Search PubMed⌕ Search

Biomedical subjects

T S Whitecloud

Publications and source records attributed to T S Whitecloud.

At least 37 records · Page 2Linked to original sources
PubMed1994

Operative treatment of the degenerated segment adjacent to a lumbar fusion.

Fourteen patients with a previous lumbosacral fusion underwent neural decompression and fusion of degenerated adjacent motion segment. The most common level was L3-L4, and there was an average of 3.2 (range 1-7) previous lumbosacral surgical procedures. The average interval from the first fusion until operative intervention on the degenerated adjacent segment was 11.5 years (range 3-29 years). Five patients had an uninstrumented fusion, of which only one progressed to arthrodesis. Three of these five patients with pseudarthrosis after uninstrumented fusion--and the remaining nine patients--had fusions with instrumentation. Ten of twelve instrumented fusions progressed to solid arthrodesis. The pseudoarthrosis rate of 80% was decreased to 17% with the use of supplemental instrumentation. There was a significant number of complications and poor results, especially in patients with advanced osteoporosis and those with a short interval between adjacent segment degeneration, respectively. Eleven of 14 patients reported some postoperative pain relief.

Female↗
PubMed1994

The effect of recombinant human osteogenic protein-1 on healing of large segmental bone defects.

A rabbit ulnar non-union model was used to evaluate the effect of recombinant human osteogenic protein-1 on the healing of a large segmental osteoperiosteal defect. A 1.5-centimeter segmental defect was created in the mid-part of the ulnar shaft of adult rabbits. The defect was filled with an implant containing either recombinant human osteogenic protein-1 or naturally occurring bovine osteogenic protein. The recombinant human osteogenic protein-1 implants consisted of a carrier of 125 milligrams of demineralized, guanidine-extracted, insoluble rabbit bone matrix (the collagen carrier), reconstituted with 3.13, 6.25, 12.5, twenty-five, fifty, 100, 200, 300, or 400 micrograms of recombinant human osteogenic protein-1. Animals that received recombinant human osteogenic protein-1 were compared with animals that received an implant of 250 micrograms of a preparation of naturally occurring bovine osteogenic protein mixed with the collagen carrier. Limbs that served as controls received either the collagen carrier alone or no implant at all. The treated and the untreated defects were examined radiographically and histologically at eight or twelve weeks after implantation. Mechanical testing was performed on six animals. All implants of recombinant human osteogenic protein-1, except for those containing 3.13 micrograms of the substance, induced complete radiographic osseous union within eight weeks. The defects that were treated with an implant of bovine osteogenic protein also healed within this time-period. The bone induced by both types of implants had new cortices with advanced remodeling and marrow elements. Histological evaluation of this new bone at eight weeks postoperatively revealed primarily lamellar bone, with the formation of new cortices and normal-appearing marrow elements. The average torsional strength and energy-absorption capacity of the union induced by recombinant human osteogenic protein-1 was comparable with that of intact bone. The control defects that had been implanted with collagen carrier alone and those with no implant showed no bridging of the defect.

Animals↗
PubMed1993

A comparison of computed tomography-myelography, magnetic resonance imaging, and myelography in the diagnosis of herniated nucleus pulposus and spinal stenosis.

The sensitivity, specificity, and accuracy of computed tomography (CT)-myelography, magnetic resonance imaging (MRI), and myelography in making the diagnosis of herniated nucleus pulposus (HNP) and spinal stenosis were compared in a retrospective study involving 59 surgical procedures in 57 patients who had all three tests performed preoperatively. One hundred nineteen levels were surgically explored for evidence of HNP and spinal stenosis. The results of each test were correlated with what was found at each surgical level explored. Overall, myelo-CT was the most accurate test for diagnosing HNP (76.4%) as well as the most sensitive (77.8%), whereas myelography was the most specific (89.2%). In making the diagnosis of spinal stenosis, myelo-CT and MRI were equally accurate (85.3%) and sensitive (87.2%), whereas myelography was the most specific (88.9%). In a special subset of patients who had revision surgery, the accuracy rate in diagnosing spinal stenosis or HNP was highest with MRI (84.9%), as was the sensitivity (69.2%) and specificity (95%). According to the results obtained from this series of patients, myelo-CT seems to be the most sensitive and accurate test in diagnosing HNP and spinal stenosis, whereas myelography is the most specific, although no statistical significance was noted in this study. However, because MRI did compare favorably with myelo-CT in most instances, particularly in revision surgery; it may be the procedure of choice due to its noninvasiveness and relative lack of side effects.

Adult↗
PubMed1993

The use of Texas Scottish-Rite instrumentation in idiopathic scoliosis. A preliminary report.

The Texas Scottish-Rite instrumentation (TSRH) is a new system for the correction of spinal deformities that uses smooth rods and hooks stabilized to the rod with a three-point interference fit. This obviates the need for the break-off hex bolts and should make for easier removal and/or revision. Twenty-three patients with TSRH instrumentation were followed for an average of 18 months after surgery. The major scoliotic curve was corrected an average of 49% with the compensatory curve averaging 37% correction. Loss of thoracic kyphosis was less than 9 degrees although it increased on average 8 degrees in those patients where kyphosis was improved. There were no acute complications, but late complications included four cases of hook pull-out. Results are comparable to those found with the CD instrumentation. The TSRH instrumentation is an attractive alternative in scoliosis surgery, particularly because of the relative ease in which revision surgery may be performed.

Adolescent↗
PubMed1992

Hydroxylapatite coating of porous implants improves bone ingrowth and interface attachment strength.

The effect of a plasma-sprayed hydroxylapatite (HA) coating on the degree of bone ingrowth and interface shear attachment strength was investigated using a canine femoral transcortical implant model. Cylindrical implants were fabricated by sintering spherical Co-Cr-Mo particles 500-710 microns in diameter; the nominal implant dimensions were 5.95 +/- 0.05 mm diameter by 18 mm in length. One half of each implant was coated with hydroxylapatite, 25-30 microns in thickness, by a plasma-spray technique. Using strict aseptic technique, the implants were placed through both femoral cortices into defects approximately 0.05 mm undersized. After 2, 4, 6, 8, 12, 18, 26, and 52 weeks, the implants were harvested and subjected to mechanical pullout testing and undecalcified histologic evaluation. The application of the HA coating to porous implants enhanced both the amount of bone ingrowth and the interface attachment strength at all time periods. These differences were statistically significant for the percent of bone ingrowth at the 4-, 6-, 12-, 18-, 26-, and 52-week time periods, and interface shear strength values were significantly different at the 6-, 8-, 12-, 18-, and 26-week time periods. The rate of development of interface strength and bone ingrowth was also more rapid for the HA-coated implants. No evidence of any disruption, mechanical failure, or biologic resorption of the HA coating was observed. The results of the present study--demonstrating a beneficial effect of the HA coating at all time periods--are believed to be due to the use of paired comparisons, which allow assessment of subtle differences that might otherwise have been obscured by normal biological variability.

Analysis of Variance↗
PubMed1992

Neurologic testing with somatosensory evoked potentials in idiopathic scoliosis.

A study was undertaken to determine if a somatosensory conduction delay is present in the posterior columns of adolescents with idiopathic scoliosis. Somatosensory evoked potentials were recorded after median and posterior tibial nerve stimulation in 12 adolescent subjects being followed for idiopathic scoliosis with an average age of 14.6 years (range, 12.0-16.6 years). Twelve normal controls matched for age, sex, race, and height underwent identical testing. Evoked potential peak latencies were measured and conduction velocities calculated. Results showed no difference between scoliotics and normal controls. Comparable posterior column conduction velocities were recorded in both groups. If a defect in posterior column function does exist in adolescent idiopathic scoliosis, as previously postulated, it is not reflected by a conduction delay as measured by somatosensory evoked potential testing.

Adolescent↗
PubMed1992

Tissue growth into porous-coated acetabular components in 42 patients. Effects of adjunct fixation.

Histologic examination was performed on 42 uncemented, porous-coated acetabular components removed for reasons not related to fixation. Included were 20 devices that had fixed pegs or spikes to aid in initial fixation and 22 devices that used screws through the component. The diagnoses and patient ages at insertion, times in situ, and reasons for removal were comparable for the two groups. Bone ingrowth was observed in 28 of the 42 acetabular components (67%). Of the 20 components with pegs or spikes, nine had no bone ingrowth, six had minimal bone ingrowth, four had moderate ingrowth, and one had extensive bone ingrowth. Of the 22 components with screws, five had no bone ingrowth, six had minimal bone ingrowth, six had moderate bone ingrowth, and five had extensive bone ingrowth. Two of the devices with screws also had external threads on the metallic shell; neither had any bone ingrowth, and the two accounted for two of the five devices having no bone ingrowth in this group. Bone ingrowth occurred more frequently, in greater amounts and was more evenly distributed anatomically in cups using screws for initial adjunct fixation. Roentgenographic and clinical findings were unreliable in predicting ingrowth of bone.

Acetabulum↗
PubMed1992

Postlaminectomy kyphosis. Causes and surgical management.

Postlaminectomy instability of the cervical spine can be managed either anteriorly or posteriorly. The posterior procedures that have been described are best performed at the time of the original decompressive procedure. Thus, the development of a kyphotic deformity is prevented. Generally, it is technically easier to achieve anterior stabilization and arthrodesis if a postlaminectomy kyphosis develops.

Cervical Vertebrae↗
PubMed1991

Vertebral aneurysmal bone cyst. A case report and review.

The case of a 16-year-old boy with an aneurysmal bone cyst of the fourth lumbar vertebra and a herniated nucleus pulposus of the L4-5 disc is presented. Symptoms included progressive lower back pain and bilateral lower extremity weakness. Roentgenographic studies were consistent with a vertebral aneurysmal bone cyst with an expansile lesion that compromised the neural canal and an L4-5 herniated nucleus pulposus. Surgical treatment included tumor excision, L4-5 discectomy, lumbar decompression, and posterolateral and anterior lumbar fusion. Postoperatively, the lower back pain and lower extremity symptoms resolved. The patient continues to do well at 1-year follow-up.

Adolescent↗
PubMed1989

Complications with the variable spinal plating system.

From January 1986 to June of 1987, 40 patients underwent transpedicle fixation and fusion using the variable spinal plate system. Nineteen patients had undergone surgery at the same level or levels, and 21 patients had undergone no previous surgery. Diagnostic categories include spondylolisthesis, thoracolumbar and lumbar fractures, internal disc derangement, spinal stenosis, pseudarthrosis, mechanical instability, and fracture mal-union. Minimum follow-up has been 14 months, with the average being 20 months. Overall results showed 13 excellent, 12 good, seven fair, and eight poor. The overall complication rate was 45%. In those patients undergoing no previous surgery, it was 29%, but with those patients having previous surgery, it was 63%. Most of these complications were minor in nature and resolved before discharge. Implant failure occurred in seven patients, and consisted of screw breakage. Design modifications currently available should help minimize this complication. Although this method of internal fixation and fusion is technically demanding and has a high complication rate, it is considered to be indicated in lumbar fractures, revision of pseudarthrosis, spondylolisthesis with or without reduction, and failed surgery with marked instability.

Bone Plates↗
PubMed1989

Roentgenographic measurement of pedicle screw penetration.

Potential complications due to pedicle screw penetration of the anterior cortex include injury to vascular, visceral, ureteral, sympathetic, and neural structures. This study examined the accuracy of lateral roentgenographic techniques in determining actual screw penetration in vertebral levels T12 through S1 of ten unilateral sets of pedicles in five anatomic specimens. A true lateral roentgenogram alone was inaccurate for determining the penetration of the anterior cortex by a pedicle screw. The greatest discrepancy between roentgenographically apparent and actual screw penetration was found at the L4 and L5 levels. Deviation from a true lateral roentgenographic axis resulted in the most pronounced change in roentgenographically apparent screw penetration at L4 and L5. The roentgenographic axes resulting in the closest approximation of actual screw penetrations were 5 degrees and 10 degrees above the true lateral axis for the T12-L3 and the L4-S1 levels, respectively. At 50% apparent penetration, the screw may be safely assumed to not be penetrating the anterior cortex using a true lateral roentgenogram. At 80% apparent penetration, 30% and 10% probabilities of actual screw penetration of the anterior cortex exist at L4 and L5, respectively. At 100% apparent penetration, there is an almost 100% probability that the screw is actually protruding through the anterior cortex.

Biomechanical Phenomena↗
PubMed1988

Anterior lumbar fusion utilizing transvertebral fibular graft.

In those instances of failed posterior arthrodesis for spondylolisthesis, iatrogenic spondylolisthesis due to posterior neural decompression or severe (grade III or IV) spondylolisthesis, anterior stabilization using a fibular strut graft appears to be feasible and successful. Eleven patients were treated with this technique and ten achieved solid anterior arthrodesi; the eleventh fused posterolaterally. All improved symptomatically with no postoperative complications, including sexual dysfunction in the male.

Adult↗
PubMed1988

Lower cervical spondylosis and myelopathy in adults with Down's syndrome.

Abnormalities in the upper cervical spine resulting in cervical myelopathy in patients with Down's syndrome have been well-documented. However, two adult Down's syndrome patients recently presented with cervical myelopathy secondary to abnormalities of the lower cervical spine. Because of this, 105 Down's syndrome patients with normal upper cervical spines were evaluated clinically and radiographically. They were found to have an increased prevalence of lower cervical spondylosis that significantly correlated with physical findings consistent with cervical myelopathy. Therefore, physicians dealing with Down's patients should closely monitor neurological function and obtain flexion/extension laterals of the cervical spine to evaluate C1-C2 instability and degenerative changes in the lower cervical spine if a change in neurologic status is noted.

Adult↗
PubMed1987

Cervical spondylotic myelopathy and myeloradiculopathy. Anterior decompression and stabilization with autogenous fibula strut graft.

Operative treatment for cervical spondylotic myelopathy and myeloradiculopathy by anterior decompression produced functional improvement of one grade (Nurick's rating system) in 16 of 21 patients evaluated at 32 months average follow-up period. The best results occurred in patients with symptoms for less than one year and classified as grades I-III. The anterior approach for decompression is preferred because it is directed toward the degenerative structures responsible for cord and root compression. The autogeneic fibula dove-tailed strut graft is favored over an iliac crest bone graft because with multilevel decompression in the cervical spine, it provided structural stability and a high union rate. There were no neurologic complications in this series of 21 cases.

Cervical Vertebrae↗
PubMed1987

Cervical discogenic syndrome. Results of operative intervention in patients with positive discography.

In order to determine the validity of cervical discography in the diagnosis and treatment of patients presenting with cervical discogenic syndrome, a retrospective analysis of 34 patients who underwent cervical arthrodesis on the basis of positive cervical discography was performed. The symptomatic cervical levels were selected by reproduction of the patient's symptoms at the time of injection. No patient had radicular symptoms, and other diagnostic modalities such as computed tomography (CT) scanning or myelography had been within normal limits. Seventy percent of patients who underwent surgical intervention had good or excellent results. With proper utilization, cervical discography is a valid diagnostic study.

Adult↗