Symptomatic Ulnar Nerve Compression After Biceps-to-Triceps Tendon Transfer for Elbow Extension Reconstruction in Tetraplegia: A Case Report.

Introduction: Medially routed biceps-to-triceps tendon transfer for elbow extension reconstruction in spinal cord injury (SCI) has proven to be a reliable procedure. This technique classically places the tendon transfer superficial to a paralyzed ulnar nerve, with a theoretical risk of compression neuropathy.

Case presentation: A 21-year-old male with a C5 American Spinal Injury Association Impairment Scale (AIS) grade B SCI who underwent bilateral biceps-to-triceps tendon transfers presented with new-onset paresthesias in the ring and small fingers 10.5 years following initial reconstructive surgery. These symptoms were accompanied by triggered upper extremity spasticity following repeated elbow flexion exercises. Clinical exam findings and ultrasound imaging were consistent with bilateral ulnar nerve compression. Surgical exploration revealed that the ulnar nerve was severely compressed by the tendinous part of the biceps bilaterally. The surgical technique used to decompress the ulnar nerve and perform an anterior transposition without taking down the rerouted biceps tendon is described. The patient demonstrated favorable post-operative outcomes.

Conclusion: Compression of a paralyzed ulnar nerve in a tetraplegic patient after medially routed biceps-to-triceps tendon transfer can present with both classical and/or atypical findings. Although rare, this complication can be managed surgically by anterior transposition of the ulnar nerve without taking down the rerouted biceps tendon. The senior authors have modified their technique and now recommend passing the rerouted biceps tendon deep to the ulnar nerve to avoid compression neuropathy.