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Biomedical subjects

R W Gaines

Publications and source records attributed to R W Gaines.

At least 37 records · Page 2Linked to original sources
PubMed1992

Skin expansion as preparation for an opening wedge osteotomy of the mid-foot in arthrogryposis.

A case report is presented in which tissue expansion is used to provide the additional skin needed during an opening wedge mid-foot osteotomy to correct a varus foot deformity in a patient with arthrogryposis multiplex congenita. Tissue expansion is a relatively new method of acquiring coverage for wounds which may have advantages over previous techniques. The risks and drawbacks of this technique will be described in detail.

Arthrogryposis↗
PubMed1992

"Backfiring" in spinal cord monitoring. High thoracic spinal cord stimulation evokes sciatic response by antidromic sensory pathway conduction, not motor tract conduction.

Spinal cord stimulation has been advocated as an alternative to motor cortex stimulation for motor tract activation. To test this theory, evoked responses were recorded from lumbar spinal cord (L2; n = 14), spinal roots (L4-L7; n = 112), peripheral nerves (sciatics; n = 28), and hind limb muscles (n = 28) after epidural stimulation of the T1-T2 segment of the spinal cord in dogs (n = 12), cats (n = 2), and monkeys (n = 2). The spinal response evoked by spinal cord stimulation was resistant to a dorsal hemisectioning (depth, 7-8 mm) of the midthoracic spinal cord. A minimal attenuation of latency and amplitude occurred with dorsal hemisectioning, suggesting signal transmission through descending or ascending pathways in the ventrolateral and ventral quadrants of the spinal cord. The sciatic nerve response was abolished by a dorsal column transection (depth, 3-4 mm) or ipsilateral lumbar dorsal rhizotomy (four dorsal roots). This shows that the evoked response recorded from the sciatic nerve in our animals was not travelling, as we expected, through the ventral roots, but rather was conducted antidromically through sensory fibers in dorsal roots.

Animals↗
PubMed1991

Experimental evaluation of seven different spinal fracture internal fixation devices using nonfailure stability testing. The load-sharing and unstable-mechanism concepts.

Fracture site immobilization capabilities of seven internal spine fixation systems were experimentally evaluated: Harrington double distraction (plain, supplemented with Edwards sleeves, supplemented with sublaminar wires), Luque rectangle, Kaneda device, transfixed Kaneda device, and Steffee plates. Stability evaluation involved comparing the three-dimensional motion that occurred across an experimentally created L1 slice fracture, and the load resistance of the implants when subjected to axial, flexion, extension, lateral bending, and torsional loads. Each implant was tested on 15 different vertebral segments from 200-250-lb calves. All implants load-shared with the fractured vertebral column to varying degrees. All except the Steffee plate system showed an obvious biomechanical weakness in one or more load modes. The unstable 4R-4bar mechanism configuration of bilevel spinal implants was identified. Mechanism configurations allow free movement with little or no resistance to the applied load until load sharing by the spinal column stops the collapse and resists the applied load.

Animals↗
PubMed1991

Magnetic resonance imaging evaluation of the spinal canal following arthrodesis and removal of sublaminar wires.

Seven patients who underwent posterior spinal fusion with Harrington instrumentation and sublaminar wires, and subsequently had these implants removed, were evaluated for evidence of spinal canal compromise with magnetic resonance imaging (MRI) at the sites of the sublaminar wires. All fusions were solid. The sites of 33 wires (27 levels) were evaluated with MRI. The average time the wires were in the spinal canal was 24.6 months. The average time following wire removal at the time of MRI was 61.7 months. Twenty-eight of 33 (85%) wire sites had no evidence of spinal canal compromise. Five sites had minimal (less than 15%) spinal canal compromise. The permanent structural changes in the spinal canal attributable to sublaminar wires appears to be quite modest.

Adolescent↗
PubMed1990

Internal forces and moments in transpedicular spine instrumentation. The effect of pedicle screw angle and transfixation--the 4R-4bar linkage concept.

The three-dimensional components of force and moment within the plates and screws of a bilevel transpedicular spine implant construct subjected to different physiological loads were determined by experimental and finite element methods. The effect of pedicle screw angle and transfixation were studied. Untransfixed 0 degrees pedicle-to-pedicle (P-P) angle constructs with limited screw-bone torsional resistance are unstable 4R-4bar linkages. They will not resist lateral load or (when not in a rectangular position) axial load until the spinal column load shares. Untransfixed constructs with (0 degrees less than P-P angle less than 60 degrees) are structures. However, as P-P angle approaches 0 degrees, the structure becomes more flexible (unstable) and some internal force and moment components exponentially increase (starting at approximately a 30 degrees P-P angle). Transfixation eliminated the linkage instability and associated exponential increase in internal loads. These observations apply to all bilevel systems that allow no relative joint motion between pedicle screw and longitudinal member. If relative motion does exist, other types of linkage instability can occur.

Biomechanical Phenomena↗
PubMed1988

Herpes zoster: a consideration in the differential diagnosis of radiculopathy.

Herpes zoster probably occurs more often than generally thought. Since it produces a radicular distribution of pain, it should be included in the differential diagnosis of radiculopathy. A case is presented in which evaluating the radicular low back pain before the characteristic rash appears was misleading. Careful history-taking concerning the exact nature of the pain and sensory changes is needed to differentiate between zoster and radiculopathy, if no rash is evident.

Back Pain↗
PubMed1987

Response variability of somatosensory evoked potentials during scoliosis surgery.

Somatosensory evoked potentials (SSEP) were recorded from the scalp for intraoperative monitoring of patients undergoing surgical correction of spine deformities or spine fractures. Alterations in the SSEP with distraction, spine manipulation, anesthesia, hypotension, and other intraoperative variables are described. When loss of the SSEP occurred and a waiting period was undertaken until it returned, all patients with an SSEP present upon closing, which was within +/- 2 SD of their anesthetized control values, had no neurologic complications. Alterations in SSEP consisting of increases in latency of 15% and decreases in amplitude of 50% were not associated with any postoperative neurologic deficits.

Adolescent↗
PubMed1987

Removal of sublaminar wires after spinal fusion.

Eighteen patients who had had spinal fusion using Harrington rods with sublaminar wires underwent removal of the implants because of tenderness over the implants. There were no important complications. At final follow-up, no patient had a change in neurological function as compared with the preoperative assessment, and all reported relief of the preoperative tenderness. We concluded that the removal of rods and sublaminar wires from patients who have had a spinal fusion is clinically safe and effective.

Adolescent↗
PubMed1986

Mersilene tapes as a substitute for wire in segmental spinal instrumentation for children.

Sublaminar wires for segmental fixation have been a useful adjunct to internal fixation of the spine. Concern over broken wires in the spinal canal or fear of cut-through in soft bone led to the use of Mersilene tape to supplement Harrington or Luque rod fixation in six scoliotic children. No problems of infection or hardware loosening were noted. Mersilene tapes for segmental fixation may be useful where there is concern for wires in the spinal canal or with patients with soft bone and flexible curves.

Bone Wires↗
PubMed1985

Treatment of spondyloptosis by two stage L5 vertebrectomy and reduction of L4 onto S1.

A new method of treatment of spondyloptosis is presented utilizing a staged approach. The first stage consists of a vertebral body resection of L5 along with the L4-5 and L5-S1 discs. The second stage procedure consists of removal of the loose posterior element, the articular processes, and pedicles of L5 and reduction of L4 onto the sacrum. The technique for the procedure is reviewed along with its results in two operated patients.

Adolescent↗
PubMed1984

A plea for judgment in management of thoracolumbar fractures and fracture-dislocations. A reassessment of surgical indications.

Until basic knowledge of fracture anatomy and stability includes experiments with comminuted anterior column injuries, posterior column injuries, and these injuries in combination with ligament and capsular injuries, and until the long-term implications of the long fusion in an otherwise healthy patient are fully known, clinicians making decisions about individual patients must assemble all the variables that bear on the patient's ability to heal and become fully functional again before making a decision about surgical stabilization of the thoracolumbar fracture. An assessment of plain roentgenograms, tomograms, and CAT scans and an understanding of the anatomy of the fracture site provide essential but insufficient data for clinical decisions about patients.

Fracture Fixation, Internal↗