2.13 | Rabbit LF degeneration and hypertrophy model
All surgical and experimental procedures were approved by the ethics committee
of Nanjing Medical University. Nine New Zealand white rabbits, weighing approximately 3.0 kg, were randomly divided into three groups in this study. The rabbits were anesthetized using 3% pentobarbital chloral hydrate (3ml/kg) and prevented infection by injection of antibiotics (10mg/kg of cefazolin sodium pentahydrate; Shenzhen, China) via the ear vein. Then, the rabbits were placed into a prone position. A dorsal midline skin incision approximately 6 cm was performed under X-ray control. As described previously (Hayashi et al., 2017), lumbosacral fascia was cut left lateral to the mammillary process, and then discovered the gap between the multifidus and longissimus muscles. Subsequently, we detached the the multifidus from the mammillary processes to expose the lamina, the root of the transverse process and posterior edge of vertebral body. The Group A just underwent surgical exposure without fixation as a control operation (n=3). The Group B underwent posterolateral fusion with instrumentation (Watson locking plate; Changzhou, China) and performed additional resection of L3-4 supraspinal muscle and interspinous ligament to obtain mechanical stress concentrating on L3-4 level (n=3). Briefly, 4-hole titanium locking plate was used on the left posterolateral side of L2-3 and L4-5, and a 2mm×10mm titanium locking screw was then inserted into each vertebra and locked to obtain mechanical stress concentrating on L3-4 level. Rabbits in Group C were treated with cyclopamine (50mg/kg every day, subcutaneous injection as described previously (Berman et al., 2003; Berman et al., 2002)) except for the same surgical procedure in Group B (n=3). All rabbits were raised independently with free access to food and water. Three groups of rabbits were sacrificed at 12 weeks after surgery.