Jean-Pierre Mobasser

Intraoperative cone beam-computed tomography with navigation (O-ARM) versus conventional fluoroscopy (C-ARM): a cadaveric study comparing accuracy, efficiency, and safety for spinal instrumentation.

Study Design. Cadaveric laboratory study. Objective. To compare the accuracy, efficiency, and safety of intraoperative cone beam–computed tomography with navigation (O-ARM) with traditional intraoperative fluoroscopy (C-ARM) for the placement of pedicle screws. Summary of Background Data. Radiation exposure remains a concern with traditional methods of intraoperative imaging in spine surgery. The use of O-ARM has been proposed for more accurate and efficient spinal instrumentation. Understanding radiation imparted to patients and surgeons by O-ARM is important for assessing risks and benefits of this technology, especially in light of evolving indications. Methods. Four surgeons placed 160 pedicle screws on 8 cadavers without deformity. Eighty pedicle screws were placed using O-ARM and C-ARM each. Instrumentation was placed bilaterally in the thoracic (T1–T6) spine and lumbosacral junction (L5–S1) using a standard open technique, whereas minimally invasive surgery technique was used at the lumbar 3 to 4 (L3–L4) level. A “postoperative” computed tomography (CT) scan was performed on cadavers where instrumentation was done using the C-ARM. An independent musculoskeletal radiologist assessed final images for screw position. Time required to set up and instrumentation was recorded. Dosimeters were placed on multiple aspects of cadavers and surgeons to record radiation exposure. Results. There were no differences in breach rate between the O-ARM and C-ARM groups (5 vs. 7, &khgr;2= 0.63, P = 0.4). The setup time for the O-ARM group was longer than that for the C-ARM group (592 vs. 297 s, P < 0.05). However, the average total time was statistically the same (1629 vs. 1639 s, P = 0.96). Radiation exposure was higher for surgeons in the C-ARM group and cadavers in the O-ARM group. When a “postoperative” CT scan was included in the estimation of the total radiation exposure, there was less of difference between the groups, but still more for the O-ARM group. Conclusion. In cadavers without deformity, O-ARM use results in similar breach rates as C-ARM for the placement of pedicle screws. Time for instrumentation is shorter with the O-ARM, but requires a longer setup time. The O-ARM exposes less radiation to the surgeon, but higher doses to the cadaver. Level of Evidence: N/A

Percutaneous pedicle screw instrumentation for temporary internal bracing of nondisplaced bony Chance fractures.

Objective and Importance Although many patients with unstable Chance fractures can heal in an external brace, others will require internal stabilization. Short-segment minimally invasive internal bracing of a Chance fracture offers the rigidity and patient compliance of internal bracing with minimal tissue disruption. This technique has not yet been described. Clinical Presentation A healthy 16-year-old female and 21-year-old male sustained classic nondisplaced Chance fractures. They were both neurologically intact. Technique An image-guided Jamshidi needle was used to percutaneously place K-wires to direct percutaneous pedicle screws. Freehand percutaneous passing of rods to connect the pedicle screw heads on each side created a short-segment construct. Conclusions Minimally invasive internal bracing of nondisplaced bony Chance fractures is an option for selected neurologically intact patients unable to tolerate external bracing.

Comparison Perioperative Factors During Minimally Invasive Pre-Psoas Lateral Interbody Fusion of the Lumbar Spine Using Either Navigation or Conventional Fluoroscopy

Study Design: Retrospective clinical study. Objectives: The aim of this study was to compare intraoperative conditions and clinical results of patients undergoing pre-psoas oblique lateral interbody fusion (OLIF) using navigation or conventional fluoroscopy (C-ARM) techniques. Methods: Forty-two patients (22 patients by navigation and 20 by fluoroscopy) underwent the OLIF procedure at 2 medical centers, and records were reviewed. Clinical data was collected and compared between the 2 groups. Patients were followed-up with a range of 6 to 24 months. Results: There were no significant differences on demographic data between groups. The navigation group had zero radiation exposure (RE) to the surgeon and radiation time compared to the C-ARM group, with total RE of 44.59 ± 26.65 mGy and radiation time of 88.30 ± 58.28 seconds (P < .05). The RE to the patient was significantly lower in the O-ARM group (9.38 mGy) compared to the C-ARM group (44.59 ± 26.65 mGy). Operating room time was slightly longer in the navigation group (2.49 ± 1.35 hours) compared to the C-ARM group (2.30 ± 1.17 hours; P > .05), although not statistically significant. No differences were found in estimated blood loss, length of hospitalization, surgery-related complications, and outcome scores with an average of 8-month follow-up. Conclusions: Compared with C-ARM techniques, using navigation can eliminate RE to surgeon and decrease RE to the patient, and it had no significant effect on operating time, estimated blood loss, length of hospitalization, or perioperative complications in the patients with OLIF procedure. This study shows that navigation is a safe alternative to fluoroscopy during the OLIF procedure in the treatment of degenerative lumbar conditions.

The Supine, Sitting, and Lithotomy Positions

The authors discuss the sitting, supine, and lithotomy positions in spine surgery. Indications for each position are discussed, as are advantages and drawbacks of each. The sitting position is utilized in posterior cervical and some thoracic procedures. It allows excellent visualization and diverts blood away from the field. However, it is associated with the major complication of air embolism and can be difficult for teams to use. The supine position is widely utilized and straightforward in its application. It is used for anterior approaches to the spine. Improper supine positioning can lead to pressure ulcers and neuropathies. The lithotomy position is rarely used in neurosurgery, but useful in the setting of anterior lumbar surgery in the patient with spondyloptosis or a very steep sacral inclination. It can, however, be associated with neuropathies and the dread complication of compartment syndrome.

Anterior Spinal Column Augmentation Techniques

With the aging population, osteoporotic compression fractures have become increasingly common throughout the United States. Many of these patients are not suitable for open surgery, but suffer from substantial pain. It has been found that through the injection of polymethylmethacrylate cement into these fracture sites (vertebroplasty), pain can be alleviated quickly and easily with little recovery time by the patient and low rates of complications. Since the development of vertebroplasty, many other augmentation techniques, including balloon-assisted peek implant-assisted techniques, have been invented. Along with new techniques, new indications for augmentation have come about both in tumor and trauma domains. In this chapter, the expanded indications and techniques involved in vertebral augmentation will be described.

Instrumented Lumbar Corpectomy and Spinal Reconstruction Comparing rhBMP-2/Compression-Resistant Matrix, rhBMP-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, and Autograft in Two Different Devices: A Study in Sheep.

Study Design. Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft. Objective. The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively. Summary of Background Data. Vertebral reconstruction with corpectomy devices requires bone graft. Bone graft substitutes have the potential to avoid a second operation, donor site pain, and attendant morbidity associated with autograft. Methods. Twenty-four sheep in 6 treatment groups underwent lumbar corpectomy via a retroperitoneal trans-psoas approach. Spines were reconstructed with autograft, rhBMP-2 on a CRM, or rhBMP-2 on an ACS mixed with ceramic granules. Grafting materials were placed in either a titanium mesh or PEEK conduit in spines with internal fixation. Computed tomographic (CT) scans were evaluated for fusion. Undecalcified histology was used to evaluate for fusion as well as the amount and extent of graft incorporation and graft resorption. Results. Regardless of corpectomy device used, rhBMP-2/CRM or rhBMP-2/ACS with MASTERGRAFT resulted in a 100% fusion rate. The autograft group had a lower (75%) radiographic fusion rate. Using either preparation of rhBMP-2 resulted in the length of the defect filling with solid bone. Autograft fragments and ceramic granules were incorporated into the fusion masses with much of the ceramic granules being resorbed by 6 months. Conclusion. Both of the rhBMP-2 formulations have the potential to effect bony fusion and vertebral reconstruction within the corpectomy devices. Level of Evidence: N/A