Thoracic facet joint innervation: identifying and accessing the articular branch

Background: The thoracic zygapophyseal (Z) joints, also known as facet joints, are potential sources of thoracic back pain. Historically, medial branch innervation of these joints was thought to mirror that of cervical and lumbar Z-joints. However, recent anatomical studies suggest that distinct thoracic articular branch nerves innervate these joints. This finding provides potential interventional targets for thoracic facet blockade and radiofrequency neurotomy. Objective: This study aimed to identify the thoracic articular branch nerves for mid-thoracic joints and develop techniques for accessing these structures under fluoroscopic guidance. Methods: Two embalmed cadavers were dissected to identify the thoracic articular branch nerves of the T6-7, T7-8, and T8-9 joints. Radiopaque markers were placed on identified nerves, and fluoroscopic imaging was used to visualize and optimize needle placement for potential articular branch blocks and neurotomy. Results: Thoracic articular branches were successfully identified, marked, and visualized on fluoroscopy. Selective blockade of the articular branch appeared feasible using the superior aspect of the rib head adjacent to the Z-joint as a target and osseous backstop. The dorsal projection of the transverse process limited optimal cannula placement for the radiofrequency neurotomy. Individual body habitus and thoracic kyphosis also impacted viable methods for radiofrequency cannula placement. These anatomical constraints prevented the establishment of a parallel approach for monopolar radiofrequency cannula placement; however, alternative approaches were developed. Conclusion: Accessing thoracic articular branches for neurotomy is feasible but presents technical challenges due to anatomical limitations. Further studies should explore the clinical efficacy of these techniques in managing thoracic facet-mediated pain.