Bildgebung des Hüftgelenks beim femoroazetabulären Impingement

Sonography-based determination of hip joint anterior head-neck offset is reliable and reproducible for CAM deformity assessment

Purpose

Native X-ray, magnetic resonance imaging (MRI), and computed tomography (CT) are standard methods for determining head-neck offset (HNO) in femoro-acetabular impingement (FAI). Our hypothesis was that sonography-assisted determination of the offset in CAM deformity of the hip is a cheap, radiation-free, and reliable alternative to conventional alpha-angle determination.

Methods

Patients with hip pain and suspected CAM impingement who underwent anterior-longitudinal hip sonography according to DEGUM standard procedures and MRI were included in this single-center study between January 2015 and December 2019. Offset was determined three times on MRI and sonography by two independent investigators.

Results

285 patients were screened and 110 patients (49 females, 61 males) met the inclusion criteria. The mean age at the time of investigation of 54 left and 56 right hip joints was 54.2 years. 1320 measurements were performed. No significant difference in HNO determination between MRI (6.11 mm+/-2.37) and sonography (5.93 mm+/-2.20) could be identified. The mean difference was 0.32 mm+/-0.32 mm (p>0.05) with a maximum deviation of 2.08 mm (outlier).

Conclusion

Sonography-assisted determination of head-neck offset is a reliable and reproducible method and is not inferior to determination with MRI. Sonography can be used initially as an alternative or additional tool for the qualitative determination of CAM deformity of the hip joint.

Association of Chondrolabral Lesions with Ultrasound-Guided Detection of Pathological Head-Neck Contour

OBJECTIVE

This study aimed to investigate whether the asphericity of the neck-head junction of the femur confirmed via ultrasound is associated with further pathology due to femoro-acetabular impingement (FAI).

METHODOLOGY

After a clinical examination with positive FAI tests, an ultrasound examination of the hip was performed. In the case of asphericity, a quantitative ultrasound-assisted assessment of the hip was performed, followed by contrast-enhanced arthro-MRI with the question of cartilage or labral damage.

RESULTS AND CONCLUSIONS

We included 51 patients with a mean age of 35.25. According to the examination algorithm, asphericity was present in all patients via ultrasonography. The average anterior alpha angle (AAA) determined in ultrasonography was 43.49°. The average AAA on the arthro-MRI was 44.19°. The mean anterior head neck offset (AHNO) in ultrasound was 5.27 mm, and in arthro-MRI, it was 5.36 mm. Arthro-MRI confirmed a bump in 47 patients and a talization disorder in 4 patients. In 49 patients, a labral lesion was found, with one being a re-rupture. Furthermore, in one patient, labral degeneration was identified. Cartilage damage to the hip joint was found in 25 patients. Two patients had neither labral nor cartilage damage in the arthro-MRI. In our study, sonographically confirmed asphericity of the head-neck junction was found in 49 cases, which was associated with further pathology and, according to the current doctrine, was attributable to the FAI and required surgical intervention. This study shows that the detection of a pathologic head and neck contour via ultrasound in combination with positive clinical signs, as present in FAI, is associated with chondrolabral lesions detected via arthro-MRI in 96.1% of cases.

Sonography-Based Determination of Hip Joint Anterior Alpha-Angle: A Reliable and Reproducible Method

PURPOSE

Femoroacetabular impingement (FAI) is a known risk factor for hip osteoarthritis. The gold standard for diagnostics is X-ray and MRI. The accuracy of hip joint alpha angle measurements obtained using sonography is equal to measurements in MRI for patients with cam impingement of the hip joint.

MATERIALS AND METHODS

Patients with hip pain and MRI and sonography were evaluated between January 2015 and December 2019 in a single center. Musculoskeletal sonography was performed according to the DEGUM guidelines by ultrasound-certified specialists. Measurements were repeated three times by two independent investigators.

RESULTS

285 patients were screened, and 110 patients (49 females, 61 males) met the inclusion criteria. The mean age at time of investigation of 54 left and 56 right hip joints was 54.2 years. 1320 measurements were performed. The mean alpha angle was 50.7° in MRI and 50.4° in sonography with a mean difference of 0.28° (p>0.05).

CONCLUSION

Determining hip alpha angle using sonography is a safe and reproducible method. No statistically significant differences between results in MRI and sonography could be seen. Although this is a retrospective, single-center study including only Caucasian mid-Europeans and with the known limitations of ultrasound imaging, it nevertheless shows that sonography can be used as a simple, cheap, and fast technique to assess the hip alpha angle without losing diagnostic quality.