Systematic review of humeral shaft fracture (OTA/AO 12) complicated with iatrogenic radial nerve injury: Can nerve fibers span a 3cm nerve defect?
Authors: Zhang Zeyu , Lin Zhongpei , Qiu Qinglin , Xiao Xincai , Su Shouwen , Wen Xiaoyue , He Bo 
Published: March 2024

Objectives: Compare and analyze the relationship between the implant (bone plate VS. intramedullary nail), surgical approach and iatrogenic radial nerve injury. Report a case which indicates the possible distance between two nerve stumps which radial never might crawl through.
Methods: Reviewed the literatures on humeral fracture (OTA/AO 11/12/13 A/B/C9) combined with radial nerve injury was retrieved in PubMed. Screening scope includes: 1) Chinese or English literature, 2) adult humeral fracture, 3) preoperative radial nerve continuity, 4) non-pathological fracture, 5) non-periprosthetic fracture, 6) must involve humeral shaft (OTA/AO 12). Exclusion criteria: 1) No full text in Chinese or English; 2) Unable to judge surgical approach. Rejection criteria: 1) Misinclusion; 2) Unable to judge whether the humeral shaft was involved (OTA/AO 12).
Results: 1. The rate of iatrogenic radial nerve injury with bone plate and intramedullary nail was 6.82% (313/4589) and 2.58% (23/893) respectively (p < 0.05). 2.In cases with open reduction and internal fixation with a plate with a definite surgical approach (excluding MIPO), the rate of radial nerve injury was 7.44% (259/3483). The corresponding rates were 3.7% (3/82) for deltopectoral approach, 5.65% (111/1963) for anterolateral approach, 13.54% (26/192) for lateral approach and 9.55% (119/1246) for posterior approach. There were statistical differences between anterolateral and lateral approaches and anterolateral and posterior approaches. 3.The injury rates of radial nerve were 7.26% (301/4145) for plate internal fixation, 2.58% (23/893) for intramedullary nail and 2.70% (12/444) for MIPO. There were statistical differences between plate fixation and intramedullary nail, plate fixation and MIPO (p < 0.05), but no difference between an intramedullary nail and MIPO (p > 0.05). 4. The radial nerve injury rates were 0.00% (0/33) for Anteromedial MIPO, 2.67% (10/374) for Anterolateral MIPO and 5.40% (2/37) for Posterior MIPO. (p > 0.05) 5. The radial nerve injury rates were 2.87% (21/732) for anterograde intramedullary nail and 1.2% (2/161) for retrograde intramedullary nail. (p > 0.05) 6. In nonunion surgery, the rate of iatrogenic radial nerve injury was 15.0% (9/60) for anterolateral approach, 16.7% (2/12) for lateral approach and 18.2% (6/33) for posterior approach. (p > 0.05)
Conclusion: During humeral shaft fracture operation, the incidence of iatrogenic radial nerve injury was 6.82% in bone plate and 2.58% in intramedullary nails, respectively. Compared with lateral and posterior approaches, the anterolateral surgical approach had a lower incidence of radial nerve injury. The rate of iatrogenic radial nerve injury in MIPO was lower than that in open reduction and internal fixation. There was no difference in the incidence of iatrogenic radial nerve injury between anterograde and retrograde intramedullary nailing. In the human body, regenerated radial nerve fibers can span a 4cm nerve defect area.
Level of Evidence: Level IV