Cage Subsidence and Fusion Rate in Extreme Lateral Interbody Fusion with and without Fixation.

OBJECTIVE: To examine the subsidence rate in patients undergoing extreme lateral interbody fusion (XLIF) using data from a 2-year retrospective study to assess the effect of supplemental fixation on the stand-alone procedure. METHODS: Demographic and perioperative data for all patients who underwent XLIF for degenerative lumbar disorders between June 2012 and January 2016 were collected and divided into 4 groups: the stand-alone (SA), lateral fixation, unilateral pedicle screw, and bilateral pedicle screw (BPS) groups. The disk height (DH), lumbar lordotic (LL) angle, and segmental lordotic (SL) angle were measured preoperatively and 3 days, 3 months, 1 year, and 2 years postoperatively. Clinical outcomes were evaluated using Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores. Fusion was defined according to computed tomography scan. RESULTS: There were 126 vertebrae in 107 patients treated. SL angle, LL angle, and DH significantly increased postoperatively in all groups. Although the preoperative and 2-year postoperative DHs in the SA group were similar, the other measures showed significant differences from baseline at each follow-up visit. No significant effects on SL angle or DH were found in any of the groups. A significant difference in the LL angle was found in the BPS group compared with the other groups. At the last follow-up, high-grade subsidence was found in 26.89% of all cases, the fusion rate was 85.71%, and the VAS and JOA scores were significantly improved in all groups. CONCLUSIONS: Supplemental fixation did not significantly influence cage subsidence or SL angle. Only BPS fixation significantly improved the LL angle. The 2-year fusion rate was satisfactory.

Atlantoaxial Joint Distraction for the Treatment of Basilar Invagination: Clinical Outcomes and Radiographic Evaluation.

OBJECTIVE: To investigate the causes of partial remission in patients with basilar invagination (BI) and irreducible atlantoaxial dislocation (IAAD) treated with transoral atlantoaxial reduction plate (TARP) without odontoidectomy and quantify the distance of odontoid descent. METHODS: Between August 2010 and July 2012, 22 consecutive patients with BI with IAAD who underwent TARP surgery were reviewed. The preoperative and postoperative radiographic parameters were evaluated. Follow-up data and the symptom treatment interval (STI), defined as the interval between the onset of symptoms and surgical treatment, were assessed. Neurological function was evaluated as neurologic improvement, defined as ([Postoperative Japanese Orthopedic Association (JOA) score] - [Preoperative JOA score])/(17 - [Preoperative JOA score]). The patients were assigned to group A (<50%) or group B (≥50%) based on their level of neurologic improvement. RESULTS: All 22 patients improved clinically to varying degrees. The mean preoperative STI was 105.6 ± 67.6 months for group A and 45.3 ± 46.7 months for group B (P < 0.05). There were no significant between-group differences in follow-up (P > 0.05) or with respect to radiographic parameters (P > 0.05). Persistent brainstem compression was observed in 1 patient, whose symptoms were not adequately relieved after revision surgery (transoral odontoidectomy and posterior decompression and fusion). No fixation failure was observed. CONCLUSIONS: Descent of the odontoid process is useful for treating basilar invagination. TARP surgery without odontoidectomy may pull the dens caudally and ventrally to achieve sufficient decompression of the spinal cord. Neurologic improvement may be associated with STI.