Does rod overhang matter? Clinical impact in adolescent idiopathic scoliosis and Scheuermann's kyphosis.

Abstract

Objectives: The aim of this study was to investigate the potential relationship between rod overhang (RO) and quality of life (QoL) scores, as well as implant-related irritation, in patients with adolescent idiopathic scoliosis (AIS) and Scheuermann's kyphosis (SK).

Patients and methods: Between October 2016 and December 2018, a total of 33 pediatric patients with AIS and SK who underwent posterior instrumentation were retrospectively analyzed. On radiographs, the longest RO at both the superior and inferior ends (right or left) was recorded, and patients were grouped according to whether RO exceeded 1 cm. Quality of life outcomes were assessed using the Scoliosis Research Society-22r (SRS-22r), Oswestry Disability Index (ODI), and Short Form-36 (SF-36) questionnaires, and patients were also asked about implant-end irritation.

Results: Of the patients, 10 were male and 23 were female. The mean age at the time of operation was 15.18 ± 1.98 years, while the mean age at the latest follow-up was 23.85 ± 1.86 years. The median follow-up was 104.08 months. The mean maximum RO was 11.3 ± 7.8 mm superiorly and 11.1 ± 6.2 mm inferiorly. Superior RO correlated significantly with SF-36 role-physical (r = -0.36, p = 0.04) and vitality (r = -0.43, p = 0.01) subdomains; no other significant QoL correlations were found. Implant-related irritation was reported in eight (n = 3 superior, n = 5 inferior) patients. There was no significant difference in RO between patients who did and did not report implant-related irritation (superior p = 0.18 vs. inferior p = 0.48). There were no significant differences in QoL scores (for superior, inferior, and either end; p > 0.05) or in the rate of implant-related irritation between patients with RO greater or less than 1 cm (superior p = 0.70; inferior and either end p = 1.00).

Conclusion: Our study results suggest that rod overhangs up to 3 cm may not be a clinically relevant determinant of patient-reported outcomes or implant-related irritation in AIS and SK surgery. From a clinical perspective, this may help reduce concern regarding minor distal or proximal overhang during posterior instrumentation, particularly when optimal correction and fixation require slight extension of the construct. The absence of a measurable association with QoL or irritation also supports a more flexible intraoperative decision-making approach, prioritizing deformity correction and implant stability over strict limitation of rod length within this range.