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SICOT e-Newsletter

Issue No. 52 - January 2013

Worldwide News

Early results of a remotely-operated magnetic growth rod in early-onset scoliosis
Z. Dannawi, F. Altaf, N. S. Harshavardhana, H. El Sebaie, H. Noordeen. Bone Joint J 2013;95-B:75–80. (Formally JBJS Br).

Comment written by Tracy Sorkin (Edited by Bassel El-Osta)

Abstract:

"Conventional growing rods are the most commonly used distraction-based devices in the treatment of progressive early-onset scoliosis. This technique requires repeated lengthenings with the patient anaesthetised in the operating theatre. We describe the outcomes and complications of using a non-invasive magnetically controlled growing rod (MCGR) in children with early-onset scoliosis. Lengthening is performed on an outpatient basis using an external remote control with the patient awake.

Between November 2009 and March 2011, 34 children with a mean age of eight years (5 to 12) underwent treatment. The mean length of follow-up was 15 months (12 to 18). In total, 22 children were treated with dual rod constructs and 12 with a single rod. The mean number of distractions per patient was 4.8 (3 to 6). The mean pre-operative Cobb angle was 69° (46° to 108°); this was corrected to a mean 47° (28° to 91°) post-operatively. The mean Cobb angle at final review was 41° (27° to 86°). The mean pre-operative distance from T1 to S1 was 304 mm (243 to 380) and increased to 335 mm (253 to 400) in the immediate post- operative period. At final review the mean distance from T1 to S1 had increased to 348 mm (260 to 420).

Two patients developed a superficial wound infection and a further two patients in the single rod group developed a loss of distraction. In the dual rod group, one patient had pull- out of a hook and one developed prominent metalwork. Two patients had a rod breakage; one patient in the single rod group and one patient in the dual rod group. Our early results show that the MCGR is safe and effective in the treatment of progressive early-onset scoliosis with the avoidance of repeated surgical lengthenings."


Summary:

Aim: Descriptive prospective study of the use of magnetically controlled growing rods (MCGR) in children with early onset scoliosis (EOS).

Background: EOS is a significant spinal deformity beginning before the age of 5 years. Goals of treatment are to control the deformity and allow spinal and chest wall growth to prevent pulmonary insufficiency. Non-operative treatment strategies are casting or bracing, but these are not always effective. Growth-friendly surgical techniques, instead of fusion, have been developing; single or dual expandable rod distraction is one example. This involves insertion of expandable spinal rods anchored with pedicle screws or hooks which are lengthened at intervals. Lengthening requires a general anaesthetic and re-opening of the original incisions; this holds the risks of infection, anaesthetic-associated complications, socioeconomic costs to the child and family, and the repeated trauma of surgery. The use of MCGR aims to avoid the need for repeated surgery. Lengthening can be performed on an awake child in an outpatient setting using an external magnet to control the length of the rod.

Method: 34 patients aged between 8 and 15 years had either single or dual MCGR inserted. These were lengthened at 3 monthly intervals for a mean of 15 months. Pre-operative and post operative Cobb angles and the distance between T1 and S1 were evaluated.

Results: Pre-operative Cobb angles were equivalent between the single and dual rod groups, with a mean of 69° (46° to 108°). Pre-operative T1 to S1 distance was 304 mm (243 to 380). Both groups showed significant improvement post-operatively; Cobb angle decreased to 47° (28° to 91°) and T1 to S1 distance increased to 335 mm (253 to 400). At final review mean Cobb angle was 41° (27° to 86°) and mean T1 to S1 distance was 348 mm (260 to 420). Improvement in Cobb angle in the dual rod group was statistically significantly better than in the single rod group. Complications were seen in both groups: 2 superficial wound infections, 2 rod breakages, and 2 loss of distractions in the single rod group. In comparison with patient series in conventional rod lengthening procedures this was less than might be expected.

Conclusion/Recommendations: Use of MCGR in the treatment of EOS is a safe and effective means of correcting deformity and allowing spinal growth.

  
Comment:

EOS is a challenging condition to manage, with the prospect of children undergoing repeated surgeries and the risk this brings. Application of technology already used in endoprostheses for lower limb reconstruction following surgery for paediatric bone tumours could create an elegant solution, allowing lengthening to be performed in an out-patient setting.

This paper succinctly describes a series of 34 patients treated with MCGR, clearly presenting the methodology and statistical analysis. There are several limitations the authors themselves recognise. It is a small study with a short follow-up period. There is also a lot of variation between the patients: different causes for scoliosis and types of curve, varying number of post operative distractions and time to achieve correction. It is also not clear upon the confounding effects of single or double rod, or how the number of rods was objectively selected for the patients. Direct comparison with existing treatment modalities is also lacking. Despite this, it serves its purpose of sharing these early findings and in due course should herald a more comprehensive study.