Clinical observation of bony union at hinge side after unilateral open-door laminoplasty plus Neulen plate instrumentation

English Keywords:Cervical canal stenosis  Expansion of unilateral open-door laminoplasty  Neulen plates  Bony fusion  CT

English Abstract:

  【Abstract】 Objectives: To observe the outcome and stability of bony union at hinge side after unilateral open-door laminoplasty plus Neulen plate instrumentation. Methods: From January 2012 to December 2012, 26 cases with cervical spinal canal stenosis underwent unilateral open-door expansive laminoplasty plus Neulen plate instrumentation. Of these patients, there were 15 males and 11 females, with a mean age of 62 years(range, 35 -81 years)． Preoperative CT and MRI showed multiple segmental disc herniation complicated with ligamentum flavum hypertrophy in 16 patients and ossification of posterior longitudinal ligament in 10 patients． Neulen plate complex was placed following routine unilateral open-door laminoplasty and decompression. 5 plates were placed in each of the 16 cases, 4 plates in each of the 7 cases, and interval use of 3 plates in each of the 3 cases. Postoperative CT scans at 1 week, 3 months and 6 months were collected. Each cortex (dorsal and ventral) was evaluated for the presence of bridging at cancellous or cortical bone. The overall bony healing of the hinge was determined by combining the status of dorsal and ventral cortices. Bony fusion was defined as bridging at the both ventral and dorsal cortices. Results: During operation, breakage of dorsal and ventral cortex occurred in three segments. But the lamina drift and instability were not noted after laminaplasty and instrumentation. No neurological deficit and other complications were noted either. CT scans at 117 segments of 26 patients at 3 months demonstrated bony fusion at 80 levels(68.4%). And of 69 segments of 15 patients at 6 months, 59 segments(85.5%) had bony fusion. During the follow-up, no instrument displacement was noted. Three segments presented with no bony fusion due to no bridging at ventral or dorsal cortices, but the expansion of the spinal canal was maintained afterwards. The segments without plate placement showed remarkable enlargement. Conclusions: Neulen plate can provide instant and early support of the expanded canals, promote early union at hinge, and maintain significant expansion of the spinal canal.