Analysis of cervical sagittal alignment variations after lumbar pedicle subtraction osteotomy for severe imbalance: study of 59 cases.

OBJECTIVE: To evaluate postoperative changes within the cervical alignment following surgical lumbar correction by pedicle subtraction osteotomy (PSO) in patients affected with sagittal global malalignment disease. METHODS: This was a monocentric, radiographic, and prospective study. 79 patients, who underwent sagittal correction by PSO, performed an EOS imaging pre- and postoperatively between January 2008 and December 2013 at the University Hospital of Bordeaux. Inclusion criteria were a performed pre- and postoperative EOS imaging and a preoperative C7SVA > 5 cm. Were excluded patients who did not allow EOS with a viewable cervical spine due to hyperkyphosis. The study involved the analysis of pelvic, lumbar, thoracic, cervical, and cranial parameters before and after the surgery. RESULTS: 59 patients met the criteria. Mean follow-up was 38 months. The lumbar PSO significantly improved sagittal alignment including L1S1 lordosis, T1T12 kyphosis, and C7SVA (p < 0.001). We did not reported a significant change within cervical parameters after PSO (C2C7 lordosis 22.7°-21.5° p = 0.64, C1C7 lordosis 50.6°-48.8° p = 0.56, C1C2 angle 28.2°-27.9° p = 0.82, C7 slope stayed constant 32.3°-30.5° p = 0.47, OC2 angle 15.54°-15.56° p = 0.99). However, cranial slope decreased significantly (p < 0.05). We did not find correlation between lumbar lordosis and cervical lordosis variations (R = 0.265). Cervical lordosis was highly correlated with the C7 slope (R = 0.597) and with the Spino Cranial Angle (R = - 0.867). CONCLUSION: Reciprocal changes in cervical spine after PSO are difficult to approach. Maintaining a horizontal gaze involves locoregional mechanisms of compensation adapting to the slope of C7. The cranial system by decreasing the cranial slope allows the gaze alignment and is the first compensation mechanism to get involved after a loss of lumbar lordosis. Restoring optimal C7SVA is necessary to prevent the development of secondary cervical painful symptomatology when the cranial compensation is outdated.

Comparison between percutaneous and traditional fixation of lumbar spine fracture: intraoperative radiation exposure levels and outcomes.

OBJECTIVE: To compare radiation exposure doses and clinical and radiological outcomes between percutaneous pedicular screwing (closed reduction internal fixation [CRIF]) and classical open reduction internal fixation (ORIF) in lumbar spine fracture without neurologic deficit. MATERIALS AND METHODS: Sixty patients (mean age, 42.5 years) were divided into two treatment groups: (Percutaneous) CRIF versus (traditional) ORIF. Screw position and anatomic vertebral reconstruction were checked on routine control X-ray and postoperative CT scan. Study parameters comprised: surgery time, radiation exposure time, radiation dose level for X-ray (DAP) and for CT (DLP),blood loss, length of hospital stay and postoperative pain (VAS). RESULTS: At a mean 25.5 months' follow-up,there were no significant inter-group differences on the epidemiological parameters: age, gender, fracture level, fracture type on the Magerl classification, preoperative local vertebral kyphosis angle, or fracture-to-surgery interval. Effective radiation dose was 3-fold higher in CRIF than in ORIF, but 6-fold lower than for the postoperative CT scan. Postoperative pain on VAS was significantly lower after CRIF, allowing earlier gait resumption and return to work and daily activity. There were no significant differences in length of hospital stay, patient satisfaction, screw malpositioning or postoperative or end-of-follow-up kyphosis angle. CONCLUSION: Percutaneous surgery provided clinical and radiological outcomes strictly comparable to those of open surgery, but with a higher effective radiation exposure dose, including for the medical team and especially for the surgeon. This higher exposure dose, however, is to be relativized by comparison to that of the postoperative CT scan, which involved a much higher exposure dose for the patient. LEVEL OF EVIDENCE: Level IV. Retrospective study.