Lumbar plexopathy following instrumented posterior lumbar interbody fusion: a complication with use of Hohmann's retractor.

INTRODUCTION: A series of 12 patients in our centre following single level instrumented posterior lumbar interbody fusion at L4-L5 developed unexplainable motor weakness in the proximal lumbar nerve roots (L2, L3) and numbness of the whole limb, a clinical picture resembling lumbar plexopathy. Even though lumbar plexopathy has been reported following gynaecological procedures and in transpsoas interbody fusion surgeries, there is no literature reporting this complication following conventional instrumented posterior lumbar interbody fusions.

STUDY DESIGN: Retrospective observational study.

OBJECTIVE: To find the possible mechanism of development of lumbar plexopathy in patients who underwent posterior lumbar interbody fusion surgeries in our centre.

MATERIAL AND METHODS: We analyzed retrospectively the medical records, electrophysiological reports of the patients, literatures on the anatomy of lumbar plexus and other literature reporting similar complications. We also dissected lumbar plexus of three cadavers and simulated surgical technique on them to find the mechanism of development of this unusual complication.

RESULTS: We found injury to lumbar plexus that probably occurred intraoperatively with Hohmann's retractor that was used for retraction of the paraspinal muscles. This theory was favoured by many clinical factors and further confirmed by cadaveric dissections.

CONCLUSION: We conclude that surgical technique with improper use of Hohmann's retractor causes traction and compression injury to the lumbar plexus resulting in this complication. We propose proper technique of insertion of Hohmann's retractor and also recommend use of modified Hohmann's retractor with shorter tips for spinal procedures to prevent such complication.