Purpose
High ulnar nerve palsy, which could be caused by chronic compression around the elbow or traumatic injury proximal to the innervation of flexor carpi ulnaris, usually ends up with disappointing outcome despite of meticulous surgical management, such as release and transposition for tardy ulnar palsy, or microsurgical repair or grafting for traumatic cases. Transfer of anterior interosseous nerve (AIN) to distal ulnar motor fascicle for traumatic ulnar nerve injuries has been documented to improve motor recovery compared with those underwent merely nerve repair or grafting. Nevertheless, the role of AIN transfer in compressive ulnar palsy was relatively unclear. In this study, we compared the functional outcomes of end-to-side AIN transfer between traumatic ulnar palsy and compressive ulnar palsy in order to identify the efficacy of AIN transfer in chronic compressive cases.
Materials and Methods
From January of 2013 to December of 2019, in CGMH, 32 patients with traumatic ulnar nerve injury or compressive ulnar palsy were included. All patients received AIN transfer in addition to nerve repair/grafting or cubital tunnel release/transposition, and their data were prospectively collected at 6 months, 12 months, 18 months and 24 months after the surgery. The motor and sensory recovery were evaluated objectively with grip/pinch power, physical findings, and two-point discrimination. Subjective measurements including Quality of Life (QOL), Brief Symptom Rating Scale (BSRS), Disability of Arm Shoulder Hand (DASH) were collected for analysis. Statistical analysis was performed with generalized estimated equation.
Results
The AIN transfer significantly improved the motor recovery since post-OP 6 months, though there was no significant difference between traumatic and compressive palsies. Totally 80% of the patients recovered from ulnar clawing, Froment sign, and were able to performed the intrinsic plus gesture 1 year after AIN transfer. However, only 40% of the patients restored the adduction of ulnar digits and recovered from Wartenberg’s sign 2 years after the transfer. Subjective measurements including QOL, BSRS, and DASH also showed significant improvement since post-OP 6 months, and there was a trend showing more improvement in traumatic cases than compressive palsies.
Conclusions
End-to-side AIN transfer to distal ulnar motor fascicle improved the motor recovery in high ulnar palsies regardless of traumatic injury or chronic compression. The procedure also subjectively lessen the physical and psychological burden of the patients and improved the patients’ quality of life based on the results of patient-reported outcomes. There was no significant difference between two groups regarding grip/pinch strength and physical signs after statistical analysis, though traumatic cases exhibited more improvement in QOL and BSRS in the long run. Our results demonstrate that end-to-side AIN transfer to ulnar motor fascicle is effective not only for traumatic high ulnar palsies, but also effective for chronic compressive ulnar palsies.

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