Douglas S. Fenton

Minimally Invasive Procedures for Disorders of the Lumbar Spine

In the past decade, there has been a substantial increase in interest in minimally invasive procedures in all areas of medicine, particularly for spinal disorders. Some of these techniques represent notable advances in spinal care and have major roles in the care of patients with back-related symptoms. Other techniques appear to offer no benefit and in some cases may be less effective than conventional treatments. Percutaneous lumbar diskectomy techniques hold considerable promise; however, lumbar microdiskectomy is the gold standard for surgical treatment of lumbar disk protrusion with radiculopathy. Intradiskal electrothermal therapy is emerging as a useful option for selected patients with intractable mechanical back pain whose only other option historically has been a spinal fusion. Percutaneous fusion techniques are in their infancy and may prove to be beneficial for these patients as well. Percutaneous vertebral augmentation, including vertebroplasty and kyphoplasty, has become the treatment of choice for many patients with intractable back pain secondary to vertebral insufficiency fractures. Spinal injections are important for evaluating and managing spinal pain and can be extremely useful diagnostically and therapeutically. This multidisciplinary review outlines the status of these procedures and offers suggestions for their use in patient care.

Fat-saturated MR imaging in the detection of inflammatory facet arthropathy (facet synovitis) in the lumbar spine.

OBJECTIVE The objectives of the study were: to illustrate the magnetic resonance (MR) imaging appearance of facet synovitis in the lumbar region using an MR fat-saturation technique; to determine how commonly facet synovitis is encountered when fat-saturation techniques are used; to classify the MR appearance of facet synovitis; and to test the correlation between the location of a lesion and the site of the patients pain. DESIGN In total, 209 consecutive MR studies of the lumbar spine were retrospectively reviewed to document the prevalence of lumbar facet synovitis in daily imaging practice. The degree of facet synovitis was graded. Medical records of 30 additional symptomatic patients with MR evidence of unilateral, single-level facet synovitis were reviewed to determine the side of the patients clinical symptoms. RESULTS Facet synovitis occurred in 41% of lumbar MR studies reviewed. No patient reviewed had evidence of active infection. Most often, signal changes were restricted to the affected joint. The side of the facet synovitis correlated with the side of the patients clinical symptoms. CONCLUSION Facet synovitis is a common condition and appears to correlate with the patients pain. Detection of active inflammatory facet osteoarthropathy (facet synovitis) within and surrounding the facet joints is possible with MR imaging using a fat-saturation technique.

Three-dimensional image-guided placement of S2 alar screws to adjunct or salvage lumbosacral fixation

BACKGROUND CONTEXT Achieving fusion across the lumbosacral junction is challenging because of the unfavorable biomechanics associated with ending a fusion at this level. Bicortical placement of S1 pedicle screws can increase the construct stability at the lumbosacral junction; however, construct failure and pseudoarthrosis can still result. Iliac screws have been shown to increase the stiffness of lumbosacral constructs, but disadvantages include difficulty in connecting the iliac screw to adjacent sacral screws, painful screw loosening or prominence requiring removal, and the inability to place the screws in some patients with previous iliac crest autograft harvest. PURPOSE The purpose of the study is to describe a technique of S2 alar screw placement using three-dimensional image guidance. STUDY DESIGN/SETTING The study design is a retrospective analysis. PATIENT SAMPLE Twenty patients undergoing lumbosacral fusion had 32 screws placed using this technique. OUTCOME MEASURES An independent radiologist graded screw placement and lumbosacral fusion on thin-cut postoperative computed tomographic (CT) scans. METHODS Image guidance in this study was accomplished with the Medtronic Stealth Station Treon (Medtronic Inc., Littleton, MA, USA) used in conjunction with the O-ARM (Medtronic Inc.). Indications for placement of S2 alar screws included the following: to adjunct S1 pedicle screws in multilevel fusion cases; as an adjunct or alternative to S1 pedicle screws in pseudoarthrosis revision cases in which the S1 screws had loosened; as an alternative to S1 pedicle screws in cases where medial trajectory of an S1 pedicle screw was difficult to obtain because of a low-set lumbosacral junction; and a combination of the above. The entry point of the screw was typically chosen lateral and superior to the S2 dorsal foramen with the trajectory directed anterior, inferior, and lateral. Attempt was made to place the screw with the tip purchasing, but not penetrating through, the triangular area of cortical bone that can be found at the anterior, inferior, and lateral boundary of the sacral ala. An independent radiologist graded the placement of the screws on the intraoperative CT scan obtained with the O-ARM or on postoperative CT scans. Lumbosacral fusion was assessed on postoperative CT scans obtained at follow-up. RESULTS No complications occurred in this study as a result of S2 alar screw placement or image guidance. Five screws did penetrate the anterior cortex of the sacrum, with no clinical consequence. At the time of abstract submission, 16 patients were able to have follow-up CT scans, 15 of which were graded as solid fusion at the lumbosacral junction by the grading radiologist. CONCLUSIONS Three-dimensional image guidance allows for safe placement of large S2 sacral alar screws that can provide additional biomechanical stability to lumbosacral constructs or serve as an alternate point of sacral fixation when S1 pedicle screws cannot be salvaged or placed in a medial trajectory.

Cerebral embolization presenting as delayed, severe obtundation in the postanesthesia care unit after total hip arthroplasty.

Catastrophic neurologic events occur rarely postoperatively and must be diagnosed quickly. A 63-year-old woman who had undergone uneventful total hip arthroplasty experienced obtundation after admission to the postanesthesia care unit. Cranial magnetic resonance imaging revealed multiple lesions consistent with ischemia or infarction, and fat cerebral embolism was diagnosed. We describe the numerous complications that may occur in patients in the postanesthesia care unit and review the differential diagnosis of altered mental status in such patients. Paradoxical cerebral fat embolization must be considered in the differential diagnosis of altered mental status after pelvic or long bone fracture or lower extremity major joint replacement, and this condition may occur despite normal pulmonary function and no patent foramen ovale or right-to-left intracardiac shunt. Magnetic resonance imaging with T2-weighted sequences is the cranial imaging study of choice for early evaluation of patients with sudden multifocal neurologic deficits and suspected fat embolism syndrome.

Three-dimensional image-guided placement of percutaneous pedicle screws without the use of biplanar fluoroscopy or Kirschner wires: technical note

Percutaneous pedicle screws are commonly used in minimally invasive spinal procedures. Traditional techniques of percutaneous pedicle screw placement have employed the use of multiplanar fluoroscopy and Kirschner wires (K‐wires). The use of multiplanar fluoroscopy for the placement of percutaneous pedicle screws likely increases radiation exposure to the surgeon when compared to open techniques. K‐wires can break or become bent during the procedure, making it difficult to insert and remove instrumentation over them. Additionally, there is also a risk of visceral or vascular injury with the use of K‐wires. The authors present a novel method of percutaneous pedicle screw placement utilizing three‐dimensional (3D) fluoroscopy‐based image guidance in which K‐wires are not used and there is minimal to no radiation exposure to the surgeon and operating room staff.

Sudden Progression of Lumbar Disk Protrusion During Vertebral Axial Decompression Traction Therapy

Vertebral axial decompression (VAX-D) is a form of spinal traction that is widely promoted as an effective and safe treatment of degenerated and herniated lumbar intervertebral disks. Information targeted at the general public emphasizes that the treatment is completely risk-free. We describe a patient with a large lumbar disk protrusion who experienced sudden, severe exacerbation of radicular pain during a VAX-D therapy session. Follow-up magnetic resonance imaging of the lumbar region showed marked enlargement of the disk protrusion, and urgent microdiskectomy was required. To our knowledge, this is the first reported complication of VAX-D therapy. This case shows that VAX-D therapy has the potential to cause sudden deterioration requiring urgent surgical intervention.

Redirecting pedicle screws: a revision spinal fusion strategy using three‐dimensional image guidance

Pedicle screws are a preferred method for spinal fixation because of their three‐column support and rigid posterior stabilization. The purpose of this study was to evaluate the outcome of patients requiring pedicle screw redirection, and to describe a technique using cone‐beam computed tomography (cbCT).