Examining Peripheral Mixed Nerve Reconstruction Failures Using Processed Nerve Allografts

INTRODUCTION

• Favorable rates of meaningful recovery (defined as >M3/S3 or >M3/S4) of processed nerve allografts (PNA) for mixed and motor nerve injuries have been reported, (36-88%) depending on nerve location and reconstruction size.

• There have been very few reports, however, of patients having complete PNA failure (defined as M0/S0).

• The purpose of this study was to provide a case series of patients who suffered a complete failure after PNA for a mixed peripheral nerve.

METHODS

• Consecutive patients who underwent nerve repair with PNA to a peripheral, mixed nerve injury of the upper or lower extremity that was >15 mm with a minimum of 6-months postoperative follow-up were included in this study.

• Patients who were under 18 or those who underwent a pure sensory or motor nerve reconstruction with PNA were excluded.

• All patients were directly operated on by a fellowship-trained hand surgeon with a clinical practice focusing on microsurgery and peripheral nerve.

• The primary outcome was whether the patient was defined as a complete failure (M0/S0) at a minimum of 6-months.

RESULTS

• 19 patients underwent peripheral mixed nerve PNA reconstruction; of these, 9 were included in our analysis (47% compliance) (age: 42.33±16.71 years, 7 females/2 males) with a mean follow-up of 9.67±4.15 months.

• Four patients underwent PNA to the median nerve, 3 to the ulnar nerve, and 2 to the common peroneal nerve.

• 3 patients were indicated for PNA due to the presence of a neuroma, 3 had a laceration with a gap, 2 sustained injuries due to a fracture, and 1 sustained iatrogenic injury from a carpal tunnel release. The average gap length was 46.44 mm (range 15-110 mm).

• At a minimum of 6-months postoperative, no patients had any motor or sensory improvement; all patients were deemed complete failures.

• Five patients underwent subsequent revision reconstruction surgery: four autograft reconstructions and one distal nerve transfer.

CONCLUSIONS

• We demonstrated a high number of failures (n=9, 100% failure).

• Failure was not observed to affect one nerve type, location, or be related to preoperative injury size.

• Intraoperative assessment of patients who underwent subsequent revision surgery demonstrated the presence of significant neural adhesions surrounding the PNA, associated with large neuromas.

• Caution should be employed when utilizing PNAs for large (> 15 mm), mixed peripheral nerve repairs.