Introduction
Ultrasound (US), besides being a widely available, noninvasive, relatively inexpensive imaging modality, allows dynamic and weight-bearing scans, hence encouraging its utilization in various musculoskeletal applications. This study is to assess the reliability of US in supine and standing (weight-bearing) positions to detect medial meniscus extrusion as an indirect sign of tear.
Patients and methods
This observational prospective study included 103 patients: 48 females and 55 males; mean age: 36.82 years. The extrusion was measured on supine and standing US. The included patients were classified into two groups according to the MRI diagnosis of tear. Statistical analysis was performed and value less than 0.05 was considered significant. Receiver-operating characteristic curve was done to reach a cutoff value for extrusion as a sign of tear.
Results
This study included 103 patients: 48 females and 55 males; mean age: 36.82 years. The medial meniscus extrusion was measured using US in supine and standing positions. The included patients were classified into two groups according to the presence or absence of tears on MRI. Forty-five (43.68%) patients had medial meniscal tears (horizontal, vertical, branching, radial, root, and bucket-handle tears). The measured extrusion in supine and standing positions, as well as the difference between the measurements in the two groups, all showed a significant value of 0.001. In patients with meniscal tears, the mean extrusion was 2.5±0.65 and 3.82±0.84 mm in supine and standing positions, respectively. The extrusion in standing position with a cutoff value more than or equal to 3.3 mm showed specificity (96.55%), positive predictive value (93.8%), and accuracy (83.5%) for detection of tear.
Conclusion
US is reliable in determining medial meniscal extrusion as an indirect sign of tear. US in standing position yields better diagnostic accuracy compared with supine position.