Rip hump correction and rotation of the lumbar spine after selective thoracic fusion

Abstract

In this study a series of 32 patients with idiopathic scoliosis, managed with selective thoracic fusion, was reviewed. Classified according to King and instrumented with the H-frame, the patients were evaluated for curve correction, rib hump correction and postoperative shift in lumbar rotation. Age and follow-up average 19.4 and 2.4 years, respectively. The 32 patients had an average primary and lumbar curve correction of, respectively, 66% (6.0% correction loss) and 53% (3.4% correction loss). The respective values for postoperative rib hump correction and shift in apical lumbar rotation averaged 8 degrees and 9.4 degrees in type II King curves 4.4 degrees and 3.5 degrees in type III and 11 degrees and -5 degrees in Type IV. Significant differences were noted between the curve types in rib hump correction and shift in lumbar rotation. The study showed that en bloc postoperative rotation of the compensatory lumbar segment, directed towards the rib hump, positively influences rib hump correction. This en bloc rotation of the unfused lumbar segments is induced by the correcting forces applied by the instrumentation. The unfused lumbar spine of a patient with a King type II curve shows a larger lumbar rotation shift and subsequent rib hump correction than that of a patient with a King type III curve. Together with factors such as lateral angulation, rib-vertebra angles and structural limitations, the rotational dynamics of the unfused lumbar spine seem to form an important component in the under-standing and surgical management of scoliosis.

Selective versus nonselective thoracic fusion in Lenke 1C curves: a meta-analysis of baseline characteristics and postoperative outcomes

“…7,8 Recent interest in determining risk factors for postoperative decompensation after STF has led to research attempting to elucidate criteria for predicting the optimal surgical strategy. Factors such as proper selection of the LIV, 1,3,4,24,29,31,37,[41][42][43] the main thoracic to thoracolumbar/lumbar (MT:TL/L) ratio, 25,28,34 thoracic "overcorrection," 5,6,12,13,16,17,19,25,45 and surgical approach have been correlated with risk of postoperative decompensation. Despite guidelines for performing STF, NSTF is still commonly performed, with one study showing only 49% of patients with Lenke 1C curves being treated with an STF.…”