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The bone healing environment in the posterolateral spine following arthrodesis surgery is one of the most challenging in all of orthopedics and our understanding of the molecular signaling pathways mediating osteogenesis during spinal fusion is limited. In this study, the spatial and temporal expression pattern of Wnt signaling factors and inhibitors during spinal fusion was assessed for the first time. Bilateral posterolateral spine arthrodesis with autologous iliac crest bone graft was performed on 21 New Zealand White rabbits. At 1-, 2-, 3-, 4-, and 6-weeks, the expression of sclerostin and a variety of canonical and noncanonical Wnts signaling factors was measured by qRT-PCR from tissue separately collected from the transverse processes, the Outer and Inner Zones of the fusion mass, and the adjancent paraspinal muscle. Immunohistochemistry for sclerostin protein was also performed. Sclerostin and many Wnt factors, especially Wnt3a and Wnt5a, were found to have distinct spatial and temporal expression patterns. For example, harvesting ICBG caused a significant increase in sclerostin expression. Furthermore, the paraspinal muscle immediately adjacent to the transplanted ICBG also had significant increases in sclerostin expression at 3 weeks, suggesting new potential mechanisms for pseudarthroses following spinal arthrodesis. The presented work is the first description of the spatial and temporal expression of sclerostin and Wnt signaling factors in the developing spine fusion, filling an important knowledge gap in the basic biology of spinal fusion and potentially aiding in the development of novel biologics to increase spinal fusion rates.
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BACKGROUND: Laminoplasty is a safe and effective procedure for multilevel degenerative cervical stenosis causing myelopathy, that allows for motion preservation. The purpose of this study was to determine the reoperation rate and associated risk factors after cervical laminoplasty. METHODS: We present a retrospective consecutive series of patients who underwent a laminoplasty procedure between January 1, 2005, and October 31, 2012, and had a minimum 2-year follow-up. Demographic data were collected and operative records were reviewed to determine the cervical levels involved in the laminoplasty procedure, any concomitant procedures, and estimated blood loss. Clinical records were reviewed and telephone interviews were conducted on those patients with less than 2-year in-person follow-up. Patients requiring reoperations and the reason for the reoperations were determined, as well as the incidence of postoperative C5 palsy. RESULTS: A total of 222 of 266 patients (83%) with a minimum 2-year follow-up had an average follow-up of 4.97 years. Overall, 26 patients underwent 30 reoperations (13.5%). A total of 15 patients underwent 16 reoperations (7.2%) in the acute postoperative period for infection requiring at least 1 irrigation and debridement, hardware-related issues, or posterior cervical wound issues. A total of 13 patients had 14 reoperations (6.3%) outside of the acute postoperative period for the development of a new radiculopathy, recurrent myelopathy, neurologic symptoms with a kyphotic deformity, or a posttraumatic focal kyphotic deformity. Patients who had a concomitant laminectomy demonstrated a significantly (P = .03) higher reoperation rate than those who did not. There were no other statistically significant associations. The C5 palsy rate was 8.1% (18 of 222). CONCLUSIONS: Although the preserved motion following laminoplasty may allow for the development of new neurologic symptoms, the reoperation rate continues to compare favorably with laminectomy and fusion and remains a reasonable option for the surgical management of multilevel cervical stenosis causing myelopathy. LEVEL OF EVIDENCE: 4.
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STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To evaluate the outcomes of patients with occipital condyle fractures (OCFs) treated nonoperatively and establish factors associated with neck disability. SUMMARY OF BACKGROUND DATA: The majority of OCFs are treated nonoperatively; however, few studies have reported long-term functional outcomes of these patients. METHODS: From 1999 to 2007, 103 patients with OCFs were identified. Of this cohort, 28 patients with 32 fractures met the inclusion criteria. Fracture and patient characteristics, including patient age and sex, Anderson and Montesano fracture type, bilaterality, associated head injury, and fracture displacement, were noted. The Neck Disability Index (NDI) was calculated at final follow-up. RESULTS: Anderson and Montesano type III fractures were the most commonly observed (54%), followed by type II (43%). The mean NDI was 14.0, which correlates with mild disability, and the NDI headache question showed the highest mean disability score of all questions. There was no statistically significant association between NDI scores and fracture type, displacement of fracture, sex, bilaterality, or presence of head injury. Age was associated with NDI scores, with age range of 40 to 60 years having a mean NDI score of 24.3. CONCLUSION: Anderson and Montessano types I, II, and III OCFs may be treated nonoperatively in the absence of ligamentous instability and concomitant cervical injuries with the expectation of mild neck disability regardless of the displacement, bilaterality, sex, or presence of head injury. Greater disability may be expected in patients aged between 40 and 60 years than in other ages.
