Lengthening Less Than 7 Months Leads to Greater Spinal Height Gain With Rib-based Distraction

Severe early-onset scoliosis (EOS) has been associated with a multitude of comorbidities, chief among them being deficient thoracic spine growth and pulmonary complications. EOS management with rib-based instrumentation involves repeated lengthening. Despite expansion practice patterns, there is limited literature and no evidence-based guidelines for optimal expansion intervals. Our study evaluates clinical outcomes in relation to lengthening intervals with the aim of optimizing the timing of surgical expansion in EOS patients.

A single-institution retrospective review of 60 EOS patients treated with rib-based growth instrumentation with a minimum of 3-year follow-up and 3 expansion/revision surgeries. Patients were separated into 2 expansion cohorts: (1) more frequent lengthening [MFL group (≤7 mo)] and (2) less frequent lengthening [LFL group (>7 mo)]. Demographic information and clinical factors were recorded. Univariate and bivariate analyses were performed.

Both the MFL group (35 patients) and LFL group (25 patients) were similar in sex distribution, diagnosis, preoperative parameters of interest, and treatment duration. The mean follow-up was 6.0 years. There was an increase in postoperative T1-S1 spine height gained in the MFL group (P=0.006) as well as a higher percent expected spine growth based on normative values (P=0.03) when compared with the LFL group. The MFL group had more expansion/revision surgeries (P=0.003) but no increase in the number of complications (P=0.86).

More frequent lengthenings were associated with statistically significant overall spinal height gain and percent expected growth without a significant increase in complication rates. It was shown that change in major curve and space available for the lungs was not associated with the lengthening intervals.

Level III-a comparative retrospective study.