Minimally invasive induction of an early lumbar disc degeneration model in rhesus monkeys.

STUDY DESIGN: Animal experimental study.

OBJECTIVE: To establish an early and reproducible intervertebral disc (IVD) degeneration model to provide a basis for studying IVD degeneration.

SUMMARY OF BACKGROUND DATA: The pathophysiology and pathogenesis of IVD degeneration, a common condition that causes low back pain, are not clearly understood. An experimental animal model of human IVD degeneration is needed.

METHODS: A total of 91 IVDs were grouped as follows: group 1, percutaneous puncture using a 20-gauge needle; group 2, percutaneous puncture using a 15-gauge needle; and group 3, nonpuncture. The pre- and postpunctured IVDs were examined and graded. Hematoxylin and eosin, Masson trichrome, safranin O staining methods, and immunohistochemistry for type II collagen were performed.

RESULTS: In group 1, the magnetic resonance imaging (MRI) signal intensity was grade I for all IVDs before puncture, and at the different time points after puncture. In group 2, the MRI signal intensity was grade III in the 4th week and grade IV in the 8th week after puncture. In group 3, the MRI signal intensity was grade I at all time points. In groups 1 and 2, a marked reduction in nucleus pulposus cells was observed in the 12th week. Fissures in the annulus fibrosus were observed in the 8th week. Decreased proteoglycans in the model discs was noted in the 8th and 12th week, and collagen II significantly decreased in the 12th week after puncture (P < 0.05). In group 2, the number of cells and fissures in the IVDs were decreased, with decreased proteoglycan and collagen II content in the 8th week. No changes were found in group 3.

CONCLUSION: Slowly progressive and mild disc degeneration can be induced by puncture using 20-gauge needles through the IVDs, which might be suitable for investigating novel therapies for disc degeneration/pain.

LEVEL OF EVIDENCE: 2.