Should instrumented spinal fusion in nonambulatory children with neuromuscular scoliosis be extended to L5 or the pelvis?

Abstract

Aims It is uncertain whether instrumented spinal fixation in nonambulatory children with neuromuscular scoliosis should finish at L5 or be extended to the pelvis. Pelvic fixation has been shown to be associated with up to 30% complication rates, but is regarded by some as the standard for correction of deformity in these conditions. The incidence of failure when comparing the most caudal level of instrumentation, either L5 or the pelvis, using all-pedicle screw instrumentation has not previously been reported. In this retrospective study, we compared nonambulatory patients undergoing surgery at two centres: one that routinely instrumented to L5 and the other to the pelvis. Methods In all, 91 nonambulatory patients with neuromuscular scoliosis were included. All underwent surgery using bilateral, segmental, pedicle screw instrumentation. A total of 40 patients underwent fusion to L5 and 51 had their fixation extended to the pelvis. The two groups were assessed for differences in terms of clinical and radiological findings, as well as complications. Results The main curve (MC) was a mean of 90° (40° to 141°) preoperatively and 46° (15° to 82°) at two-year follow-up in the L5 group, and 82° (33° to 116°) and 19° (1° to 60°) in the pelvic group (p < 0.001 at follow-up). Correction of MC and pelvic obliquity (POB) were statistically greater in the pelvic group (p < 0.001). There was no statistically significant difference in the operating time, blood loss, or complications. Loss of MC correction (> 10°) was more common in patients fixated to the pelvis (23% vs 3%; p = 0.032), while loss of pelvic obliquity correction was more frequent in the L5 group (25% vs 0%; p = 0.007). Risk factors for loss of correction (either POB or MC) included preoperative coronal imbalance (> 50 mm, odds ratio (OR) 11.5, 95%confidence interval (CI) 2.0 to 65; p = 0.006) and postoperative sagittal imbalance (> 25 mm, OR 11.0, 95% CI1.9 to 65; p = 0.008). Conclusion We found that patients undergoing pelvic fixation had a greater correction of MC and POB. The rate of complications was not different. Preoperative coronal and postoperative sagittal imbalance were associated with increased risks of loss of correction, regardless of extent of fixation. Therefore, we recommend pelvic fixation in all nonambulatory children with neuromuscular scoliosis where coronal or sagittal imbalance are present preoperatively. Cite this article: Bone Joint J 2020;102-B(2):261–267.

Clinical Issues in Indication, Correction, and Outcomes of the Surgery for Neuromuscular Scoliosis: Narrative Review in Pedicle Screw Era

“…The simple comparison between these 2 studies is inappropriate because Takaso et al [ 31 ] included only flaccid neuromuscular scoliosis. In contrast, the patients in the study by Tøndevold et al [ 32 ] had a different etiology (52% of CP, 12% of central motor neuron involvement, 10% of SMA, and others). The advantage of the mobile L5–S1 disc space may be the absorption of stress during wheelchair activities, sitting on the floor, or crawling.…”

“…On the contrary, Tøndevold et al [ 32 ] recommended pelvic fixation in neuromuscular scoliosis because correction of the main curve and pelvic obliquity was superior in patients with pelvic fixation in their retrospective study on 91 nonambulatory neuromuscular scoliosis patients. Loss of pelvic obliquity correction was also more frequently seen in the L5 group (25% vs. 0%).…”

Is it necessary to fuse to the pelvis when correcting scoliosis in cerebral palsy?

“…Pelvic fusion did not increase the operative time or blood loss compared to higher levels of fusion. Published studies have differed, with some demonstrating longer surgeries and more blood loss with pelvic fixation, while other studies did not find a difference[ 13 , 19 - 21 ]. The long duration of surgery and magnitude of blood loss along with case to case variation may make it difficult to detect differences with statistical significance.…”

“…The studies that discuss pelvic fusion either focus on children with flaccid forms of paralysis or include a pooled patient cohort including both spastic and flaccid disorders[ 9 - 13 ]. Since these neuromuscular disorders have varying levels of pelvic obliquity and do not necessarily act the same way, we sought to analyze our patients with cerebral palsy (CP) with regards to radiographic outcomes and complications as a function of fusion to the pelvis compared with higher levels of fusion.…”

A retrospective cohort study of bleeding characteristics and hidden blood loss after segmental pedicle screw instrumentation in neuromuscular scoliosis as compared with adolescent idiopathic scoliosis

“…The literature has described different indications for pelvic fixation in neuromuscular scoliosis [ 5 , 6 ]. Non-ambulatory children with neuromuscular scoliosis typically undergo spinal fusion extending from upper thoracic spine to pelvis [7] , [8] , [9] , [10] …”