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Thomas A Zdeblick

Publications and source records attributed to Thomas A Zdeblick.

5 recordsLinked to original sources
PubMed2003

Interbody cage devices.

STUDY DESIGN: A literature review was conducted of basic science research and clinical experiences describing the use of interbody cage devices for the management of degenerative spinal abnormalities. OBJECTIVES: To summarize current knowledge regarding the use of interbody fusion cages. SUMMARY OF BACKGROUND DATA: Degenerative conditions of the lumbar and cervical spine are a major societal expense and a leading cause of disability. Fusion surgery may be used to treat patients with some of these conditions. During the past decade, interbody cages have been popularized as a useful fusion technique with high rates of clinical and radiographic success reported. Cages may be implanted using a variety of surgical approaches to the disc space and can be used alone or with supplemental posterior fixation. METHODS: A literature review of biomechanical, biologic, and clinical studies of threaded interbody cages was performed. RESULTS: Interbody cages have been shown to successfully promote fusion in a variety of animal models. In biomechanical studies, anteriorly placed threaded cages significantly stabilize the motion segment in all directions except extension. Posteriorly placed cages provide less stability as a result of the facetectomy required for placement of an appropriately sized device. Successful clinical and radiographic results have been reported with the use of interbody cages. Most reported cage failures are the result of technical difficulties with implantation or poor patient selection. Accurate radiographic assessment of fusion in the presence of a metal interbody cage remains challenging, and studies evaluating alternate biomaterial cages are underway. CONCLUSION: Interbody cages are a useful technique for achieving spinal fusion and have been shown to have an acceptable clinical success rate in appropriately selected patients.

Animals↗
PubMed2003

The biomechanical effects of spondylolysis and its treatment.

STUDY DESIGN: Biomechanical analysis of the level above pars defects was performed using calf lumbar spines. OBJECTIVES: To evaluate whether complete spondylolysis contributes to the pathology of the upper adjacent motion segment to the pars defect. SUMMARY OF BACKGROUND DATA: It is well recognized that patients with spondylolysis show a higher incidence of spondylolisthesis or degenerative disc changes at the level of the pars defects. However, some authors have referred to the fact that disc damage may occur at the level above the defect and give rise to symptoms. However, no previous studies have been directed to the kinematic influence on the upper adjacent segment to pars defects. METHODS: Nine fresh-frozen calf lumbar spines were used for this study. The bony defects were created on the L4 pars articularis bilaterally. Three linear extensometers and one specially designed angular extensometer were mounted across the L3-L4 and L4-L5 motion units. Nondestructive static loads, including axial compression, flexion-extension, and axial rotation, were applied on the specimens in four different conditions as follows: 1) intact spine; 2) bilateral pars defects on the L4 laminae; 3) pars defect repair with Buck technique; and 4) pedicle screw-rod fixation at L4-L5 after removal of the interarticular screws. Testing was performed on a material testing machine (MTS 858 Bionix test system, Minneapolis, MN), and load-displacement curves were recorded with the extensometers. Each test was performed for over five full sinusoidal loading cycles, and data from the fifth cycle were collected and analyzed. RESULTS: After creating the pars interarticularis defects at L4, mobility at both the L3-L4 and L4-L5 motion units were increased in all loading conditions. The normalized range of motion (% ROM) as compared with the intact specimens showed that the pars defects increased the mobility at the upper adjacent level (L3-L4) to 106.4% in flexion-extension and to 120.1% in axial rotation; the differences were significant (P < 0.01). Consequently, the increased mobility was stabilized by applying Buck screws through the defects on both sides; however, the effect was not statistically significant. Furthermore, pedicle screw-rod fixation applied at the L4-L5 segment increased the intervertebral motion at the upper adjacent level, and % ROM in axial rotation was significantly increased to 119.2% of the intact spine (P < 0.05). Comparing the treatments' effects on the L3-L4 segment and that on L4-L5, the Buck screws restored the stability of both segments to the level of the intact spine, whereas the pedicle screw system limited the motion of L4-L5 motion and, on the contrary, increased the L3-L4 motion. CONCLUSIONS: This biomechanical study exhibited that bilateral pars interarticularis defects increased the intervertebral mobility, not only at the involved level but also at the upper adjacent level to the lysis. The increased mobility at the upper segment was reduced by the Buck screw technique. However, this was increased again by the pedicle screw system applied on the involved segment. If clinically applicable, fixation of the pars defect alone appears to cause less adjacent level mechanical stress than pedicle screw-rod motion segment fixation.

Animals↗
PubMed2003

Is INFUSE bone graft superior to autograft bone? An integrated analysis of clinical trials using the LT-CAGE lumbar tapered fusion device.

Multicenter human clinical studies of patients undergoing anterior lumbar fusion have been conducted using recombinant bone morphogenetic protein or rhBMP-2 on an absorbable collagen sponge, marketed as INFUSE Bone Graft, or autograft implanted in the LT-CAGE Lumbar Tapered Fusion device. An integrated analysis of multiple clinical studies was performed using an analysis of covariance to adjust for preoperative variables in a total of 679 patients. Of these patients, 277 had their cages implanted with rhBMP-2 on an absorbable collagen sponge and 402 received autograft transferred from the iliac crest. The patients treated with rhBMP-2 had statistically superior outcomes with regard to length of surgery, blood loss, hospital stay, reoperation rate, median time to return to work, and fusion rates at 6, 12, and 24 months. Oswestry Disability Index scores and the Physical Component Scores and Pain Index of the SF-36 scale at 3, 6, 12, and 24 months showed statistically superior outcomes in the rhBMP-2 group.

Analysis of Variance↗
PubMed2002

Anterior lumbar interbody fusion using rhBMP-2 with tapered interbody cages.

In a multicenter, prospective, randomized, nonblinded, 2-year study, 279 patients with degenerative lumbar disc disease were randomly divided into two groups that underwent interbody fusion using two tapered threaded fusion cages. The investigational group (143 patients) received rhBMP-2 on an absorbable collagen sponge, and a control group (136 patients) received autogenous iliac crest bone graft. Plain radiographs and computed tomographic scans were used to evaluate fusion at 6, 12, and 24 months after surgery. Mean operative time (1.6 hours) and blood loss (109.8 mL) were less in the investigational rhBMP-2 group than in the autograft control group (2.0 hours and 153.1 mL). At 24 months the investigational group's fusion rate (94.5%) remained higher than that of the control group (88.7%). New bone formation occurred in all investigational patients. At all intervals, mean postoperative Oswestry, back pain, and leg pain scores and neurologic status improved in both treatment groups with similar outcomes. In the control group, eight adverse events related to the iliac crest graft harvest occurred (5.9%), and at 24 months 32% of patients reported graft site discomfort and 16% were bothered by its appearance. Lumbar fusion using rhBMP-2 and a tapered titanium fusion cage can yield a solid union and eliminate the need for harvesting iliac crest bone graft.

Adult↗