SHOULDER HEIGHT AFTER SURGICAL CORRECTION OF THORACIC ADOLESCENT IDIOPATHIC SCOLIOSIS.

Background: It is commonly observed that a good correction of the Cobb angle at scoliosis surgery is accompanied by an acute asymmetry of shoulder height. Kuklo et al in 2002 described (Spine. 26(18):1966–1975) spontaneous reversal of this, using radiographic measures and patient questionnaires. Objective: To determine the incidence and extent of shoulder-imbalance before posterior spinal surgery and to ascertain its outcome, using radiographic and topographic measures. Methods: Patients with right thoracic adolescent idiopathic scoliosis who had undergone corrective posterior spinal fusion by one surgeon were identified. Pre- and all postoperative spinal radiographs and surface topography were evaluated and correlated. Any effect from concomitant anterior release procedures was sought. Results: Sixty six patients were identified, 56 girls and 10 boys. Their pre-operative major Cobb angle was 73°±14.0 and mean correction was 38.8°±12.333 (56%). Before surgery, surface topography showed the mid-point of the right shoulder to be at a mean or 18.3mm.±10.9 higher than the equivalent left point; eight days later, the difference was −6.7 mm. ±9.68, a mean change of 25.9mm±11.8. At six months, it was −5.1 ±6.86, statistically unchanged. At two years, it was −2.16 (p=0.051) and at three years, 1.76± 6.53 and indistinguishable from zero or perfect balance. The difference between pre-operative and final shoulder level difference was 19.54mm.±9.09. The Cobb angle of the compensatory upper thoracic curve was not significantly changed throughout. There was no statistically significant difference in shoulder height between patients undergoing single or two-stage surgery, either before or at any stage after. Discussion and conclusion: Correction of post-operative shoulder imbalance does occur spontaneously, as reported by Kuklo et al. and is not a function of spinal accommodation to the new anatomy.