Abstract
Introduction
Anterior stabilization with cages/iliac bone graft and corpectomy in addition with posterior spondylodesis is the gold standard for the treatment of anterior unstable Magerl types A and B fractures of the thoracolumbar junction.1,2 The effect of temporary fixation on the intervertebral disc as well as on progression of kyphosis, especially after dorsal implant removal to unblock the caudal nonfused segment, is unclear.
Materials and Methods
Retrospective case series of all patients treated with posterior stabilization in combination with vertebroplasty/kyphoplasty between 2000 and 2010 with secondary implant removal 8 to 12 months after the index operation. All cases were assessed for loss of reduction, Cobb angle, and disc height after implant removal by anteroposterior and lateral radiographs.
Results
Overall 20 (m: 13; f: 7) (age: 40.9 ± 14.4 years) out of 59 patients treated with bridging dorsal instrumentation with transpedicular vertebroplasty underwent implant removal. Fractures were classified as A 3.21 in 15, A 3.1 in 3, and B 2.3 in 2 cases. The fracture location was Th12 in 5, L1 in 11, L2 and L3 in 2 cases. The implant removal was performed 9.6 ± 3.2 month after initial surgery. In all but one case increase of kyphosis was found 6 month later. The mean increase of kyphosis was 8 ± 6 degrees (max: 12 degrees; min: 0 degrees), mainly in the upper motion segment. Significant loss of disc height was found in the upper motion segment compared with before implant removal, whereas vertebral height remains stable. Age highly correlated to loss of reduction and disc height (r = 0.51). No differences between the fracture location and types were found.
Conclusion
After temporary fixation of the intervertebral disc by internal fixation an increase of kyphosis in the segment above the augmented/fractured vertebra is to be expected, especially because of degeneration of the disc above the affected vertebra. This effect is age dependent. In how far this has clinical relevance is topic of ongoing investigations.
None declared
Harris MB. The role of anterior stabilization with instrumentation in the treatment of thoracolumbar burst fractures. Orthopedics 1992;15(3):347–350
Mariotti AJ, Diwan AD. Current concepts in anterior surgery for thoracolumbar trauma. Orthop Clin North Am 2002;33(2):403–412