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.

Minimizing complications with single submuscular growing rods: a review of technique and results on 88 patients with minimum two-year follow-up.

STUDY DESIGN: Retrospective clinical and radiologic review of consecutive series of patients treated with single submuscular growing rods from a single center with a minimum of 2-year follow-up. OBJECTIVES: To describe the surgical technique and methods used to minimize complications and to report on the outcomes of a large consecutive series of patients treated with single submuscular growing rods for scoliosis in the immature spine from a single center. SUMMARY OF BACKGROUND DATA: Previous studies have reported on the safety and efficacy of single and dual growing-rod constructs; however, these studies have been of small patient numbers with varying results. METHODS: Between 1999 and 2007, 88 patients underwent the insertion of a single, submuscular growing-rod construct for scoliosis. A clinical and radiologic review of these 88 consecutive patients with a minimum of 2-year follow-up was conducted. Diagnoses include idiopathic, neuromuscular, syndromic, and congenital. Data include Cobb angle measurements, T1-S1 heights, number, and frequency of lengthening as well as complications. RESULTS: The patients underwent single submuscular growing-rod insertion at an average age of 7.0 years. The mean follow-up period was 42 months. Twenty-eight patients had a simultaneous apical fusion. Growing-rod lengthening was performed on an average at 9-month intervals. The average initial Cobb angle was 73° (range: 40-117) and improved to 44° (range: 9-90) at final follow-up. T1-S1 height gain was 3.37 cm; this translates to 1.04 cm growth/yr. No significant difference was noted between those who had undergone apical fusion and those without. Complications noted in this series include 8 incidences of superficial infection and 3 of deep infection, proximal junctional kyphosis in 2 patients requiring early fusion, 31 rod fractures, 10 cases of proximal anchor failure, and 6 distal anchor failures. Thirty patients within study group have reached definitive fusion. CONCLUSION: Favorable outcomes have been demonstrated in this large single-center series of growing-rod constructs used to treat scoliosis in the growing spine. Their safety and efficacy in controlling spinal deformity and allowing spinal growth along with an acceptable rate of complications would support the continued use of single growing-rod constructs as a scoliosis management option.

Lordoscoliosis and large intrathoracic airway obstruction.

STUDY DESIGN: Case series. OBJECTIVE: We report the treatment of 2 children with right main bronchus obstruction complicating thoracic lordoscoliosis. SUMMARY OF BACKGROUND DATA: The preoperative investigation and treatment of large airway obstruction caused by lordoscoliosis has not been reported in the literature. METHODS: Obstruction of the right main bronchus was confirmed before surgery by ventilation-perfusion scans, bronchogram, and computed tomography scan. Deformity correction was achieved using a submuscular growth rod construct in one child, and posterior spinal fusion in the other. Clinical examination and repeat ventilation-perfusion scans were performed 8 weeks after surgery. RESULTS: In both children, ventilation to the right "convex" lung was reestablished after surgery. Lung function improved in both patients after surgery. CONCLUSION: This is the first report of large airway obstruction associated with thoracic lordoscoliosis in which ventilation was reestablished after spinal deformity correction. Early deformity correction is indicated in such cases because of the risk of irreversible compromise to lung ventilation and perfusion.

The surgical treatment of congenital kyphosis.

STUDY DESIGN: Retrospective study with clinical and radiologic evaluation of 15 patients with congenital kyphosis or kyphoscoliosis who underwent anterior instrumented spinal fusion for posterolateral or posterior hemivertebra (HV). The management of congenital kyphosis has been described in the literature using a variety of techniques. The presentation of patients at diagnosis is discussed. The question of when to begin treatment is reviewed. The pitfalls in the management and how to avoid these are discussed. The different published techniques are reviewed. We present our own techniques and our results of treatment of congenital kyphosis in very young children. OBJECTIVE: To evaluate the safety and efficacy of early surgical anterior instrumented fusion with partial preservation of the HV in the treatment of progressive congenital kyphosis in children below the age of 3. We discuss the management of patients presenting with neurologic compromise. We aim to systematically review the literature and to present our own experience in the management of these deformities, so that the issues common to treating physicians may be explored. SUMMARY OF BACKGROUND DATA: A variety of treatments have been described in the literature for the treatment of congenital kyphosis due to HV. We report the results of our technique. METHODS: Between 1997 and 2005 we have treated 15 consecutive patients with progressive congenital kyphosis with anterior instrumented fusion and strut grafting. Thirteen patients had a single posterolateral HV and 2 patients had a single posterior HV. Of the 15 patients in the study, 5 were girls and 10 boys. Mean age at surgery was 22 months (range, 8-33). Mean follow-up period was 6.8 years. Thirteen HV were located in the thoracolumbar junction (T10-L2) and 2 in the thoracic spine. RESULTS: The average operating time of procedure was 150 minutes (range, 130-210 minutes). The average blood loss was 180 mL (range, 100-330 mL), equivalent to a mean external blood volume loss of 15% (range, 11%-24%).Preoperative segmental Cobb angle averaging 34 degrees at last follow-up. Compensatory coronal cranial and caudal curves were corrected by 50%. The angle of segmental kyphosis averaged 39 degrees (range, 20 degrees-80 degrees) before surgery and 21 degrees (range, 11 degrees-40 degrees) at last follow-up. This represents a 43% of improvement of the segmental kyphosis, and a 64% of improvement of the segmental scoliosis at last follow-up. One case with initial kyphosis of 80 degrees continued to progress and required revision anterior and posterior surgery. There were no neurologic complications.

Charcot spinal arthropathy in a paraplegic weight lifter: case report.

STUDY DESIGN: A case report of aggressive multilevel Charcot spinal arthropathy treated with staged spinal instrumentation. OBJECTIVES: To report an unusual case of Charcot spinal arthropathy, given the rapidity of progression and extent of tissue destruction, and present the results of successful spinal instrumentation and stabilization. SUMMARY OF BACKGROUND DATA: Charcot spinal arthropathy in the long-standing paraplegic patient is more commonly seen in those who have undergone prior spinal surgery and is usually restricted to 2 spinal levels. METHODS: A 36-year-old amateur weight lifter with T6 complete paraplegia presented with lower thoracic back pain, a kyphotic deformity of the thoracolumbar region, and gross spinal instability on transferring. Imaging revealed extensive bony destruction from T10-T12 and complete absence of spinal tissue over the affected levels. Staged anterior and posterior spinal instrumentation from T3 to L4 was performed. RESULTS: Spinal stabilization was achieved, and the patient was pain free and able to resume light training at 6-month follow-up. CONCLUSIONS: We would advise a high index of suspicion of Charcot arthropathy in the active paraplegic patient presenting with back pain caudal to their sensory level. Staged spinal instrumentation is an effective treatment for multilevel Charcot spinal arthropathy.

Traumatic lumbosacral dislocation: report of two cases.

STUDY DESIGN: A retrospective study of 2 patients with traumatic lumbosacral dislocation. OBJECTIVES: To discuss the difficulty in making diagnosis and the effect of surgical treatment. SUMMARY OF BACKGROUND DATA: Traumatic lumbosacral dislocation is an uncommon injury, which creates diagnostic difficulty and is typically managed by open reduction internal fixation of the lumbosacral spine. METHODS: Medical notes and imaging of the 2 patients were reviewed. RESULTS: Both patients were engaged in high-energy accidents and had concomitant injuries. Patient 1 was initially misdiagnosed as having L5 lytic spondylolisthesis and was treated with a lumbar corset. She developed progressive low back and left leg pain. Eleven months after the accident, a bilateral lumbosacral dislocation with right S1 superior facet fracture, disc rupture, posterior soft tissue disruption, and a resultant Grade 4 L5-S1 traumatic spondylolisthesis was identified. She underwent open reduction, followed by a staged anteroposterior spinal arthrodesis using instrumentation with excellent results. Patient 2 sustained a unilateral L5-S1 facet dislocation without neurologic deficit, which reduced spontaneously. The evaluation demonstrated a grossly disturbed posterior ligamentous complex adjacent to the lumbosacral articulation. A combined anteroposterior spinal fusion with instrumentation was performed with favorable outcome. CONCLUSION: Meticulous clinical examination and careful imaging assessment, including CT and MRI, assist an early diagnosis in cases of lumbosacral dislocation. Open reduction and circumferential bony fusion restore segmental stability and painless function.

Spinal cord monitoring using intraoperative somatosensory evoked potentials for spinal trauma.

BACKGROUND: Intraoperative spinal cord monitoring is commonplace in scoliosis surgery as an adjunct to evaluate functional integrity of the cord; however, limited information is available on its applicability in spinal trauma. METHODS: We investigated the efficacy of somatosensory evoked potential (SEP) recording during reconstructive procedures in 82 patients who sustained 20 cervical, 8 thoracic, 6 thoracolumbar, and 48 lumbar vertebral fractures or fractures-dislo-cations. Seventy-one patients underwent single anterior or posterior operations and 11 combined anterior-posterior procedures. Forty patients had incomplete injuries, and 42 had no preoperative neurologic deficit. SEP trace amplitude at insertion of electrode was considered as the baseline value and was compared with the lowest intraoperative signal amplitude and the amplitude at completion of operation. RESULTS: Fifty-nine patients had a depression in wave amplitude of >25% during surgery; in 25 patients, the trace fell by >50%, and in 7 cases, a >75% diminution was recorded. A loss of 50% in SEP signal amplitude showed 67% sensitivity and 71% specificity in predicting neurologic outcome. Increasing trace deterioration threshold from 50% to 60% improved specificity to 81% without compromising sensitivity. A loss of >50% in SEP amplitude occurred with significantly increased incidence during the anterior compared with the posterior spinal procedures. More than 20% recovery in signal amplitude at the conclusion of the procedure in patients with incomplete injuries was correlated with favorable neurologic function. CONCLUSION: Persistent intraoperative decrement in SEP amplitude and poor restitution at completion of surgery increase the risk for postoperative neurologic compromise.