ABSTRACT
Background: Free-hand and fluoroscopic-guided pedicle screw placement has been associated with higher rates of pedicle breaches (frequency range 15-40% especially in deformed pedicles). Neurological complications are more "critical" (i.e., frequent and significant) with medial and inferior pedicle-wall breaches due to the proximity of the neural elements. Here, we analyzed the effectiveness of O-arm navigation in minimizing "critical" pedicle wall breaches and their complications in 21 complex spinal deformity cases. Methods: Twenty-one complex spinal deformity cases were prospectively managed with O-arm-navigated posterior-instrumented fusions. Preoperative assessment included; evaluation of the type of scoliosis, the magnitude of the deformity, and the anatomy of the pedicles - (i.e., classified using Watanabe et al.). The O-arm was used to confirm and grade both the intraoperative and postoperative location of screws. Other variables analyzed included; duration of surgery, estimated blood loss, complications, and radiation exposure. Results: In 21 patients, 259 (63.45%) of 384 pedicles were instrumented; we observed 22 of 259 pedicle screw breaches. Significant (>2 mm) breaches were observed in two medial and one inferior wall cases that required revision; the overall biomechanically significant screw breach rate was (3/259) 1.2% with an accuracy rate of 98.8%. Pedicle screw placement resulted in another 14 nonsignificant (<2 mm) breaches; ten were medial and four involved the inferior wall. As anterior, lateral, and "in-out-in" trajectory pedicle screws beaches were nonsignificant, they were not included in our analysis. Conclusion: O-arm navigation decreased the incidence of medial and inferior (i.e., >2 mm "critical") pedicle screw breaches applied in 21 patients with deformed pedicles due to scoliosis. Further, the O-arm minimized the operating time, decreased the estimated blood loss, and reduced the incidence of complications.
ABSTRACT
Background: Gross-total excision of spinal osteoblastomas remains challenging as they are typically found in close proximity to major neural and/or vascular structures. Here, we found that O-arm navigation allowed for safe/effective excision of a spinal osteoblastoma in a 29-year-old male. Case Description: A 29-year-old male presented neurologically intact with mid back pain of 8 months' duration and 2 months of the left-sided chest wall discomfort. X-rays showed a sclerotic left D12 pedicle, while the MRI revealed an extradural lesion in extending into the left D11-12 neural foramen (i.e., hypointense on both T1- and T2-weighted images). The CT scan suggested a "floating" foraminal radiolucent lesion with surrounding vertebral body/posterior elements sclerosis and dense peripheral rim enhancement. These findings were diagnostic for an osteoblastoma. Utilizing O-arm navigation, the nidus and full extent of the lesion were excised (i.e., utilizing intralesional curettage). Two year's postoperatively, there was no MR evidence of tumor recurrence. Conclusion: O-arm navigation provided accurate intraoperative localization to safely and fully excise a left D11- D12 spinal osteoblastoma.
ABSTRACT
Osteoblastomas are bone forming lesions arising mainly from posterior elements of the vertebra. They are commonly encountered in the cervical and lumbar regions. We present a case of a thoracic osteoblastoma which is extra osseous and is not communicating with any part of the vertebra present intraforaminally. This is a rare presentation of an osteoblastoma. Imaging studies do not accurately diagnose the osteiod lesion. The size of the lesion and cortical erosion seen on the computed tomography scan help in differentiating the osteoid osteoma and osteoblastoma, but they are less sensitive and specific. Thus a histopathology is the investigation of choice to diagnose the osteoblastoma. Early and adequate removal of mass prevents malignant transformation, metastasis, and recurrence. In our case we excised the pars interarticularis unilaterally, removed the osteoid mass intact, and performed unilateral instrumented fusion. There was no recurrence and solid fusion was seen at 3 years follow up.
