Reverse shoulder arthroplasty following end-to-end triceps to axillary nerve transfer: a case series

BackgroundThe combination of rotator cuff dysfunction, due to either rotator cuff tear or suprascapular nerve injury, coupled with axillary nerve palsy is a devastating injury. For patients with chronic rotator cuff deficiency, reverse shoulder arthroplasty (RSA) can be utilized but requires a functioning deltoid muscle. Nerve transfer of a triceps branch to the axillary nerve can restore deltoid strength, but it remains unclear if this procedure provides sufficient strength to power a RSA. This series reports 3 cases of successful RSA following end-to-end triceps to axillary nerve transfer.MethodsElectromyography (EMG) and nerve conduction study (NCS) testing performed 4-5 months after initial injury confirmed complete axillary nerve palsy without signs of deltoid recovery. Preoperatively, all patients demonstrated 0/5 deltoid strength and no active shoulder forward flexion or abduction. Transfer of one triceps nerve branch into the anterior division of the axillary nerve was performed in an end-to-end fashion between 5-6 months from initial injury. Postoperatively, EMG confirmed reinnervation of the deltoid muscle. Once deltoid strength was deemed adequate, RSA was performed. Follow-up after RSA ranged from 2.5-5 years.ResultsThree patients underwent end-to-end triceps to axillary nerve transfer followed by RSA. Rotator cuff dysfunction was due to chronic rotator cuff tear in 2 patients and suprascapular nerve palsy in 1 patient. After nerve transfer, patients experienced return of deltoid contraction at 6-12 months postoperatively. Prior to RSA, patients demonstrated at least moderate deltoid muscle contraction but continued difficulty with forward elevation and abduction of the arm, as well as evidence of reinnervation (presence of polyphasics) on EMG deltoid testing. All patients had improvement in shoulder range of motion including forward flexion and abduction after RSA. All patients were able to achieve at least 95 degrees of active forward elevation. All patients reported improvement in quality of life and activities of daily living. Disabilities of the Arm, Shoulder and Hand (DASH) scores obtained for 2 of the 3 patients were 35 and 48. There were no complications.ConclusionsIn this series of patients with combined axillary nerve palsy and rotator cuff deficiency, all patients achieved improved shoulder range of motion and improved function from RSA following end-to-end triceps to axillary nerve transfer. When triceps to axillary nerve transfer results in sufficient reinnervation of the deltoid, RSA can be performed to improve shoulder range of motion and function in carefully selected patients.