Repair of peripheral nerve defect with direct gradual lengthening of the nerve stumps: first clinical case series.

BACKGROUND: Repairing large nerve defects remains challenging, and no definitive method has been established. We developed a nerve lengthening device for humans and achieved nerve defect repair through nerve lengthening in three cases. The purpose of this report is to describe the clinical course of three cases treated by nerve lengthening and to discuss its effectiveness in the treatment of nerve defects. METHODS: The target population included males and females aged 20-65 years with peripheral nerve injuries that cannot undergo primary suturing in the limbs were recruited. Three patients were included in this study. The nerve gaps were 13 mm, 15 mm and 100 mm, respectively. We developed a special nerve lengthening device. Starting from postoperative day 1, nerve lengthening was initiated on the proximal and distal ends at a rate of 0.5-1 mm daily (0.25 mm x 2-4 times) using the device. Monthly evaluations post-nerve suturing assessed nerve regeneration, pain, and adverse events. We observed postoperative courses for over 2 years. RESULTS: There were two radial nerve injury cases and one median nerve injury case. Functional recovery was observed in cases of shorter nerve defects repaired through nerve lengthening. However, significant functional restoration was not attainable for cases of longer nerve defects or those with prolonged post-injury intervals. Furthermore, in chronic cases, it was confirmed that this method could be used to gradually lengthened and repair severed nerves. There were no reports of pain or lengthening-related troubles during nerve lengthening. CONCLUSION: It was found that good nerve regeneration can be achieved with short nerve defects. Compared to free nerve grafting, this new treatment is promising as it does not require the sacrifice of healthy nerves from the donor site or leave surgical scars. We demonstrated the potential of nerve lengthening as a new treatment option for nerve defects. This study is registered and published in the Japan Registry of Clinical Trials (Project No. jRCTs032180098, https://jrct.niph.go.jp/re/reports/detail/17847 ). Registration date: 28/01/2019.