Femoral cam deformity due to anterior capsular force: A theoretical model with MRI and cadaveric correlation

Correlation of hip capsule morphology with patient symptoms from femoroacetabular impingement

The relationship between morphological characteristics of the hip capsule and patient symptoms in the setting of femoroacetabular impingement (FAI) is undefined. In this study, patients with symptomatic FAI prospectively underwent 3T magnetic resonance (MR) imaging of the affected hip and completed the hip disability and osteoarthritis outcome score (HOOS) to determine the correlation between hip capsule anatomy and patient symptoms. Anterior hip capsule volume, posterior capsule volume, anterior-posterior capsule volume ratio, and proximal-distal volume ratio in the anterior capsule were quantified and measured using axial-oblique intermediate-weighted 3D fast spin echo MR images. A total of 35 patients (35 hips) were included for analysis (mean age: 30.6 years; mean body mass index [BMI]: 24.9 kg/m² ; 57% male). The mean alpha angle was 62.2° ± 4.7°, the mean anterior hip capsule volume was 1705.1 ± 450.3 mm³ , the mean posterior hip capsule volume was 1284.8 ± 268.5 mm³ , the mean anterior to posterior capsule volume ratio was 1.1 ± 0.39, and the mean proximal to distal volume ratio of the anterior capsule was 0.65 ± 0.28. There was no correlation between age, gender, or BMI, and any hip capsule characteristics. Worse scores on the HOOS pain scale were correlated with increased anterior to posterior volume ratio (r = -.38; 95% confidence interval: -0.06 to -0.63). In conclusion, hip capsule morphology correlates with patient symptoms in the setting of FAI as increased anterior capsular volume, relative to posterior capsular volume, is associated with greater patient pain.

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

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

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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