Ossifications After Vertical Expandable Prosthetic Titanium Rib Treatment in Children With Thoracic Insufficiency Syndrome and Scoliosis

Study Design. Retrospective analysis of 1328 spinal radiographs of 57 patients after vertical expandable prosthetic titanium rib (VEPTR) implantation with an average follow-up of 30 months. Objective. To evaluate the incidence, time of onset, as well as the underlying factors influencing the occurrence of ossifications in children treated with VEPTR. Summary of Background Data. Spontaneous spinal fusions and ossifications are well known in children treated with spinal implants. In theory, children with spinal deformity and VEPTR implantation are less likely to develop these complications because of either little or no implant contact to the spine. Methods. Fifty-seven patients had a primary VEPTR implantation due to spinal deformity and thoracic insufficiency syndrome and repeated lengthening procedures. The mean age at the time of primary surgery was 7.7 years, the mean duration of follow-up was 29.8 months, and the mean number of operations was 5.9. A total of 1328 spinal radiographs were analyzed with respect to the occurrence and growth of ossifications, implant migration, and other complications. Results. Overall, 24% of the patients (n = 13) had ossifications, which affected in 92% the main load sharing VEPTR implant. The fusions involved in 54% of cases the lumbar spine and in each 23% the ribs and the iliac crest. Ossifications developed in 11% of children within the first year of treatment and increased by about the same rate per annum. After 53 months, 48% of the radiographs showed some ossifications. There was a significant correlation to the stiffness of the deformity and the number of surgical procedures. Conclusion. Contrary to previous assumptions, it was shown that in children treated with the VEPTR system, 48% of children showed ossifications after 53 months. Ossifications were observed significantly more often in children with stiff deformities and after multiple surgical procedures. It is a much more common problem than previously thought.