Lateral Interbody Fusion for Hyperlordosis and Negative Sagittal Vertical Axis Because of Accordion Phenomenon: A Case Report.

CASE: The accordion phenomenon is defined as the difference in the disc space observed on x-ray or computed tomography images taken in both standing and supine positions, which results in a discrepancy of local spinal alignment. Oblique lateral interbody fusion (OLIF) is a less invasive method of potentially correcting both coronal and sagittal spinal alignment. We present the case of a 66-year-old woman with rheumatoid arthritis treated with OLIF for degenerative disc disease presenting with hyperlordosis and negative sagittal vertical axis (SVA) because of the accordion phenomenon. CONCLUSION: OLIF for severe degenerative disc disease presenting with hyperlordosis and negative SVA because of the accordion phenomenon may be effective.

Cervical Lordosis Ratio as a Novel Predictor for the Loss of Cervical Lordosis After Laminoplasty.

OBJECTIVE: Maintaining cervical lordosis (CL) after laminoplasty is important for indirect decompression of the spinal cord. This study aimed to identify preoperative dynamic radiographic predictors for the loss of CL after laminoplasty. METHODS: We retrospectively analyzed 141 consecutive patients who underwent cervical laminoplasty for cervical myelopathy. The following radiographic parameters were measured before surgery and at 1 year of follow-up: CL, C7 slope, C2-7 sagittal vertical axis (SVA), C2-7 range of motion (ROM), CL in flexion, CL in extension, ROM of flexion (Flex ROM), and ROM of extension. The CL ratio (CLR) was defined as 100 × Flex ROM/ C2-7 ROM. ΔCL was defined as postoperative CL minus preoperative CL. Patients were classified into 2 groups: group K (kyphotic change group, ΔCL ≤ -10) and group C (control group, ΔCL > -10). RESULTS: The patient population comprised 94 men and 47 women (mean age, 70.9 ± 9.4 years), with 24 patients (17.0%) classified into group K. CL, C7 slope, and CLR were significantly higher in group K than in group C. The groups did not significantly differ in age, sex, C2-7 SVA, and C2-7 ROM. On multivariable analysis, the CLR was significantly associated with postoperative kyphotic changes. On receiver-operating characteristic curve analysis (area under the curve = 0.717, p < 0.001), the cutoff value for CLR was 68.9%, with sensitivity and specificity of 87.5% and 57.3%, respectively. CONCLUSION: The CLR, reflecting the balance between flexion and extension mobility, was identified as a novel predictor for CL loss after laminoplasty, with a cutoff value of 68.9%.

Unilateral atlantal lateral mass hypertrophy associated with atlanto-occipital fusion.

PURPOSE: Unilateral hypertrophy of the lateral mass of the atlas is an extremely rare condition. The authors present a rare type of unilateral atlantal mass hypertrophy with atlanto-occipital fusion which is associated with an invaginated lateral mass of the atlas and the odontoid process into the foramen magnum. METHODS: A 45-year-old woman presented with a 2-year history of progressive bilateral weakness in the upper and lower extremities and gait disturbance. The left lateral mass of the atlas was hypertrophied and had invaginated into the foramen magnum with the odontoid. The spinal cord was severely compressed at the level of the foramen magnum, surrounded by the lateral mass of the atlas, the odontoid process and the occipital bone. RESULTS: First, ventral decompression was performed using a transmandibular approach. The anterior arch of the atlas, the medial side of the hypertrophied lateral mass and the odontoid process were resected. Two weeks after primary surgery, posterior occipitocervical fusion was performed. The postoperative course of the patient was uneventful. Three years after the operation, she could walk without assistance and her paresthesia improved. CONCLUSIONS: To our knowledge, such a case of unilateral atlantal mass hypertrophy associated with atlanto-occipital fusion has not been described previously. The authors discuss the pathology of this case and review the literature on unilateral atlantal mass hypertrophy and associated anomalies of the upper cervical spine.

Risk factors for acute cervical spinal cord injury associated with ossification of the posterior longitudinal ligament.

STUDY DESIGN: Retrospective review. OBJECTIVE: To identify risk factors for traumatic cervical spinal cord injury (SCI) associated with ossification of the posterior longitudinal ligament (OPLL) by comparing patients with SCI and those with cervical myelopathy (CM) associated with OPLL. SUMMARY OF BACKGROUND DATA: Although the prevalence of OPLL among patients with cervical SCI is high, little is published about the risk factors for SCI associated with OPLL. METHODS: We evaluated 3 groups of patients: 34 with SCI associated with OPLL, 32 with CM associated with OPLL, and 32 normal controls. Developmental canal diameter, spinal canal stenosis, type of OPLL, and presence of ossification of the anterior longitudinal ligament (OALL) were evaluated using 3-dimensional computed tomography. RESULTS: The mean age of the SCI group was 71.5 years, significantly more than that of the CM group (63.3 years). The SCI and CM groups had significantly smaller developmental canals than controls. Canal stenosis caused by OPLL was significantly more severe in the CM group than in the SCI group. There were no significant differences in sex distribution or the type of OPLL. Mixed or segmental types of OPLL were the main cause of SCI and CM. The SCI group showed a significantly higher incidence of OALL (56%) than the CM group (22%). Cervical SCI occurred at the edge of the OPLL or OALL in 20 patients (59%). If limited to mixed or continuous types of OPLL, 18 of the 19 patients (95%) sustained SCI at the edge of the OPLL or OALL. CONCLUSION: Risk factors for cervical SCI associated with OPLL were being elderly, having a mixed or segmental type of OPLL, and presence of OALL. Most instances of SCI occurred at edges of the OPLL or OALL. Severe spinal canal stenosis caused by OPLL was not an essential risk factor for developing SCI.