Outcomes of retained growing rods without final fusion in early-onset scoliosis: What happened after graduation?

Abstract

Traditionally, final fusion has been the standard endpoint surgery for patients with early-onset scoliosis (EOS) completing growing-rod treatment. Recently, an observation strategy has emerged as a reasonable alternative to avoid the final fusion. However, current study focuses primarily on short-term outcomes at the time of graduation, and the safety of this strategy until complete skeletal maturity remains unclear. This study aimed to evaluate the safety and clinical outcomes of an observation strategy without final fusion for skeletally mature EOS patients. We retrospectively reviewed 55 patients with EOS who underwent traditional growing-rod treatment with a minimum of 3 lengthenings, and reached skeletal maturity with satisfactory spinal balance and little length gained (< 1 cm) at the final lengthening. The graduation strategy was observation with implant retention. Radiographic parameters, spinal growth, complications, and the rate and clinical data of unplanned final fusion were evaluated. Fifty-five patients underwent a mean of 5.6 lengthening procedures, achieving significant Cobb angle improvement from 75.3° to 49.3°. During the observation period, 92.7% (51/55) of patients maintained satisfactory spinal balance without requiring definitive fusion. Spontaneous autofusion was radiographically evident in 60.0% of patients, including 23.6% high-grade fusion. Despite a slight loss of main curve correction (49.3° to 52.1°, p = 0.020), apical vertebral translation, global kyphosis, and sagittal/coronal balance exhibited no significant deterioration. Spinal and thoracic growth were firmly consolidated during observation: T1-T12 height increased slightly to 186.7 mm, thoracic width continued to mildly increase, and space available for lung (SAL) remained stable at approximately 90%. Although 34.5% experienced mild curve progression, only 4 patients (7.3%) required unplanned definitive fusion. For selected EOS patients with satisfactory balance, observation without final fusion is a feasible management strategy. As residual malalignment is associated with subsequent decompensation, achieving stringent spinal balance at graduation may help minimize reoperation risk.