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Biomedical subjects

T S Whitecloud

Publications and source records attributed to T S Whitecloud.

At least 19 recordsLinked to original sources
PubMed2001

Lumbar cauda equina syndrome associated with the use of gelfoam: case report.

STUDY DESIGN: A case of cauda equina syndrome is reported. OBJECTIVE: To recognize a serious complication related to the use of Gelfoam in the lumbar spine. SUMMARY AND BACKGROUND DATA: Absorbable hemostatic gelatin sponges have long been used to control bleeding around the spinal cord. Despite widespread use and a safe history with few reported adverse reactions, Gelfoam sponges have potential for complications that may be overlooked. METHOD: A case of cauda equina syndrome is reported and discussed. RESULTS: A retained Gelfoam sponge was found in the epidural space after lumbar decompression and fusion for spinal stenosis. The retained gelatin sponge had expanded and solidified, causing a mass affect. The resultant nerve compression led to progressive myelopathy. On removal of the Gelfoam, symptoms rapidly resolved. CONCLUSIONS: Although the use of Gelfoam in spine surgery generally is considered safe, care must be taken to avoid placing a large mass of sponge in a potentially closed space. If Gelfoam is not handled properly, it can engorge and fail to be resorbed appropriately, thus causing a mass effect. If neurologic compromise develops, Gelfoam should be considered a potential cause and subsequently removed.

Bone Screws↗
PubMed2001

Transforaminal interbody fusion versus anterior-posterior interbody fusion of the lumbar spine: a financial analysis.

Lumbar interbody fusion can be performed anteriorly or posteriorly. An anterior approach generally requires an access surgeon and often is combined with a posterior fusion. A traditional posterior interbody fusion can destabilize the spinal motion segment and requires neural retraction. A new surgical technique, a transforaminal lumbar interbody fusion (TLIF), was recently described. It requires minimal neural retraction, and the disk space is exposed posterolaterally with removal of only one facet joint. This study compares the cost of an anterior-posterior one-level lumbar fusion with the cost of the same procedure performed using the TLIF technique. Table 1 lists the specific demographics. A retrospective review of the hospital charges of 80 patients undergoing interbody lumbar stabilization was conducted. The two groups consisted of 40 patients with an anterior-posterior fusion and 40 patients who were fused circumferentially using the TLIF technique. A cost analysis with normalization of 1998 dollars between the two groups was performed. The TLIF group had an average operative time of 213 minutes, compared with 269 minutes for the anterior-posterior group. In addition, an average additional 38 minutes were required to turn the patient from the anterior or posterior position. The average blood loss for the anterior-posterior procedure was 969 mL, compared with 489 mL for the TLIF group. Twenty-three of the anterior-posterior patients received an average of 2.2 units of blood and six of the TLIF patients received an average of 1.3 units. Use of the surgical intensive care unit was much lower in the TLIF group (38 of 40 patients versus 2 of 40 patients). The average length of stay was 6.1 days for the anterior-posterior group compared with an average of 3.3 days for the TLIF group. The average cost of the anterior-posterior patients was $49,085, compared with $33,784 for the TLIF group. Cost analysis between the two groups show the TLIF patients had an average savings of approximately $15,000 per admission. This cost comparison was conducted only for the time of the operative procedure. No attempt was made to analyze rates of fusion between the two groups or ultimate clinic outcome. There were no major complications in either group, and no patient returned to surgery for a lumbar spinal problem at the authors' hospital within 1 year of the index procedure.

Adult↗
PubMed2001

The impact of the Tulane-HCA joint venture on academic and clinical missions.

As with any joint venture in any given industry, positive and negative impacts are felt. Tulane University School of Medicine experienced impacts on its academic and clinical missions as a result of the joint venture between Tulane University and HCA, a for-profit public company. The laws of business had entered the halls of medicine. Although patients, personnel, and physicians experienced culture shock and inconveniences, Tulane University School of Medicine has been able to maintain viable training programs, and its faculty physicians have a hospital and corporately run clinics across the street. In addition, multidisciplinary centers of excellence, long spoken of in the academic realm, came to fruition through the corporate world. This may not have been the case, had Tulane University not entered into ajoint venture with HCA. Is it worth the effort? For Tulane University, whether one likes the entire package or not, the answer must be yes. The greatest impact is that the orthopaedic surgeons still are in a position to fulfill their academic and clinical missions.

Academic Medical Centers↗
PubMed2001

Biomechanical testing and clinical experience with the OMEGA-21 spinal fixation system.

The role of spinal instrumentation is to provide mechanical stability, obtain and maintain anatomic alignment, and promote fusion. The American Society for Testing and Materials (ASTM) introduced guidelines and procedures so that biomechanical properties of different implant designs could be compared in a consistent manner. Combined with biomechanical analyses, clinical evaluation allows the safety and efficacy of a spinal implant system to be determined before construction. The objective of our study was to determine the biomechanical properties and clinical performance of the OMEGA-21 Spinal Fixation System. Static and dynamic (fatigue) biomechanical testing was performed per ASTM guidelines and recommendations on individual components and on the system assembled in a corpectomy model. Clinical and radiographic evaluation of 57 consecutive patients with indications for instrumented spinal arthrodesis of the lower dorsal lumbar and sacral segments of the spine was performed at a mean follow-up of 31.9 months. Static and fatigue testing revealed superior biomechanical properties of the individual components and of the assembled system. The mechanical-strength values of the system were comparable with maximum reported values for existing implant designs. At final clinical follow-up, 86% of patients obtained relief of their symptoms; 84% considered their clinical results to be excellent or good. Ninety-one percent of patients satisfied radiographic criteria for bony fusion. There were 5 implant-related complications: 2 misplaced screws (2 patients), local pain above the implant (2 patients), and 2 broken expansive screws (1 patient). Biomechanical and clinical results indicate that the OMEGA-21 system is feasible and performs well as a spinal instrumentation system for the lower dorsal, lumbar, and sacral spine.

Adult↗
PubMed2000

Biomechanical evaluation and preliminary clinical experience with an expansive pedicle screw design.

The advantages of pedicle screw fixation depend on their ability to retain bony purchase until the fusion mass is stable. Osteoporotic bone and removal and replacement of pedicle screws in revision procedures substantially reduce screw mechanical fixation strength and can lead to clinical failure. The objective of this study was to determine if an expansive pedicle screw design could be used to improve biomechanical fixation in bone of compromised quality. Axial mechanical pullout testing was performed on paired expansive and conventional pedicle screws placed in fresh, unembalmed cadaveric vertebrae. Bone mineral density measurements (made using a dual-energy X-ray absorption meter) were used to characterize bone quality. A preliminary clinical and radiographic evaluation of 14 patients was also performed at a minimum 2-year follow-up. The mean axial pullout force in bone of all qualities was increased 30% when the expansive pedicle screw design was used. This included an appropriate 50% increase in pullout force in bone of poor quality (low bone mineral density). The preliminary clinical and radiographic results were supportive of the biomechanical design rationale and mechanical testing. The results were similar to those expected for spinal instrumentation using pedicle screws, even though compromised bone was present in two thirds of the cases in which the expansive screw was used.

Adult↗
PubMed2000

A cost analysis of two anterior cervical fusion procedures.

Multilevel anterior cervical discectomy and fusion (ACDF) remains a difficult problem. A recently described surgical technique for multilevel ACDF has eliminated the morbid complications associated with harvesting iliac crest bone graft (ICBG) while maintaining the advantages of using autologous bone graft. A matched-pairs t test was used to compare the estimated costs of 27 ACDFs using titanium surgical mesh, local autologous bone graft, and anterior plate instrumentation with 27 ACDFs using ICBG and plate fixation. The three variables considered were cage cost, operating time (cost), and hospitalization cost. The estimated costs for the two surgical procedures were not significantly different. Thus, the time saved by not harvesting an ICBG was comparable to the cost of the cage. Harvesting ICBG also increased the morbidity rate by 22%.

Bone Transplantation↗
PubMed2000

The Otto Aufranc Award. Strut allograft healing to the femur with recombinant human osteogenic protein-1.

Allograft struts are used to reinforce the deficient proximal femur in hip arthroplasty or for fixation of a periprosthetic fracture. Although the use of strut grafts wired or cabled to the proximal femur generally has been successful, the time for healing is slow. The purpose of the current study was to determine whether cortical strut graft healing to the femur could be enhanced by the addition of recombinant human osteogenic protein-1. Fourteen adult dogs underwent bilateral onlay allograft strut procedures to the midfemur using stainless steel cables. In each animal one femur received 500 mg of osteogenic protein-1 device (2.5 mg recombinant human osteogenic protein-1/g Type I collagen) interposed between the graft and host bone. The results showed that the healing of cortical strut grafts to the femur was enhanced dramatically by the addition of the osteogenic protein-1 device. The sites treated with osteogenic protein-1 had significantly greater radiographic, histologic, and microradiographic scores at all times. Rapid formation of new bone and graft incorporation was observed in sites treated with the osteogenic protein-1 device. Strut healing with the osteogenic protein-1 device at 4 weeks postoperative was superior to the healing in control sites at 8 weeks. Improving and accelerating the course of cortical strut graft healing should provide a substantial clinical benefit in lowering the risk of graft nonunion and fracture and shorten the time of protected weightbearing and functional disability.

Animals↗
PubMed1999

Modern alternatives and techniques for one-level discectomy and fusion.

Monosegmental cervical spondylosis with radiculopathy requiring operative intervention responds well to anterior disc excision and fusion with autograft. However, there is a 20% to 25% morbidity from the donor site. Several new surgical techniques using biomechanical spacers or internal fixation have been developed that can be used with local bone or allograft, thus eliminating donor site morbidity. Surgical outcomes are comparable with those of traditional anterior cervical discectomy and fusion.

Bone Transplantation↗
PubMed1998

Degenerative conditions of the lumbar spine treated with intervertebral titanium cages and posterior instrumentation for circumferential fusion.

Thirty-five consecutive patients were evaluated at an average follow-up time of 20 months after circumferential lumbar spinal fusion. All patients had degenerative conditions of the lumbar spine and same-day anterior spinal fusion by using titanium cages packed with autograft bone and posterior instrumentation combined with a posterolateral autogenous bone graft. The purpose of this study was to determine whether anterior titanium cage placement and posterior instrumentation with autologous bone graft was a safe and efficacious procedure in patients with degenerative disease of the lumbar spine. Fusion rates, complications, pain relief, medication use, and work status were specifically analyzed. Although previous reports documented the use of this technique for trauma and tumor cases, few studies assessed clinical and radiographic results in patients with degenerative conditions of the lumbar spine. Plain radiographs were used to determine spinal fusion at each spinal level. All patients were administered preoperative and postoperative questionnaires regarding three specific clinical-outcome parameters. These consisted of pain level, medication use, and work status. Intraoperative and postoperative complications were also documented. Radiographic results showed that 61 (97%) of 63 lumbar levels undergoing an arthrodesis procedure fused either anteriorly, posteriorly, or both. Of the 35 patients in this series, 33 (94%) fused at all levels, and two did not. Substantial pain relief was reported in 46% of all patients. Thirteen (37%) patients had one or more surgical complications. Circumferential spinal fusion in patients with degenerative etiologies yields excellent radiographic fusion rates and good pain relief. The procedure is technically demanding and is associated with a high rate of complications.

Adult↗
PubMed1997

The impact of gunshot wounds on an orthopaedic surgical service in an urban trauma center.

OBJECTIVE: To determine the prevalence of gunshot wound related orthopaedic injuries in an urban trauma center and outline the socioeconomic background of this patient population. DESIGN: Retrospective study conducted from January 1, 1994, through December 30, 1994. SETTING: University-affiliated level 1 trauma center. PATIENTS: Strict inclusion and exclusion criteria were established. INCLUSION CRITERIA: All patients were admitted through the emergency room with a gunshot wound for which the orthopaedic surgery service was consulted. The study group consisted of 284 patients. EXCLUSION CRITERIA: Those individuals excluded from the study were patients with an orthopaedic injury who died during or before attempts at resuscitation in the emergency room and patients treated on an outpatient basis. MAIN OUTCOME MEASURES: Orthopaedic and nonorthopaedic diagnoses, etiology, procedures performed, number of hours from admission to the first surgical procedure, average daily hospital census, drug and alcohol screen results, and patient financial status. RESULTS: The orthopaedic service was consulted on 284 patients admitted with gunshot wounds. This group comprised 24% of all orthopaedic admissions, 33% of the average daily orthopaedic census, and 14% of all orthopaedic surgery cases performed. Ninety-four percent were African American and 87% were male, with a mean age of 27 years. Approximately half were tested for alcohol and/or drugs, 45% of whom were positive for alcohol and 65% for drugs. Only 4% of the patients were privately insured. CONCLUSIONS: During the period of this study, gunshot wound injuries required more orthopaedic trauma resources than any other single diagnosis.

Adult↗
PubMed1995

Transpedicular fixation for the treatment of isthmic spondylolisthesis in adults.

STUDY DESIGN: This study analyzed the fusion rate and clinical success rate in adult patients undergoing surgical treatment for symptomatic, low grade, isthmic spondylolisthesis. A postoperative questionnaire and grading scale were used to judge clinical success. Successful fusion was judged using radiographic criteria. OBJECTIVE: To evaluate the clinical success and fusion success in a group of adult patients undergoing instrumented posterolateral arthrodesis for symptomatic isthmic spondylolisthesis. SUMMARY OF BACKGROUND DATA: Seventeen consecutive adult patients with symptomatic low grade isthmic spondylolisthesis underwent the identical surgical procedure consisting of Gill laminectomy, L5 nerve root decompression, Luque pedicle-screw plate instrumentation, and posterolateral arthrodesis at L5-S1 using autogenous iliac crest bone graft. Results were analyzed at an average 30-month follow-up. METHODS: An independent observer reviewed the results using a postoperative questionnaire to determine rates of return to work, symptom relief, and analgesic medication usage. Radiographs were evaluated to determine the fusion status. RESULTS: Seventeen patients were evaluated at an average of 30 months after the index procedure. Sixteen of 17 had solid fusions using radiographic criteria. Sixteen of 17 had satisfactory clinical results. Eight of 13 (62%) employed patients, including three of six patients with worker's compensation, returned to their usual jobs. CONCLUSIONS: An instrumented posterolateral arthrodesis in combination with a Gill procedure and L5 nerve root decompression results in a high rate of fusion, satisfactory clinical success, and a high rate of return to work.

Adolescent↗
PubMed1995

In vivo evaluation of demineralized bone matrix as a bone graft substitute for posterior spinal fusion.

STUDY DESIGN: Posterior lumbar spinal fusion segments were evaluated in 9 adult mongrel dogs 6, 12, and 26 weeks after implantation. Four sites on each animal received implants consisting of demineralized bone matrix alone, demineralized bone matrix with allograft bone, allograft bone alone, and autograft bone. Each unilateral fusion spanned one motion segment with one intervening vertebral level left undisturbed using T13-L7. The fusions were evaluated radiographically, mechanically, and histologically. OBJECTIVE: The purpose of this study was to determine the efficacy of demineralized bone matrix as a bone graft substitute for stable posterior spinal fusion. SUMMARY OF BACKGROUND DATA: Posterior spinal fusion is a procedure commonly performed for spinal stabilization. Increasing the incidence and speed of stable spinal fusion is a primary goal in spinal surgery. Concerns have developed regarding the graft material used to induce bone healing at the fusion site. The advent of osteoinductive materials, such as demineralized bone matrix, may eliminate the need to harvest autograft bone and may circumvent the immunologic response and lower osteogenic potential associated with allograft bone. METHODS: The quality of fusion and new bone formation was evaluated radiographically using plain films, computed tomography, and magnetic resonance imaging. After the dogs were killed, each fusion segment was evaluated mechanically in torsion to determine stiffness and histologically to determine qualitative parameters of new bone formation and remodeling. RESULTS: Radiographic studies showed that autograft bone sites achieved stable fusion by 26 weeks after surgery. Conversely, the demineralized bone matrix alone and with allograft bone demonstrated some new bone formation at 6 and 12 weeks, but did not achieve fusion by 26 weeks. The fusion sites of allograft bone alone showed minimal new bone formation at all time periods. Mechanically, the autograft fusion sites demonstrated torsional stability that was significantly greater than that of all other fusion sites at all time periods. The remaining fusion sites showed equivalent torsional stiffness at all time periods. Histologic analysis confirmed the radiographic and mechanical findings. CONCLUSIONS: The results indicate that demineralized bone matrix alone or with allograft bone is ineffective in achieving stable posterior spinal fusions.

Animals↗
PubMed1995

Intraspinal extradural ganglion cyst.

Occurrence of ganglion cysts in the spine is extremely rare. Common symptoms include intermittent lumbar pain and pain at night. Neurological examination to distinguish from other etiologies of radicular pain may be difficult. The L4-L5 level is the most common sight of occurrence. Radiographically, degenerative changes, particularly spondylolisthesis, are a common finding. MRI appearance of the cysts is variable, according to the composition of the cyst. A ganglion cyst should be considered in the differential of radicular pain in the presence of degenerative changes of the lumbar spine.

Aged↗
PubMed1994

Effects of bone mineral density on pedicle screw fixation.

STUDY DESIGN: In an attempt to evaluate the effects of bone mineral density on the quality of fixation of pedicle screws in the lumbar spine, the axial pullout force was determined and compared in normal and osteoporotic human lumbar spines. OBJECTIVES: Four techniques of screw hole preparation were evaluated. Two pedicle screw/offset laminar hook constructs also were evaluated to determine whether the adjunct fixation of the laminar hooks would improve quality of fixation to a level sufficient to allow their use in the osteoporotic lumbar spine. METHODS: Pedicle screws were inserted by one of the listed techniques into fresh frozen cadaveric human spines. The fixation strength then was evaluated by pullout on a uniaxial testing frame. RESULTS: Bone mineral density was a strong influence on axial pullout force. In normal bone, the method of screw hole preparation did not significantly affect the quality of fixation. However, in the osteoporotic spine, either an untapped screw hole or the tapping of a screw hole with a 5.5 mm tap improved the pullout force a statistically significant amount (P < 0.003). Also, a pedicle screw with offset hooks at two adjacent levels improved the fixation significantly, increasing the pullout force to twice the expected value. CONCLUSION: Pedicle screw pullout strength was highly correlated with bone mineral density. A 5.5 mm tap or preparation with a ganglion knife improved pullout strength. Use of pedicle screws in conjunction with laminar hooks at two levels improved pullout strength.

Biomechanical Phenomena↗
PubMed1994

Reduction in perineural scar formation after laminectomy with Polyactive membrane sheets.

STUDY DESIGN: The effectiveness of Polyactive (Osteotech, Inc., Shrewsbury, NJ), an elastomeric segmental copolymer, as a barrier material for the prevention of perineural scar formation was evaluated in eight adult mongrel dogs. Two animals each were killed at 2, 4, 8, and 12 weeks postoperation. OBJECTIVE: This study determined the ability of a Polyactive membrane to prevent perineural scar and compared the results to those obtained using free fat graft and nonimplanted control subjects. SUMMARY OF BACKGROUND DATA: Perineural scar formation after laminectomy presents considerable morbidity in lumbar surgery. To date, a wide variety of materials has been evaluated to prevent scar formation including free fat grafts, mechanical barrier devices, hemostatic agents, and anti-inflammatory drugs. However, all studies indicate scar formation is present, and the search for an effective barrier continues. METHODS: Gross dissection, radiographic studies, including computed tomography and magnetic resonance imaging, and histologic sections were used to evaluate the presence and degree of perineural scarring. If scarring was evident in each of the evaluations, the degree was graded on a 0-3 scale where: 0 = no scarring; 1 = mild scarring; 2 = moderate scarring; and 3 = extensive scar formation. RESULTS: Polyactive membranes were an effective barrier with only minimal scar formation to the dura observed at any time period. Free fat graft was an effective barrier to scar formation at early time periods; however, progressive fat graft degradation with some increased scarring was observed at latter time periods. Nonimplanted control defect sites resulted in moderate to severe scar formation to the dura as early as 2 weeks postimplantation. CONCLUSIONS: The results indicate Polyactive is a reliable and effective means of reducing perineural scar formation. The effectiveness of the Polyactive membrane could be improved markedly if techniques or methods to ensure retention of the membrane in the proper position were developed.

Adipose Tissue↗
PubMed1994

In vivo evaluation of anterior cervical fusions with hydroxylapatite graft material.

STUDY DESIGN: The efficacy of solid hydroxylapatite (HA) blocks for obtaining cervical interbody fusion was studied in a canine model. Each of 21 adult colony-reared hounds received a hydroxylapatite implant and an autogenous bone graft in the C3-C4 and C5-C6 disc interspaces. Seven dogs each were killed at 6, 12, and 26 weeks postoperation. OBJECTIVE: This study determined the rate, mechanical strength, and histologic characteristics of cervical interbody fusions achieved using a hydroxylapatite (HA) block and compared the results to those obtained with autogenous iliac crest bone graft. SUMMARY OF BACKGROUND DATA: The use of corticocancellous autograft has been successful in a high percentage of anterior cervical interbody fusions. Calcium phosphate ceramics may provide an alternative to autogenous and allogenous tissue. These materials are biocompatible and capable of direct intimate bonding with bone because of their chemical similarity to bone mineral. METHODS: Radiographic evaluation including plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) studies were used to determine fusion quality. Specimens were also subjected to mechanical testing to determine bending and torsional stiffness as well as ultimate load to failure. Histologic evaluation included integrity and incorporation of the graft materials and interface characterization. RESULTS: The CT images were well correlated with plain radiographs and demonstrated progressive incorporation of the graft materials with time. Magnetic resonance images were of little value in evaluating quality of fusion; the autograft sites demonstrated progressive disc height loss with time. Minimal disc height loss was observed with HA blocks. There was no statistical difference in torsional stiffness for the HA blocks and autogenous bone grafts at any time period. In bending, the HA block sites were significantly stiffer at 6 weeks (P < 0.005). There was no statistical difference in the ultimate failure load for the HA and autogenous bone grafts. Histologically, the HA blocks demonstrated areas of direct bone apposition with increased bone appositions and implant incorporation with time. At 6 and 12 weeks postoperation, the autograft sites demonstrated areas of graft resorption and some new bone formations. By 26 weeks, new bone was continuous with the vertebral endplates. CONCLUSIONS: The results indicate that HA blocks may provide an alternative to autogenous graft materials for anterior cervical interbody fusion. Block slippage and/or fracture may occur in a small number of patients but is primarily related to insertion technique and does not appear to significantly alter the final result.

Animals↗
PubMed1994

In vivo evaluation of recombinant human osteogenic protein (rhOP-1) implants as a bone graft substitute for spinal fusions.

STUDY DESIGN: Posterior spinal fusion segments were evaluated in adult mongrel dogs at 6, 12, and 26 weeks post-implantation. Four sites on each animal received implants consisting of recombinant human osteogenic protein-1 on a bone collagen carrier, bone collagen carrier alone, autogenous iliac crest bone, or no implant material. OBJECTIVE: To determine the efficacy of recombinant human osteogenic protein-1 as a bone graft substitute in achieving posterior spinal fusion and compare the results to those obtained using autogenous bone graft. SUMMARY OF BACKGROUND DATA: Posterior spinal fusion generally includes onlay grafting of autogenous or allogeneic bone after decortication of bony surfaces of the vertebral elements. The search for an acceptable bone graft substitute material has in recent years centered upon proteins capable of inducing bone in vivo. Recombinant human osteogenic protein-1 has demonstrated efficacy in healing large segmental osteoperiosteal defects in rabbits, dogs, and monkeys and appears ideally suited as a bone graft substitute for spinal fusions. METHODS: The quality of fusion and new bone formation was evaluated using plain films, computed tomography, and magnetic resonance imaging. RESULTS: Radiographic and histologic studies demonstrated that recombinant human osteogenic protein-1-treated fusion segments attained a stable fusion by 6 weeks post-implantation and were completely fused by 12 weeks. The autograft sites demonstrated fusion at 26 weeks post-implantation. CONCLUSIONS: The results indicated that recombinant human osteogenic protein-1 is an effective bone graft substitute for achieving stable posterior spinal fusions in a significantly more rapid fashion than can be achieved with autogenous bone graft.

Animals↗