INTRODUCTION: Conservative treatments are sufficient for patients with discogenic pain; however, fusion surgery is performed to relieve unresolved pain. Of several available fusion techniques, the method remains controversial. This study used pain assessment to compare ALIF versus PLF in a rat punctured disc model.
METHODS: Forty rats were divided into disc injured (L4/5 discs were injured with a 26‐gauge needle; n=30) and control (n=10) groups. The neurotracer fluoro‐gold was applied to detect dorsal root ganglion (DRG) neuron disc innervation. One week after surgery, disc injured animals were divided into non‐fusion, ALIF, and PLF groups (n=10, each). Iliac crest bone graft was performed in fusion animals. Four and eight weeks after surgery, bone union was verified using micro CT, back pain was analyzed using CatWalk analysis (18 parameters), and the proportion of CGRP (pain neuropeptide)‐immunoreactive, FG‐labeled DRG neurons was determined.
RESULTS: Bone union was confirmed at 4 and 8 weenks in both fusion groups, but not in non‐fusion animals. CatWalk analysis revealed significant change for 3 parameters in all disc injured groups compared to controls (p<0.05). However in ALIF animals the changes improved over 8 weeks compared to PLF animals (p<0.05). CGRP‐immunoreactive DRG neurons increased in the non‐fusion group compared to controls (p<0.01); however, these decreased in the fusion groups to control levels at 8 weeks. No significant difference in number of CGRP‐immunoreactive DRG neurons between ALIF and PLF animals was observed at 8 weeks (p>0.1).
CONCLUSION: After completion of bone union, punctured disc‐related pain decreased to control levels in both fusion groups; however, ALIF animals showed faster recovery in back pain than PLF animals. These results suggest that PLF is effective for pain originated from degenerated discs, but posterior muscle injury may also influence postoperative back pain.