Current status of the magnetically controlled growing rod in treatment of early-onset scoliosis: What we know after a decade of experience

Abstract

The magnetically controlled growing rod (MCGR) has had approximately 10 years of clinical experience worldwide. Clinical effectiveness to control early-onset scoliosis is consistent even at final surgery. MCGRs have significantly lower relative percentage of infection or wound complications as compared to traditional growing rods. Most common complications include foundation failure and failure of distraction. Contouring of the rod especially at the proximal segment while accommodating for the straight actuator remains a difficult task and its failure may lead to proximal junctional kyphosis. Unique complications of MCGR include clunking, temporary diminishing distraction gains, and metallosis. Temporary reductions in distraction gains are observed as the MCGR lengthens but return to normal baseline distraction gains after rod exchange. Lack of standardization for rod configuration, distraction strategies and decisions of whether to keep the rods in situ, remove without fusion surgery or to perform spinal fusion at skeletal maturity will require further study.

Understanding the implant performance of magnetically controlled growing spine rods: a review article

“…TGRs are considered the gold standard to which the other operative treatments are usually compared [26]. These distraction-based constructs provide stability and deformity correction while allowing for growth of the spine.…”

“…Unlike VEPTRs and TGRs, MCGRs use an external magnetic distraction system aimed at avoiding repeated surgeries for rod lengthenings. Distractions are performed in an outpatient environment, virtually enabling more frequent rod distractions mimicking physiological spinal growth [26]. While the potential benefit of outpatient distraction procedure is huge, concerns still remain about its risks.…”

“…Some surgeons might consider using single rods to prevent prominent metalware in slim patients [45] , diversely increasing evidence suggests dual rods are less prone to rod breakage and slippage [3,5,46,47] . For this reason, recent reports suggest the use of dual rods where possible [26,38,48]. Differently from TGRs, in MCGRs rod contouring is limited to the proximal and distal regions of the rod, being that it is not allowed in the distracting mechanism portion.…”

“…Differently from TGRs, in MCGRs rod contouring is limited to the proximal and distal regions of the rod, being that it is not allowed in the distracting mechanism portion. Accordingly, the actuator region is normally placed along the straight thoracolumbar spine [26,48]. Following rod distractions, the flat region of the MCGR construct becomes even larger.…”

“…Pedicle screws and hooks can be used to anchor the MCGR to the spine, and no superior technique has yet been identified [26], nonetheless if pedicle screws are used caution is needed when instrumenting additional levels. While this choice might help achieving better balance in particularly severe curves, foundation failure is not uncommon and re-operation requires these levels to be fused [35].…”