Diagnostic Musculoskeletal Ultrasound in the Evaluation of the Extensor Digitorum Longus

The extensor digitorum longus muscle and tendons are among the longer muscle-tendon units in the lower leg and foot. This feather-like, unipennate muscle is part of the anterior ankle group, attaching proximally along the lateral side of the lateral condyle of the tibia and the upper three-quarters of the fibula’s inner surface. Near the ankle, the tendon narrows as it passes beneath the extensor retinacula and divides into four smaller tendons that connect to the toes. Since it crosses the ankle joint and attaches to the second through fifth toes, it facilitates dorsiflexion of the foot and extension of the toe joints. An accurate diagnosis of extensor digitorum longus tendonitis or rupture is crucial for appropriate treatment planning and optimal patient outcomes. Diagnostic musculoskeletal ultrasound (MSKUS) has become a widely used imaging modality for assessing many ankle and foot pathologies. It offers a portable, real-time, and cost-effective alternative that is gaining traction in rehabilitation and sports medicine settings. MSKUS has emerged as a valuable, non-invasive imaging modality for evaluating ankle and foot injuries. This manuscript reviews the utility of MSKUS in evaluating the quality, size, sonographic techniques, and clinical implications for rehabilitation professionals who need to visualize the extensor digitorum longus. By integrating MSKUS into clinical practice, providers can improve diagnostic accuracy, increase diagnostic confidence, monitor healing progression, and guide rehabilitation strategies to optimize outcomes for patients with ankle and foot injuries.