Lengthening of magnetically controlled growing rods caused minimal pain in 25 children: pain assessment with FPS-R, NRS, and r-FLACC

Study design: Descriptive case series.

Objective: The aim of the study is to investigate the pain associated with magnetically controlled growing rod (MCGR) lengthening procedures. MCGRs have gained popularity because they offer non-surgical lengthening procedures in early-onset scoliosis (EOS) instead of semi-annual open surgery elongations with traditional growing rods. Many aspects of MCGR treatment have been investigated, but pain in conjunction with distraction is only sparsely described in the literature.

Methods: Pain intensity was assessed in 25 EOS patients before, during and after MCGR lengthening procedures in an outpatient setup. They underwent at least two (range 2-16) lengthening procedures prior to this study. The pain intensity was estimated using patient-reported Faces Pain Scale (FPS-R), caregiver-reported pain numeric rating scale (NRS), and NRS and revised Face, Legs, Activity, Cry, Consolability scale (r-FLACC) by two medically trained observers. The inter-rater reliability and correlation between instruments were analyzed.

Results: 23 of 25 EOS patients (8- to 16-year old) with mixed etiology were able to self-report pain. The average pain intensity was mild: median 1 (range 0-6) on all four instruments on a 0-to-10 scale. Afterward, 22/25 patients (88%) were completely pain free and the remaining 3 patients had a pain score of 1. MCGR stalling (i.e. clunking) was encountered in 14/25 (56%) of the patients without impact on the pain intensity.

Conclusions: The average maximum pain intensities during the lengthening procedures were mild and pain ceased within few minutes. The inter-rater reliability was good to excellent for NRS and r-FLACC, and there were high correlations between all the four pain instruments, indicating high criterion validity.

Level of evidence: Level IV, case series.