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Bruce V Darden

Publications and source records attributed to Bruce V Darden.

4 recordsLinked to original sources

Adjacent segment disc pressures following two-level cervical disc replacement versus simulated anterior cervical fusion.

Anterior cervical fusion (ACF) has been shown to alter the biomechanics of adjacent segments of the cervical spine. The goal of total disc replacement is to address pathology at a given disc with minimal disruption of the operated or adjacent segments. This study compares the pressure within discs adjacent to either a two-level simulated ACDF or a two-level total disc replacement with the ProDisc-C. A special automated motion testing apparatus was constructed. Four fresh cadaveric cervical spine specimens were affixed to the test stand and tested in flexion and extension under specific loads. Intradiscal, miniature strain-gauge-based transducers were placed in the discs above and below the "treated" levels. The specimens were then tested in flexion and extension. Pressure and overall angular displacement were measured. In the most extreme and highest quality specimen the difference at C3/C4 registered 800 kPa and the difference at C6/C7 registered 50 kPa. This same quality specimen treated with the ProDisc reached a flexion angle at much lower moments, 24.3 degrees at 5 N-m, when compared to the the SACF 12.2 degrees at 8.6 N-m. Therefore, the moment needed to achieve 15 degrees of flexion with the SACF treatment was 5.5 N-m and the ProDisc treatment was only 2.9 N-m. This initial data would indicate that adjacent level discs experience substantially lower pressure after two-level disc replacement when compared to two-level SACF. Additional testing to further support these observations is ongoing.

Biomechanical Phenomena↗

Recurrent transverse myelitis after lumbar spine surgery: a case report.

STUDY DESIGN: A case of recurrent idiopathic transverse myelitis occurring after surgery is reported. OBJECTIVES: To present a case of idiopathic transverse myelitis recurring after surgery and to heighten awareness for the diagnosis and management of this disorder. SUMMARY AND BACKGROUND DATA: Transverse myelitis presenting with acute spinal pain and neurologic deficit must be considered along with structural causes of myelopathy by the spine specialist. This intramedullary spinal cord disorder may be caused by parainfectious and postvaccinal sequelae, multiple sclerosis, spinal cord ischemia, autoimmune disorders, and paraneoplastic syndromes. These various etiologies are often difficult to differentiate. However, a patient's history, clinical course, MRI studies, and laboratory findings often allow such classification. Determination of etiology provides pertinent information regarding potential recurrence, treatment, and prognosis. METHODS: The patient history, physical examination, radiologic and laboratory studies, and pertinent literature were reviewed. RESULTS: Thoracolumbar myelitis developed in the reported patient 6 weeks after lumbar spine surgery during an otherwise uncomplicated postoperative recovery. The workup did not identify a specific cause, and the patient recovered to ambulatory status. However, 4 months after surgery, acute transverse myelitis developed again, this time affecting the cervical spinal cord. Despite aggressive intervention with corticosteroids, the patient has remained nonambulatory with severe neurologic residua. In spite of an extensive workup, a definitive cause was not determined, although an autoimmune etiology was suspected. The patient has stabilized without recurrence using immunosuppressant therapies. CONCLUSIONS: Acute transverse myelitis is an intramedullary spinal cord disorder that may present to the spine specialist during the postoperative period. This diagnosis requires swift and aggressive diagnostic and treatment intervention. Although sometimes difficult, establishment of causation may help to determine therapy and prognosis.

Aged↗

Upper cervical spine injuries.

The unique anatomy of the upper cervical spine and the typical mechanisms of injury yield a predictable variety of injury patterns. Traumatic ligamentous injuries of the atlanto-occipital joint and transverse atlantal ligament are relatively uncommon, have a poor prognosis for healing, and often respond best to surgical stabilization. Bony injuries, including occipital condyle fractures, atlas fractures, most odontoid fractures, and traumatic spondylolisthesis of the axis, generally respond well to nonsurgical management. Controversy in management remains, however, especially with type II odontoid fractures.

Atlanto-Occipital Joint↗