Analysing a mechanism of failure in retrieved magnetically controlled spinal rods.

PURPOSE: We aim to describe a mechanism of failure in magnetically controlled growth rods which are used for the correction of the early onset scoliosis. METHODS: This retrieval study involved nine magnetically controlled growth rods, of a single design, revised from five patients for metal staining, progression of scoliosis, swelling, fractured actuator pin, and final fusion. All the retrieved rods were radiographed and assessed macroscopically and microscopically for material loss. Two implants were further analysed using micro-CT scanning and then sectioned to allow examination of the internal mechanism. No funding was obtained to analyse these implants. There were no potential conflicts interests. RESULTS: Plain radiographs revealed that three out of nine retrieved rods had a fractured pin. All had evidence of surface degradation on the extendable telescopic rod. There was considerable corrosion along the internal mechanism. CONCLUSIONS: We found that a third of the retrieved magnetically controlled growth rods had failed due to pin fracture secondary to corrosion of the internal mechanism. We recommend that surgeons consider that any inability of magnetically controlled growth rods to distract may be due to corrosive debris building up inside the mechanism, thereby preventing normal function.

Can postoperative Cobb and pelvic obliquity corrections be predicted using supine traction X-rays in non-ambulatory patients with cerebral palsy fused to L5? A case series study.

PURPOSE: This study aimed to determine whether Cobb and pelvic obliquity corrections can be predicted using supine traction radiographs in patients with cerebral palsy (CP) who underwent posterior spinal fusion (PSF) from T2/3 to L5. METHODS: From January 2010 to January 2020, 167 non-ambulatory patients with CP scoliosis underwent PSF using pedicle screws in two quaternary centers with a minimum of 2 years follow-up (FU). Radiological measurements and chart reviews were performed. RESULTS: A total of 106 patients aged 15.6 ± 0.4 years were included. All patients had significant correction of the Cobb angle (MC), pelvic obliquity (PO), thoracic kyphosis (TK), and lumbar lordosis (LL) without loss of correction at the last FU (LFU). Curve flexibility was significantly correlated with Cobb correction (δMC) immediately postoperatively (p < 0.0001, r = 0.8950), followed by the amount of correction in pelvic obliquity under traction (δPOT) (p = 0.0252, r = 0.2174). For correction in PO (δPO), the most significant variable was δPOT (p < 0.0001, r = 0.7553), followed by curve flexibility (p = 0.0059, r = 0.26) and the amount of correction in Cobb under traction (p = 0.0252, r = 0.2174). CONCLUSIONS: Cobb and PO corrections can be predicted using supine traction films for non-ambulatory CP patients treated with PSF from T2/3 to L5. The variables evaluated were interconnected, reinforcing preoperative planning for these patients. Comparative large-scale studies on patient-related clinical outcomes are required to determine whether this predicted correction is associated with improved surgical outcomes and reduced complication rates. LEVEL OF EVIDENCE: IV.

Distal level in scoliosis surgery for non-ambulatory patients with cerebral palsy: is L5 an option? A case series study.

PURPOSE: This study aimed to determine the radiographic outcomes of patients with cerebral palsy (CP) who underwent posterior spinal fusion from T2/3 to L5 at two quaternary hospitals. METHODS: From January 2010 to January 2020, 167 non-ambulatory patients with CP scoliosis underwent posterior spinal fusion using pedicle screws from T2/3 to L5 in both centers, with a minimum of 2 years follow-up (FU). Radiological measurements and chart reviews were performed. RESULTS: A total of 106 patients aged 15.6 ± 0.4 years were included. None of the patients was lost to FU. All patients had significant correction of the Cobb angle (MC) and pelvic obliquity (PO), thoracic kyphosis (TK), and lumbar lordosis (LL), without loss of correction at the last FU (LFU). The mean values for preoperative, immediate postoperative, and LFU were MC 93.4°, 37.5°, and 42.8°; PO 25.8°, 9.9°, and 12.7°; TK 52.2°, 44.3°, and 45°; and LL - 40.9°, - 52.4°, and - 52.9°, respectively. Higher residual PO at LFU was associated with more severe MC and PO baselines, lower implant density, and an apex located at L3. CONCLUSIONS: CP scoliosis and PO can be corrected, and this correction is maintained over time with posterior spinal fusion using pedicle screws, with L5 as the lowest instrumented vertebra. Larger preoperative MC and PO values associated with the apex at L3 appear to be related to residual PO. Comparative large-scale studies of patient-related clinical outcomes are required to determine whether this intervention is associated with improved surgical outcomes and reduced complication rates. LEVEL OF EVIDENCE: IV.

Distal fusion in Duchenne scoliosis: the relevance of preoperative pelvic obliquity. A case series study.

PURPOSE: The aim of this study was to determine clinical and radiographic outcomes for Duchenne Muscular Dystrophy (DMD) patients who underwent posterior spinal fusion from T2/3 to L5 (without pelvic fixation), at this single centre. METHODS: From January 2012 to January 2020, 29 consecutive DMD scoliosis patients underwent posterior spinal fusion using pedicle screws from T2/3 to L5 in a single center with a minimum of 3 years follow-up (FU). Radiologic measurements and chart review were performed. RESULTS: Twenty nine patients aged 14 ± 1.5 years were included. No patient was lost to FU. All patients had significant correction in Cobb angle, pelvic obliquity (PO) and lumbar lordosis (LL), without loss of correction at last FU. The mean values for preoperative, immediate postoperative and last FU were CA 62o, 15o and 17o, PO: 21o, 8o and 9o; and LL 10o, -41o and -41o respectively. Correction in CA was independent of any variable analysed including implant density, rod diameter, traction, or bone density. Regarding PO, it was inversely related to age and independent of all other variables. Factors associated with postoperative complications were age and respiratory function. CONCLUSIONS: It appears from our results that pelvic fixation might not always be required in DMD scoliosis surgery, when using pedicle screws with lowest instrumented vertebra at L5. However, larger preoperative PO values can be related with residual PO. It seems that probably related to the underlying condition, early surgery may decrease incidence of complications. LEVEL OF EVIDENCE: IV.

Single vs dual rod constructs in early onset scoliosis treated with magnetically controlled growing rods.

BACKGROUND: Non-invasive distractions of recently introduced magnetically controlled growing rods (MGCRs) spare multiple operations in the surgical treatment of early onset scoliosis (EOS). Since the costs of the implants are high, concerns have been raised regarding cost-effective, optimal but safe MGCR options: single or dual constructs. OBJECTIVES: To report deformity control, spinal growth and complication incidence in EOS patients treated with MCGR singleor dual-rod constructs. MATERIAL AND METHODS: The study involved 47 patients with MCGRs inserted at Great Ormond Street Hospital, London (UK) in 2013-2014, who were followed up for at least 1 year. In 32 patients, T1-S1 distances, and coronal and sagittal curves were measured on preoperative and postoperative X-rays, and at a one-year follow-up. All complications were recorded. The patients were analyzed in 2 groups: those with single-rod constructs (24 patients) and those with dual-rod constructs (23 patients). RESULTS: Comparing postoperative with one-year follow-up measurements, T1-S1 length increase was better in the dual-rod group (3.29%) than in the single-rod group (0.34%) (p = 0.031). In the whole series, mean scoliosis magnitude dropped by 27.5% at the one-year follow-up. The dual-rod group showed better mean curve correction: 36.5% compared to 15.3% in the single-rod group (p = 0.0076). Overall, 34.04% of the patients had complications: 45.8% in the single-rod group and 30.4% in the dual-rod group (p = 0.0413). Metalwork failure was observed in 8 patients, lengthening problems in 5 and wound infections in 2; there was also 1 case of proximal junctional kyphosis (PJK). Preoperative hyperkyphosis was associated with more complications (75%, p = 0.037), most of which were metalwork failure (41.6%). CONCLUSIONS: The MCGRs are efficient at controlling EOS; however, the complication rate is high, particularly in single-rod constructs. The use of dual-rod constructs allows for better curve control, greater T1-S1 length increase and a lower complication rate.

Halo Femoral Traction for 1 Week Between Staged Anterior and Posterior Fusion Surgeries for Severe Adolescent Scoliosis Is Effective and Safe.

OBJECTIVE: To report the outcomes of halo femoral traction (HFT) used for 1 week between anterior release and definitive posterior fusion in adolescents with severe rigid scoliosis. METHODS: A retrospective single-center review of 22 consecutive patients (mean age at surgery, 14.1 years; range, 10.5-18.2 years; 17 girls) with severe, rigid scoliosis treated with anterior release, followed by HFT for 7 days prior to posterior instrumented fusion. Cobb angles were measured preoperatively, 1 week after anterior release and traction, after posterior fusion, and at a minimum 2-year follow-up. Complications were recorded. RESULTS: Mean preoperative Cobb angle was 97° (range, 80°-118°), correcting to 52° with anterior release and HFT and 31° after posterior fusion. This equated to a 68% deformity correction and was maintained at final follow-up. Three traction-related complications were experienced, including 1 case of neck pain and 2 cases of brachial plexopathy that resolved with traction weight reduction. CONCLUSIONS: Three-staged deformity correction using HFT for 1 week only offers gradual correction of the spine over sufficient time to optimize deformity correction yet minimizes neurologic dysfunction.