A significant number of patients present with atypical symptoms from the hip. In these patients there is a need to distinguish the cause of the symptoms, that is, whether they in fact originate from the hip, because of femoroacetabular impingement, or from other anatomical areas (lumbar disc herniation, muscle strains, etc.).
A new study assessed the diagnosis of femoroacetabular impingement in patients with atypical symptoms using ultrasound-guided injection of the hip, over the two years between January 2017 and February 2019.
All the patients underwent a systematic physical examination, ultrasound examination, MRI examination and ultrasound-guided injection of the hip before surgery. The patients with a positive response to the hip injection underwent arthroscopic surgery in order to treat the intra-articular pathology.
The sensitivity, specificity, accuracy and positive predictive value of ultrasound and of MRI were assessed, using the arthroscopic technique as the reference standard for diagnostic performance in intra-articular problems. The accuracy of the ultrasound-guided injection of the hip was also recorded. The hip outcome measures Visual analog scale and modified Harris Hip Score were also assessed both preoperatively and postoperatively.
In total, 78 patients with atypical symptoms were diagnosed with femoroacetabular impingement. Among them, 50 patients had a positive response to the injection, and 28 a negative one. In all, 38 patients ultimately underwent hip arthroscopy. The response to the ultrasound-guided injection was 91.7% accurate in detecting the presence of intra-articular lesions. There were no complications from the injections in any of the patients. The sensitivity, positive predictive value and accuracy of the ultrasound technique were 82.9%, 96.7% and 80.6% respectively. The sensitivity and accuracy of ultrasound assessment for tears of the labrum in the anterosuperior region were 72.2%. For MRI the sensitivity, positive predictive value and accuracy were 72.2%, 96.3% and 74.3% respectively. For MRI the diagnosis of a labral tear was 88.9%.
The authors concluded that ultrasound examination and ultrasound-guided injection of the hip have a high accuracy in the diagnosis of femoroacetabular impingement in patients with atypical symptoms.
Source: “Arthroscopy”, August 2020
