Unilateral C1 Lateral Mass and C2 Pedicle Screw Fixation for Atlantoaxial Instability in Rheumatoid Arthritis Patients: Comparison with the Bilateral Method

OBJECTIVE: Bilateral C1 lateral mass and C2 pedicle screw fixation (C1LM-C2P) is an ideal technique for correcting atlantoaxial instability (AAI). However, the inevitable situation of vertebral artery injury or unfavorable bone structure may necessitate the use of unilateral C1LM-C2P. This study compares the fusion rates of the C1 lateral mass and C2 pedicle screw in the unilateral and bilateral methods. METHODS: Over five years, C1LM-C2P was performed in 25 patients with AAI in our institute. Preoperative studies including cervical X-ray, three-dimensional computed tomography (CT), CT angiogram, and magnetic resonance imaging were performed. To evaluate bony fusion, measurements of the atlanto-dental interval (ADI) and CT scans were performed in the preoperative period, immediate postoperative period, and postoperatively at 1, 3, 6, and 12 months. RESULTS: Unilateral C1LM-C2P was performed in 11 patients (44%). The need to perform unilateral C1LM-C2P was due to anomalous course of the vertebral artery in eight patients (73%) and severe degenerative arthritis in three patients (27%). The mean ADI in the bilateral group was 2.09 mm in the immediate postoperative period and 1.75 mm in 12-months postoperatively. The mean ADI in the unilateral group was 1.82 mm in the immediate postoperative period and 1.91 mm in 12-months postoperatively. Comparison of ADI measurements showed no significant differences in either group (p=0.893), and the fusion rate was 100% in both groups. CONCLUSION: Although bilateral C1LM-C2P is effective for AAI from a biomechanical perspective, unilateral screw fixation is a useful alternative in patients with anatomical variations.

Clinical Features of Percutaneous Hemivertebroplasty in Patients with Osteoporotic Vertebral Compression Fractures / 대한신경손상학회지

OBJECTIVE: Unilateral percutaneous vertebroplasty is a widely accepted treatment for osteoporotic vertebral compression fractures (VCFs). However, bone cement may fail to fill both hemivertebra from the single needle. We assessed the radiographic and clinical outcome of hemivertebroplasty (HVP) and evaluated the factors that affect subsequent VCFs after HVP. METHODS: Fifty two patients who underwent HVP were reviewed. VCFs were identified based on clinical and radiological findings. The patients were grouped into two groups: 1) no subsequent VCFs, 2) subsequent VCFs. We evaluated the association between age, sex, body mass index (BMI) and bone mineral density (BMD) and subsequent VCFs. We also assessed the impact of location, type and grade of fracture, endplate fracture, burst fracture, bone cement volume on subsequent VCFs. We analyzed the compression ratio, wedge angle, kyphotic angle, and visual analogue scale (VAS) score in both groups. RESULTS: There were no significant differences in age, gender, BMI, and BMD between two groups. No significant difference was also found in pre-existing VCF, location, type and grading of fracture, endplate fracture, burst fracture, amount of bone cement, and radiological findings such as compression ratio, wedge angle, and kyphotic angle between two groups. The final mean VAS scores of patients with or without subsequent VCFs were 3.11 and 4.02, respectively. CONCLUSION: No major risk factors for the subsequent VCFs after HVP were found. However, we identified adjacent fractures, refractures, and remote fractures after HVP in chronological order. Therefore, long-term follow-up is necessary to evaluate the effectiveness of HVP to osteoporotic VCFs.