Can magnetically controlled growing rods be successfully salvaged after deep surgical site infection?

Unplanned return to the operating room (UPROR) occurs in 40% of MCGR patients at an average of 2 years after initial implantation

PURPOSE

This study calculated the rates of Unplanned Return to the Operating Room (UPROR) in early-onset scoliosis patients who had no previous spine surgery and underwent Magnetically Controlled Growing Rod (MCGR) implantation.

METHODS

We reviewed surgical, radiographic, and UPROR outcomes for EOS patients treated with the MCGR implant < 12 years + 11 months of age, had complete preop/postop major curve measurements, and had complete MCGR details.

RESULTS

376 patients underwent MCGR implantation at a mean age of 7.7 years (1.8-12.9). Diagnoses included 106 (28%) idiopathic, 84 (22%) syndromic, 153 (41%) neuromuscular, and 33 (9%) congenital. The mean preop-cobb was 76.7° (9-145°), and an immediate postop correction was 41% (0-84%). We found that 38% (142/376) of patients experienced an UPROR prior to the maximal actuator length being achieved. UPROR occurred at mean 2 years (3 days-5 years) after initial implantation. Of the 142 patients who experienced UPROR there were 148 complications that lead to an UPROR. The most common reason for UPROR was anchor (55/148: 37%) or MCGR implant related (33/148: 22%). Wound related (22/148:15%), Neuro related 4/148: 3%), and other (34/148: 23%) accounted for the remaining UPROR occurrences.

CONCLUSION

In conclusion, the MCGR UPROR rate was 142/376 (38%) after an average of 2 years post implantation. At 2-year follow-up, only 20% of MCGR patients had experienced an UPROR. However, between 2 and 5 years, the development of an UPROR increased precipitously with only 39% of MCGR patients remaining UPROR free at 5 years post MCGR implantation. The most common reason for UPROR was related to anchor or MCGR implant-related complications. This information can be utilized to set realistic expectations about the need and timing of future surgical procedures with patients and their families.

A Comparative Analysis of Revision Surgery Before or After 2 Years After Graduation From Growth-friendly Surgery for Early Onset Scoliosis

INTRODUCTION

After discontinuation of growth-friendly (GF) surgery for early onset scoliosis, patients are termed graduates: they undergo a spinal fusion, are observed after final lengthening with GF implant maintenance, or are observed after GF implant removal. The purpose of this study was to compare the rates of and reasons for revision surgery in two cohorts of GF graduates: before or after 2 years of follow-up from graduation.

METHODS

A pediatric spine registry was queried for patients who underwent GF spine surgery with a minimum of 2 years of follow-ups after graduation by clinical and/or radiographic evidence. Scoliosis etiology, graduation strategy, number of, and reasons for revision surgery were queried.

RESULTS

There were 834 patients with a minimum of 2-year follow-up after graduation who were analyzed. There were 241 (29%) congenital, 271 (33%) neuromuscular, 168 (20%) syndromic, and 154 (18%) idiopathic. 803 (96%) had traditional growing rod/vertical expandable titanium rib as their GF construct and 31 (4%) had magnetically controlled growing rod. Five hundred ninety-six patients (71%) underwent spinal fusion at graduation, 208 (25%) had GF implants retained, and 30 (4%) had GF implants removed.In the entire cohort, there were 108/834 (13%) patients who underwent revision surgery. Of the revisions, 71/108 (66%) occurred as acute revisions (ARs) between 0 and 2 years from graduation (mean 0.6 y), and the most common AR indication was infection (26/71, 37%). The remaining 37/108 (34%) patients underwent delayed revision (DR) surgery >2 years (mean 3.8 y) from graduation, and the most common DR indication was implant issues (17/37, 46%).Graduation strategy affected revision rates. Of the 596 patients with spinal fusion as a graduation strategy, 98/596 (16%) underwent revision, compared with only 8/208 (4%) patients who had their GF implants retained, and 2/30 (7%) that had their GF implants removed (P ≤ 0.001).A significantly higher percentage of the ARs had a spinal fusion as the graduation strategy (68/71, 96%) compared with 30/37 DRs, (81%, P = 0.015). In addition, the 71 patients who underwent AR undergo more revision surgeries (mean: 2, range: 1 to 7) than 37 patients who underwent DR (mean: 1, range: 1 to 2) (P = 0.001).

CONCLUSION

In this largest reported series of GF graduates to date, the overall risk of revision was 13%. Patients who undergo a revision at any time, as well as ARs in particular, are more likely to have a spinal fusion as their graduation strategy. Patients who underwent AR, on average, undergo more revision surgeries than patients who underwent DR.

LEVEL OF EVIDENCE

Level III, comparative.

The evolving stall rate of magnetically controlled growing rods beyond 2 years follow-up

PURPOSE

Magnetically controlled growing rods (MCGR) have become the dominant distraction-based implant for the treatment of early onset scoliosis (EOS). Recent studies, however, have demonstrated rising rates of implant failure beyond short-term follow-up. We sought to evaluate a single-center experience with MCGR for the treatment of EOS to define the rate of MCGR failure to lengthen, termed implant stall, over time.

METHODS

A single-center, retrospective review was conducted identifying children with EOS undergoing primary MCGR implantation. The primary endpoint was the occurrence of implant stalling, defined as a failure of the MCGR to lengthen on three consecutive attempted lengthening sessions with minimum of 2 years follow-up. Clinical and radiographic variables were collected and compared between lengthening and stalled MCGRs. A Kaplan-Meier survival analysis was conducted to assess implant stalling over time.

RESULTS

A total of 48 children met inclusion criteria (mean age 6.3 ± 1.8 years, 64.6% female). After a mean 56.9 months (range of 27 to 90 months) follow-up, 25 (48%) of children experienced implant stalling at a mean of 26.0 ± 14.1 months post-implantation. Kaplan-Meier survival analysis demonstrated that only 50% of MCGR continue to successfully lengthen at 2 years post-implantation, decreasing to < 20% at 4 years post-implantation.

CONCLUSION

Only 50% of MCGR continue to successfully lengthen 2 years post-implantation, dropping dramatically to < 20% at 4 years, adding to the available knowledge regarding the long-term viability and cost-effectiveness of MCGR in the management of EOS. Further research is needed to validate these findings.