Rib-on-Pelvis Deformity and Reported Pain in Neuromuscular Early-Onset Scoliosis

Background: Neuromuscular early-onset scoliosis (N-EOS) often presents with a long sweeping thoracolumbar scoliosis and pelvic obliquity. With severe pelvic obliquity, the ribs come into contact with the high side of the pelvis, termed rib-on-pelvis deformity (ROP). The goal of this study is to evaluate whether ROP is associated with reported pain and other health-related quality of life (HRQOL) measures. We hypothesize that ROP is associated with increased pain and negative HRQOL.

Methods: A multicenter international registry was queried for all nonambulatory patients with N-EOS from 2012 to 2022. Both surgical and nonsurgical patients were included. ROP was classified as a binary radiographic assessment of preoperative (surgical patients) and most recent follow-up (nonsurgical patients) upright radiographs. Reported pain and other HRQOL measures were assessed through the 24-Item Early Onset Scoliosis Questionnaire (EOSQ-24). Patients with nonupright radiographs or EOSQ-24 questionnaires and corresponding radiographs >4 months apart were excluded.

Results: Totally, 225 patients (8.4±3.1 y, 55% female) were included. The median major curve was 63.3 (IQR: 40.6 to 81.2) degrees and median pelvic obliquity was 15.5 degrees (IQR: 8.8 to 26.4). Eighty-three patients (37%) had ROP. ROP was associated with both frequency ( P <0.001) and severity ( P <0.001) of pain. ROP was associated with worse general health ( P =0.01), increased difficulty with vocalization ( P =0.02), increased frequency of shortness of breath ( P =0.002), and increased difficulty sitting upright ( P =0.04). Regarding overall EOSQ-24 domains, ROP was associated with worse general health, pain/discomfort, pulmonary function, and physical function ( P <0.01). In a subanalysis of 76 patients who underwent surgical intervention with at least 2 years of follow-up, patients with preoperative ROP experienced significantly greater improvements in both frequency ( P =0.004) and severity ( P =0.001) of pain than the patients without preoperative ROP at 2 years postoperatively.

Conclusions: The overall incidence of ROP in N-EOS is about 37%. ROP is associated with greater pain and worse HRQOL through the EOSQ-24 questionnaire. Furthermore, these patients experienced a greater reduction in pain after surgery. Clinicians and parents must be aware that ROP is possibly a pain generator, but responds positively to surgical intervention.

Level of evidence: Level III.