Scoliosis therapy of children and youth with MAGEC® (magnetic expansion control)-spinal system in combination with VEPTR (vertical expandable prosthetic titanium rib)-instrument

The past decades have seen the increasing use of telescoping systems for the management of pediatric spinal deformities. The Vertical Expandable Prosthetic Titanium Rib (VEPTR) concept facilitates scoliosis therapy while also enlarging the thorax. This can help prevent or treat thoracic insufficiency syndrome (TIS) . In the present study, 18 children were treated using an innovative VEPTR/MAGEC® method that combines a long-established VEPTR system involving fixation between rib cage and iliac crest with novel externally telescopic magnetic implants (MAGEC®). As a result, a successive series of further extension surgeries can be avoided. This study was conducted to investigate the frontal profile (Cobb angle for measuring scoliosis) and sagittal profile (age-adapted thoracic kyphosis and lumbar lordosis), spinal length (thoracic and lumbar), pelvic tilt, body mass index (BMI), BMI percentile, BMI weight category and complication rate and determine whether effective and/or reliable distraction is possible. 18 patients were treated with MAGEC® rods in combination with bilateral VEPTR implants, respectively anchored to one or two ribs and the bony pelvis. 7 children had an average VEPTR pretreatment of 33 (16 – 57) months, during which they underwent a mean number of 4.7 (2 – 9) VEPTR extension surgeries for a total of 33 distraction surgeries overall. For follow-up, 18 patients with the combined VEPTR/MAGEC® construct were reexamined over an average of 15.1 (4 – 26) months. During this time, they received an average of 4.5 (1 – 8) non-invasive distractions of 5 mm each with a total of 81 external MAGEC® rod extensions; these took place at 3-month intervals, with very few exceptions (e.g. every 2 or 4/5 months). By the end of the study period, none of the patients (n=18) had completed treatment with the combined VEPTR/MAGEC® construct. A total of 611 digital X-rays were analyzed with the Centricity™ processing software (General Electric Healthcare, Chalfont St Giles in Buckinghamshire, UK). The statistical data were analyzed using Excel (Microsoft Corporation, Redmond, USA) and the Statistica software package, versions 12.0 and 13.0 (Dell, USA ). Implantation of the VEPTR/MAGEC® construct significantly reduced the Cobb angle by 48% on average. Primary implantation of the VEPTR/MAGEC® system achieved a significant approximation to the age-adapted standard (59%). The surgical therapy did not have a significant influence on age-adapted lordosis. In the study cohort, every type of primary spinal corrective surgery significantly increased spinal length. The expected increase in spinal length resulting from the extensions could not be demonstrated. During the distractions, less length gain was observed than the distraction segment achieved. In the study patients (n=17), the pelvic tilt before primary VEPTR/MAGEC® implantation averaged 9.4° and was significantly reduced by 72.3% to 2.6º. In the 18 patients, the weight class, BMI and BMI percentiles did not change significantly from the time of primary VEPTR/MAGEC® implantation to the time after an average of 4.5 distractions (BMI: 15.4 kg/m² to 15.2 kg/m², p=0.728; BMI percentile 37.3 to 36.4, p=0.829). Six complications (6.1%) occurred in 18 VEPTR/MAGEC® implants and 81 external distractions. During VEPTR pretreatment with 7 VEPTR implantations and 33 extension surgeries, there were 3 complications (7.5%) that occurred in 7 children, albeit over a longer study period. There was no significant difference in the measured implant extension between the convex and concave sides. The implant telescoped in 15 patients but temporarily did not in 3 children . This could not be attributed to a material defect, since all of the implants functioned properly and could be telescoped when tested externally at a later time. In the remaining 15 patients, the desired distraction was consistent with the true distraction. This system cannot currently be used to treat patients, for whom cranial and spinal MRIs are required to diagnose their underlying disease, e.g. myelomeningocele. A further limitation of the method, at present, is that more frequent X-rays are taken at shorter intervals, thereby exposing the children to higher doses of irradiation. In the future, however, this might be reduced to half-year radiographic follow-ups once the safety of the technique has been demonstrated and/or simply by ultrasound, which has recently become possible. Based on the available data from this study cohort, the novel VEPTR/MAGEC® system achieved and maintained a correction of the spinal deformities over the clinical course that is similarly as effective as the classic VEPTR method while exhibiting a synergistic effect thanks to the advantages of non-invasive extensions.2018-08-0