Ex vivo biomechanical testing of Funkquist B dorsal laminectomy between the sixth and seventh cervical vertebrae in dogs

ABSTRACT: Dorsal laminectomy is routinely performed for spinal cord compressions or stenosis of the cervical vertebral canal. However, despite good results, relevant complications have been described in dogs. Considering the incomplete understanding of the necessity for complementary surgical stabilization after performing laminectomies in the cervical region, this study compared the resistance and range of motion (ROM) of the cervical spinal column subjected to Funkquist B laminectomy between the sixth and seventh vertebrae in dogs. Forty-four cervical vertebral columns (C2-T1) of dogs, with an average weight of 26.2±3.8 kg, were selected using radiography and computed tomography. Four experimental groups (n=11) were established according to the mechanical test: two control groups (flexion and extension control) and two laminectomy groups (flexion and extension laminectomies). Numerical results of the maximum load for measuring the resistance and ROM of the columns of the two control groups and the two laminectomy groups were compared. The laminectomy groups showed a lower maximum load, regardless of the mechanical test performed (P<0.001). The ROM was not influenced by laminectomy, the type of mechanical test (ventral flexion or extension), or its interaction (P<0.05). There was no interaction between the effect of the laminectomy factors (yes or no) and the effect of the mechanical tests for ventral flexion or extension (P<0.05). In conclusion, Funkquist B dorsal cervical laminectomy between C6 and C7 decreases mechanical resistance with a supraphysiological loading force but does not alter the ROM, suggesting that it can be used without additional mechanical stabilization in dogs.

摘要：背侧椎板切除术是治疗脊髓压迫或颈椎管狭窄的常规术式。尽管该术式疗效确切，但已有犬术后相关并发症的报道。鉴于目前对颈椎椎板切除术后是否需行辅助手术固定的认知仍不充分，本研究对比了犬第6至第7颈椎行Funkquist B型背侧椎板切除术后颈椎脊柱的抗载荷能力与活动度（range of motion, ROM）。
本研究通过X线摄影与计算机断层扫描筛选出44例犬的C2-T1节段颈椎脊柱标本，受试犬平均体重为26.2±3.8 kg。根据力学测试类型将标本分为4组（每组n=11）：2个对照组（屈曲对照组与伸展对照组）及2个椎板切除实验组（屈曲组与伸展组）。对两组对照组与两组椎板切除实验组的脊柱抗载荷能力及活动度的最大载荷测量数据进行对比分析。
结果显示，无论采用何种力学测试方式，椎板切除实验组的最大载荷均显著低于对照组（P<0.001）。椎板切除术、力学测试类型（腹侧屈曲或伸展）及其交互作用均未对活动度产生显著影响（P<0.05）；椎板切除与否与腹侧屈曲/伸展力学测试的效应间亦无交互作用（P<0.05）。
综上，犬第6至第7颈椎行Funkquist B型背侧椎板切除术在超生理载荷条件下会降低脊柱的机械抗载荷能力，但不会改变其活动度，提示该术式无需额外辅以机械固定即可应用于犬类。