MRI genicular nerve mapping: a novel approach to sagittal genicular nerve localization.

Background and objectives: Chronic knee pain, including postarthroplasty knee pain, is a major cause of morbidity. Radiofrequency ablation of genicular nerve branches is a treatment option. The literature to date has demonstrated and recommended consistent rhizotomy targets in the coronal and axial position of the three primary genicular nerve branches (superomedial genicular nerve, superolateral genicular nerve, inferomedial genicular nerve). The debate on genicular nerve positions focuses on the anterior-posterior courses of the nerve branches.

Methods: The sagittal positions of the three primary genicular neurovascular bundles were measured in 28 consecutive knee MRI and described relative to the total anterior-posterior depth of the bony cortex. Standard radiofrequency capture radius at the classic rhizotomy targets sites was compared with identified nerve position to report proportion of observed nerves within the capture radius.

Results: The genicular neurovascular bundles were found further posterior than classic landmark targets. Proportion of visualized nerve branches captured by classic rhizotomy target radius varied by genicular nerve branch.

Conclusions: This study supports updated guidance on genicular rhizotomy targets. Nerve localization studies using MRI data may be a promising avenue in future nerve localization research pertinent to rhizotomy.