Spinal imbalance and decompensation problems in patients treated with Cotrel-Dubousset instrumentation

Abstract

The basic principles of current idiopathic scoliosis treatment are three-dimensional correction and rigid fixation. Although it is accepted that Cotrel-Dubousset instrumentation (CDI) meets these goals, there is concern about the potential risk of trunk imbalance and spinal decompensation during the derotation manoeuvre. The results of 45 patients with idiopathic scoliosis treated with CDI between December 1988 and August 1992 were retrospectively analysed. Mean age was 14.3 years and mean follow-up period was 48.6 months. An average correction of 49.6% was achieved in the major curves. The best results were obtained in King type III curves, with a 69.4% correction. Spinal imbalance was evaluated by measuring lateral trunk shift (LT), shift of head (SH) and shift of stable vertebra (SS). Decompensation was measured by the increase in secondary curves. When all curve types were included, the average preoperative LT value of 1.96 vertebral units (VU) was brought down to 0.91 VU postoperatively, achieving a 55.9% correction. Fourteen patients had an SH value of zero preoperatively and remained balanced after instrumentation. Of the 41 remaining patients, 21 achieved an SH value of zero postoperatively. When all cases were included, the average preoperative SH value was 1.0 VU, which was corrected to 0.42 VU with CDI (69% correction). An average correction of SS of 75.5% was obtained, with the mean preoperative value of 0.73 VU being corrected to 0.19 VU. At the last follow-up visit, a secondary curve had formed above the major curve in one patient, and three patients had a junctional kyphosis. Loss of correction in the frontal plane correlated with loss of correction of LT. The rigid and semiflexible lumbar curves had a tendency to progress when they were not instrumented, especially in type II curves. Junctional kyphosis could be prevented when concave laminar claws were used in the thoraco-lumbar region. It was concluded that spinal decompensation and imbalance could be minimized with careful preoperative planning, avoidance of overcorrection and use of long instrumentation in double major curves.

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

“…2,6,31,43 Imrie et al 18 report high correction rates with modern instrumentation without increased rates of decompensation in Lenke 1C curves. When patients with an MT curve correction greater than 80% are compared with patients with correction less than 40%, the high correction group is able to achieve a lumbar correction that approaches what is seen on the lateral-bending film, resulting in a more balanced spine.…”

Decompensation following scoliosis surgery: treatment by decreasing the correction of the main thoracic curve or "letting the spine go"

“…Improper selection of the distal fusion level was thought to be the causative factor in a number of cases in which the distal fusion level was not the stable vertebra [19] or when the fusion did not include the lumbar curve, especially in double major curves [2]. Hypercorrection of the main thoracic curve [2] has been blamed for postoperative imbalance, as the non-fused lumbar compensatory curve cannot compensate for the excessive correction of the main thoracic curve. Improper hook strategy and use of distraction forces were also blamed for postoperative imbalance [6,17].…”

“…The rod derotation maneuver of Cotrel-Dubousset and similar instrumentation was blamed for producing torsional changes in the non-instrumented area that could result in spinal imbalance [3,12,19]. Improper selection of the distal fusion level was thought to be the causative factor in a number of cases in which the distal fusion level was not the stable vertebra [19] or when the fusion did not include the lumbar curve, especially in double major curves [2]. Hypercorrection of the main thoracic curve [2] has been blamed for postoperative imbalance, as the non-fused lumbar compensatory curve cannot compensate for the excessive correction of the main thoracic curve.…”

“…Spinal imbalance and decompensation following spinal fusion for adolescent idiopathic scoliosis (AIS) with current instrumentation remains a frequent and unsolved postoperative complication [2,3,6,7,9,11,12,15,16,19]. This complication arose with the use of Cotrel Dubousset instrumentation, and did not seem to occur with the use of the Harrington instrumentation [9], where guidelines for selecting the fusion level have been given by King et al [4].…”

Results of complete hemivertebra excision followed by circumferential fusion and anterior or posterior instrumentation in patients with type-IA formation defect

“…So, it is not possible to make a clear suggestion; no such comparative study exists in the literature. Our results suggest that: [20] hemivertebrectomy can be easily performed at adolescent ages and the space formed after the excision can be easily closed by instrumentation [27]; surgical procedure is neurologically safe and high correction rates can be obtained at frontal plane [6]; it is possible to obtain physiological sagittal contours and body balance in most of the patients. Therefore, we suggest that hemivertebra excision is a convenient, successful, and safe method, particularly in untreated or neglected congenital scoliosis cases due to type I-A hemivertebra.…”