Long Term Follow-up of Luque Trolley Growing-Rod Construct in the Surgical Treatment of Early Onset Idiopathic Scoliosis

Purpose: Early onset idiopathic scoliosis cases treated with Luque Trolley instrumentation were reviewed to evaluate the factors affecting the effect of a growing-rod construct on curve progression during adolescent growth spurt.

Methods: 31 cases of early onset idiopathic scoliosis were surgically treated using convex epiphysiodesis and Luque Trolley instrumentation due to progressive deformity during 1984-1992. 23 (14 male, 9 female) out of these 31cases, who reached a minimum 16 years of age at final follow-up, were reviewed. All these cases also had anterior convex epiphysiodesis. Overlapped ‘L’ rod construct was used in 14 cases operated prior to 1988, and overlapped ‘U’ rod construct was used in the subsequent 9 cases. No postoperative bracing was used.

Results: Mean age at operation was 4.36 years (range, 1.5-9 years). Preoperative mean Cobb angle was 65° (30°- 95°), and direct postoperative Cobb angle was 28° (range 10°- 60°). Mean follow-up was 14.2 years (range, 7-25 years). 4 cases needed revision for exchange of longer Luque rods at mean age of 7.5 years. Definitive fusion and removal of Luque Trolley was needed at a mean age of 14.5 years (range 12-23 years), due to progression of scoliosis in 9 cases (mean Cobb angle 55°), and development of junctional kyphosis in 4 cases. 10 cases maintained their correction till skeletal maturity without definitive fusion (mean Cobb angle at final FU 33°). Regression of curve was noted in 3 cases. Mean Instrumented segment growth was 3.2 cm (42% of the expected growth). Progression of scoliosis was predicted by preoperative apical convex rib-vertebra angle (RVA) (p=0.002). Excessive instrumented segment growth was predictive of junctional kyphosis but not of scoliosis progression. Age at operation and initial curve size was not found to be significant predictive factor. 72% of overlapped ‘L’ rod construct (10 cases), and only 33% of overlapped ‘U’ rod construct (3 cases) had curve progression and needed definitive fusion.

Conclusions: Luque Trolley instrumentation along with convex epiphysiodesis was an effective method in controlling early onset idiopathic scoliosis, while maintaining significant growth. Preoperative convex RVA was predictive of curve progression. Junctional kyphosis was common with larger instrumented, segmented growth. Overlapped ‘U’ rod construct was more effective than ‘L’ rod construct in preventing curve progression.