On-line version ISSN 2309-8309
SA orthop. j. vol.8 n.4 Pretoria Jan. 2009
RG FinnI; JA ShipleyII
IMBChB, MMed(Orth); Registrar, Department of Orthopaedic Surgery, University of the Free State
IIMBChB, MMed(Orth); Professor and Head of Department of Orthopaedic Surgery, University of the Free State
AIM: To determine how accurately pre-operative stress radiographs predict the final outcome in adolescent idiopathic scoliosis surgery.
METHODS: Records of 20 patients were reviewed retrospectively. Pre-operative correction was measured by comparing the initial Cobb angle of the main structural curves on plain standing radiographs to values measured at corresponding levels after correction on traction and fulcrum bending radiographs. Post-operative correction was obtained by measurements at corresponding levels of the instrumented and uninstrumented curves.
RESULTS: Mean correction of the main instrumented curve by traction was 24.2° (40.9%), and by fulcrum bending 32.3° (56.0%). Post-operative correction yielded a mean value of 41.1° (68.2%). Expressing pre-operative values as a percentage of final correction, traction views predicted 60%, and fulcrum bending radiographs 82% of the final correction. If agreement within 10° of pre- and post-operative values is regarded as clinically significant, only 18% of traction and 45% of fulcrum bending views came within that range.
DISCUSSION: We concluded that fulcrum bending views are of superior predictive value in terms of surgical correction to be expected, but still correlate poorly with final surgical correction achieved.
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