Incidence of hip pain in a prospective cohort of asymptomatic volunteers: is the cam deformity a risk factor for hip pain?

Femoroacetabular Impingement: Critical Analysis Review of Current Nonoperative Treatments

» Femoroacetabular impingement (FAI) is the premature contact of the femoral head-neck junction with the superior acetabular rim during hip range of motion, which may further damage intra-articular soft tissue structures and lead to the accelerated development of osteoarthritis.» FAI syndrome is diagnosed by a triad of symptoms, clinical signs, and imaging findings, and is a common cause of hip pain in young patients that have a significant impact on patient hip-related function and quality of life.» The treatment of FAI syndrome begins with noninvasive nonoperative modalities such as patient education and supervised exercise-based physical therapy. For recalcitrant symptoms, various injections have been explored for both diagnostic and therapeutic purposes; however, the efficacy of these interventions have generally not been demonstrated outside of the short term» In this article, we examine the available literature regarding the nonoperative treatment of FAI and provide insight into the effectiveness of current treatment modalities.

Asymptomatic female softball pitchers have altered hip morphology and cartilage composition

Few studies have explored hip morphology and cartilage composition in female athletes or the impact of asymmetric repetitive loading, such as occurs during softball pitching. The current cross-sectional study assessed bilateral bony hip morphology on computed tomography imaging in collegiate-level softball pitchers ('Pitch1', n = 25) and cross-country runners ('Run', n = 13). Magnetic resonance imaging was used to assess cartilage relaxation times in a second cohort of pitchers ('Pitch2', n = 10) and non-athletic controls ('Con', n = 4). Pitch1 had 52% greater maximum alpha angle than Run (p < 0.001) and were 21.3 (95% CI 2.4 to 192.0) times more likely to have an alpha angle ≥ 60° within at least one hip. Pitch2 had longer T2 relaxation times in the superior femoral cartilage of the drive leg (same side as the throwing arm) and stride leg than Con (all p < 0.02). The drive leg in Pitch2 had longer T1ρ and T2 relaxation times in the superior femoral cartilage compared to the stride leg (all p ≤ 0.03). Asymptomatic softball pitchers exhibit altered bony hip morphology and cartilage composition compared to cross-country runners and non-athletic controls, respectively. They also exhibit asymmetry in cartilage composition. Further studies with larger sample sizes are warranted and any potential long-term consequences of the changes in terms of symptom and osteoarthritis development requires investigation.

Short-term prediction of clinical and radiographic contralateral hip osteoarthritis after index total hip arthroplasty

INTRODUCTION

Patients with primary hip osteoarthritis undergoing unilateral total hip arthroplasty (THA) often face uncertainty about the future need for arthroplasty in the contralateral hip. We aimed to identify parameters that have predictive value with regard to the necessity for contralateral THA or the development of contralateral radiographic osteoarthritis (OA) phenotypes following index surgery.

MATERIALS AND METHODS

In this retrospective study, we analyzed 220 patients undergoing THA. Of these, 24.1% required contralateral THA at a mean follow-up of 18.3months. Our assessments included preoperative and follow-up pelvis radiographs as well as bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry prior to index THA. Comprehensive radiological measurements such as the Kellgren-Lawrence OA grade, osteophyte evaluation as well as joint shape and alignment (including alpha and CE angles) were performed.

RESULTS

We identified three indicators at the initial assessment for predicting the need for contralateral THA: higher BMI (odds ratio (OR) 1.1 [95%-CI 1.0-1.2], p = 0.033), higher alpha angles (> 61.5°) (OR 2.5 [95%-CI 1.0-6.3], p = 0.045) and the presence of multiple osteophytes (OR 2.6 [95%-CI 1.4-4.9], p = 0.004). Moreover, higher alpha angles were linked to more severe radiographic OA, especially osteophytosis. Higher BMD T-scores were also associated with progressive formation of multiple and large osteophytes but not joint space narrowing.

CONCLUSION

Three factors - BMI, alpha angle, and osteophyte number - are key short-term predictors for contralateral THA after index THA. We also identified BMD as a surrogate for osteophyte formation. These findings provide novel and valuable insights for patients and surgeons regarding risks and counseling for contralateral OA and THA.

The association between cam morphology and hip pain in males and females within 10 years: A national prospective cohort study (CHECK)

OBJECTIVES

To determine the association between baseline cam morphology and self-reported hip pain assessed at annual visits over a 10-year follow-up period stratified by biological sex. The secondary aim was to study the association between the magnitude of cam morphology and the severity of pain in symptomatic hips.

METHODS

The nationwide prospective Cohort Hip and Cohort Knee (CHECK) study includes 1,002 participants aged 45-65 years. Logistic regression with generalized estimating equations were used to determine the strength of the associations between (1) baseline cam morphology (both alpha angle ≥60° and as a continuous measure) and the presence of hip pain at 10 annual follow-up visits and (2) the alpha angle (continuous) and the severity of pain as classified by Numerical Rating Scale at 5-,8-, 9-, and 10-years. The results are expressed as odds ratios (OR), adjusted for age, biological sex (only in the sex-combined group), body mass index, and follow-up Kellgren and Lawrence grade.

RESULTS

In total, 1,658 hips were included at baseline (1,335 female hips (79.2%)). The prevalence of cam morphology was 11.1% among all hips (29.1% in males; 6.4% in females). No association was found between cam morphology at baseline and the presence of hip pain at any follow-up in the female or sex-combined group. In males, only at 5-year follow-up, significant adjusted ORs were observed for the presence of cam morphology (1.77 (95%CI: 1.01-3.09)) and the alpha angle (1.02 (95%CI:1.00-1.04)). No evidence of associations was found between the alpha angle and the severity of hip pain in any of three groups.

CONCLUSION

Within this study, no consistent associations were found between cam morphology and hip pain at multiple follow-ups. There might be a weak relationship between cam morphology and hip pain in males, while no such relation was found in females. We did not identify an association between the alpha angle and severity of hip pain.

Association between Hip/Groin Pain and Hip ROM and Strength in Elite Female Soccer Players

Background/Objectives: Hip strength and range of motion have been compared in soccer players with and without hip and groin pain but only in male footballers or gender-combined samples. In female soccer players, the biomechanics contributing to this injury remain poorly understood compared to other sporting injuries. The aim of the present study is to investigate whether differences exist in adductor and abductor isometric test values and hip joint range of motion between elite female soccer players with longstanding groin pain and injury-free controls. Methods: Ten female elite soccer players with current longstanding hip and groin pain and twenty-five injury-free controls from the same teams were included in the study. Hip adductor and abductor isometric strength were evaluated with a hand-held dynamometer. A bent knee fall-out test was also utilized to examine the hip joint range of motion. Results: A significant difference in abductor isometric test values was observed between the control group (2.29 ± 0.53 N/Kg) and the hip and groin pain group (2.77 ± 0.48 N/Kg; p = 0.018). Furthermore, the injured group showed a decreased adductor/abductor ratio compared to the control group (1.00 ± 0.33 vs. 1.27 ± 0.26; p = 0.013). No differences were observed in the bent knee fall-out test (p = 0.285). Conclusions: Female elite soccer players with current longstanding hip and groin pain exhibited higher abductor isometric strength and lower adductor/abductor ratio compared to non-injured women players. There were no differences in the BKFO test between groups.

Femoroacetabular Impingement and Groin Injuries Among Soccer Players

Groin injuries and femoroacetabular impingement are common among soccer players and can provide a challenge in diagnosis, as well as treatment. Nonoperative and operative measures are the 2 predominant treatments. This current review investigates the recent literature on groin and femoroacetabular impingement injuries in soccer players, as well as potential treatment modalities.

Are hip joint imaging findings associated with symptoms and early hip osteoarthritis features in elite male Australian Football League draftees?

1) describe intra-articular features (prevalence and severity) and bony hip morphology (prevalence and size) in elite male Australia Football League (AFL) draftees; 2) examine the relationship between bony hip morphology (cam and pincer morphology) and intra-articular features (cartilage defects and labral tears); and 3) examine the relationship between intra-articular features, bony hip morphology, and the Copenhagen Hip and Groin Outcome Score (HAGOS). Cross-sectional study. 58 male AFL draftees underwent 3-tesla hip MRI. Alpha angle determined cam morphology and acetabular depth defined pincer morphology. For each hip, intra-articular features were scored semi-quantitatively. All players completed the HAGOS to determine hip/groin symptoms and sports function. Logistic regression determined whether bony hip morphology was associated with labral tears and cartilage defects. Mann-Whitney U tests evaluated the difference in HAGOS subscale scores between football players with and without intra-articular features and bony hip morphology. Cam and pincer morphology were evident in 20% and 19% of hips, respectively. Nearly half of hips (41%) had a labral tear, with only 14% having a cartilage defect. Greater alpha angle was associated with the presence of labral tears (OR 1.14, 95%CI 1.07 to 1.21, p < 0.001) but not cartilage defects. Hip imaging findings were not associated with lower (worse) HAGOS scores. Hip joint imaging findings were common in elite male AFL draftees but not associated with worse pain, symptoms, or sport function. Cam morphology may contribute to the development of labral tears in male AFL draftees.

A New Clinical Examination Algorithm to Prescribe Conservative Treatment in People with Hip-Related Pain

Hip-related pain is a common issue in active adults affecting their quality of life, mobility, and overall function, and it can lead to persistent disability. However, diagnosing hip-related pain is challenging due to the many potential sources and causes, including intra-articular and extra-articular pathology, and referred pain from other areas (lumbar or groin related pain). To address this, there is a need for a clinical algorithm based on the best available evidence and expert consensus. This algorithm could guide healthcare professionals in assessing and managing patients with hip-related pain, during the diagnosis, test selection, intervention, monitoring, and promoting collaboration among various healthcare providers. This clinical algorithm for hip-related pain is a comprehensive, flexible, adaptable to different settings, and regularly updated to incorporate new research findings. This literature review aims to establish a clinical algorithm specifically for prescribing exercise treatment to patients with hip-related pain, addressing their individual needs and enhancing their overall care.

Increased Alpha Angles and Younger Age Increase the Risk of Contralateral Femoral Acetabular Impingement Syndrome Symptom Development and Surgical Intervention: A Systematic Review

PURPOSE

To identify the preoperative risk factors associated with contralateral symptom development and surgical intervention for patients presenting with unilateral femoral acetabular impingement (FAI) syndrome.

METHODS

A literature search was performed using PubMed and Scopus computerized databases according to the 2020 Preferred Reporting Items for Systematic Meta-Analyses guidelines. Studies evaluating preoperative risk factors associated with the contralateral progression of FAI were included. Quality assessment was completed using the Methodological Index for Non-Randomized Studies criteria.

RESULTS

A total of 5 studies (n = 1,011 patients; mean age, 29.9 years) published from 2013 to 2022 met the inclusion/exclusion criteria. Mean follow-up ranged from 12 to 132 months. The overall rate of contralateral progression of symptomatic FAI ranged from 32.4% to 81%. Increased alpha angle was frequently reported factor associated with contralateral symptom progression, followed by decreased total arc of rotation, decreased internal rotation, reduced neck-shaft angle, and head-neck offset. The incidence rate of progression to contralateral surgery ranged from 15.7% to 24% of patients. Younger age was frequently reported factor associated with contralateral surgical intervention, followed by male sex, increased level of activity, and increased alpha angle.

CONCLUSIONS

Increased alpha angle and younger age were commonly reported risk factors associated with an increased risk of symptom development and surgical progression of contralateral FAI, respectively. The overall rate of contralateral progression of symptomatic FAI and the rate of progression to surgical intervention ranged up to 81% and 24%, respectively. This information may help both patients and surgeons to establish expectations regarding development of contralateral hip symptoms and possible need for surgery.

LEVEL OF EVIDENCE

Level III; systematic review of Level II-III studies.

Does femoroacetabular impingement syndrome affect range of motion? A systematic review with meta-analysis

BACKGROUND

It is unclear whether femoroacetabular impingement syndrome (FAIS) affect hip range of motion (ROM).

SOURCES OF DATA

We performed a systematic review with meta-analysis searching six electronic databases from inception to March 21, 2022. We included studies assessing hip ROM in FAIS, FAI morphology without symptoms (FAIm), and healthy controls. Mean differences between groups were measured in ROM degrees with 95% confidence interval (CI).

AREAS OF AGREEMENT

A total of 17 studies (1702 hips) were included. Comparison of FAIS patients versus healthy controls showed that hip ROM was clinically and statistically reduced in FAIS for internal rotation (90° hip flexion, -8.01°, 95% CI: -11.21, -4.90; 0° hip flexion -6.38°, 95% CI: -9.79, -2.97); adduction (90° hip flexion, -4.74°, 95% CI: -8.13, -1.34); flexion (-5.41°, 95% CI: -7.05, -3.49), abduction (0° hip flexion, -5.76°, 95% CI: -8.38, -3.23), and external rotation (90° hip flexion, -3.5°, 95% CI: -5.32, -1.67) ranging from low to high certainty of evidence. Comparison of FAIm versus healthy controls showed no statistically significant differences in any direction of movement, albeit with uncertainty of evidence.

AREAS OF CONTROVERSY

The certainty of evidence was unclear, particularly for asymptomatic FAIm.

GROWING POINTS

Hip ROM may be reduced in all directions except extension in FAIS compared to controls. Hip ROM may not be restricted in asymptomatic FAIm.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further studies are needed to resolve the uncertainty of evidence about ROM restrictions in asymptomatic FAIm compared to healthy controls.

Hip Labral Morphological Changes in Patients with Femoroacetabular Impingement Speed Up the Onset of Early Osteoarthritis

Over the last decade, evidence has mounted for a prominent etiologic role of femoroacetabular impingement (FAI) in the development of early hip osteoarthritis (OA). The aim of this study was to compare the ultrastructure and tissue composition of the hip labrum in healthy and pathological conditions, as FAI and OA, to provide understanding of structural changes which might be helpful in the future to design targeted therapies and improve treatment indications. We analyzed labral tissue samples from five healthy multi-organ donors (MCDs) (median age, 38 years), five FAI patients (median age, 37 years) and five late-stage OA patients undergoing total hip replacement (median age, 56 years). We evaluated morpho-functional by histology and transmission electron microscopy. Extracellular matrix (ECM) structure changes were similar in specimens from FAI compared to those from patients with OA (more severe in the latter) showing disorganization of collagen fibers and increased proteoglycan content. In FAI and in OA nuclei the chromatin was condensed, organelle degenerated and cytoplasm vacuolized. Areas of calcification were mainly observed in FAI and OA labrum, as well as apoptotic-like features. We showed that labral tissue of patients with FAI had similar pathological alterations of tissue obtained from OA patients, suggesting that FAI patients might have high susceptibility to develop OA.

Is Internal Rotation Measurement of the Hip Useful for Ruling in Cam or Pincer Morphology in Asymptomatic Males? A Diagnostic Accuracy Study

BACKGROUND

Cam and pincer morphologies are associated with limited internal rotation. However, the routine clinical examination for hip rotation has limited reliability. A more standardized method of measuring hip rotation might increase test-retest and interobserver reliability and might be useful as a screening test to detect different hip morphologies without the need for imaging. We developed an examination chair to standardize the measurement of internal hip rotation, which improved interobserver reliability. However, the diagnostic test accuracy for this test is unknown.

QUESTION/PURPOSE

Is a standardized method of determining internal hip rotation using an examination chair useful in detecting cam and pincer morphology with MRI as a reference standard?

METHODS

A diagnostic test accuracy study was conducted in a sample of asymptomatic males. Using an examination chair with a standardized seated position, internal rotation was measured in 1080 men aged 18 to 21 years who had been conscripted for the Swiss army. The chair prevents compensatory movement by stabilizing the pelvis and the thighs with belts. The force to produce the internal rotation was standardized with a pulley system. Previous results showed that the measurements with the examination chair are similar to clinical assessment but with higher interobserver agreement. A random sample of 430 asymptomatic males was invited to undergo hip MRI. Of those, 244 White European males responded to the invitation and had a mean age of 20 ± 0.7 years and a mean internal rotation of the hip of 33° ± 8.5°. Using MRI as the reference standard, 69% (169 of 244) had a normal hip, 24% (59 of 244) a definite cam morphology (Grades 2 and 3), 3% (8 of 244) an increased acetabular depth, and 3% (8 of 244) a combination of both. One experienced radiologist graded cam morphology as follows: 0 = normal, 1 = mild, 2 = moderate, and 3 = severe. Pincer morphology was defined by increased acetabular depth (≤ 3 mm distance between the center of the femoral neck and the line connecting the anterior and posterior acetabular rims). The intraobserver agreement was substantial (weighted κ of 0.65). A receiver operating characteristic (ROC) curve was fitted, and sensitivity, specificity, and likelihood ratios were estimated for different internal rotation cutoffs.

RESULTS

For cam morphology, the area under the ROC curve was 0.75 (95% CI 0.67 to 0.82). Internal hip rotation of less than 20° yielded a positive likelihood ratio of 9.57 (sensitivity 0.13, specificity 0.99), and a value of 40° or more resulted in a negative likelihood ratio of 0.36 (sensitivity 0.93, specificity 0.20). The area under the curve for detecting the combination of cam and pincer morphologies was 0.87 (95% CI 0.74 to 1.0). A cutoff of 20° yielded a positive likelihood ratio of 9.03 (sensitivity 0.33, specificity 0.96).

CONCLUSION

This examination chair showed moderate-to-good diagnostic value to rule in hip cam morphology in White European males. However, at the extremes of the 95% confidence intervals, diagnostic performance would be poor. Nonetheless, we believe this test can contribute to identifying cam morphologies, and we hope that future, larger studies-ideally in more diverse patient populations-will seek to validate this to arrive at more precise estimates of the diagnostic performance of this test.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Outcomes of Staged Bilateral Hip Arthroscopic Surgery in the Context of Femoroacetabular Impingement Syndrome: A Nested Matched-Pair Control Study Focusing on the Effect of Time Between Procedures

BACKGROUND

Bilateral hip symptoms from femoroacetabular impingement syndrome (FAIS) are a common finding in patients regardless of athletic involvement. Oftentimes, patients and surgeons choose to stage bilateral hip arthroscopic surgery.

PURPOSE/HYPOTHESIS

The purpose of this study was (1) to compare minimum 2-year outcomes between patients who underwent staged bilateral hip arthroscopic surgery for FAIS to a propensity score-matched control group that underwent unilateral hip arthroscopic surgery and (2) to investigate the effect of time between bilateral procedures on patient-reported outcomes (PROs). We hypothesized that, after bilateral hip arthroscopic surgery, the improvement in outcomes would be similar to that after unilateral hip arthroscopic surgery and the time duration between bilateral procedures would not affect the final outcome.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were retrospectively reviewed on a consecutive series of patients who underwent primary hip arthroscopic surgery at our institution between June 2008 and November 2017. Patients who underwent bilateral hip arthroscopic surgery with minimum 2-year PROs for the modified Harris Hip Score (mHHS), the Nonarthritic Hip Score (NAHS), the Hip Outcome Score-Sports Specific Subscale (HOS-SSS), patient satisfaction, and a visual analog scale (VAS) for pain were included. The study group was matched 1:1 based on age, sex, and body mass index to a control group that only required unilateral hip arthroscopic surgery. Additionally, a subanalysis was performed on the study group to determine the effect of time between arthroscopic procedures. Rates of achieving the minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) for the mHHS and HOS-SSS were determined. The P value was set at <.05.

RESULTS

A total of 205 patients (410 hips) were included. The mean age and body mass index of the study group were 32.3 ± 13.2 years and 25.0 ± 5.1, respectively. All 410 hips that met the inclusion criteria were matched. There were no significant differences in patient, radiographic, or procedural data. A significant and comparable improvement was reported for all PRO measures and the VAS (P < .0001) in both groups. Similarly, rates of achieving the MCID and PASS were comparable. After dividing the study group based on whether the contralateral procedure was performed <3 months or >3 months after the first procedure, it was determined that patients had a significant improvement and favorable outcomes regardless of time between bilateral procedures.

CONCLUSION

Patients who underwent unilateral and bilateral hip arthroscopic surgery for FAIS had a significant and comparable improvement in PROs at a minimum 2-year follow-up. A time interval of <3 months or >3 months between bilateral procedures did not affect PROs.

[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.

Cam morphology is associated with MRI-defined cartilage defects and labral tears: a case-control study of 237 young adult football players with and without hip and groin pain

Objective

Football players are at risk of developing hip osteoarthritis (OA). Cam morphology (present in almost two of every three football players) may explain this heightened risk, but there is limited research on its role in hip OA development in younger athletes. Knowledge of this relationship will advance our understanding of the aetiology of hip OA in football players. We aimed to study the relationship between cam morphology size and MRI-defined cartilage defects and labral tears, and if this relationship differs by symptomatic state in young adult football players.

Methods

For this case–control study, 182 (288 hips) symptomatic (hip and/or groin pain >6 months and positive flexion-adduction-internal-rotation (FADIR) test) and 55 (110 hips) pain-free football players (soccer or Australian football) underwent anteroposterior and Dunn 45° radiographs, and 3-Tesla MRI. Cam morphology size was defined using alpha angle, and cartilage defects and labral tears were scored semiquantitatively. Presence, location and score (severity) of cartilage defects and labral tears were determined. Each participant completed the International Hip Outcome Tool 33 and Copenhagen Hip and Groin Outcome Score.

Results

Greater alpha angle was associated with cartilage defects (OR 1.03, 95% CI 1.01 to 1.04) and labral tears (OR 1.02, 95% CI 1.01 to 1.04). Greater alpha angle was associated with superolateral cartilage defects (OR 1.03, 95% CI 1.02 to 1.05) and superior labral tears (OR 1.03, 95% CI 1.02 to 1.05). The association of alpha angle with MRI-defined cartilage defects and labral tears was no greater in football players with symptoms than in those without (p=0.189–0.937)

Conclusion

Cam morphology size was associated with cartilage defects and labral tears in young adult football players with and without pain. This study provides evidence that cam morphology may contribute to the high prevalence of hip OA in football players. Prospective studies of football players are now needed to establish if cam morphology causes progression of cartilage defects and labral tears and development of hip OA.

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.

Pre- and postoperative in silico biomechanics in individuals with cam morphology during stair tasks

BACKGROUND

Osteochondroplasty for cam femoroacetabular impingement is a common treatment to improve hip function and prevent joint degeneration. The purpose was to compare in-silico hip biomechanics during stair tasks in pre- and postoperative patients matched with healthy controls.

METHODS

Ten symptomatic cam femoroacetabular impingement patients performed stair ascent and descent pre- and 2 years postoperatively. Patients were age, and body-mass-index matched to controls. Full-body kinematics and kinetics were computed and, muscle and hip contact forces were estimated using musculoskeletal modeling and static optimization. Stance-phases were time-normalized and compared using statistical non-parametric mapping.

FINDINGS

Preoperatives showed lower hip abduction than controls during stairs ascent (76-100%, P = .007). Pre- and postoperative showed lower hip external rotation compared to controls on stair ascent (Pre-op vs controls: 71-100%, P = .005; Post-op vs controls: 72-100%, P = .01) and stair descent (Pre-op vs controls: 0-62%, P = .001; Post-op vs controls: 0-60%, P = .001). Postoperatives showed lower iliacus force compared to preoperative (1-3%, P = .012) and control (3-6%, P = .008), and higher gluteus maximus and piriformis forces compared to controls during stair descent. Lower postoperative anterior hip contact force (0-7%, P = .004) during descent, and superior (33-35%, P = .018) during ascent compared to controls were observed. Postoperative contact forces were medialized compared to preoperative (0-2%, P = .011) and controls (1-2%, P = .016).

INTERPRETATION

Forcing participants to adhere to standardized step length/rise minimized sagittal kinematic differences between conditions and groups. Persistent reduced hip external rotation postoperatively and minor muscle force adaptations led to reduced superior hip contact force during stair ascent and reduced anterior and more medialized contact forces during stair descent.

Prevalence of Morphological Variations Associated With Femoroacetabular Impingement According to Age and Sex: A Study of 1878 Asymptomatic Hips in Nonprofessional Athletes

Background:

Radiographic findings related to the cam and pincer variants of femoroacetabular impingement (FAI) include measurements of the alpha angle and lateral center-edge angle (LCEA). The function of these radiographic findings has been put into question because of high heterogeneity in reported studies.

Purpose:

The aim of this study was 3-fold: (1) to determine the prevalence of cam and pincer variants according to sex and age on anteroposterior (AP) pelvic radiographs from an asymptomatic nonathletic population, (2) to identify the most common radiographic signs of cam- and pincer-type variants, and (3) to determine if there are variations in the prevalence of these radiographic signs according to sex and age.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

There were 3 independent observers who retrospectively analyzed the 939 AP pelvic radiographs (1878 hips) of patients aged 18 to 50 years who did not have hip symptoms and who were not professional athletes. The prevalence of the cam and pincer variants according to the alpha angle and LCEA, respectively, and the presence of other radiographic signs commonly associated with these variables were determined in the overall population and by subgroup according to sex and age group (18-30, 31-40, and 41-50 years). Descriptive and inferential statistics were used to analyze the study sample.

Results:

The mean age of the included population was 31.0 ± 9.2 years, and 68.2% were male. The prevalence of the cam-type variant was 29.7% (558/1878), and that of the pincer-type variant was 24.3% (456/1878). The radiographic signs that were most associated with the cam and pincer variants were a pistol-grip deformity and the crossover sign, respectively. Significant differences (P < .001) in the prevalence of these variants were identified between men and women in both variants. No differences were observed in the alpha angle or LCEA according to sex or age.

Conclusion:

Radiographic findings suggestive of FAI had significant variations with respect to sex and age in this study sample. This study provides information to determine the prevalence of these anatomic variants in the general population.

Hip Muscle Forces and Contact Loading During Squatting After Cam-Type FAI Surgery

BACKGROUND

The purpose of this study was to compare muscle forces and hip contact forces (HCFs) during squatting in patients with cam-type femoroacetabular impingement (cam-FAI) before and after hip corrective surgery and with healthy control participants.

METHODS

Ten symptomatic male patients with cam-FAI performed deep squatting preoperatively and at 2 years postoperatively. Patients were matched by age and body mass index to 10 male control participants. Full-body kinematics and kinetics were computed, and muscle forces and HCFs were estimated using a musculoskeletal model and static optimization. Normalized squat cycle (%SC) trials were compared using statistical nonparametric mapping (SnPM).

RESULTS

Postoperatively, patients with cam-FAI squatted down with higher anterior pelvic tilt, higher hip flexion, and greater hip extension moments than preoperatively. Preoperative patients demonstrated lower anterior pelvic tilt and lower hip flexion compared with the participants in the control group. Postoperative patients showed increased semimembranosus force compared with their preoperative values. Preoperative forces were lower than the control group for the adductor magnus, the psoas major, and the semimembranosus; however, the preoperative patients showed greater inferior gluteus maximus forces than the patients in the control group, whereas the postoperative patients did not differ from the control patients. Higher posterior, superior, and resultant HCF magnitudes were identified postoperatively in comparison with the preoperative values. Preoperative posterior HCF was lower than in the control group, whereas the postoperative posterior HCF did not differ from those in the control group.

CONCLUSIONS

Higher postoperative anterior pelvic tilt was associated with an indication of return to closer to normal pelvic motion, which resembled data from the control group. Lower preoperative anterior pelvic tilt was associated with muscle force imbalance, indicated by decreased semimembranosus and increased gluteus maximus forces. The overall increased postoperative muscle forces were associated with improved pelvic mobility and increased HCFs that were comparable with the control-group standards.

CLINICAL RELEVANCE

Muscle forces and HCFs may be indicative of postoperative joint health restoration and alleviated symptoms.

Surgery is no more effective than conservative treatment for Femoroacetabular impingement syndrome: Systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To summarize the effects of surgical treatment compared to conservative treatment in femoroacetabular impingement syndrome in the short, medium, and long term.

STUDY DESIGN

Systematic review.

METHODS

The following databases were searched on 14/09/2020: MEDLINE, EMBASE, CENTRAL, Web of Science, and PEDro. There were no date or language limits. The methodological quality assessment was performed using the PEDro scale and the quality of the evidence followed the GRADE recommendation. The outcomes pain, disability, and adverse effects were extracted.

RESULTS

Of 6264 initial studies, three met the full-text inclusion criteria. All studies were of good methodological quality. Follow up ranged from six months to two years, with 650 participants in total. The meta-analyses found no difference in disability between surgical versus conservative treatment, with a mean difference (MD) between groups of 3.91 points (95% CI -2.19 to 10.01) at six months, MD of 5.53 points (95% CI -3.11 to 14.16) at 12 months and 3.8 points (95% CI -6.0 to 13.6) at 24 months. The quality of the evidence (GRADE) varied from moderate to low across all comparisons.

CONCLUSION

There is moderate-quality evidence that surgical treatment is not superior to conservative treatment for femoroacetabular impingement syndrome in the short term, and there is low-quality evidence that it is not superior in the medium term.

LEVEL OF EVIDENCE

Therapy, level 1a.

REGISTRATION NUMBER

PROSPERO CRD42019134118.

Hip pain and its correlation with cam morphology in young skiers-a minimum of 5 years follow-up

BACKGROUND

There is conflicting evidence regarding the association between cam morphological changes and hip pain, and it remains unclear who with cam morphology will develop hip pain and who will not. This study aimed to investigate the correlation between cam morphology, hip pain, and activity level at a 5-year follow-up in young Alpine and Mogul skiers.

METHOD

All students (n = 76) at Åre Ski National Sports High School were invited and accepted participation in this prospective study at baseline. Magnetic resonance imaging (MRI) of both hips was conducted to evaluate the presence of cam morphology (α-angle ≥ 55°) and its size alongside the reporting of hip pain, type, and frequency of training by the Back and hip questionnaire, at baseline. After 5 years, the skiers were invited to complete a shortened version of the same questionnaire.

RESULTS

A total of 60 skiers (80%) completed the follow-up questionnaire, of which 53 had concomitant MRI data. Cam morphology was present in 25 skiers (47.2%, 39 hips). Hip pain at baseline and at follow-up was reported in 17 (28.3%) and 22 (36.7%) skiers, respectively. No correlations were found between the activity level, the frequency, and the size of cam morphology and hip pain, except for the right hip α-angle at 1 o'clock and hip pain in skiers with cam morphology at baseline (rs = 0.49; P = 0.03) and at follow-up (rs = 0.47; P = 0.04). A total of 73.3% skiers had retired, of which 48% reported this was due to injuries.

CONCLUSION

Hip pain was not shown to be correlated, or had a low correlation, with activity level and the presence and size of cam morphology in young skiers on a 5-year follow-up. Based on these results, cam morphology or activity level did not affect hip pain to develop during 5 years of follow-up in young skiers. Furthermore, this study highlights that almost 75% of young elite skiers had retired from their elite career with almost 50% reporting that this was due to injuries sustained from skiing.

Classifying Cam Morphology by the Alpha Angle: A Systematic Review on Threshold Values

Background

The alpha angle is the most often used measure to classify cam morphology. There is currently no agreement on which alpha angle threshold value to use.

Purpose

To systematically investigate the different alpha angle threshold values used for defining cam morphology in studies aiming to identify this threshold and to determine whether data are consistent enough to suggest an alpha angle threshold to classify cam morphology.

Study Design

Systematic review; Level of evidence, 3.

Methods

The Embase, Medline (Ovid), Web of Science, Cochrane Central, and Google Scholar databases were searched from database inception to February 28, 2019. Studies aiming at identifying an alpha angle threshold to classify cam morphology were eligible for inclusion.

Results

We included 4 case-control studies, 10 cohort studies, and 1 finite-element study from 2437 identified publications. Studies (n = 3) using receiver operating characteristic (ROC) curve analysis to distinguish asymptomatic people from patients with femoroacetabular impingement syndrome consistently observed alpha angle thresholds between 57° and 60°. A 60° threshold was also found to best discriminate between hips with and without cam morphology in a large cohort study based on a bimodal distribution of the alpha angle. Studies (n = 8) using the upper limit of the 95% reference interval as threshold proposed a wide overall threshold range between 58° and 93°. When stratified by sex, thresholds between 63° and 93° in male patients and between 58° and 94° in female patients were reported.

Conclusion

Based on the available evidence, mostly based on studies using ROC curve analysis, an alpha angle threshold of ≥60° is currently the most appropriate to classify cam morphology. Further research is required to fully validate this threshold.

Running with Femoral Acetabular Impingement: Operative Vs Nonoperative Treatment

A 31-year-old female lawyer presents with right hip pain starting approximately 3 years ago and worsening over the past 2 to 3 months. She is an avid runner, running 20 to 30 miles weekly, and noticed that her pain started after a running program training for the marathon. Her pain is primarily over the lateral aspect of her hip with some radiation into the groin. The pain is made worse with impact exercises such as running and made better with walking and cycling. She has done physical therapy for the past 3 months without any significant improvement. She has not had any injections or taken anti-inflammatories because of a history of gastric ulcer disease. On physical examination she has mild tenderness over her right greater trochanter and her range of motion tests are full in terms of flexion, internal rotation, and external rotation. She has a positive FADIR (flexion-adduction-internal rotation) impingement that causes both groin and lateral hip pain. Radiograph of the right hip revealed preservation of the joint space and an anterior cam lesion with reduced offset at the femoral head neck junction. Magnetic resonance imaging (MRI) of the right hip revealed a tear at the anterior superior labrum at the 1 to 2 o'clock position along with subjacent bone marrow edema in the femoral head that is likely reactive. Computed tomography (CT) scan of the right hip confirmed a combined cam and pincer type femoral acetabular impingement of the right hip with overcoverage of the femoral head. There was 15° of femoral anteversion and the coronal lateral center of edge angle (LCEA) is 34°. Dr. Peter Moley argues that a focused rehabilitation program to restore strength and motor control of the deep hip stabilizers will provide optimal functional recovery. Dr. Jakub Tatka argues that right hip arthroscopy with labral repair and possible osteochondralplasty are indicated in order to prevent early hip arthritis and prevent long-term sequela of femoral acetabular impingement.

Arthroscopic surgery versus physiotherapy for femoroacetabular impingement: a meta-analysis study

INTRODUCTION

Femoroacetabular impingement (FAI) is thought to play an important role in the development of hip osteoarthritis. However, there is no consensus about the optimal treatment options, since non-operative therapy such as physiotherapy and surgical treatment such as arthroscopic hip surgery can both improve symptoms. Therefore, the aim of the present meta-analysis was to compare the outcomes between two different treatment regimes; physiotherapy versus arthroscopic treatment for FAI.

METHODS

The present meta-analysis was carried out according to the PRISMA guidelines. In November 2019, the main online databases were accessed. All the randomized clinical trials (RCTs) comparing surgical arthroscopic treatment versus physiotherapy for FAI were considered for inclusion. Only articles reporting quantitative data under the outcomes of interest were included. For the all analysis, we used Review Manager Software. Data from 644 patients were analysed.

RESULTS

Data from 644 patients were evaluated with a mean follow-up of 14.67 ± 8.3 months. The unpaired t test detected an optimal baseline comparability in terms of side, gender, years, duration of symptoms and BMI (p = 0.08-0.9). The VAS subscale of the score EQ-5D and the mean iHOT33 reported favourable values in the arthroscopic group (p = 0.03 and p < 0.0001, respectively). Similar findings were evidenced in the iHOT33 subgroup 6-months (p = 0.70) and 12-months (p = 0.0002). The HOS score, the ADL (p < 0.0001) and the sport (p = 0.0003) subscales reported both greater values in the arthroscopic group. No statistical significance was found concerning the risk to incur in further total hip arthroplasty (p = 0.72).

CONCLUSION

Based on only three high-quality RCTs, arthroscopic hip surgery is an effective therapeutic treatment for FAI revealing superior results than a non-surgical approach with physiotherapy.

The relationship between cam morphology and hip and groin symptoms and signs in young male football players

Background

Conflicting and limited high‐quality prospective data are available on the associations between cam morphology and hip and groin symptoms and range of motion (ROM).

Objectives

This cross‐sectional cohort study investigated associations between cam morphology presence, size and duration and symptoms and ROM.

Methods

Academy male football players (n = 49, 17‐24 years) were included. Standardized antero‐posterior pelvic and frog‐leg lateral radiographs were obtained at baseline, 2.5‐ and 5‐year follow‐up. The femoral head‐neck junction was quantified by:

Visual score. Cam morphology (flattening or prominence), large cam (prominence).

Alpha angle. Cam morphology (≥60°), large cam (≥78°).

Cam morphology duration was defined as long (first present at baseline) or short (only from 2.5‐ to 5‐year follow‐up). Current symptoms at 5‐year follow‐up were assessed using a hip and groin pain question and by the “Hip and Groin Outcome Score” (HAGOS). HAGOS scores were categorized into: most symptoms (≥2 domains in lowest interquartile range [IQR]), least symptoms (≥2 domains in highest IQR). Hip ROM was measured by goniometry at 5‐year follow‐up.

Results

Large cam morphology based on visual score was associated with hip and groin pain (23.8% vs. 7.1%, OR: 3.17, CI: [1.15‐8.70], P = .026), but not with HAGOS scores. Cam morphology presence, size, and duration were associated with limited flexion of around 6° and/or 3° to 6° for internal rotation.

Conclusion

Cam morphology presence, size, and duration were associated with limited hip flexion and/or internal rotation, but differences might not exceed the minimal clinical important difference. Whether cam morphology results in symptoms is uncertain.

Labral calcification plays a key role in hip pain and symptoms in femoroacetabular impingement

BACKGROUND

Hip osteoarthritis (HOA) is the most common hip disorder and a major cause of disability in the adult population, with an estimated prevalence of end-stage disease and total hip replacement. Thus, the diagnosis, prevention, and treatment of the early stages of the disease in young adults are crucial to reduce the incidence of end-stage HOA. The purpose of this study was to determine whether (1) a relationship among the inflammatory status of labrum and synovium collected from patients with femoroacetabular impingement (FAI) would exist; and (2) to investigate the associations among the histopathological features of joint tissues, the pre-operative symptoms and the post-operative outcomes after arthroscopic surgery.

METHODS

Joint tissues from 21 patients undergoing hip arthroscopy for FAI were collected and their histological and immunohistochemical features were correlated with clinical parameters.

RESULTS

Synovial mononuclear cell infiltration was observed in 25% of FAI patients, inversely correlated with the hip disability and osteoarthritis outcome score (HOOS) pain and function subscales and with the absolute and relative change in total HOOS. All the labral samples showed some pattern of degeneration and 67% of the samples showed calcium deposits. The total labral score was associated with increased CD68 positive cells in the synovium. The presence of labral calcifications, along with the chondral damage worsened the HOOS post-op symptoms (adjusted R-square = 0.76 p = 0.0001).

CONCLUSIONS

Our study reveals a relationship between the histologic labral features, the synovial inflammation, and the cartilage condition at the time of FAI. The presence of labral calcifications, along with the cartilage damage and the synovitis negatively affects the post-operative outcomes in patients with FAI.

Acetabular Version Increases During Adolescence Secondary to Reduced Anterior Femoral Head Coverage

BACKGROUND

Acetabular version influences joint mechanics and the risk of impingement. Cross-sectional studies have reported an increase in acetabular version during adolescence; however, to our knowledge no longitudinal study has assessed version or how the change in version occurs. Knowing this would be important because characterizing the normal developmental process of the acetabulum would allow for easier recognition of a morphologic abnormality.

QUESTIONS/PURPOSES

To determine (1) how acetabular version changes during adolescence, (2) calculate how acetabular coverage of the femoral head changed during this period, and (3) to identify whether demographic factors or hip ROM are associated with acetabular development.

METHODS

This retrospective analysis of data from a longitudinal study included 17 volunteers (34 hips) with a mean (± SD) age of 11 ± 2 years; seven were male and 10 were female. The participants underwent a clinical examination of BMI and ROM and MRIs of both hips at recruitment and at follow-up (6 ± 2 years). MR images were assessed to determine maturation of the triradiate cartilage complex, acetabular version, and degree of the anterior, posterior, and superior acetabular sector angles (reflecting degree of femoral head coverage provided by the acetabulum anteriorly, posteriorly and superiorly respectively). An orthopaedic fellow (GG) and a senior orthopaedic resident (PJ) performed all readings in consensus; 20 scans were re-analyzed for intraobserver reliability. Thereafter, a musculoskeletal radiologist (KR) repeated measurements in 10 scans to test interobserver reliability. The intra- and interobserver interclass correlation coefficients for absolute agreement were 0.85 (95% CI 0.76 to 0.91; p < 0.001) and 0.77 (95% CI 0.70 to 0.84), respectively. All volunteers underwent a clinical examination by a senior orthopaedic resident (PJ) to assess their range of internal rotation (in 90° of flexion) in the supine and prone positions using a goniometer. We tested investigated whether the change in anteversion and sector angles differed between genders and whether the changes were correlated with BMI or ROM using Pearson's coefficient. The triradiate cartilage complex was open (Grade I) at baseline and closed (Grade III) at follow-up in all hips.

RESULTS

The acetabular anteversion increased, moving caudally further away from the roof at both timepoints. The mean (range) anteversion angle increased from 7° ± 4° (0 to 18) at baseline to 12° ± 4° (5 to 22) at the follow-up examination (p < 0.001). The mean (range) anterior sector angle decreased from 72° ± 8° (57 to 87) at baseline to 65° ± 8° (50 to 81) at the final follow-up (p = 0.002). The mean (range) posterior (98° ± 5° [86 to 111] versus 97° ± 5° [89 to 109]; p = 0.8) and superior (121° ± 4° [114 to 129] to 124° ± 5° [111 to 134]; p = 0.07) sector angles remained unchanged. The change in the anterior sector angle correlated with the change in version (rho = 0.5; p = 0.02). The change in version was not associated with any of the tested patient factors (BMI, ROM).

CONCLUSIONS

With skeletal maturity, acetabular version increases, especially rostrally. This increase is associated with, and is likely a result of, a reduced anterior acetabular sector angle (that is, less coverage anteriorly, while the degree of coverage posteriorly remained the same). Thus, in patients were the normal developmental process is disturbed, a rim-trim might be an appropriate surgical solution, since the degree of posterior coverage is sufficient and no reorientation osteotomy would be necessary. However, further study on patients with retroversion (of various degrees) is necessary to characterize these observations further. The changes in version were not associated with any of the tested patient factors; however, further study with greater power is needed.

LEVEL OF EVIDENCE

Level II, prognostic study.

Demographic and Radiographic Factors Associated With Intra-articular Hip Cartilage Injury: A Cross-sectional Study of 1511 Hip Arthroscopy Procedures

BACKGROUND

Moderate to severe (grade 3-4) hip joint cartilage injury seems to impair function in patients with femoroacetabular impingement syndrome.

PURPOSE

To investigate whether demographic and radiographic factors were associated with moderate to severe hip joint cartilage injury.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients were identified in the Danish Hip Arthroscopy Registry. The outcome variables were acetabular cartilage injury (modified Beck grade 0-2 vs 3-4) and femoral head cartilage injury (International Cartilage Repair Society grade 0-2 vs 3-4). Logistic regressions assessed the association with the following: age (<30 vs 30-50 years); sex; sport activity level (Hip Sports Activity Scale); alpha angle (AA) assessed as normal (AA <55°), cam (55°≤ AA <78°), or severe cam (AA ≥78°); lateral center-edge angle (LCEA) assessed as normal (25°≤ LCEA ≤ 39°), pincer (LCEA >39°), or borderline dysplasia (LCEA <25°); joint space width (JSW) assessed as normal (JSW >4.0 mm), mild reduction (3.1 mm ≤ JSW ≤ 4.0 mm), or severe reduction (2.1 mm ≤ JSW ≤ 3.0 mm).

RESULTS

A total of 1511 patients were included (mean ± SD age: 34.9 ± 9.8 years). Male sex (odds ratio [OR], 4.42), higher age (OR, 1.70), increased AA (cam: OR, 2.23; severe cam: OR, 4.82), and reduced JSW (mild: OR, 2.04; severe: OR, 3.19) were associated (P < .05) with Beck grade 3-4. Higher age (OR, 1.92), increased Hip Sports Activity Scale (OR, 1.13), borderline dysplasia (OR, 3.08), and reduced JSW (mild: OR, 2.63; severe: OR, 3.04) were associated (P < .05) with International Cartilage Repair Society grade 3-4.

CONCLUSION

Several demographic and radiographic factors were associated with moderate to severe hip joint cartilage injury. Most notably, increased cam severity and borderline dysplasia substantially increased the risk of grade 3-4 acetabular and femoral head cartilage injury, respectively, indicating that specific deformity may drive specific cartilage injury patterns in the hip joint.

Bilateral Femoroacetabular Impingement: What is the Fate of the Asymptomatic Hip?

BACKGROUND

Bilateral symptomatic femoroacetabular impingement (FAI) is common. However, the fate of asymptomatic hip in patients with the radiographic diagnosis of bilateral FAI and unilateral symptoms remains unknown.

QUESTIONS/PURPOSES

(1) What is the likelihood of the asymptomatic hip becoming painful in patients with unilateral symptoms but with radiographic evidence of bilateral femoroacetabular impingement? (2) What radiological and clinical factors are associated with the development of symptoms in an asymptomatic hip diagnosed with FAI?

METHODS

A longitudinally maintained institutional FAI database was queried to collect relevant data for this retrospective study. To answer our research questions, we created a cohort of patients with bilateral radiographic signs of FAI but only unilateral symptoms at the time of initial presentation. Between 2004 and 2016, a senior surgeon (JP) at one institution treated 652 patients for hip pain determined to be from FAI, a diagnosis we made based on clinical symptoms, physical exam, and diagnostic imaging. We excluded 95 patients (15%) because of inadequate data or other diagnoses, which left 557 patients. Of those, 170 patients (31%) had bilateral radiological diagnosis of FAI, and 88 (52%) of them had bilateral hip symptoms, and so were excluded. Of the remaining 82 patients, eight (10%) underwent bilateral FAI surgery under the same anesthetic despite having only unilateral symptoms, leaving 74 for analysis in this study. Patients were followed with annual clinic visits, or contacted by phone and electronically. We defined onset of symptoms using a modified Harris Hip Score (mHHS) or the University of California at Los Angeles (UCLA) activity scale, and used a logistic regression model to identify factors associated with the development of symptoms.

RESULTS

Of the 74 patients with bilateral FAI and an asymptomatic hip at initial presentation, 60 (81%) became symptomatic at a mean 2 years (range, 0.3-11 years) followup. Of these 60 patients, 43 (72%) eventually underwent subsequent surgical intervention. After controlling for potential confounding variables such as sex, age, BMI, history of trauma we identified that reduced neck-shaft angle (r = -0.243, p = 0.009), increased lateral center-edge angle (r = 0.123, p = 0.049), increased alpha angle (r = 0.069, p = 0.025), and younger age (r = -0.071, p = 0.046) were associated with the development of symptoms in the contralateral hip. With the numbers available, none of the other examined variables such as sex, BMI, history of trauma, psychiatric condition, employment, Tönnis grade, Tönnis angle, crossover sign, type of impingement, and joint congruency were found to be associated with symptom progression.

CONCLUSIONS

Bilateral FAI may be observed about one-third of patients. Most patients with unilateral symptomatic FAI and radiographic diagnosis of bilateral FAI in this cohort became symptomatic relatively quickly and most of them underwent subsequent surgical intervention in the contralateral hip. Reduced neck-shaft angle, increased lateral center-edge angle, increased alpha angle, and younger age were associated with symptom development in the contralateral hip. Hip preservation surgeons may use the finding of this study to counsel patients who present with bilateral FAI but only unilateral symptoms about the natural history of their condition.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Cam FAI and Smaller Neck Angles Increase Subchondral Bone Stresses During Squatting: A Finite Element Analysis

BACKGROUND

Individuals with a cam deformity and a decreased (varus) femoral neck-shaft angle may be predisposed to symptomatic femoroacetabular impingement (FAI). However, it is unclear what combined effects the cam deformity and neck angle have on acetabular cartilage and subchondral bone stresses during an impinging squat motion. We therefore used finite element analysis to examine the combined effects of cam morphology and femoral neck-shaft angle on acetabular cartilage and subchondral bone stresses during squatting, examining the differences in stress characteristics between symptomatic and asymptomatic individuals with cam deformities and individuals without cam deformities and no hip pain.

QUESTIONS/PURPOSES

Using finite element analysis in this population, we asked: (1) What are the differences in acetabular cartilage stresses? (2) What are the differences in subchondral bone stresses? (3) What are the effects of high and low femoral neck-shaft angles on these stresses?

METHODS

Six male participants were included to represent three groups (symptomatic cam, asymptomatic cam, control without cam deformity) with two participants per group, one with the highest femoral neck-shaft angle and one with the lowest (that is, most valgus and most varus neck angles, respectively). Each participant's finite element hip models were reconstructed from imaging data and assigned subject-specific bone material properties. Hip contact forces during squatting were determined and applied to the finite element models to examine maximum shear stresses in the acetabular cartilage and subchondral bone.

RESULTS

Both groups with cam deformities experienced higher subchondral bone stresses than cartilage stresses. Both groups with cam deformities also had higher subchondral bone stresses (symptomatic with high and low femoral neck-shaft angle = 14.1 and 15.8 MPa, respectively; asymptomatic with high and low femoral neck-shaft angle = 10.9 and 13.0 MPa, respectively) compared with the control subjects (high and low femoral neck-shaft angle = 6.4 and 6.5 MPa, respectively). The symptomatic and asymptomatic participants with low femoral neck-shaft angles had the highest cartilage and subchondral bone stresses in their respective subgroups. The asymptomatic participant with low femoral neck-shaft angle (123°) demonstrated anterolateral subchondral bone stresses (13.0 MPa), similar to the symptomatic group. The control group also showed no differences between cartilage and subchondral bone stresses.

CONCLUSIONS

The resultant subchondral bone stresses modeled here coincide with findings that acetabular subchondral bone is denser in hips with cam lesions. Future laboratory studies will expand the parametric finite element analyses, varying these anatomic and subchondral bone stiffness parameters to better understand the contributions to the pathomechanism of FAI.

CLINICAL RELEVANCE

Individuals with a cam deformity and more varus neck orientation may experience elevated subchondral bone stresses, which may increase the risks of early clinical signs and degenerative processes associated with FAI, whereas individuals with cam morphology and normal-to-higher femoral neck-shaft angles may be at lesser risk of disease progression that would potentially require surgical intervention.

Does Cartilage Degenerate in Asymptomatic Hips With Cam Morphology?

BACKGROUND

The management of asymptomatic individuals with cam femoral morphology that predisposes their hips to femoroacetabular impingement has received little attention. Such hips may have subclinical articular damage; however, whether this cartilage damage will progress is unknown as is whether any particular bone morphologies are associated with this progression. Such knowledge could help determine the natural history and guide management of such individuals.

QUESTIONS/PURPOSES

The purpose of this study was to determine whether (1) asymptomatic hips with cam morphology are at risk of further cartilage degeneration (as evaluated by T1ρ); (2) T1ρ changes are predictive of symptom onset; and (3) bony morphologic parameters are associated with T1ρ signal changes.

METHODS

In a prospective, longitudinal study, 17 asymptomatic volunteers/hips (16 men; 33 ± 6 years) with cam morphology underwent two T1ρ MRI scans and functional assessment (WOMAC) at recruitment and at 4 years (range, 2-6 years). Volunteers were recruited from a previous study, which reported on the prevalence of cam morphology among asymptomatic individuals using hip MRI; cam morphology was defined as an α angle ≥ 60° anterolaterally and/or ≥ 50.5° anteriorly relative to the neck axis. The differences in T1ρ values (ΔT1ρ) and relative differences (%ΔT1ρ) were calculated as: ΔT1ρ = T1ρFollowup - T1ρInitial and %ΔT1ρ = ΔT1ρ/T1ρInitial. A %ΔT1ρ > 17.6% was considered clinically important. Using CT data, femoral, acetabular, and spinopelvic parameters were measured. Whether ΔT1ρ and/or %ΔT1ρ was associated with any of the bone morphologic parameters was tested using Spearman's correlation coefficient.

RESULTS

The global T1ρ in these asymptomatic hips with cam morphology remained unchanged between initial (mean, 35 ± 5 ms) and followup scans (mean, 34 ± 3 ms; p = 0.518). No differences with the numbers available in T1ρ values were seen initially between the anterolateral and posterolateral (34 ± 6 ms versus 33 ± 4 ms; p = 0.734) regions; at followup, T1 values were higher posterolaterally (36 ± 5 ms versus 32 ± 5 ms; p = 0.031). The mean global ΔT1ρ was 1 ± 5 ms (95% confidence interval, -1 to +3 ms) and the mean global %ΔT1ρ was 2% ± 13%. Two volunteers reported lower WOMAC scores; one patient exhibited a clinically important increase in %ΔT1ρ (-26%). The degree of acetabular coverage correlated with %ΔT1ρ (rho = 0.59-0.61, p = 0.002); the lesser the acetabular coverage anterolaterally, the greater the corresponding area's T1ρ at followup.

CONCLUSIONS

Although signs of posterolateral joint degeneration were detected, these were not generally associated with symptoms, and only one of the two volunteers with the onset of symptoms had a clinically important increase in %ΔT1ρ. We found that reduced acetabular coverage may increase the likelihood that preclinical cartilage degeneration will arise within 2 to 6 years; thereby reduced acetabular coverage should be considered when stratifying asymptomatic hips at risk of degeneration. Future studies should be performed with a larger cohort and include femoral version among the parameters studied.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Femoroacetabular Impingement in Pediatric Patients

Subacute, nontraumatic hip pain is often a diagnostic challenge. Femoroacetabular impingement (FAI) is a common cause of atraumatic hip pain that is poorly understood. FAI is a result of abnormal morphologic changes in either the femoral head or the acetabulum. FAI is more prevalent in people who perform activities requiring repetitive hip flexion, but it remains common in the general population. Evaluation begins with physical examination maneuvers to rule out additional hip pathology and provocation tests to reproduce hip pain. Diagnosis is often made by radiography or magnetic resonance imaging. Initial treatment is generally more conservative, featuring activity modification and physical therapy, whereas more aggressive treatment requires operative management.

Arthroscopic hip surgery compared with physiotherapy and activity modification for the treatment of symptomatic femoroacetabular impingement: multicentre randomised controlled trial

OBJECTIVE

To compare arthroscopic hip surgery with physiotherapy and activity modification for improving patient reported outcome measures in patients with symptomatic femoroacetabular impingement (FAI).

DESIGN

Two group parallel, assessor blinded, pragmatic randomised controlled trial.

SETTING

Secondary and tertiary care centres across seven NHS England sites.

PARTICIPANTS

222 participants aged 18 to 60 years with symptomatic FAI confirmed clinically and with imaging (radiography or magnetic resonance imaging) were randomised (1:1) to receive arthroscopic hip surgery (n=112) or a programme of physiotherapy and activity modification (n=110). Exclusion criteria included previous surgery, completion of a physiotherapy programme targeting FAI within the preceding 12 months, established osteoarthritis (Kellgren-Lawrence grade ≥2), and hip dysplasia (centre-edge angle <20 degrees).

INTERVENTIONS

Participants in the physiotherapy group received a goal based programme tailored to individual patient needs, with emphasis on improving core stability and movement control. A maximum of eight physiotherapy sessions were delivered over five months. Participants in the arthroscopic surgery group received surgery to excise the bone that impinged during hip movements, followed by routine postoperative care.

MAIN OUTCOME MEASURES

The primary outcome measure was the hip outcome score activities of daily living subscale (HOS ADL) at eight months post-randomisation, with a minimum clinically important difference between groups of 9 points. Secondary outcome measures included additional patient reported outcome measures and clinical assessment.

RESULTS

At eight months post-randomisation, data were available for 100 patients in the arthroscopic hip surgery group (89%) and 88 patients in the physiotherapy programme group (80%). Mean HOS ADL was 78.4 (95% confidence interval 74.4 to 82.3) for patients randomised to arthroscopic hip surgery and 69.2 (65.2 to 73.3) for patients randomised to the physiotherapy programme. After adjusting for baseline HOS ADL, age, sex, and study site, the mean HOS ADL was 10.0 points higher (6.4 to 13.6) in the arthroscopic hip surgery group compared with the physiotherapy programme group (P<0.001)). No serious adverse events were reported in either group.

CONCLUSIONS

Patients with symptomatic FAI referred to secondary or tertiary care achieve superior outcomes with arthroscopic hip surgery than with physiotherapy and activity modification.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01893034.

Hip Joint Torsional Loading Before and After Cam Femoroacetabular Impingement Surgery

BACKGROUND

Surgical management of cam femoroacetabular impingement (FAI) aims to preserve the native hip and restore joint function, although it is unclear how the capsulotomy, cam deformity, and capsular repair influence joint mechanics to balance functional mobility.

PURPOSE

To examine the contributions of the capsule and cam deformity to hip joint mechanics. Using in vitro, cadaveric methods, we examined the individual effects of the surgical capsulotomy, cam resection, and capsular repair on passive range of motion and resistance of applied torque.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twelve cadaveric hips with cam deformities were skeletonized to the capsule and mounted onto a robotic testing platform. The robot positioned each intact hip in multiple testing positions: (1) extension, (2) neutral 0°, (3) flexion 30°, (4) flexion 90°, (5) flexion-adduction and internal rotation (FADIR), and (6) flexion-abduction and external rotation. Then the robot performed applicable internal and external rotations, recording the neutral path of motion until a 5-N·m of torque was reached in each rotational direction. Each hip then underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested to reach 5 N·m of internal and external torque again after each stage. During the capsulotomy and cam resection stages, the initial intact hip's recorded path of motion was replayed to measure changes in resisted torque.

RESULTS

Regarding changes in motion, external rotation increased substantially after capsulotomies, but internal rotation only further increased at flexion 90° (change +32%, P = .001, d = 0.58) and FADIR (change +33%, P < .001, d = 0.51) after cam resections. Capsular repair provided marginal restraint for internal rotation but restrained the external rotation compared with the capsulotomy stage. Regarding changes in torque, both internal and external torque resistance decreased after capsulotomy. Compared with the capsulotomy stage, cam resection further reduced internal torque resistance during flexion 90° (change -45%, P < .001, d = 0.98) and FADIR (change -37%, P = .003, d = 1.0), where the cam deformity accounted for 21% of the intact hip's torsional resistance in flexion 90° and 27% in FADIR.

CONCLUSION

Although the capsule played a predominant role in joint constraint, the cam deformity provided 21% to 27% of the intact hip's resistance to torsional load in flexion and internal rotation. Resecting the cam deformity would remove this loading on the chondrolabral junction.

CLINICAL RELEVANCE

These findings are the first to quantify the contribution of the cam deformity to resisting hip joint torsional loads and thus quantify the reduced loading on the chondrolabral complex that can be achieved after cam resection.

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.

Unravelling the hip pistol grip/cam deformity: Origins to joint degeneration

This article reviews a body of work performed by the investigators over 9 years that has addressed the significance of cam morphology in the development of hip osteoarthritis (OA). Early hip joint degeneration is a common clinical presentation and preexisting abnormal joint morphology is a risk factor for its development. Interrogating Hill's criteria, we tested whether cam-type femoroacetabular impingement leads to hip OA. Strength of association was identified between cam morphology, reduced range-of-movement, hip pain, and cartilage degeneration. By studying a pediatric population, we were able to characterize the temporality between cam morphology (occurring 1st) and joint degeneration. Using in silico (finite element) and in vivo (imaging biomarkers) studies, we demonstrated the biological plausibility of how a cam deformity can lead to joint degeneration. Furthermore, we were able to show a biological gradient between degree of cam deformity and extent of articular damage. However, not all patients develop joint degeneration and we were able to characterize which factors contribute to this (specificity). Lastly, we were able to show that by removing the cam morphology, one could positively influence the degenerative process (experiment). The findings of this body of work show consistency and coherence with the literature. Furthermore, they illustrate how cam morphology can lead to early joint degeneration analogous to SCFE, dysplasia, and joint mal-reduction post-injury. The findings of this study open new avenues on the association between cam morphology and OA including recommendations for the study, screening, follow-up, and assessment (patient-specific) of individuals with cam morphology in order to prevent early joint degeneration. Statement of significance: By satisfying Hill's criteria, one can deduct that in some individuals, cam morphology is a cause of OA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3125-3135, 2018.

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.

Assessment of cam morphology of the hip with ultra sound imaging by physical therapists is reliable and valid

BACKGROUND

Femoroacetabular impingement syndrome is considered present when a combination of clinical symptoms, signs and morphological features of the hip co-exist. Imaging is increasingly popular in primary health care settings with physical therapists performing ultrasound (US).

OBJECTIVE

The aim of this study was to assess the diagnostic accuracy and inter-rater reliability of ultrasound in determining presence of cam morphology.

DESIGN

A concurrent validity and inter-rater reliability study.

METHODS

The presence of cam morphology of the hip was determined by α angle measures using Kinovea software. A cam was defined present when the α angle >60°. The index test was US and radiographs served as a gold standard.

RESULTS

Correlation between the radiographic α angle and ultrasound measures was r = 0.82 (p < 0.01). Inter-rater reliability was high with an ICC of 0.74 (95% CI 0.61-0.84). The predictive value for presence of cam morphology had a sensitivity of 79% and a specificity of 94%. The positive predictive value was 79% whereas the negative predictive value was 94%. Total accuracy was 90%.

CONCLUSIONS

Ultrasound conducted by trained physical therapists is a valid, reliable, specific and sensitive diagnostic tool to assess the presence of cam morphology.

The natural alpha angle of the femoral head-neck junction

Aims

Asphericity of the femoral head-neck junction is common in cam-type femoroacetabular impingement (FAI) and usually quantified using the alpha angle on radiographs or MRI. The aim of this study was to determine the natural alpha angle in a large cohort of patients by continuous circumferential analysis with CT.

Methods

CT scans of 1312 femurs of 656 patients were analyzed in this cross-sectional study. There were 362 men and 294 women. Their mean age was 61.2 years (18 to 93). All scans had been performed for reasons other than hip disease. Digital circumferential analysis allowed continuous determination of the alpha angle around the entire head-neck junction. All statistical tests were conducted two-sided; a p-value < 0.05 was considered statistically significant.

Results

The mean maximum alpha angle for the cohort was 59.0° (sd 9.4). The maximum was located anterosuperiorly at 01:36 on the clock face, with two additional maxima of asphericity at the posterior and inferior head-neck junction. The mean alpha angle was significantly larger in men (59.4°, sd 8.0) compared with women (53.5°, sd 7.4°; p = 0.0005), and in Caucasians (60.7°, sd 9.0°) compared with Africans (56.3°, sd 8.0; p = 0.007) and Asians (50.8°, sd 7.2; p = 0.0005). The alpha angle showed a weak positive correlation with age (p < 0.05). If measured at commonly used planes of the radially reconstructed CT or MRI, the alpha angle was largely underestimated; measurement at the 01:30 and 02:00 positions showed a mean underestimation of 4° and 6°, respectively.

Conclusion

This study provides important data on the normal alpha angle dependent on age, gender, and ethnic origin. The normal alpha angle in men is > 55°, and this should be borne in mind when making a diagnosis of cam-type morphology. Cite this article: Bone Joint J 2018;100-B:570–8.

Patient-specific parameterised cam geometry in finite element models of femoroacetabular impingement of the hip

BACKGROUND

Impingement resulting in soft tissue damage has been observed in hips with abnormal morphologies. Geometric parameterisation can be used to automatically generate a range of bone geometries for use in computational models, including femurs with cam deformity on the femoral neck.

METHODS

This study verified patient-specific parametric finite element models of 20 patients with cam deformity (10 female, 10 male) through comparison to their patient-specific segmentation-based equivalents. The parameterisation system was then used to generate further models with parametrically defined geometry to investigate morphological changes in both the femur and acetabulum and their effects on impingement.

FINDINGS

Similar findings were observed between segmentation-based and parametric models when assessing soft tissue strains under impingement conditions, resulting from high flexion and internal rotations. Parametric models with cam morphology demonstrated that clinically used alpha angles should not be relied on for estimating impingement severity since planar views do not capture the full three-dimensional geometry of the joint. Furthermore, the parametric approach allowed study of labral shape changes, indicating higher strains can result from bony overcoverage.

INTERPRETATION

The position of cams, as well as their size, can affect the level of soft tissue strain occurring in the hip. This highlights the importance of reporting the full details of three-dimensional geometry used when developing computational models of the hip joint and suggests that it could be beneficial to stratify the patient population when considering treatment options, since certain morphologies may be at greater risk of elevated soft tissue strain.

The Prevalence of Cam and Pincer Morphology and Its Association With Development of Hip Osteoarthritis

Synopsis Our understanding of femoroacetabular impingement syndrome is slowly improving. The number of studies on all aspects (etiology, prevalence, pathophysiology, natural history, treatment, and preventive measures) of femoroacetabular impingement syndrome has grown exponentially over the past few years. This commentary provides the latest updates on the prevalence of cam and pincer hip morphology and its relationship with development of hip osteoarthritis (OA). Cam and pincer morphology is highly prevalent in the general population and in this paper is presented for different subgroups based on age, sex, ethnicity, and athletic activity. Methodological issues in determining prevalence of abnormal hip morphology are also discussed. Cam morphology has been associated with development of hip OA, but the association between pincer morphology and hip OA is much less clear. Results from reviewed studies, as well as remaining gaps in literature on this topic, are critically discussed and put into perspective for the clinician. J Orthop Sports Phys Ther 2018;48(4):230-238. doi:10.2519/jospt.2018.7816.

Impingement-type bony morphology was related to cartilage defects, but not pain in professional ballet dancers' hips

OBJECTIVES

Professional ballet dancers may have hip bony morphology that predisposes them to cartilage or labral injury. However, the relationship between bony morphology and pathology has not been investigated in ballet. This study investigates associations between bony morphology, chondrolabral defects and hip pain in ballet dancers.

DESIGN

Cross-sectional study.

METHODS

33 male and female professional ballet dancers, (mean age 27 years (range 19-39)), completed questionnaires with hip pain measured on a visual analogue scale; and underwent 3.0-T magnetic resonance imaging (3T MRI) to measure lateral centre edge angles (LCEA), alpha angles in the anterior and superior position, femoral neck-shaft angles (NSA) and acetabular version angles; and to detect acetabular labral tear and articular cartilage defects.

RESULTS

Seventeen dancers (51.5%) had impingement-type (alpha angle>50.5° or acetabular version <10° or >20°) and 19 (58%) had instability-type (LCEA<25° or NSA>135°) bony morphology. Cartilage defect prevalence was higher in dancers with impingement-type bony morphology (n=14) compared to those without impingement-type morphology (n=4, p=0.001). There was no relationship between instability-type bony morphology and cartilage defects (p>0.05). There was no relationship between labral tears and bony morphology (p>0.05). Neither chondrolabral pathology nor any morphological feature were associated with hip pain (p>0.05 for all).

CONCLUSIONS

Impingement-type bony morphology was related to cartilage defects, but not labral tear. Hip pain was not associated with pathology or bony morphology. Longitudinal studies are warranted to determine if bony features, such as cam morphology, acetabular retroversion or anteversion, are precursors to symptomatic hip joint injury or osteoarthritis.

Gluteus maximus contraction velocity assessed by tensiomyography improves following arthroscopic treatment of femoroacetabular impingement

PURPOSE

Muscular impairment, particularly for the gluteus maximus (GM), has been observed in femoroacetabular impingement (FAI). The purpose of this study was to evaluate the tensiomyographic changes of the GM, rectus femoris (RF) and adductor longus (AL) before and after arthroscopic surgery for FAI. It was hypothesized that arthroscopic treatment of FAI would improve the preoperative muscular impairment.

METHODS

All patients undergoing arthroscopic treatment of FAI between January and July 2015 were approached for eligibility. Patients included had a tensiomyography (TMG) evaluation including maximal displacement (Dm) and contraction time (Tc) of these muscles in both lower extremities. TMG values between the injured and healthy sides were compared at the preoperative and post-operative (3, 6 and 12 months after surgery) periods.

RESULTS

There were no significant differences for the RF and AL, and Dm of the GM for any of the comparisons (n.s.). However, GM Tc was significantly lower at 3 (p = 0.016), 6 (p = 0.008), and 12 (p = 0.049) months after surgery in the injured side compared to preoperatively. GM Tc of the healthy side was significantly lower than the injured side at the preoperative period (p = 0.004) and at 3 (p = 0.024) and 6 (p = 0.028) months after surgery, but these significant differences were no longer observed at 12 months after surgery (n.s.). There was a significant reduction of pain in the GM area at 1 year after surgery compared to preoperatively (p < 0.0001).

CONCLUSIONS

Arthroscopic treatment of FAI and the subsequent rehabilitation improves contraction velocity of the GM of the injured side. Despite Tc is elevated in the GM of the injured compared to the healthy side preoperatively and at 3 and 6 months after surgery, differences in Tc between both sides are no longer significant at 12 months. Athletes with FAI participating in sports with great involvement of GM may benefit from arthroscopic treatment and its subsequent rehabilitation. TMG can be used as an objective measurement to monitor muscular improvements of the GM after surgery in these patients.

LEVEL OF EVIDENCE

II.

Trunk, pelvis and hip biomechanics in individuals with femoroacetabular impingement syndrome: Strategies for step ascent

BACKGROUND

Femoroacetabular impingment (FAI) syndrome is common among young active adults and a proposed risk factor for the future development of hip osteoarthritis. Pain is dominant and drives clinical decision-making. Evidence for altered hip joint function in this patient population is inconsistent, making the identification of treatment targets challenging. A broader assessment, considering adjacent body segments (i.e. pelvis, trunk) and individual movement strategies, may better inform treatment programs. This exploratory study aimed to compare trunk, pelvis, and hip biomechanics during step ascent between individuals with and without FAI syndrome.

METHODS

Fifteen participants diagnosed with symptomatic cam-type or combined (cam plus pincer) FAI who were scheduled for arthroscopic surgery, and 11 age-, and sex-comparable pain- and disease-free individuals, underwent three-dimensional motion analysis during a step ascent task. Trunk, pelvis and hip biomechanics were compared between groups.

RESULTS

Participants with FAI syndrome exhibited altered ipsilateral trunk lean and pelvic rise towards the symptomatic side during single-leg support compared to controls. Alterations were not uniformly adopted across all individuals with FAI syndrome; those who exhibited more pronounced alterations to frontal plane pelvis control tended to report pain during the task. There were minimal between-group differences for hip biomechanics.

CONCLUSION

Exploratory data suggest biomechanics at the trunk and pelvis during step ascent differ between individuals with and without FAI syndrome. Those with FAI syndrome implement a range of proximal strategies for task completion, some of which may have relevance for rehabilitation. Longitudinal investigations of larger cohorts are required to evaluate hypothesized clinical and structural consequences.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

KEY POINTS

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

A Comparison of Clinical Outcomes After Unilateral or Bilateral Hip Arthroscopic Surgery: Age- and Sex-Matched Cohort Study

BACKGROUND

A significant number of patients undergoing hip arthroscopic surgery for femoroacetabular impingement (FAI) have bilateral deformities and may require surgery for both hips.

PURPOSE

To compare outcomes between patients who underwent bilateral hip arthroscopic surgery to a matched cohort of patients who underwent unilateral hip arthroscopic surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A consecutive series of patients who underwent primary hip arthroscopic surgery for FAI by a single fellowship-trained surgeon from January 2012 to January 2014 and had a minimum follow-up of 2 years were evaluated. Patients who underwent staged bilateral hip arthroscopic surgery were identified and matched 1:2 to patients who underwent unilateral hip arthroscopic surgery based on age, sex, and body mass index (BMI). Demographic, preoperative, and postoperative variables were compared between the groups.

RESULTS

Forty-three patients in the bilateral group were matched with 86 patients in the unilateral group based on sex (24 female [56%] vs 48 female [56%], respectively; P > .99), age (28.6 ± 10.8 years vs 28.9 ± 10.8 years, respectively; P = .88), and BMI (24.8 ± 5.8 kg/m² vs 24.8 ± 4.0 kg/m², respectively; P = .98). There were no significant preoperative demographic or radiographic differences between the groups. Both groups demonstrated significant preoperative to postoperative improvements in the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), and modified Harris Hip Score (mHHS) ( P < .0001 for all). When compared with patients in the unilateral group, patients who underwent bilateral hip arthroscopic surgery had less improvement in mHHS and pain scores. Sixty-five (76%) patients in the unilateral group achieved the minimum clinically important difference (MCID) for the mHHS compared with 21 (49%) in the bilateral group ( P = .03), while 64 (74%) patients achieved the patient acceptable symptomatic state (PASS) for the mHHS compared with 22 (51%) in the bilateral group ( P = .02). Patients in the bilateral group with greater than 10 months between surgical procedures had lower postoperative HOS-ADL scores ( P = .04) and lower improvement in pain and HOS-SS scores ( P < .0001 and P = .05, respectively).

CONCLUSION

Patients who underwent unilateral and bilateral hip arthroscopic surgery for FAI had improved functional outcomes after 2 years. However, patients who underwent bilateral hip arthroscopic surgery had less improvement in their mHHS and pain scores compared with those who underwent unilateral hip arthroscopic surgery but no differences in HOS-ADL, HOS-SS, or satisfaction scores. Patients in the bilateral group with longer than 10 months between surgical procedures had lower outcome scores than patients who underwent their second surgical procedure within 10 months of their primary surgery.

Three-dimensional assessment of impingement risk in geometrically parameterised hips compared with clinical measures

Abnormal bony morphology is a factor implicated in hip joint soft tissue damage and an increased lifetime risk of osteoarthritis. Standard 2-dimensional radiographic measurements for diagnosis of hip deformities, such as cam deformities on the femoral neck, do not capture the full joint geometry and are not indicative of symptomatic damage. In this study, a 3-dimensional geometric parameterisation system was developed to capture key variations in the femur and acetabulum of subjects with clinically diagnosed cam deformity. The parameterisation was performed for computed tomography scans of 20 patients (10 female and 10 male). Novel quantitative measures of cam deformity were taken and used to assess differences in morphological deformities between males and females. The parametric surfaces matched the more detailed, segmented hip bone geometry with low fitting error. The quantitative severity measures captured both the size and the position of cams and distinguished between cam and control femurs. The precision of the measures was sufficient to identify differences between subjects that could not be seen with the sole use of 2-dimensional imaging. In particular, cams were found to be more superiorly located in males than in females. As well as providing a means to distinguish between subjects more clearly, the new geometric hip parameterisation facilitates the flexible and rapid generation of a range of realistic hip geometries including cams. When combined with material property models, these stratified cam shapes can be used for further assessment of the effect of the geometric variation under impingement conditions.