Lower limb biomechanics in femoroacetabular impingement syndrome, asymptomatic cam morphology, and controls during bilateral and single-leg squatting.

The hip joint biomechanics of people with femoroacetabular impingement (FAI) syndrome are different from those of healthy people during a double-leg squat. However, information on biomechanics during a single-leg squat is limited. To compare hip joint biomechanics between people with FAI syndrome and people without hip pain during double-leg and single-leg squats. Fourteen people with FAI syndrome (cam, n = 7; pincer, n = 1; mixed, n = 6) and 14 people without hip pain participated in this cross-sectional, case-control, laboratory-based study. Three-dimensional biomechanics data were collected while all participants performed a double-leg and a single-leg squat. Two-way mixed-model analyses of variance were used to assess group-by-task interactions for hip joint angles, thigh and pelvis segment angles, hip joint internal moments, and squat performance variables. Post hoc analyses for all variables with a significant group-by-task interaction were performed to identify between-group differences for each task. There were significant group-by-task interactions for peak hip joint (P = .014, η2 = 0.211) and thigh segment (P = .009, η2 = 0.233) adduction angles, and for peak hip joint abduction (P = .002, η2 = 0.308) and extension (P = .016, η2 = 0.203) internal moments. There were no significant group-by-task interactions for squat performance variables. Biomechanical differences at the hip between people with FAI syndrome and those without hip pain were exaggerated during a single-leg squat compared to a double-leg squat task. Diagnosis, level 4. J Orthop Sports Phys Ther 2019;49(12):908-916. Epub 23 Jul 2019. doi:10.2519/jospt.2019.8356.

Trunk, pelvis and lower limb walking biomechanics are similarly altered in those with femoroacetabular impingement syndrome regardless of cam morphology size

Background: Impairments in squat depth have been reported in patients with femoroacetabular impingement syndrome (FAIS). However, little is known about single-leg squat (SLS) performance in these patients, despite this task being commonly used in the rehabilitation and training settings. Purpose/Hypothesis: The aims of this study were (1) to investigate whether patients with FAIS demonstrate differences in SLS performance compared with healthy controls and (2) to determine whether dynamic range of motion (ROM), muscle strength, hip morphologic measures, hip pain, and hip-specific function predict SLS performance in patients with FAIS. We hypothesized that patients with FAIS would demonstrate impaired SLS performance and that impaired hip biomechanics, muscle strength, and hip-specific function would predict squat performance in patients with FAIS. Study Design: Controlled laboratory study. Methods: Three-dimensional (3D) kinematic data were collected at 100 Hz using a 20-camera 3D motion capture system during 3 SLS trials in 34 patients with FAIS and 26 healthy controls. Isometric muscle strength was tested with a stationary handheld dynamometer in all participants. Squat performance was quantified by squat depth (in meters), and the biomechanical variables of dynamic ROM of the pelvis, the hip, the knee, and the ankle in all planes were calculated. In patients with FAIS, femoral and acetabular morphology were measured using radiographic alpha angles and lateral center-edge angles. Hip pain and hip-specific function were measured using the visual analog scale for pain and the Hip Outcome Score Activities of Daily Living subscale, respectively. Two-tailed independent-samples t tests were used to determine between-group differences for squat depth, dynamic ROM variables, and muscle strength. A hierarchical multiple linear regression (MLR) model was used to determine whether biomechanical variables, muscle strength, hip morphology measures, hip pain, and hip-specific function were predictors of squat depth. All statistical analyses were performed using SPSS Version 26. Results: There were no between-group differences in age (FAIS, 30.0 ± 7.0 years vs controls, 27.3 ± 7.0 years; P = .18) or body mass index (FAIS, 23.1 ± 2.8 vs controls, 22.6 ± 3.2; P = .51). Squat depth was less in patients with FAIS compared with healthy controls (FAIS, 0.24 ± 0.4 m vs controls, 0.29 ± 0.05 m; P < .001). In the sagittal plane, patients with FAIS demonstrated less dynamic ROM of the hip (FAIS, 67.8°± 12.4° vs controls, 79.2°± 12.5°; P = .001) and the knee (FAIS, 71.9°± 9.4° vs controls, 78.9°± 13.2°; P = .02) compared with controls. Patients with FAIS also demonstrated a less dynamic coronal plane pelvis ROM (FAIS, 11.3°± 5.0° vs controls, 14.4°± 6.7°; P = .044). Patients with FAIS had reduced hip muscle strength of the hip external rotator (FAIS, 1 ± 0.3 N/kg vs controls, 1.2 ± 0.3 N/kg; P = .034), hip internal rotator (FAIS, 0.8 ± 0.3 N/kg vs controls 1 ± 0.3 N/kg; P = .03), and hip flexor (FAIS, 4 ± 1.1 N/kg vs controls, 4.8 ± 1.2 N/kg; P = .013) muscle groups. The hierarchical MLR revealed that the dynamic ROM of the hip, the knee, and the pelvis, the hip external rotation muscle strength, and the femoral alpha angles were all significant predictors of squat performance, and the final MLR model explained 92.4% of the total variance in squat depth in patients with FAIS. Conclusion: Patients with FAIS demonstrate impaired SLS squat performance compared with healthy controls. This impaired squat performance is predominantly predicted by sagittal plane knee and hip biomechanics and hip external rotator strength, and less by frontal plane pelvic ROM and hip morphology in patients with FAIS. Clinical Relevance: Clinicians should focus treatment on improving dynamic ROM and hip external rotator muscle strength to improve squat performance; however, femoral morphology should also be considered in the treatment paradigm.

Introduction Patients with intra-articular hip pathology see an average of three clinicians prior to diagnosis. A 2015 study by Rankin et al. suggested femoroacetabular impingement (FAI) syndrome was described in 40% of hip joint pathology. FAI syndrome occurs when irregularities in femoral and acetabular anatomy create abnormal contact forces across the joint, leading to labral and chondral damage. These anatomical irregularities are categorised into three morphologies: cam (an aspherical femur head resulting in superior acetabulum impingement), pincer (over-coverage of the femoral head by the acetabulum) and mixed. This case highlights this tricky diagnosis in a young and active patient. Case description A 28-year-old fit and active man presented with a three-year history of gradually worsening atraumatic right hip pain. He described a constant ache in the anterior aspect of the right hip, occasionally referring to the groin and right knee. He experienced significant morning stiffness of the right hip, lasting approximately 30 minutes. His symptoms were aggravated by prolonged walking and running. He denied lower limb paraesthesia, numbness, incontinence, rashes and was otherwise systemically well. He reported no past medical history, family history and was on no regular medications. He practises yoga a few times a week but has had to stop his recreational running due to his pain. Examination revealed no deformity of the lumbar or sacral spine. There was no swelling, redness, or tenderness on palpation. Range of motion of the right hip was significantly limited, with flexion to 90 degrees, abduction to 30 degrees, external rotation to 25 degrees and internal rotation to 0 degrees (in flexion). Trendelenburg's test was negative. Functional assessment revealed poor pelvic control on right side during single-leg squat and lunge. The modified Thomas test showed tense hip flexors bilaterally, worse on right. FADIR test was strongly positive on the right but all other special tests for the hip, including Laslett’s cluster of sacroiliac provocation tests, were negative. After significant discussion regarding radiation exposure, he was referred for an X-ray pelvis and right hip. This revealed significant widening of both femoral heads and necks, with joint space narrowing with articular sclerosis. This was worse on the right side with femoral osteophyte formation. Appearances were in keeping with bilateral cam morphology, with associated changes in the right hip joint indicative of femoral acetabular impingement. He has since been referred to physiotherapy and orthopaedics to explore management options, whilst encouraged to continue his yoga practise. Discussion A 2014 cross-sectional study by Clohisy et al. reported the average age of FAI syndrome to be 28 years and the Frank et al. 2015 systematic review revealed cam morphology was more prevalent in men and three times more likely in athletes than the general population. This patient exemplifies these demographics. His history and examination contained features typical of FAI syndrome: his description of pain on movement, positive FADIR test, restricted internal rotation restriction, and poor single leg balance. However, classical symptoms of clicking, catching, and locking were not reported. This corroborates with the 2016 Warwick Consensus statement that FAI syndrome diagnosis does not rely on a single symptom or clinical sign. The statement confirms that X-Ray is the initial imaging modality of choice, which includes AP, lateral and Dunn views as was requested in this case. Treatment options to allow our patient to return to running include conservative management with patient education, anti-inflammatory agents, and physiotherapy. The Hoit et al. 2019 systematic review showed that physiotherapy, targeting core stability, proprioception, and correction of hip destabilising imbalances, provided significant improvements in functional outcomes compared to controls without. This supports a trial of physiotherapy before further interventions and commends the patient’s participation in yoga. Evidence for intra-articular injections of corticosteroids, hyaluronic acid or platelet-rich plasma is currently limited and are unlikely to be considered for this patient. Surgery aims to arthroscopically correct anatomical abnormalities. Two RCTs, UK FASHIoN and FAIT, compared surgery and physiotherapy interventions in FAI syndrome patients and showed statistically significant improvement in symptoms and functional outcomes with surgery, particularly in those with cam morphology like our patient. Orthopaedics may offer this option to our patient due to his lack of negative prognostic indicators related to surgery with the exception of his extended duration of symptoms. Key learning points Hip and pelvic pain with morning stiffness in a young adult male is not always inflammatory in nature, and femoroacetabular impingement (FAI) syndrome should be considered in these patients. FAI is associated with pain on movement, positive FADIR test, restricted internal rotation, and poor single leg balance, but clicking/locking is not always described. In primary care where access to MR imaging may be limited, AP, lateral and Dunn view X-rays of the pelvis and femoral neck can help clinch the diagnosis if there is uncertainty Cam morphology of the hip, revealed by X-ray, is more prevalent in men and athletes and has better treatment outcomes with surgery compared to physiotherapy. Referral to a specialist musculoskeletal service is recommended to discuss management options of physiotherapy, intra-articular injections and surgery alongside patient education and anti-inflammatory medication. Discussing the clinical experience of peers evaluating, diagnosing, treating, and monitoring long-term outcomes of similar patients will contribute to the understanding of the rapidly evolving evidence base.

Objective(1) Identify differences in hip and pelvic biomechanics in patients with femoroacetabular impingement syndrome (FAIS) compared with controls during everyday activities (eg, walking, squatting); and (2) evaluate the effects of...

Sprinting often provokes hip pain in individuals with femoroacetabular impingement syndrome (FAIS). Asphericity of the femoral head-neck junction (cam morphology) characteristic of FAIS can increase the risk of anterior-superior acetabular cartilage damage. This study aimed to 1) compare hip contact forces (magnitude and direction) during sprinting between individuals with FAIS, asymptomatic cam morphology (CAM), and controls without cam morphology, and 2) identify the phases of sprinting with high levels of anteriorly directed hip contact forces. Forty-six recreationally active individuals with comparable levels of physical activity were divided into three groups (FAIS, 14; CAM, 15; control, 17) based on their history of hip/groin pain, results of clinical impingement tests, and presence of cam morphology (alpha angle >55°). Three-dimensional marker trajectories, ground reaction forces, and electromyograms from 12 lower-limb muscles were recorded during 10-m overground sprinting trials. A linearly scaled electromyogram-informed neuromusculoskeletal model was used to calculate hip contact force magnitude (resultant, anterior-posterior, inferior-superior, medio-lateral) and angle (sagittal and frontal planes). Between-group comparisons were made using two-sample t -tests via statistical parametric mapping ( P < 0.05). No significant differences in magnitude or direction of hip contact forces were observed between FAIS and CAM or between FAIS and control groups during any phase of the sprint cycle. The highest anteriorly directed hip contact forces were observed during the initial swing phase of the sprint cycle. Hip contact forces during sprinting do not differentiate recreationally active individuals with FAIS from asymptomatic individuals with and without cam morphology. Hip loading during early swing, where peak anterior loading occurs, may be a potential mechanism for cartilage damage during sprinting-related sports in individuals with FAIS and/or asymptomatic cam morphology.

Relationships between hip strength and hip biomechanics during running in people with femoroacetabular impingement syndrome

There is no agreement on how to classify, define or diagnose hip-related pain—a common cause of hip and groin pain in young and middle-aged active adults. This complicates the work...

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It is unknown if football players with femoroacetabular impingement (FAI) syndrome report worse burden than those with other causes of hip/groin pain, and to what extent this is mediated by cartilage defects and labral tears. Football players with FAI syndrome would report worse burden than other symptomatic players, with the effect partially mediated by cartilage defects and/or labral tears. Cross-sectional study. Level 4. Football (soccer and Australian football) players (n = 165; 35 women) with hip/groin pain (≥6 months and positive flexion-adduction-internal rotation test) were recruited. Participants completed 2 patient-reported outcome measures (PROMs; the International Hip Outcome Tool-33 [iHOT-33] and Copenhagen Hip and Groin Outcome Score [HAGOS]) and underwent hip radiographs and magnetic resonance imaging (MRI). FAI syndrome was determined to be present when cam and/or pincer morphology were present. Cartilage defects and labral tears were graded as present or absent using MRI. Linear regression models investigated relationships between FAI syndrome (dichotomous independent variable) and PROM scores (dependent variables). Mediation analyses investigated the effect of cartilage defects and labral tears on these relationships. FAI syndrome was not related to PROM scores (unadjusted b values ranged from -4.693 (P = 0.23) to 0.337 (P = 0.93)) and cartilage defects and/or labral tears did not mediate its effect (P = 0.22-0.97). Football players with FAI syndrome did not report worse burden than those with other causes of hip/groin pain. Cartilage defects and/or labral tears did not explain the effect of FAI syndrome on reported burden. FAI syndrome, cartilage defects, and labral tears were prevalent but unrelated to reported burden in symptomatic football players.

Cam morphology size and location might affect the severity of reported burden in people with femoroacetabular impingement (FAI) syndrome. We investigated the relationship between cam morphology size (i.e., alpha angle) and self‐reported hip/groin burden (i.e., scores for the International Hip Outcome Tool‐33 (iHOT‐33) and Copenhagen Hip and Groin Outcome Score (HAGOS)), examined separately for the anteroposterior pelvis (AP) and Dunn 45° radiographs in football players with FAI syndrome. In total, 118 (12 women) subelite football (soccer or Australian football) players with FAI syndrome with cam morphology (alpha angle ≥60°) participated. One blinded assessor quantified superior and anterosuperior cam morphology size by measuring alpha angles for the AP and Dunn 45° radiographs, respectively. Linear regression models investigated relationships between alpha angle (continuous independent variable, separately measured for the AP and Dunn 45° radiographs) and iHOT‐33 and HAGOS scores (dependent variables). Larger anterosuperior cam morphology (seen on the Dunn 45° radiograph) was associated with lower (i.e., worse) scores for the iHOT‐Total, iHOT‐Symptoms, iHOT‐Job, and iHOT‐Social subscales (unadjusted estimate range −0.553 to −0.319 [95% confidence interval −0.900 to −0.037], p = 0.002 to 0.027), but not the iHOT‐Sport (p = 0.459) nor any HAGOS scores (p = 0.110 to 0.802). Superior cam morphology size (measured using the AP radiograph) was not associated with any iHOT‐33 or HAGOS scores (p = 0.085 to 0.975). Larger anterosuperior cam morphology may be more relevant to pain and symptoms in football players with FAI syndrome than superior cam morphology, warranting investigation of its effects on reported burden and hip disease over time.

Current trends in sport and exercise hip conditions: Intra-articular and extra-articular hip pain, with detailed focus on femoroacetabular impingement (FAI) syndrome.

Hip morphology has emerged as an important factor in the development of hip osteoarthritis (OA). Cam morphology is one of the most common hip morphologies, characterized by a bony prominence around the femoral head-neck junction of the hip that alters the normal shape of the femoral head. Cam morphology can contribute to intra-articular joint damage by generating abnormal contact stresses at this junction, initiating femoroacetabular impingement (FAI) syndrome and eventually leading to hip OA. Cam morphology is a causal risk factor for hip OA, but not everybody with this morphology will develop FAI syndrome or OA. The pathogenesis of hip disease is probably driven by the interplay between cam morphology, other coexisting hip morphologies (such as pincer morphology), femoral version, spinopelvic parameters and biomechanical and environmental factors. Early identification of FAI syndrome could enable timely, multidisciplinary intervention and offers the potential to modify the trajectory of disease. Cam morphology can develop during skeletal maturation, particularly in adolescents participating in high-joint-load physical activity, raising important questions about preventative approaches. Management of FAI syndrome includes both surgical and non-surgical approaches. Emerging insights into the pathogenesis and detection of cam morphology are paving the way for more targeted interventions and a deeper understanding of its role in FAI syndrome and hip OA development.

Does cam morphology size and location affect self-reported burden in football players with femoroacetabular impingement syndrome?

Femoroacetabular impingement syndrome (FAIS) is a movement-related condition associated with pain and impaired function; yet the evidence for level ground walking hip biomechanics is limited and inconsistent. Challenging the hip with inclined walking for individuals with FAIS might be important for elucidating mechanically driven function loss and informing tailored rehabilitation. The purpose of this study was to determine the effects of progressive inclined walking on sagittal hip biomechanics and hip flexor and extensor activity in individuals with FAIS. Cross-sectional. Fourteen participants (7 individuals with FAIS and 7 asymptomatic individuals) underwent motion capture and electromyographic analysis during 3 treadmill walking conditions (0°/5°/10°). Statistical parametric mapping was used to compare the sagittal hip kinematic waveforms and hip flexor (rectus femoris) and extensor (gluteus maximus) waveforms between groups and walking conditions. Hip flexion was significantly increased throughout the gait cycle in individuals with FAIS compared with asymptomatic individuals (P < .01) but was not dependent on incline. Rectus femoris activation was significantly increased throughout stance in individuals with FAIS compared with asymptomatic individuals (P < .01). Gluteus maximus activity significantly increased with progressive inclination in asymptomatic individuals (P < .01), with no significant change in activity for individuals with FAIS. Hip biomechanics and muscle activity during inclined walking mirrored that of arthrogenic muscle inhibition, highlighted by a prominent flexor role and lack of hip extensor activity in individuals with FAIS. Future research investigating discordant activity between hip flexors and extensors during complex functional tasks may help identify rehabilitation targets.