• V J Leferink, K W Zimmerman, E F Veldhuis, E M ten Vergert, and H J ten Duis.
• Department of Surgery, University Hospital Groningen, The Netherlands. v.j.m.leferink@chir.azg.nl
• Eur Spine J. 2001 Dec 1; 10 (6): 517-23.

AbstractIn internal posterior fixation of thoracolumbar fractures combined with transpedicular cancellous bone graft and posterior fusion of the intervertebral facet joints at the level of the destroyed end plate it is still uncertain as to whether significant vertebral body collapse and loss of correction of the regional angle (RA) and the intervertebral angle (IVA) occur (after removal of the implants). These questions were investigated in a retrospective study of 183 consecutive patients, 18-65 years old, with a spinal fracture between the 9th thoracic and the 5th lumbar vertebral body (inclusive), treated operatively between 1988 and 1996 (27% had objective neurological deficit, 37% had multiple injuries). According to the Comprehensive Classification, 128 type A, 32 type B and 21 type C fractures were identified preoperatively. Changes in the anterior wedge angle (AWA), the IVA and the RA were measured preoperatively, and within 1 month, 9 months and 24 months postoperatively. The effect of implant failure was also evaluated. The normality of the distribution was tested using the Kolmogorov-Smirnov (K-S) test. The one-sample runs test and the t-test were used to evaluate angle changes. Angles in patients with and without implant failure were compared using the unpaired t-test. Almost complete restoration of the AWA could be achieved during operation. Postoperative changes in AWA were either very small or not significant. The reduced vertebral body did not collapse after 9 months, when most of the patients (170) underwent removal of the implants, but significant changes in IVA were found after implant removal. Correction of the RA was statistically significant before implant removal, but the RA 2 years after surgery had become almost the same as the preoperative values. Changes at the level of the intervertebral space, occurring after implant removal, contributed to the loss in the RA. Broken pedicle screws (10.9% of the patients) resulted in significant changes in the AWA and RA before implant removal, but did not influence the IVA.

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