CT-based bony morphology of the peripheral epiphyseal cupping differ between patients with a cam-type morphology and asymptomatic controls (individuals who did not have hip pain)? (2) Does the CT-based bony morphology of the epiphyseal tubercle differ between patients with a cam-type morphology and asymptomatic controls? (3) Does the CT-based bony morphology of the metaphyseal fossa differ between patients with a cam-type morphology and asymptomatic controls?

METHODS

After obtaining institutional review board approval for this study, we retrospectively searched our institutional database for patients aged 8 to 15 years with a diagnosis of an idiopathic cam morphology who underwent a preoperative CT evaluation of the affected hip between 2005 and 2018 (n = 152). We excluded 96 patients with unavailable CT scans and 40 patients with prior joint diseases other than cam-type FAI. Our search resulted in 16 patients, including nine males. Six of 16 patients had a diagnosis of bilateral FAI, for whom we randomly selected one side for the analysis. Three-dimensional (3-D) models of the proximal femur were generated to quantify the size of the peripheral cupping (peripheral growth of the epiphysis around the metaphysis), epiphyseal tubercle (a beak-like prominence in the posterosuperior aspect of the epiphysis), and metaphyseal fossa (a groove on the metaphyseal surface corresponding to the epiphyseal tubercle). A general linear model was used to compare the quantified anatomic features between the FAI cohort and 80 asymptomatic hips (aged 8 to 15 years; 50% male) after adjusting for age and sex. A secondary analysis using the Wilcoxon matched-pairs signed rank test was performed to assess side-to-side differences in quantified morphological features in 10 patients with unilateral FAI.

RESULTS

After adjusting for age and sex, we found that patients with FAI had larger peripheral cupping in the anterior, posterior, superior, and inferior regions than control patients who did not have hip symptoms or radiographic signs of FAI (by 1.3- to 1.7-fold; p < 0.01 for all comparisons). The epiphyseal tubercle height and length were smaller in patients with FAI than in controls (by 0.3- to 0.6-fold; p < 0.02 for all comparisons). There was no difference in tubercle width between the groups. Metaphyseal fossa depth, width, and length were larger in patients with FAI than in controls (by 1.8- to 2.3-fold; p < 0.001 for all comparisons). For patients with unilateral FAI, we saw similar peripheral cupping but smaller epiphyseal tubercle (height and length) along with larger metaphyseal fossa (depth) in the FAI side compared with the uninvolved contralateral side.

CONCLUSION

Consistent with prior studies, we observed more peripheral cupping in patients with cam-type FAI than control patients without hip symptoms or radiographic signs of FAI. Interestingly, the epiphyseal tubercle height and length were smaller and the metaphyseal fossa was larger in hips with cam-type FAI, suggesting varying inner bone surface morphology of the growth plate. The docking mechanism between the epiphyseal tubercle and the metaphyseal fossa is important for epiphyseal stability, particularly at early ages when the peripheral cupping is not fully developed. An underdeveloped tubercle and a large fossa could be associated with a reduction in stability, while excessive peripheral cupping growth would be a factor related to improved physeal stability. This is further supported by observed side-to-side differences in tubercle and fossa morphology in patients with unilateral FAI. Further longitudinal studies would be worthwhile to study the causality and compensatory mechanisms related to epiphyseal and metaphyseal bony morphology in pathogenesis cam-type FAI. Such information will lay the foundation for developing imaging biomarkers to predict the risk of FAI or to monitor its progress, which are critical in clinical care planning.

LEVEL OF EVIDENCE

Level III, prognostic study.

FUNCTIONAL OUTCOMES OF ARTHROSCOPIC TREATMENT IN 230 FEMOROACETABULAR IMPINGEMENT CASES

Objective:

To analyze the functional outcomes after arthroscopic treatment of femoroacetabular impingement (FAI).

Methods:

194 patients (131 males and 63 females), with a mean age of 39 (15-68) years old for men and 43 (16-58) years old for women. The average follow-up was 17 months (2 to 71). 103 patients presented Cam-type FAI, 102 mixed and 25 Pincer. “Unilateral” arthroscopy was performed in 161 cases, “Bilateral” (only once each side) in 46 cases and, “Multiple” (more than one procedure on the same hip) in 23. The female sex was prevalent in the Pincer type FAI (76%), while males were prevalent in Mixed and Cam type, 74.5% and 72.8%, respectively.

Results:

The mean HHSpre score was 63.7 and 87.1 for HHSpost, i.e. 73.11%. Differences appeared between “mixed” and “unilateral” groups. The complications percentage in this series was 18.7% and 7% progressed to total hip arthroplasty.

Conclusion:

The arthroscopic FAI treatment improved the postoperative clinical scores of these patients, especially in cases of mixed-type FAI, which presented a higher improvement rate. Insufficient femoral osteoplasty was the main cause for surgical re-intervention, particularly in the initial cases of this series. Level of Evidence II, Retrospective study.

Trends in Adolescent Hip Arthroscopy From the PHIS Database 2008-2018

BACKGROUND

Previous studies have suggested that hip arthroscopy has been performed with increasing frequency. Few studies have examined this trend in the adolescent population. The purpose of this study was to evaluate the trend in the frequency of hip arthroscopy in adolescents standardized by total orthopaedic surgeries in adolescents at pediatric hospitals in the United States.

METHODS

The Pediatric Health Information System (PHIS) database was queried for patients aged 10 to 19 years who underwent orthopaedic surgery at any of the PHIS-participating hospitals from 2008 to 2018. The subgroup of patients in this age cohort who underwent hip arthroscopy was identified using Current Procedural Terminology procedure codes. The yearly rate was expressed as the number of hip arthroscopies per 1000 orthopaedic surgeries. A linear model was used to fit the data and illustrate the relative trend.

RESULTS

A total of 432,309 orthopaedic surgeries including 9491 hip arthroscopies were performed for patients 10 to 19 years of age. Hip arthroscopies were performed at a yearly rate of 22 per 1000 orthopaedic surgeries. Over the 10-year period, the number of hip arthroscopies increased 6.2-fold, whereas the number of orthopaedic procedures increased 1.6-fold. There was a 3.9-fold increase in hip arthroscopies relative to total orthopaedic surgeries.

CONCLUSIONS

The number of hip arthroscopic procedures in adolescent patients has increased by 3.9-fold times relative to total orthopaedic surgeries in adolescents over a 10-year span, on the basis of data from PHIS-participating institutions. This finding mirrors the trends in the adult population over similar time periods. This may be because of increasing participation in sports in the adolescent population, and a better understanding of the diagnosis and treatment of femoroacetabular impingement and other sports-related hip pathologies.

LEVEL OF EVIDENCE

Level IV.

Clinical and radiological hip parameters do not precede, but develop simultaneously with cam morphology: a 5-year follow-up study

PURPOSE

The aim of this study was to (1) investigate whether radiographic and clinical parameters, which influence how stresses during sporting activities act on the proximal femur, are associated with cam morphology or (2) precede cam morphology development.

METHODS

Young male football players participated at baseline (n = 89, 12-19 years of age), 2.5-year (n = 63) and 5-year follow-up (n = 49). Standardized anteroposterior pelvic and frog-leg lateral radiographs were obtained at each time-point. Cam morphology was quantified by an alpha angle ≥ 60°, and large cam morphology ≥ 78°. The neck-shaft angle (NSA), epiphyseal extension (EE), lateral center-edge angle (LCEA) and hip internal rotation (IR) were also measured. Cross-sectional associations between NSA, EE, LCEA and IR and (large) cam morphology were studied at all time-points. To study whether these variables preceded cam morphology development, hips without cam morphology at baseline were studied prospectively.

RESULTS

A lower NSA, a higher EE and limited IR were consistently associated with cam morphology at all three time-points. These differences were more pronounced in hips with large cam morphology. No association between cam morphology and the LCEA was found. None of the parameters studied preceded cam morphology development.

CONCLUSION

Cam morphology developed simultaneously with a varus orientation, growth plate extension towards the femoral neck and limited hip internal rotation. These parameters did not precede cam morphology development. The hip parameters studied cannot be used to identify individuals at risk of developing cam morphology.

LEVEL OF EVIDENCE

Level II.

Hip arthroscopy for lateral cam morphology: how important are the vessels?

The purpose of this narrative review is to identify the anatomy and relevant blood supply to the femoral head as it pertains to hip arthroscopy and lateral cam morphology. The primary blood supply to the femoral head is the lateral ascending superior retinacular vessels, which are terminal branches of the medial femoral circumflex artery. These vessels penetrate the femoral head at the posterolateral head–neck junction. Surgeons performing posterolateral femoral osteoplasty must respect this vasculature to avoid iatrogenic avascular necrosis (AVN). Avoidance of excessive traction, avoidance of distal posterolateral capsulotomy and avoidance of disruption of the superior retinacular vessels should keep the risk for AVN low. Hip extension, internal rotation and distraction are useful in hip arthroscopy to better visualize lateral/posterolateral cam morphology to facilitate an accurate comprehensive cam correction and avoid vascular disruption.

Femoroacetabular Impingement and Acetabular Labral Tears - Part 1: Pathophysiology and Biomechanics

Femoroacetabular impingement (FAI) is an important cause of hip pain, and the main etiology of hip osteoarthritis in the young population. Femoroacetabular impingement is characterized by subtle alterations in the anatomy of the acetabulum and proximal femur, which can lead to labrum tearing. The acetabular labrum is essential to the stability of the hip joint. Three types of FAI were described: cam (anespherical femoral head), pincer (acetabular overcoverage) and mixed (characteristics of both cam and pincer). The etiology of FAI is related to genetic and environmental characteristics. Knowledge of this condition is essential to adequately treat patients presenting with hip pain.

Return to Sports After Joint Preservation Hip Surgery

Femoroacetabular impingement results from a mismatch of congruency between the femoral head and the acetabulum. This condition is most common among young, active patients and may lead to pain, decreased quality of life, and inability to participate in athletics. Hip preservation surgery is widely performed is used as a definitive treatment option in athletes at all levels of competition. Athletes have reported high rates of return to play and satisfaction and expect rehabilitation to require approximately 4 to 6 months. This article provides an overview of femoroacetabular impingement, including diagnosis and treatment, with focus on athletes and return to play.

The history of femoroacetabular impingement

Aims

Femoroacetabular impingement (FAI) describes abnormal bony contact of the proximal femur against the acetabulum. The term was first coined in 1999; however what is often overlooked is that descriptions of the morphology have existed in the literature for centuries. The aim of this paper is to delineate its origins and provide further clarity on FAI to shape future research.

Methods

A non-systematic search on PubMed was performed using keywords such as “impingement” or “tilt deformity” to find early anatomical descriptions of FAI. Relevant references from these primary studies were then followed up.

Results

Although FAI has existed for almost 5,000 years, the anatomical study by Henle in 1855 was the first to describe it in the literature. The relevance of the deformity was not appreciated at the time but this triggered the development of further anatomical studies. Parallel to this, Poland performed the first surgical correction of FAI in 1898 and subsequently, descriptions of similar procedures followed. In 1965, Murray outlined radiological evidence of idiopathic cam-type deformities and highlighted its significance. This led to a renewed focus on FAI and eventually, Ganz et al released their seminal paper that has become the foundation of our current understanding of FAI. Since then, there has been an exponential rise in published literature but finding a consensus, especially in the diagnosis of FAI, has proven to be difficult.

Conclusion

Current research on FAI heavily focuses on new data, but old evidence does exist and studying it could be equally as important in clarifying the aetiology and classification of FAI.

Cite this article: Bone Joint Res 2020;9(9):572–577.

Normative Values for Capital Femoral Epiphyseal Extension of the Developing Hip Based on Age, Sex, and Oxford Bone Age

BACKGROUND

Recent evidence suggests that increasing capital femoral epiphyseal extension may be an adaptive response that underlies the development of most cam morphology, whereas slipped capital femoral epiphysis is associated with its deficiency. However, there is an absence of rigorous data on the normal development of epiphyseal extension in the hip joint in modern adolescents. The aim of this study was to establish normative values for anterior and superior epiphyseal extension in a normal adolescent control population.

METHODS

A total of 210 pediatric subjects (420 hips) between the ages of 8 and 17 years old at the time of presentation who received pelvic radiographs were retrospectively reviewed. Basic demographic data were collected. All subjects with underlying hip pathology were excluded. Epiphyseal extension ratio (EER) was measured, defined as the ratio of extension of the capital femoral epiphysis down the femoral neck relative to the diameter of the femoral head. Superior EER was measured on the anterioposterior view and anterior EER on the frog-leg lateral view bilaterally. Skeletal maturity was graded based on Oxford bone age (OBA) at the proximal femur.

RESULTS

The superior EER increased from 0.63±0.05 at age 8 to 0.80±0.05 at age 17. The anterior EER similarly increased from 0.56±0.06 at age 8 to 0.74±0.05 at age 17. The superior and anterior EERs increased with age in a linear fashion for males (r=0.80 and 0.75, respectively) and females (r=0.67 and 0.65) through physeal closure. When subjects were standardized by the OBA stage of the femoral head, females and males showed no statistical difference at OBA stages 6, 7 or 8.

CONCLUSIONS

Superior and anterior EER increased throughout adolescent development until physeal closure. When controlling for skeletal maturity, there were no significant differences between sexes. This normative data may help guide future management and research of slipped capital femoral epiphysis and cam morphology.

LEVEL OF EVIDENCE

Level II, Diagnostic.

Using Magneto-Inertial Measurement Units to Pervasively Measure Hip Joint Motion during Sports

The use of wireless sensors to measure motion in non-laboratory settings continues to grow in popularity. Thus far, most validated systems have been applied to measurements in controlled settings and/or for prescribed motions. The aim of this study was to characterize adolescent hip joint motion of elite-level athletes (soccer players) during practice and recreationally active peers (controls) in after-school activities using a magneto-inertial measurement unit (MIMU) system. Opal wireless sensors (APDM Inc., Portland OR, USA) were placed at the sacrum and laterally on each thigh (three sensors total). Hip joint motion was characterized by hip acceleration and hip orientation for one hour of activity on a sports field. Our methods and analysis techniques can be applied to other joints and activities. We also provide recommendations in order to guide future work using MIMUs to pervasively assess joint motions of clinical relevance.

Capital Femoral Epiphyseal Cupping and Extension May Be Protective in Slipped Capital Femoral Epiphysis: A Dual-center Matching Cohort Study

BACKGROUND

Peripheral cupping of the capital femoral epiphysis over the metaphysis has been reported as a precursor of cam morphology, but may also confer stability of the epiphysis protecting it from slipped capital femoral epiphysis (SCFE). The purpose of this study was to investigate the relationship between a novel morphologic parameter of inherent physeal stability, epiphyseal cupping, and the development of SCFE in a dual-center matched-control cohort study.

METHODS

We performed a dual-center age-matched and sex-matched cohort study comparing 279 subjects with unilateral SCFE and 279 radiographically normal controls from 2 tertiary children's hospitals. All SCFE patients had at least 18 months of radiographic follow-up for contralateral slip surveillance. Anteroposterior and frog lateral pelvis radiographs were utilized to measure the epiphyseal cupping ratio and the current standard measure of inherent physeal stability, the epiphyseal extension ratio.

RESULTS

Control hips were found to have greater epiphyseal cupping than the contralateral uninvolved hip of SCFE subjects both superiorly (0.28±0.08 vs. 0.24±0.06; P<0.001) and anteriorly (0.22±0.07 vs. 0.19±0.06; P<0.001). The 58/279 (21%) subjects who went on to develop contralateral slip had decreased epiphyseal cupping superiorly (0.25±0.07 vs. 0.23±0.05; P=0.03) and anteriorly (0.20±0.06 vs. 0.17±0.04; P<0.001). When we compared controls with hips that did not progress to contralateral slip and hips that further developed a contralateral SCFE, 1-way ANOVA demonstrated a stepwise decrease in epiphyseal cupping and epiphyseal extension ratio in the anterior and superior planes from control hips to contralateral hips without subsequent slip to contralateral hips that developed a SCFE (P<0.01 for each).

CONCLUSIONS

This study provides further evidence that epiphyseal cupping around the metaphysis is associated with decreased likelihood of SCFE and may reflect increased inherent physeal stability. Epiphyseal cupping may represent an adaptive mechanism to stabilize the epiphysis during adolescence at the long-term cost of the eventual development of associated cam-femoroacetabular impingement deformity.

LEVELS OF EVIDENCE

Level III-prognostic Study.

Corrections in alpha angle following two different operative approaches for CAM-type femoral acetabular impingement - Ganz surgical hip dislocation vs anterior mini-open

BACKGROUND

Femoroacetabular impingement (FAI) is a predisposing factor for secondary osteoarthritis of the hip joint. The two extensively described impingement mechanisms of FAI are CAM and Pincer-type. Initially managed conservatively, operative intervention should be offered to the persistently symptomatic patient. The measurement of the alpha angle is considered a standard method of assessing the severity of pathology in Cam-type FAI on pre-operative plain radiographs. The radiological correction of the alpha angle has not been previously compared between different surgical approaches. We hypothesize that there is no difference in alpha angle correction between Ganz surgical hip dislocation and the anterior mini-open approach.

AIM

To compare the magnitude of alpha angle correction achieved by using the Ganz surgical hip dislocation and the anterior mini-open approach.

METHODS

This is a retrospective study assessing seventy-nine patients identified in a 5-year period. These patients had preoperative radiographic evidence of FAI and underwent surgery by a single surgeon at our institution, a tertiary care center. Patients with missing radiographic documentation, radiographs with insufficient quality which then precluded accurate measurement of the angle α, a diagnosed congenital condition, isolated type II pathology (Pincer), and history of prior surgery were excluded from the study. Either the Ganz surgical hip dislocation or the anterior mini open approach was used. Postoperative radiographic evaluation of the alpha angle between the two surgical methods was done and corrected for age and gender using two-sample t-tests and Chi-square analyses.

RESULTS

A total of 79 patients met the inclusion and exclusion criteria. Forty-seven males (mean age of 35.3, range 16-53) and 32 females (mean age 36.7, range 16-60) were enrolled. Forty-seven patients underwent the anterior mini-open approach, and 32 underwent the Ganz surgical hip dislocation. There were no significant differences in age between the two surgical groups or in pre- and post-operative alpha angles based on patient gender. The mean pre-operative alpha angle for the Ganz surgical hip dislocation group was 88.0 degrees (SD 12.3) and 99.4 degrees (SD 7.2) for the anterior mini-open group. Mean post-operative angles were 49.9 degrees (SD 4.3) for the Ganz surgical hip dislocation and 43.8 (SD 4.3) degrees for the anterior mini-open group. There was a statistically significant difference in patient’s pre-operative and post-operative angles (P = 0.000) with both surgical approaches.

CONCLUSION

Statistically significant decreases in alpha angle were noted for both surgical techniques, with larger decreases seen in the anterior mini-open group.

Young elite Alpine and Mogul skiers have a higher prevalence of cam morphology than non-athletes

PURPOSE

To investigate the prevalence of cam morphology in (1) a group of young elite Mogul and Alpine skiers compared with non-athletes and (2) between the sexes.

METHOD

The hip joints of 87 subjects [n = 61 young elite skiers (29 females and 32 males) and n = 26 non-athletes (17 females and 9 males)] were examined using MRI, for measurements of the presence of cam morphology (α-angle ≥ 55).

RESULTS

The skiers had a significantly higher prevalence of cam morphology compared with the non-athletes (49% vs 19%, p = 0.009). A significant difference (p < 0.001) was also found between females and males, where 22% of the females and 61% of the males had cam morphology. Among the skiers, there was also a significant difference (p < 0.001) between the sexes, where 28% of the females and 68% of the males had cam morphology. This difference between the sexes was not found in the non-athletic group. No significant differences were found between Mogul and Alpine skiers.

CONCLUSION

Young male elite skiers have a higher prevalence of cam morphology of the hips compared with non-athletes.

LEVEL OF EVIDENCE

II.

Can preoperative imaging predict the outcomes after arthroscopic release for elbow arthritis?

INTRODUCTION

The primary symptoms of elbow osteoarthritis are the progressive development of stiffness along with pain at the end range of motion due to osteophyte impingement. Surgical treatment involves resecting these "bone stops". In the literature, these osteophytic lesions are more common than cartilage lesions, which suggests they may occur beforehand. The aim of our study was to confirm osteophytes are more common than cartilage lesions, and also to establish a link between these lesions and the functional outcomes.

METHODS

This was a prospective multicenter (8 hospitals) study conducted in the context of a symposium of the Francophone Arthroscopy Society (SFA). Eighty-seven patients with elbow osteoarthritis treated by arthroscopic release were included. The clinical outcomes (range of motion in flexion, extension and pronation-supination; strength; pain at rest and during activity; satisfaction; Andrews and Carson score; QuickDASH, Patient-Rated Elbow Evaluation (PREE), Mayo Elbow Performance Score (MEPS), Self-Evaluation Elbow (SEE) were determined before the procedure and at the 6-month follow-up visit. A standard radiographic assessment was done before the surgery and at the last follow-up visit. A CT arthrogram was done before the procedure. The presence of joint narrowing, osteophytes, filling of fossa along with secondary osteochondroma was evaluated in terms of their location, severity, size and/or number. The presence of radial head subluxation was recorded. The Bröberg & Morrey and Rettig & Hastings classification systems were applied. All the postoperative clinical data along with their change (difference between preoperative and postoperative values) were compared to the imaging findings.

RESULTS

Osteophytes were found in 95% of our patients. They were located at the olecranon in 85% of cases and at the coronoid process in 81%. Filled fossae found in 94% of cases. The olecranon, coronoid and radial fossa were filled in 83%, 80% and 60% of elbows, respectively. On the initial X-rays, joint narrowing was found in 68% of elbows. CT arthrogram identified narrowing in 70% of cases. Narrowing was present in the humeroradial joint in 60% of cases and in the humeroulnar joint in 23% of cases. The presence of joint narrowing on CT arthrogram was a negative prognostic factor for pain during activity (p<0.05) along with the Quick DASH (p<0.01) and PREE (p<0.05). Involvement of the humeroradial joint impacted pain at rest (p<0.01). Narrowing of the humeroulnar joint was associated with worse outcomes in terms of pain at rest (p<0.05) and during activity (p<0.05), QuickDASH (p<0.005), MEPS (p<0.05), PREE (p<0.05) and the SEE (p<0.05). The presence of loose bodies before the procedure was associated with better outcomes in terms of pain at rest (p<0.05), QuickDASH (p<0.001), MEPS (p<0.001), Andrews & Carson score (p<0.05) and PREE (p<0.005). The osteoarthritis stage in the Bröberg & Morrey or the Rettig & Hastings classification systems did not impact the various clinical parameters or functional outcome scores.

DISCUSSION/CONCLUSION

In the imaging work-up, signs of impingement (osteophytes and filling of fossa) are more common than signs of joint narrowing. The presence of humeroulnar and/or humeroradial impingement when there are no cartilage lesions visible may correspond to a pre-arthritic stage. The outcomes of arthroscopic release are better in elbows with isolated impingement than in those with cartilage lesions, especially at the humeroulnar joint. Excision of secondary osteochondromas is also an excellent surgical indication. Current classification systems cannot be used to determine the prognosis before arthroscopic release of elbow osteoarthritis cases.

LEVEL OF EVIDENCE

III, Prospective multicenter observational cohort study.

Assessment of Acetabular Morphology Using the Acetabular Anterior Center-Edge Angle on Modified False-Profile Radiographs

PURPOSE

To compare radiographic parameters of acetabular morphology between standard and modified false-profile (FP) radiographs.

METHODS

Standard and modified FP radiographs were obtained in 225 hips in 200 consecutive patients evaluated for hip pain and suspected femoroacetabular impingement. Radiographs were retrospectively reviewed by 2 readers to determine the anterior center-edge angle (ACEA), as assessed to the sourcil and to the bone edge. Inter-rater reliability of radiographic measurements was assessed using the intraclass correlation coefficient. Measurements were evaluated for normality with the Shapiro-Wilk test, averaged between the 2 readers, and compared between views using the paired Wilcoxon test.

RESULTS

The intraclass correlation coefficient values for standard and modified FP views were 0.923 and 0.932, respectively, measuring to the sourcil and 0.867 and 0.896, respectively, measuring to the lateral bone edge. The median difference in ACEA measurements to the sourcil was 1° between the standard and modified FP view (45° vs 44°, P < .001). The median difference in ACEA measurements to the bone edge was 2° (34° vs 32°, P < .001).

CONCLUSIONS

Thirty-five degrees of femoral internal rotation for a modified FP hip radiographic view provides similar clinical information regarding acetabular morphology to that of the standard FP view. Given that the modified FP view also provides better visualization of the anterosuperior head-neck junction cam lesion, the modified FP view may be preferred over the standard FP view in evaluation of hip pain in the young patient.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The clinical presentation, diagnosis and pathogenesis of symptomatic sports-related femoroacetabular impingement (SRFAI) in a consecutive series of 1021 athletic hips

AIM

To examine the pathogenesis and clinical presentation of sports-related femoroacetabular impingement (SRFAI) in a large consecutive series of symptomatic athletes.

METHODS

Between January 2009 and February 2017 prospectively collected data from competitive athletes within the Gaelic Athletic Association (GAA), and who subsequently underwent arthroscopic treatment for symptomatic FAI, were analysed. Data was collected using internationally validated health questionnaires (Harris Hip Score, UCLA, SF-36, WOMAC) and recognised clinical (ROM, symptom presentation, provocation tests) and radiological (AP pelvis, Dunn, False profile) indicators/measures of FAI.

RESULTS

A total of 1021 consecutive cases (mean 26.6 ± 6.2 years) were included. In every case, conservative treatment failed to resolve symptoms with athletes attending an average of 2.4 ± 1.1 health care professionals prior to referral. Symptoms developed gradually (78%) and consisted primarily of groin pain (76.1%) and hip stiffness (76.5%) following activity. An acetabular rim deformity (pincer) was present in all cases; a cam deformity in 72.1%. The prevalence and degree of cam deformity increased with progressing age groups (p < 0.001); mean lateral centre-edge angle remained static (p = 0.456). Increasing CEA, alpha angle and presence of rim fracture was associated with a reduction in all ranges of hip movement (p < 0.001).

CONCLUSION

Symptomatic SRFAI presented in this large series of GAA athletes failed to resolve with non-operative treatment. Increasing hip deformity resulted in poorer ROM. Abnormal acetabular morphology remains static with increasing athletic age while cam deformity is progressive and most likely a secondary pathology.

Etiology and Pathomechanics of Femoroacetabular Impingement

PURPOSE OF REVIEW

Femoroacetabular impingement is a common cause of hip pain in young patients and has been shown to progress to osteoarthritis. The purpose of this review is to better understand the development of femoroacetabular impingement.

RECENT FINDINGS

Recent literature shows little genetic transmission of FAI. However, molecular studies show strong similarities with the cartilage in osteoarthritis. The development of cam lesions has a strong association with sports participation, particularly at the time of physeal closure suggesting abnormal development. Lumbar, pelvis, and femoral biomechanics may also play an important role in dynamic impingement. In summary, femoroacetabular impingement is a dynamic process with many influences. Further research is needed to clarify the pathophysiology of FAI development in hopes of finding preventative options to reduce symptoms and progression to osteoarthritis.

Biomechanical Evaluation of the Depth of Resection During Femoral Neck Osteoplasty for Anterior Impingement Following Slipped Capital Femoral Epiphysis

BACKGROUND

Femoroacetabular impingement as a result of slipped capital femoral epiphysis (SCFE) has been treated traditionally with a proximal femoral osteotomy, but open and arthroscopic femoral osteoplasty is becoming increasingly popular. Cam lesions result from excess bone primarily at the anterolateral femoral head-neck junction. SCFEs result from posterior and inferior slippage of the femoral epiphysis, causing the metaphysis to move anteriorly. This study's purpose was to compare fourth-generation sawbones standard femurs with SCFE femurs to determine whether bone resection from the anterior metaphysis results in similar biomechanical properties.

METHODS

A custom fourth-generation composite SCFE sawbone was created with a 30-degree slip angle. Control group consisted of fourth-generation composite standard nondeformed medium femurs. The femoral neck at the head-neck junction was divided into 4 quadrants. All resections were done in the anterolateral quadrant. Twenty SCFE sawbones and 20 standard sawbones were divided into 4 subgroups based on resection depths of 0%, 10%, 30%, and 50% of the metaphysis at the head-neck junction. After resection, all proximal femurs were loaded to failure in an Instron testing machine to determine the ultimate load to failure, stiffness, and energy to failure.

RESULTS

The standard femurs were significantly stronger than the SCFE femurs (P<0.001) and the strength of the femurs decreased significantly as the resection amount increased (P<0.001). Similarly, the standard femurs withstood significantly more energy before failing than the SCFE femurs (P<0.001) and the energy to failure decreased significantly with varying resection amounts (P<0.001).

CONCLUSIONS

SCFE femurs demonstrate a significant reduction in strength and energy to failure after osteoplasty compared with nondeformed femurs in a sawbone model. Strength and energy to failure are inversely proportional to the depth of bone resection.

CLINICAL RELEVANCE

Aggressive femoral neck osteoplasty for treatment of a SCFE deformity may lead to increased risk of fracture. Further studies are necessary to determine the safe depth of resection in a clinical setting.

Relative contribution of epiphyseal tubercle and peripheral cupping to capital femoral epiphysis stability during daily activities

Epiphyseal tubercle and peripheral cupping can influence the development of slipped capital femoral epiphysis (SCFE) and Cam morphology. During normal skeletal growth, epiphyseal tubercle shrinks while the peripheral cupping grows. We hypothesized that epiphyseal tubercle act as the primary stabilizer of the head-neck junction at early stages and this role is gradually transferred to epiphyseal cupping as the tubercle shrinks and cupping grows. From a cohort of 80 boys and girls (8-15 years old) with normal hips, CT scans of 5 subjects corresponding to minimum, 25th percentile, median, 75th percentile and maximum relative tubercle and cupping height were used to develop 3D finite element models. In vivo measured hip loads were used to study load sharing between the tubercle and peripheral cupping under combined and uniaxial loads exerted on femoral head during a range of daily activities. Lower epiphyseal tubercle height, larger epiphyseal cupping height and bigger differences in tubercle and cupping heights were strongly associated with increased epiphyseal cupping to epiphyseal tubercle stress ratios (R²  > 0.7). We found lower peripheral cupping stresses relative to the tubercle (cupping to tubercle stress ratio <1) in hips with larger tubercle and smaller cupping. The relative decreases in tubercle size along with increased in peripheral cupping in our models gradually shifted the load distribution to higher stresses in the periphery compared to the epiphyseal tubercle area (cupping to tubercle stress ratio >1). Both tubercle and cupping play a substantial role in sharing the generated stresses across the head-neck junction under all tested loading conditions. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1571-1579, 2019.

The Natural History of Femoroacetabular Impingement

BACKGROUND

Structural hip abnormalities have long been suspected of causing hip osteoarthritis. The concept of deformity of the proximal femur as a cause of osteoarthritis (OA) started with description of the tilt deformity and progressed to the pistol grip, then eventually cam-type femoroacetabular impingement (FAI). Acetabular over-coverage or retroversion as a cause of impingement is commonly referred to as pincer-type FAI. The primary research question we asked was: what is the natural history of hips with FAI?

METHODS

We reviewed the literature to identify studies with cross-sectional and longitudinal evidence of the effect of FAI on the development of or association with hip OA.

RESULTS

In cross-sectional and longitudinal natural history studies of hip OA, cam-type FAI has consistently shown an association with developing OA. In regard to pincer-type FAI, the data are less convincing with some studies suggesting an increased risk and others showing a protective effect of the acetabular over-coverage. It is clear that not all patients with cam FAI get OA but the altered anatomy does increase the relative risk of developing OA.

CONCLUSIONS

Cam-type FAI is associated with the development of hip OA; however, there is no role for prophylactic surgery in the asymptomatic hip with the anatomy predisposing to FAI. Further interventional studies are needed to determine whether surgical correction of cam-type FAI in the symptomatic hip alters the natural history of the condition.

Capital Femoral Epiphyseal Extension May Confer Physeal Stability in Slipped Capital Femoral Epiphysis

BACKGROUND

Factors including obesity and morphologic parameters around the hip that increase physeal stress are associated with an increased risk of slipped capital femoral epiphysis (SCFE). Recent evidence suggests that superior epiphyseal extension may confer stability to the physis and help protect against SCFE. The purpose of this study is to investigate the relationship between epiphyseal extension and SCFE using an age-matched and sex-matched cohort study.

METHODS

We generated 2 separate cohorts for comparison: 89 patients with unilateral SCFE and 89 healthy subjects with no evidence of hip disease or deformity. We utilized the anterior-posterior and lateral films of the hip to measure the Southwick angle and the epiphyseal extension ratio (EER), defined as the ratio of extension of the capital femoral epiphysis down the femoral neck relative to the diameter of the femoral head. We then compared these measurements between cohorts and in subgroup analysis based on slip stability and whether subjects progressed to a contralateral slip.

RESULTS

The SCFE cohort demonstrated a decreased superior epiphyseal extension ratio compared with control (superior EER 0.71 vs. 0.68, P=0.002). There was also a significant downward trend in superior EER from the control subjects (0.71±0.07) to the stable slips (0.69±0.06) to the unstable slips (0.65±0.04) with an overall difference between the groups (P=0.001). Eighteen of 44 (41%) subjects with unilateral stable slips and at least 6 months of follow-up went on to develop SCFE of the contralateral limb. The subjects who developed contralateral slips were younger (11.6±1.2 vs. 12.7±1.4 y, P=0.008); however, there was no difference in superior or anterior epiphyseal extension (P=0.75 and 0.23, respectively). There was no significant linear correlation between Southwick angle and superior or anterior EER (r=0.13 and 0.17, respectively, P>0.05 for both).

CONCLUSIONS

Increasing capital femoral epiphyseal extension may confer physeal stability in the setting of SCFE. We propose that this epiphyseal extension reflects an adaptive response to limit physeal stress and reduce the risk for progression to SCFE.

LEVEL OF EVIDENCE

Level III-prognostic study.

3D-MRI versus 3D-CT in the evaluation of osseous anatomy in femoroacetabular impingement using Dixon 3D FLASH sequence

OBJECTIVE

To determine if hip 3D-MR imaging can be used to accurately demonstrate femoral and acetabular morphology in the evaluation of patients with femoroacetabular impingement.

MATERIALS AND METHODS

We performed a retrospective review at our institution of 17 consecutive patients (19 hips) with suspected femoroacetabular impingement who had both 3D-CT and 3D-MRI performed of the same hip. Two fellowship-trained musculoskeletal radiologists reviewed the imaging for the presence and location of cam deformity, anterior-inferior iliac spine variant, lateral center-edge angle, and neck-shaft angle. Findings on 3D-CT were considered the reference standard. The amount of radiation that was spared following introduction of 3D-MRI was also assessed.

RESULTS

All 17 patients suspected of FAI had evidence for cam deformity on 3D-CT. There was 100% agreement for diagnosis (19 out of 19) and location (19 out of 19) of cam deformity when comparing 3D-MRI with 3D-CT. There were 3 type I and 16 type II anterior-inferior iliac spine variants on 3D-CT imaging with 89.5% (17 out of 19) agreement for the anterior-inferior iliac spine characterization between 3D-MRI and 3D-CT. There was 64.7% agreement when comparing the neck-shaft angle (11 out of 17) and LCEA (11 out of 17) measurements. The use of 3D-MRI spared each patient an average radiation effective dose of 3.09 mSV for a total reduction of 479 mSV over a 4-year period.

CONCLUSION

3D-MR imaging can be used to accurately diagnose and quantify the typical osseous pathological condition in femoroacetabular impingement and has the potential to eliminate the need for 3D-CT imaging and its associated radiation exposure, and the cost for this predominantly young group of patients.

Predicting Risk of Contralateral Slip in Unilateral Slipped Capital Femoral Epiphysis: Posterior Epiphyseal Tilt Increases and Superior Epiphyseal Extension Reduces Risk

BACKGROUND

Femoral morphology may influence the etiology of slipped capital femoral epiphysis (SCFE). We investigated whether radiographic parameters of femoral head-neck morphology are associated with a subsequent contralateral slip in patients presenting with unilateral SCFE.

METHODS

We evaluated 318 patients treated for unilateral SCFE between 2000 and 2017. There were 145 males (46%), and the mean age in the series was 12.4 ± 1.7 years. The patients were followed for a minimum of 18 months or until the development of a contralateral slip (70 patients, 22%). We measured the epiphyseal tilt, epiphyseal extension ratio, alpha angle, and epiphyseal angle of the uninvolved, contralateral hip at initial presentation. Multivariable logistic regression analysis was used to assess whether femoral measurements were associated with the occurrence of a contralateral slip. Receiver operating characteristic (ROC) curves were used to determine optimal thresholds of radiographic measures to determine an increased risk of a contralateral slip. A number-needed-to-treat (NNT) analysis was conducted to evaluate the effectiveness of the femoral measurement thresholds in preventing a contralateral slip.

RESULTS

Multivariable analysis, controlling for triradiate cartilage status, identified the lateral tilt angle and the superior epiphyseal extension ratio as independent factors associated with the likelihood of a contralateral slip. For each additional degree of posterior tilt, the odds of a contralateral slip increase by 8% (odds ratio [OR] = 1.08; 95% confidence interval [CI] = 1.02 to 1.14; p = 0.008), and for each 0.01 increase in the superior epiphyseal extension ratio, the odds of a contralateral slip decrease by 6% (OR = 0.94; 95% CI = 0.88 to 0.99; p = 0.03). A threshold for the epiphyseal tilt of 10° corresponded to a predicted probability of a contralateral slip of 54% in patients with open triradiate cartilage and an NNT of 3.3.

CONCLUSIONS

In patients presenting with unilateral SCFE, a higher posterior tilt of the epiphysis increases the risk while an increased superior extension of the epiphysis reduces the risk of a contralateral slip. Our findings may assist the discussion about contralateral prophylactic pinning in patients with unilateral SCFE.

LEVEL OF EVIDENCE

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

Adolescent elite skiers with and without cam morphology did change their hip joint range of motion with 2 years follow-up

PURPOSE

To investigate how range of motion of the hips and the lumbar spine are affected by continued elite, alpine skiing in young subjects, with and without a magnetic resonance imaging verified cam morphology, in a 2-year follow-up study. The hypothesis is that skiers with cam morphology will show a decrease in hip joint range of motion as compared with skiers without cam, after a 2-year follow-up.

METHOD

Thirty adolescent elite alpine skiers were examined at the baseline (mean age 17.3 ± 0.7 years) and after 2 years. All skiers were examined for the presence of cam morphology (α-angle > 55°) using magnetic resonance imaging at the baseline. Clinical examinations of range of motion in standing lumbar flexion and extension, supine hip flexion, internal rotation, FABER test and sitting internal rotation and external rotation were performed both at the baseline and after 2 years.

RESULTS

Skiers with and without cam morphology showed a significant decrease from baseline to follow-up in both hips for supine internal rotation (right: mean - 13.3° and - 10.9° [P < 0.001]; left: mean - 7.6° [P = 0.004] and - 7.9° [P = 0.02]), sitting internal rotation (right: mean - 9.6° and - 6.3° [P < 0.001]; left: mean - 7.6° [P = 0.02] and - 3.3° [P = 0.008]) and sitting external rotation (right: mean - 16.9° and - 11.4° and left: mean - 17.9° and - 14.5° [P < 0.001]) and were shown to have an increased left hip flexion (mean + 8.4° and + 4.6° [P = 0.004]). Skiers with cam were also shown to have an increased right hip flexion (mean + 6.4° [P = 0.037]). Differences were found between cam and no-cam skiers from baseline to follow-up in the sitting internal rotation in both hips (right: mean 3.25°, left: mean 4.27° [P < 0.001]), the right hip flexion (mean 6.02° [P = 0.045]) and lumbar flexion (mean - 1.21°, [P = 0.009]).

CONCLUSION

Young, elite alpine skiers with cam morphology decreased their internal rotation in sitting position as compared with skiers without the cam morphology after 2 years of continued elite skiing.

LEVEL OF EVIDENCE

II.

Novel model for the induction of postnatal murine hip deformity

Acetabular dysplasia is a common, multi-etiological, pre-osteoarthritic (OA) feature that can lead to pain and instability of the young adult hip. Despite the clinical significance of acetabular dysplasia, there is a paucity of small animal models to investigate structural and functional changes that mediate morphology of the dysplastic hip and drive the subsequent OA cascade. Utilizing a novel murine model developed in our laboratory, this study investigated the role of surgically induced unilateral instability of the postnatal hip on the initiation and progression of acetabular dysplasia and impingement up to 8-weeks post-injury. C57BL6 mice were used to develop titrated levels of hip instability (i.e., mild, moderate, and severe instabillity or femoral head resection) at weaning. Joint shape, acetabular coverage, histomorphology, and statistical shape modeling were used to assess quality of the hip following 8 weeks of destabilization. Acetabular coverage was reduced following severe, but not moderate, instability. Moderate instability induced lateralization of the femur without dislocation, whereas severe instability led to complete dislocation and pseudoacetabulae formation. Mild instability did not result in morphological changes to the hip. Removal of the femoral head led to reduced hip joint space volume. These data support the notion that hip instability, driven by mechanical loss-of-function of soft connective tissue, can induce morphometric changes in the growing mouse hip. This work developed a new mouse model to study hip health in the murine adolescent hip and is a useful tool for investigating the mechanical and structural adaptations to hip instability during growth. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

3D CT segmentation of CAM type femoroacetabular impingement-reliability and relationship of CAM lesion with anthropomorphic features

OBJECTIVE:

Evaluate feasibility and reliability of 3DCT semi-automatic segmentation and volumetrics of CAM lesions in femoroacetabular impingement and determine correlations with anthropometrics.

METHODS:

A consecutive series of 43 patients with CAM type FAI underwent 3DCT. 20 males and 23 females (30 unilateral and 13 bilateral symptomatic hips) were included. 56 CAM lesions and femoral heads were segmented by two readers. Radial images were obtained for alpha angles. Pearson and ICC correlations were used for analysis.

RESULTS:

In 43 patients (male: female = 1 : 1.15), mean ± SD of age, height, BMI were 36.6 ± 11.47 years, 1.72 ± 0.10 meters and 26.25 ± 4.31  kg m^-². Femoral head and bumps were segmented in 4  min. Inter reader reliability was good to excellent for volumetrics and poor for alpha angles. Mean ± SD of CAM lesion and femoral head volumes were significantly larger (6.7 ± 2.5 cc³ and 62.9 ± 10.8 cc³) for males than females (p < 0.001) and these increased with increasing patient height (Pearson correlation and p-values = 0.45, 0.0006; 0.82, < 0.0001 respectively).

CONCLUSION:

Volumetric analysis of CAM lesion shows better inter reader reliability than alpha angle measurements. CAM and femoral head volumes exhibit significant positive correlations with patient heights and male gender that may aid in pre-operative planning for femoroplasty.

ADVANCES IN KNOWLEDGE:

Femoral head & CAM volumes are segmented three times faster than alpha angles with superior inter reader reliability than alpha angles. Femoral head & CAM volumes are significantly larger in males and positively correlate with patients' heights.

Asymptomatic Participants With a Femoroacetabular Deformity Demonstrate Stronger Hip Extensors and Greater Pelvis Mobility During the Deep Squat Task

Background:

Cam-type femoroacetabular impingement (FAI) is a femoral head-neck deformity that causes abnormal contact between the femoral head and acetabular rim, leading to pain. However, some individuals with the deformity do not experience pain and are referred to as having a femoroacetabular deformity (FAD). To date, only a few studies have examined muscle activity in patients with FAI, which were limited to gait, isometric and isokinetic hip flexion, and extension tasks.

Purpose:

To compare (1) hip muscle strength during isometric contraction and (2) lower limb kinematics and muscle activity of patients with FAI and FAD participants with body mass index–matched healthy controls during a deep squat task.

Study Design:

Controlled laboratory study.

Methods:

Three groups of participants were recruited: 16 patients with FAI (14 male, 2 female; mean age, 38.5 ± 8.0 years), 18 participants with FAD (15 male, 3 female; mean age, 32.5 ± 7.1 years), and 18 control participants (16 male, 2 female; mean age, 32.8 ± 7.0 years). Participants were outfitted with electromyography electrodes on 6 muscles and reflective markers for motion capture. The participants completed maximal strength tests and performed 5 deep squat trials. Muscle activity and biomechanical variables were extrapolated and compared between the 3 groups using 1-way analysis of variance.

Results:

The FAD group was significantly stronger than the FAI and control groups during hip extension, and the FAD group had greater sagittal pelvic range of motion and could squat to a greater depth than the FAI group. The FAI group activated their hip extensors to a greater extent and for a longer period of time compared with the FAD group to achieve the squat task.

Conclusion:

The stronger hip extensors of the FAD group are associated with greater pelvic range of motion, allowing for greater posterior pelvic tilt, possibly reducing the risk of impingement while performing the squat, and resulting in a greater squat depth compared with those with symptomatic FAI.

Clinical Relevance:

The increased strength of the hip extensors in the FAD group allowed these participants to achieve greater pelvic mobility and a greater squat depth by preventing the painful impingement position. Improving hip extensor strength and pelvic mobility may affect symptoms for patients with FAI.

Age- and Sex-Specific Morphologic Variations of Capital Femoral Epiphysis Growth in Children and Adolescents Without Hip Disorders

Background:

Understanding the development of the capital femoral epiphysis is essential to identify pathologic variations that may lead to cam morphology.

Purpose/Hypothesis:

The purpose of this study was to investigate the development of the capital femoral epiphysis during childhood and adolescence, with specific morphologic analysis of the peripheral growth and the metaphyseal surface of the growth plate. We hypothesized that age- and sex-dependent morphologic variations of the peripheral growth (cupping) and surface anatomy (epiphyseal tubercle) of the epiphysis would be evident with increasing age.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Pelvic computed tomography scans of 80 children and adolescents (range, 8-15 years; n = 10 per age group; 50% male), imaged because of suspected appendicitis, were used to reformat the proximal femur. All patients had asymptomatic hips with no signs or history of hip disorder. We measured the peripheral cupping of the epiphysis and the epiphyseal tubercle dimensions from 3-dimensional models. All measurements were normalized to the epiphyseal diameter. The effect of age on these parameters was evaluated by use of linear regression analysis. A 2-way analysis of variance (ANOVA) was used to compare these parameters between males and females.

Results:

The mean epiphyseal cupping increased with increasing age (R² = 0.54; P < .001). The mean normalized epiphyseal cupping was consistently higher in the anterior and posterior directions compared with the inferior and superior locations. Male patients aged 10 and 11 years had lower (P = .002) mean epiphyseal cupping compared with female patients of the same age. We observed no difference between male and female participants after 12 years of age (P > .3). The normalized epiphyseal tubercle height (R² = 0.08; P = .009), width (R² = 0.13; P = .001), and length (R² = 0.45; P < .001) decreased with increasing age, with no differences between male and female patients. On average, a 2.6-fold increase was found in epiphyseal cupping from 8 to 15 years of age, whereas normalized tubercle height decreased by 0.4-fold.

Conclusion:

Peripheral cupping of the epiphysis over the metaphysis increases with age, while the relative epiphyseal tubercle dimensions decrease. Females have an earlier onset of rapid increase in the peripheral cupping compared with males; however, no differences in epiphyseal tubercle dimensions were found between male and female patients. These findings may guide future studies investigating the development of cam morphology, which should consider the surface morphologic characteristics of the capital femoral epiphysis, the growth plate, and the differences in morphologic characteristics according to age and sex.