Operative Behandlung von Frakturen des thorakolumbalen Überganges mit spinalem Einstand unter besonderer Berücksichtigung der Methode der ventralen spinalen Clearance

Introduction: Conservative management and operation are treatment options for fractures of the thoraco-lumbar transition with encroachment of the spinal canal. Operative treatment is usually preferred if there is neurological deficit, instability or significant encroachment of the spinal canal. Decompression can be indirect (removal of fragments by distraction and realignment of the vertebral body due to ligamentotaxis or vacuum effects) or direct. Ventral spinal decompression (clearance) is the most effective method for fragment removal, but also the most invasive. Both remodelling (with lysis of remnant bony fragments in the canal) and secondary spinal canal stenosis have been described. Aims: Main objectives of that study were to determine whether ventral spinal clearance is more effective than other methods in decompressing the spinal canal and improving neurological outcome, whether and to what extent postoperative restructuring of the spinal canal takes places (remodelling/spontaneous resorption/stenosis formation) and what method of operation is most effective in reconstructing and maintaining the spinal profile. Design: 105 patients with traumatic fractures between Th10 and L3 and radiological evidence of bony encroachment of the spinal canal were analysed in 4 treatment groups: dorsal operation only (n= 10), dorsal operation with transpedicular spongiosaplastic (n =19), combined dorso-ventral operation (n = 52) and combined dorso-ventral operation with clearance of the canal (n=24). Data concerning accident and operation was gathered retrospectively. Mechanism of injury, fracture type (according to AO), neurological status pre- and postoperatively (Frankel/ASIA), functional parameters, CT scans and X-rays were analysed. Follow-up was 3 years postoperatively with re-assessment of neurological status, functional parameters and CT scanning ofthe affected and neighbouring vertebrae. Results: Average age was 38 (14-74) years. Most common mechanism was fall from a height (43.8%). Most frequently injured vertebra was L1 (41%) und most common fracture type was A3 (48.6%). 54,3% of patients had associated injuries requiring treatment, 19% had polytrauma. Average duration of dorsal operation was 1:48 h, ventral operation without clearance 2:49 h and ventral operation with clearance 4:38 h (p < 0.005). Probability for severe bleeding at the operation site was higher with clearance (p<0.0001). Complications occurred more often with combined dorso-ventral operations (p = 0.016). 74.3% of patients were followed up. There were no differences between the treatment groups concerning functional parameters (content with the operation/limitation of spinal mobility/professional and leisure activities/Hannover spine score). 61% of patients that were in employment preoperatively remained in work. 27.6% of patients had neurological deficits after the accident. In 65.5% neurological function recovered by 1 score on the Frankel/McBride scale until discharge from hospital. Clearance operation improved neurological function in 8 out of 10 (80%), combined dorso-ventral operation without clearance improved neurological deficit in 10 out of 17 cases (59%). There was no statistical significance. Failure of the dorsal implant (break of pedicle screws) occurred more often in patients operated only dorsally as opposed to combined operated patients (p<0.01). Breaks of ventral single clamp-single rod constructs (US1S) occurred in 17,6%. Kyphosis angle and sagittal index were preoperatively -14.8° and 0.66 and postoperatively - 5.8° and 0.87 (p < 0.001) respectively for all patients. At follow-up, a loss of correction was noted with the kyphosis angle - 8.2° and the sagittal index 0.82. Patients with combined operations had the smallest loss of correction where as in the dorsal group patients lost 50% of the initial correction. The average encroachment of the spinal canal for all groups was preoperatively 48% and at follow-up 17% (p < 0.001).