LAUSR

BACKGROUND The incidence of intervertebral disc (IVD) degeneration has increased in recent years. A simple, reliable, and reproducible animal model is critical for understanding the underlying mechanisms of IVD degeneration. The caudal discs of rats have been proposed as a common puncture model in which to induce IVD degeneration. However, there is still no consensus on the size of needle to be used. OBJECTIVES The present study aimed to identify the appropriate needle size to establish an IVD degeneration model. STUDY DESIGN A randomized, experimental trial. SETTING Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, China. METHODS Validity was verified by magnetic resonance imaging (MRI) and histology. RESULTS From T2-weighted MRI imaging and histological examination, the IVD punctured by the 16-gauge needle degenerated acutely one week after the operation, whereas the 26-gauge needle puncture did no harm to the IVD. An 18-gauge needle showed a progressive degeneration in IVD. LIMITATIONS The observation period was not very long (4 weeks). CONCLUSIONS An 18-gauge needle can be used to induce IVD degeneration in rats. Therefore, an 18-gauge needle is the optimal selection to establish the degenerative IVD model on rats, whereas the 26-gauge needle failed to cause IVD degeneration. Thus, to study the prevention and treatment of IVD degeneration, a 26-gauge needle can be used for IVD injection of growth factors, plasmids, and drugs. A 16-gauge needle may be used to induce acute disc injury, but not IVD degeneration. KEY WORDS Low back pain, degenerative intervertebral disc, animal model, puncture needle, rat model, optimal choice.