Korean J Neurotrauma.  2014 Oct;10(2):60-65. 10.13004/kjnt.2014.10.2.60.

Midline Splitting Cervical Laminoplasty Using Allogeneic Bone Spacers: Comparison of Fusion Rates between Cervical Spondylotic Myelopathy and Ossification of Posterior Longitudinal Ligament

• Sheen JJ
• Jeon SR

• KMID: 2256232
• DOI: http://doi.org/10.13004/kjnt.2014.10.2.60

Abstract

OBJECTIVE
To analyze factors associated with fusion using allogeneic bone spacers for midline splitting cervical laminoplasty (MSCL).
METHODS
During April 2012 and September 2013, seventeen patients with cervical spondylotic myelopathy (CSM) or ossification of posterior longitudinal ligament (OPLL) underwent MSCL with allogeneic bone spacers by a single surgeon. Mean follow up periods was 11.3 months (range, 6-19 months). Clinical outcomes were evaluated by the Japanese Orthopedic Association (JOA) scores at preoperative and postoperative 6 months. Simple cervical X-rays were taken preoperatively, immediate postoperatively, 3, and 6 months after operation. Computed tomography (CT) scans were performed preoperatively, immediate postoperatively and 6 months postoperatively. The differences between two diseases were analyzed on cervical lordosis, canal dimension, anteroposterior (AP) distance, fusion between lamina and allogeneic bone spacer and affecting factors of fusion.
RESULTS
All surgeries were performed on 59 levels. There were no significant differences on the changes of lordosis (p=0.602), canal dimension (p=0.554), and AP distance (p=0.924) as well as JOA scores (p=0.257) between CSM and OPLL groups. Overall fusion rate was 51%. Multivariate analysis on the factor for the fusion rates between lamina and spacers showed that the immediate postoperative contact status between lamina and spacers in CT as significant factor of fusion (p=0.024).
CONCLUSION
The present study suggests that CSM and OPLL did not show difference of surgical outcome in MSCL using allogeneic bone spacer. In addition, we should consider the contact status between lamina and bone spacer for the better fusion rates for this surgery.

Keyword

Allografts; Spondylosis; Spinal fusion; Spinal cord diseases; Ossification of posterior longitudinal ligament

MeSH Terms

Allografts
Animals
Asian Continental Ancestry Group
Follow-Up Studies
Humans
Lordosis
Multivariate Analysis
Orthopedics
Ossification of Posterior Longitudinal Ligament*
Spinal Cord Diseases*
Spinal Fusion
Spondylosis

Figure

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  FIGURE 1 Cervical lordosis, defined as the angle between C2 and C7 inferior end plates.

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  FIGURE 2 Four categories of immediate post-operative contact status between the spacer and the lamina. A: Excellent: complete touch on both sides of the spacer to the splitted spinous process. B: Good: complete touch on one side and more than half touch on the other side. C: Fair: more than half touch on both sides. D: Poor: half or less touch on at least one side.

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  FIGURE 3 Fusion status between lamina and allogeneic bone spacer (Ichikawa classification). A: Bone resorption occurs around the implant. B: A clear space is present between the spacer and the bone without new bone formation. C: There is a space between the implant and the bone; however, new laminar bone formation is observed at the inner surface of the spinal canal. D: No space at the interface with new bone formation. E: Bridging of the new bone at the inner surface of the canal. When the different types were present at both interfaces, a lower degree of classification was applied.

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  FIGURE 4 Changes in cervical lordosis in the cervical spondylotic myelopathy and ossification of posterior longitudinal ligament groups. AP: anteroposterior, CSM: cervical spondylotic myelopathy, OPLL: ossification of posterior longitudinal ligament, Preop: preoperative, Postop: postoperative.

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  FIGURE 5 Changes of spinal canal dimension in the cervical spondylotic myelopathy and ossification of posterior longitudinal ligament groups. CSM: cervical spondylotic myelopathy, OPLL: ossification of posterior longitudinal ligament, Preop: preoperative, Postop: postoperative.

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  FIGURE 6 Changes of AP distance of the spinal canal in the cervical spondylotic myelopathy and ossification of posterior longitudinal ligament groups. AP: anteroposterior, CSM: cervical spondylotic myelopathy, OPLL: ossification of posterior longitudinal ligament, Preop: preoperative, Postop: postoperative.

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