Flexor Digitorum Longus Strain in a Spinal Cord Injury Patient: A Case Report of a Rare Diagnosis

Calf injuries are common, and they are often described in the gastrocnemius, soleus, or plantaris muscle. They are also documented in the flexor hallucis longus and the tibialis posterior, although less frequently. We present a case of an acute flexor digitorum longus muscle strain, a rare injury, often underreported and not well-documented in the literature. We describe the case of a 34-year-old active female undergoing rehabilitation for an incomplete tetraplegia, with suspected multiple sclerosis and left limb monoparesis. She sustained acute pain in her right leg during eccentric plantar flexion movement. Examination revealed pain with flexion of the second to fifth toes. High-resolution ultrasound confirmed disruption of flexor digitorum longus muscle fibers. The patient underwent conservative rehabilitation and returned to her pre-injury activity level within eight weeks, although subclinical strength deficits in the right limb were evident in the gait analysis. Flexor digitorum longus strains are rare but exist and should be considered in the differential diagnosis of calf muscle injuries in healthy and disabled patients. Baseline neurological deficits can influence presentation and rehabilitation progression. Further research is needed to clarify prognosis and return-to-activity criteria for flexor digitorum longus strains.