Influence of two consecutive partial lateral corpectomies on passive motion of the canine lumbar spine.

OBJECTIVE: To assess the effects of a first and second consecutive partial lateral corpectomy (PLC) on the passive range of motion (ROM) of canine lumbar spinal segments. STUDY DESIGN: Controlled, ex vivo biomechanical study. SAMPLE POPULATION: Adult canine cadaveric spines (n = 10). METHODS: Ten canine lumbar spinal segments were embedded in cast resin and aluminium tubes at their respective ends and attached to a spine testing bench. The ROM was measured under a torque of 2 Nm in three movement directions before and after the first PLC at L2-L3 and the second PLC at L3-L4. RESULTS: In the sagittal plane, mean ROM increased by 2.4° after the first PLC and by an additional 1.1° after the second PLC. In the dorsal plane, mean ROM increased by 2.3° after a first PLC and by an additional 1.5° after a second PLC (p < .05). Differences in mean rotational ROM before and after one or two PLCs were not identified. CONCLUSION: Each of the two PLCs resulted in a significant increase in ROM in the sagittal and dorsal planes (p < .05). The second PLC did not increase the ROM to a greater extent than the first. CLINICAL IMPACT: Performing each of two adjacent PLCs can lead to a reduction in the stability of the lumbar spine in dogs. However, in this study, the destabilizing effect of the second PLC was not greater than the effect of the first PLC.