Long-term follow-up of adolescent idiopathic scoliosis surgery with Harrington instrumentations: a systematic review and meta-analysis.

purposeIn the 1960s, Harrington instrumentation (HRI) revolutionized the surgical treatment of adolescent idiopathic scoliosis (AIS). Despite the transition to more innovative techniques, concerns regarding its impact on sagittal alignment, associations with low back pain, and correction loss have consistently persisted. The aim of this meta-analysis is precisely to evaluate the clinical and radiological outcomes, as well as the complications of patients treated with HRI over an extended follow-up period. A systematic search of articles about AIS patients who underwent HRI and reported long-term outcomes (> 10 years) was conducted on electronic databases according to PRISMA guidelines. Data regarding radiographic and clinical outcomes were extracted and meta-analyses were performed. Eleven studies comprising 644 patients were included. The mean follow-up ranged from 10.8 to 51.7 years. Radiographic analysis revealed a decrease in the main curve Cobb angle from 60.6° to 38.3°, with a correction loss of - 9.49° between postoperative and last follow-up. Concerning sagittal parameters, preoperative thoracic kyphosis was 19.65° at last follow-up, and preoperative lumbar lordosis was 42.94°. Additional spine surgeries were required in 42% of patients. Clinical outcomes varied among studies, but overall, HRI patients showed comparable quality of life and function to controls, although a higher incidence of low back pain was reported. Patients who underwent HRI exhibited suboptimal correction of rib deformity and a flattened sagittal spinal alignment. However, they generally displayed favourable long-term functional outcomes. Despite the implant's tendency to reduce lumbar curvature, patients achieved good clinical outcomes and functional scores comparable to age-matched individuals, suggesting that disability is not an inevitable consequence of lumbar flattening.