"Critical pedicle wall" breaches analysis in complex spinal deformity using O-arm navigation.

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.

Chronic Intramedullary Spinal Cord Abscess Mimicking Intramedullary Spinal Cord Tumor-"Phantom Tumor": A Case Report.

CASE: A 33-year-old woman with back pain and radiculopathy had presented with bilateral ankle weakness. MRI showed an intramedullary conus lesion suggestive of neoplasm, but posterior midline durotomy revealed only pus. Pus samples showed Staphylococcus aureus, which was treated with 6 weeks of antibiotics. Two-year follow-up showed complete neurological recovery with no clinicoradiological signs of recurrence. CONCLUSION: Usually, intramedullary spinal cord abscess (ISCA) has an acute presentation and warrants an emergent line of treatment with a risk of mortality. Very rarely chronic ISCA can mimic intramedullary spinal cord tumor. It is the first case reported in the literature of chronic ISCA mimicking conus IMST.

Efficacy of less Invasive modified O-arm navigated delta fixation in osteoporotic high-grade spondylolisthesis: "a LIMO delta technique".

PURPOSE: In 1994, the technique of transdiscal screws fixation in spondylolisthesis was introduced but did not gained popularity as it failed to address problems with spinal sagittal imbalance, retroverted pelvis, pseudoarthrosis, implant failure and neural injury. Majority of problems were due to lack of clear indications; hence, in this study, with modification of traditional technique and use of O-arm navigation for selected group of patients, we have addressed the above problems and given good to excellent functional outcomes. METHODS: We did prospective study on 15 patients with osteoporotic high-grade spondylolisthesis Meyerding grade 3 & 4 admitted in period 2020-2021. Intraoperative assessment was done in form of blood loss, incision length, operative time and complications. The preoperative & postoperative assessment was done in the form of clinical and radiological parameters. RESULTS: The average follow-up was of 21.2 months (18-24 months). There was no significant difference between pre- & postoperative spinopelvic parameters. Intraoperative average blood loss was 100 ml (90-120 ml) with mean surgical time of 138 min (120-150 min). Incision length was about 5-6-cms-posterior midline with two paraspinal 1-cm incisions for transdiscal screws. Patients were mobilized on postoperative day-2. There was statistically significant improvement in mean ODI, COMI and VAS for LBP and radicular pain with no intra- or postoperative complication observed till latest follow-up with all patients showing solid monoblock fusion on 1-year follow-up CT scan. CONCLUSIONS: LIMO delta technique is a newly modified version of conventional transdiscal screw technique. Minimal incision, decreased blood loss & operative time with in situ 3-column rigid fixation and solid fusion minimizing risk of complications makes this novel technique safer, simpler & effective in osteoporotic HGS.

Less invasive O-arm navigation-guided excision of thoracic extraosseous intraforaminal osteoblastoma: A case report.

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.