Upper thoracic pedicle screw loss of fixation causing spinal cord injury: a review of the literature and multicenter case series.

STUDY DESIGN: Case Series and Review of the Literature. OBJECTIVE: To report on cases of spinal cord injury from loss of fixation of upper thoracic pedicle screws. SUMMARY OF BACKGROUND DATA: Despite generally low rates of intraoperative neurological injury from pedicle screws, there is 1 reported case of T2 pedicle screw pullout causing spinal cord injury. METHODS: A review of the literature and an informal poll of 2 professional societies searching for cases in which thoracic pedicle screws migrated postoperatively into the spinal canal was performed. RESULTS: Three patients had failure of spinal instrumentation with the most cephalad pedicle screws (T2, T4 and T4) plowing into the spinal canal, causing direct trauma to the spinal cord with resulting clinical and neurological injury. Failure of fixation occurred at 1 month, 1 year, and 2 years after index procedure. In 2 patients, neurological injury was severe enough that they became nonambulatory; the third patient had rapidly progressive leg weakness. In each case, there were only 1 or 2 pedicle screws at the top of the construct, and a span of 6 to 7 vertebrae without rigid fixation below this. One similar case was found in the literature. CONCLUSIONS: Spinal instrumentation with only 1 to 2 pedicle screws at the top of the construct, and a span of >5 vertebrae below these screws without rigid fixation may be at risk for implant failure and catastrophic spinal cord injury. In the rare instance in which only 1 to 2 pedicle screws can be placed at the cephalad half of long spinal constructs, one may consider using hooks that would fail posteriorly and may present less risk to the spinal cord.

Improvement of Kyphoscoliosis in a 9-Year-Old Using Growth Modulation With a Posterior Tether: A Case Report.

OBJECTIVE: Our aim was to report the first case of a posterior tether used for growth modulation in the treatment of spinal deformity. METHODS: A 9-year-old boy with progressive kyphoscoliosis failed multiple attempts of brace treatment; the deformity progressed to kyphosis of 73° and scoliosis of 41° on standing radiographs. We placed a posterior tether using hydroxyapatite-coated pedicle screws with a flexible polymer cord under modest compression unilaterally from T3 to T11 with no subperiosteal dissection and no attempt at fusion. RESULTS: Immediately postoperatively, the kyphosis improved from 73° to 65° and the scoliosis from 41° to 26°. At 26 months postoperatively, the kyphosis improved to 42° and the scoliosis to 26°. At 31 months postoperatively, distal junctional kyphosis developed. The patient then underwent a spine fusion at age 11 years. We noted at surgery that the previously tethered spine from T3 to T11 was fused with no motion present even after implants were removed. CONCLUSION: A posterior unilateral tether was successful at progressively improving kyphosis and preventing worsening of scoliosis in a 9-year-old boy, but it led to fusion of the spine within 31 months.