Posterolateral intertransverse lumbar fusion in a mouse model: surgical anatomy and operative technique

Background contextAnimal models are frequently used for studying the effect of bone graft substitutes or allogeneic materials on osterolateral lumbar fusion. Transgenic technology in the mouse provides a unique opportunity to further understand the biology of spine fusion.PurposeTo describe pertinent lumbar spine anatomy and formulate a surgical protocol for posterolateral fusion in the mouse model.Study designDiagnostic model: development of an animal model for biologic evaluation of posterolateral spine fusion.MethodTen mice were killed to study relevant lumbar spine anatomy and develop a protocol for lumbar spine fusion. The L4–L6 fusion protocol was validated in 46 mice for ease of exposure, preparation of the posterolateral fusion bed, introduction of bone inductive agents, and perioperative care.ResultsAnatomy and surgical technique for posterolateral intertransverse lumbar fusion in the mouse model are described. A paraspinal approach allows exposure of the transverse processes, decortication, and graft placement at the L4–L6 intertransverse fusion site. Decortication alone did not result in fusion, whereas the use of bone graft resulted in satisfactory fusion rates. Perioperative morbidity and mortality rates were low.ConclusionThe mouse posterolateral lumbar spine fusion model is reproducible, inexpensive, and has low complication rates. Knowledge of the relevant anatomy and adherence to a well-defined surgical protocol provides a reliable and reproducible experimental spine fusion model.