Magnetically controlled growing rods yield curve correction, growth similar to traditional rods

However, patients with the magnetic rods required fewer surgeries for lengthening.

Issue: July 2014

Although a case-matched study of pediatric patients with early onset scoliosis showed comparable curve correction and growth for those treated with traditional rods and magnetically controlled growing rods, the magnetic growing rod group had fewer surgical procedures after minimum 2-year follow-up.

“The major curve correction, annual T1-S1 growth and annual T1-T12 growth were similar,” Behrooz A. Akbarnia, MD, said during his presentation at the American Academy of Orthopaedic Surgeons Annual Meeting.

“The incidence of unplanned surgeries was similar with [magnetically controlled growing rod] MCGR patients having 57 fewer surgical procedures than [traditional growing rod] TGR patients. While it appears the procedure reduces the number of open surgical procedures, it will not change the natural history of the underlying disease. You have to look at that as a really important thing,” he said.

Preoperative major curves

The researchers studied patients aged 10 years or younger who had major curves of at least 30°, a T1 to T12 height shorter than 22 cm and who did not have any previous spine surgery. All of the patients had at least 2 years follow-up. Of the 17 MCGR patients identified, 12 patients had complete data, Akbarnia said. These patients were matched to a group of TGR patients from Growing Spine Study Group database by gender, age, major curve, etiology and by whether single or dual rods were used for initial correction. Because a same sex match could not be made for one MCGR male patient, the patient was matched to a female patient in the TGR group.

Patients in the MCGR group had a mean age of 6.8 years and a mean follow-up of 2.5 years. The TGR group had a mean follow-up of 4.1 years. The major curve was 59° in the MCGR group preoperatively and 60° preoperatively in the TGR cohort. The preoperative T1-S1 spinal length was 270 mm in the MCGR group and 264 mm in the TGR group.

Number of lengthenings

Akbarnia and colleagues found no significant differences between the groups for major curve correction, or annual T1-S1 growth. Annual T1-S1 growth, defined as the change in measurements taken after the index surgery through final follow-up, divided by the length of follow-up, was also similar between the TGR and MCGR groups. However, the investigators discovered the TGR patients had 73 surgeries during the study period compared to 16 surgeries for the MCGR group. According to the study abstract, most of the 73 surgeries in the TGR group were lengthenings. The MCGR group had 137 non-invasive lengthenings.

“Total unplanned surgeries were the same [between the groups],” Akbarnia said. The investigators noted five in the TGR group and four in the MCGR group. – by Gina Brockenbrough, MA

Reference:

Akbarnia BA. Paper #161. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 11-15, 2014; New Orleans.

For more information:

Behrooz A. Akbarnia, MD, can be reached at San Diego Center for Spinal Disorders, 4130 La Jolla Village Dr., La Jolla, CA 92037; kostial.pat@sandiegospinefoundation.org.
Disclosure: Akbarnia receives royalties and research or institutional support as a principle investigator from DePuy Spine and NuVasive; is a paid consultant to NuVasive, K2M, Ellipse and K Spine; and has stock options in Alphatec Spine, NuVasive, Ellipse, K Spine and Nocimed.