Complications of Therapies for Metabolic Bone Disease in Children

Surgical

Complications occur in up to 25% of children undergoing instrumentation in the cervical spine region, and in 5% multiple complications occur (15). Both early and late complications need to be considered.

Early

  • Injury to the spinal cord or brainstem: These injuries may occur as a result of inadequate reduction of spinal deformity, direct surgical trauma during bony decompression, or instrumentation.
  • Vascular injury: Vascular injury may occur, particularly vertebral artery injury, which is a particular risk in C2 pedicle or C1 lateral mass screw fixation. Venous sinus injury may occur during occipital screw placement (14).
  • CSF leakage due to dural injury: This condition represents a high risk for deep wound infection if not adequately dealt intraoperatively.
  • Malposition of instrumentation: Incorrect screw placement results in inadequate stabilization, leading to screw loosening, screw/wire breakage, and subsequent construct failure.
  • Infection: Meticulous attention to wound healing is essential in the postoperative period. Infection of metal implants requires prolonged antibiotic therapy and may require removal of the implants. Implant infection increases the risk of mechanical failure.
  • Respiratory: Spinal instrumentation, prolonged anesthesia, and immobilization increase the risks of respiratory morbidity in children with metabolic bone disease who may have pre-existing impaired respiratory function due to thoracic deformity, central disturbance of respiratory control (e.g., sleep apnea), and a tendency to aspiration.

Late

  • Failure of stabilization: Fusion is achieved in more than 90% of craniovertebral and cervical fixations (15, 21). Failure to achieve fusion may occur early or late. Imaging postoperatively and during follow-up is essential to assess the efficacy of fixation. Bone window CT scan is useful to assess postoperative alignment, decompression, and screw placement. Plain x-rays with dynamic views are usually satisfactory for subsequent surveillance.
  • Bone graft resorption: Inadequate immobilization, poor bone quality, and infection all increase the risk of bone graft resorption.
  • Adjacent segment deformity: Immobilizing the craniovertebral region or long segments of the spine increases the mechanical strain on adjacent mobile segments. This may result in pain, early degenerative changes, or secondary deformity.