587 - Rapid Diagnosis of Peroneus Longus Tendon Grade 1 Strain with Musculoskeletal Ultrasound Optimizes Rehabilitation Course: A Case Report

Case Diagnosis: Grade 1 Strain of Left peroneus longus tendon

Case Description: A 33-year-old male sustained an ankle injury while jogging and stepping on an uneven surface, which led to exaggerated inversion at the ankle joint with an accompanying “pop”. In the following hours, there was immediate swelling, sharp localized pain along the lateral malleolus and limited ROM with inversion, eversion, plantar flexion and dorsiflexion.

Post-injury, a high-resolution musculoskeletal ultrasound (MSKUS) revealed significant fluid accumulation within the synovial sheath distal to the lateral malleolus. The peroneus longus and brevis were intact but there was significant enlargement at the point of maximum tenderness consistent with a Grade 1 strain. The ATFL was intact.

The patient began the alphabet exercise one day s/p injury, and implemented stability work the day after. He subsequently progressed his rehabilitation with more advanced exercises four days s/p injury, light eccentric exercises the two days thereafter, and felt good enough to start strength training seven days s/p injury.

Discussions: Early use of MSKUS in this case was able to quickly identify the injured structure and rule out severe pathology. This allowed for aggressive early mobilization and allowed the patient to return to regular physical activity 10 days s/p injury. This is much faster than the traditional diagnostic and treatment timeline allows.

Conclusions: Rapid diagnosis of fibular tendon injuries with high-resolution MSKUS can enable clinicians to confidently prescribe therapy shortly after injury and lead to an optimized rehabilitation course for these patients.