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C Thomas Vangsness

Publications and source records attributed to C Thomas Vangsness.

18 recordsLinked to original sources
PubMed2006

Overview of safety issues concerning the preparation and processing of soft-tissue allografts.

With the increasing use of allograft tissue and the recent infections found in patients undergoing surgical procedures, the current practices that prepare grafts for implantation must be examined. Initially, most tissue banks harvest allografts aseptically. There are many steps in the different techniques of preparation and processing of allograft tissue. Before allograft tissue is ready for clinical use, it undergoes specific disinfection methods, according to the individual tissue bank's specific process. Tissue banks use in-process bactericidal and virucidal steps via physical cleaning, chemical treatments, or application of irradiation to the allografts (or some combination thereof). Gamma irradiation may also be used as a terminal processing method to reach an assurance of sterility after the allograft has been packaged. Because of the allograft toxicity potential, the use of ethylene oxide as a final tissue sterilization measure is really nonexistent. The role of the Food and Drug Administration and American Association of Tissue Banks in allograft tissue handling is presented, as well as the new rules that regulate tissue banks and affect their processing methods.

Adult↗
PubMed2005

Effects of radiofrequency energy on human articular cartilage: an analysis of 5 systems.

BACKGROUND: Previous radiofrequency work has not rigidly controlled energy application to the articular cartilage, giving uncertain results published to date. HYPOTHESIS: At minimal settings, radiofrequency probes cause cell death in measurable areas when applied to human articular cartilage. STUDY DESIGN: Controlled laboratory study. METHODS: Simulating operating room conditions, 5 commercially available radiofrequency probes were attached to a customized jig to standardize a minimal contact pressure of each probe tip to 2.0 g. Keeping all variables the same, probes were placed on specific points of fresh grade II human cartilage with treatment times of 1 and 3 seconds at the manufacturer's recommended settings. Grade III cartilage was also tested with a treatment time of 3 seconds, and grade II cartilage was studied with the probe held 1 mm off the cartilage surface. Cartilage was blindly analyzed by confocal microscopy using a live/dead cell viability assay to determine the extent of cell death. RESULTS: Radiofrequency probes produced significant cellular death in the form of a half-circle into the cartilage to variable depths. For treatment times of 1 and 3 seconds, cell death measurements ranged from 404 to 539 mum and 1034 to 1283 mum, respectively. One probe failed to show any effect, with minimal evidence of cell death or cartilage smoothing. When probes were kept a 1.0-mm distance above the cartilage, no cell death or cartilage smoothing was noted. Radiofrequency treatment of grade III cartilage penetrated to the subchondral bone. There was no statistically significant difference between the damage caused by monopolar and bipolar probes when tested under these rigidly controlled conditions. CONCLUSION: These results showed significant cellular death at these minimal conditions to the underlying chondrocytes with radiofrequency probes. Surgeons using this technology need to be aware of the power and dangerous potential these probes can have on articular cartilage.

Aged↗
PubMed2005

Radiofrequency use on articular cartilage lesions.

The incidence of knee arthritis is increasing in our society and presents many dilemmas to the patient and doctor. Recent advances in arthroscopic treatment of arthritis have lead to the development of radiofrequency energy as an adjunctive tool for many arthroscopic procedures. Of great concern is the recent use of radiofrequency energy to treat articular cartilage lesions in the knee.

Animals↗
PubMed2004

Thermal profile of radiofrequency energy in the inferior glenohumeral ligament.

PURPOSE: Currently, two different methods of applying radiofrequency (RF) energy (monopolar and bipolar) are available to the surgeon for thermal shortening of the shoulder capsule. The objective of this study was to investigate the temperature changes and the thermal conduction across the human inferior glenohumeral ligament (IGHL) during radiofrequency energy application. METHODS: Thermistors were secured onto both the intra-articular and extra-articular surfaces of human IGHL. Monopolar RF energy and bipolar RF energy were delivered to the intra-articular surface at the manufacturer's recommended settings. Pre-treatment and post-treatment ligament lengths, widths, heating times, and temperatures were measured and compared. RESULTS: For the monopolar devices, temperature spikes to 89 degrees C were recorded for the set temperature of 67 degrees C, averaging 77 degrees C +/- 10 degrees C. Temperatures across the ligament averaged 48 degrees C +/- 3 degrees C. For both devices, the IGHL became thicker with higher RF settings. Recorded temperatures decreased as distance increased from the point of application. Maximum temperatures occurred at least 6 to 7 seconds after cessation of energy application. CONCLUSIONS: The bipolar and monopolar devices had similar conduction times across the ligament, suggesting that this occurs by simple diffusion of heat. Bipolar and monopolar devices were equally efficacious for capsular shrinkage if the extent of the shortening is tightly defined. CLINICAL RELEVANCE: The thermal probe should not rest in one position for an extended period of time during RF energy application because, as our study showed, the monitoring of temperature or the visualization of tissue change is not efficacious for determining the end point of thermal shrinkage of the shoulder capsule.

Cadaver↗
PubMed2004

Recent advances in glucosamine and chondroitin supplementation.

Glucosamine and chondroitin are alternative solutions to previous pharmaceutical options for the treatment of osteoarthritis. This article describes the mechanisms of action, pharmacokinetics, recent findings, and upcoming studies of these two natural remedies. The majority of studies on the mechanisms behind glucosamine and chondroitin have been performed in vitro or on animal models; however, the results have shown favorable effects on the balance between cartilage matrix synthesis and degradation. The pharmacokinetics of the three main forms of glucosamine were compared, and glucosamine hydrochloride displayed the greatest compound purity, despite the compounds having equal oral absorption rates of 90%. Chondroitin sulfate has been the principal clinical formulation with a slightly lower oral absorption of 70%. Clinical trials were evaluated based on two categories-radiographic changes and symptom improvement of pain and function. Although adverse effects of these two remedies were minor, the quality and labeled quantity of these relatively unregulated products must be considered. More randomized controlled studies on humans in vivo need to evaluate the efficacy, long-term effects, and quality of these compounds.

Cartilage, Articular↗
PubMed2004

Custom-fit versus premanufactured braces.

Custom-made and off-the-shelf functional knee orthoses from four manufacturers were evaluated. Anterior tibial translation testing was performed using a pneumatic mechanical surrogated knee. The mechanical surrogate was interfaced with a servohydraulic materials testing system, which applied all anterior/posterior displacements to an ultimate anterior load of 400 N. Comparison of the individual custom versus premanufactured braces showed that the custom braces demonstrated a statistically significant difference for restraining anterior displacement (P=.0001 to P=.0005). Pooled data from all tests showed that the custom brace measurements as a group restrained anterior displacement better than the premanufactured brace group by a mean difference of 0.84 mm (P=.0001). The authors question whether such small, sub-millimeter findings between custom and off-the-shelf functional derotation braces represent any clinically significant differences.

Braces↗
PubMed2004

Nonsurgical approaches to pain management for osteoarthritis of the knee.

The effective management of pain in osteoarthritis of the knee is complex and subject to many treatment- and patient-related variables. This article reviews the broad range of nonsurgical options available to the clinician, which include pharmacologic and nonpharmacologic measures such as weight loss, physical and occupational therapy, exercises, and the use of assistive devices. Pharmacotherapeutic options for osteoarthritis of the knee include the use of oral agents, topical creams, and intra-articular injections of hyaluronans or glucocorticoids. Since pain in the osteoarthritic knee can vary widely from patient to patient in its origins, pain management should address the individual patient's symptoms, level of pain, and functional disabilities.

Humans↗
PubMed2004

Restoring articular cartilage in the knee.

Following damage or injury, as well as normal wear and tear, articular cartilage in adults has limited healing potential. Repair of cartilage is dependent on the extent and depth of the injury, its location, and the surviving chondrocytes and extracellular matrix. The ultimate goal of cartilage repair is to restore the normal composition and matrix of the cartilage, but for most patients this is not feasible. In these cases, filling the defect using interventions that provide adequate, albeit not optimal, functionality and pain relief is desirable. Therefore, a more realistic goal in these patients may be restoration of their respective activity levels and the delay or avoidance of prosthetic replacement. Depending on the age, activity level, and degree of cartilage damage, several methods to decrease pain and attempt cartilage repair are available; these include lavage and debridement, abrasion arthroplasty, and tissue and cell transplantation. Future strategies for cartilage repair may involve tissue engineering techniques, possibly coupled with specific growth factors. Randomized clinical trials must be established.

Cartilage, Articular↗
PubMed2002

Laser-assisted chondroplasty.

Laser-assisted chondroplasty is a controversial issue in arthroscopy. Some preliminary research has demonstrated that laser energy can stimulate DNA synthesis and matrix production in articular cartilage. Other studies cite the dangers of thermal energy with laser use on articular cartilage. Commonly used lasers and their current research are discussed in this chapter. It is unclear whether or not the laser will remain in the arthroscopists' arsenal for chondroplasty, and further research is warranted.

Cartilage↗
PubMed2002

The prevalence of soft tissue injuries in nonoperative tibial plateau fractures as determined by magnetic resonance imaging.

OBJECTIVE: To determine the incidence of meniscus tears and complete ligament disruption in nondisplaced and minimally displaced tibial plateau fractures, which are otherwise amenable to nonoperative management. DESIGN: Prospective clinical study. SETTING: Level I urban trauma center. INTERVENTION: Magnetic resonance imaging of 20 consecutive nonoperative tibial plateau fractures. RESULTS: Magnetic resonance imaging was performed on 20 consecutive nonoperative (nondisplaced or minimally displaced) tibial plateau fractures to determine the frequency of significant soft tissue injuries. Ninety percent (18 of 20) had magnetic resonance imaging-diagnosed significant injuries to the soft tissues, including 80% (16 of 20) with meniscal tears, and 40% (8 of 20) with complete ligament disruptions. CONCLUSIONS: This study found a high prevalence of soft tissue injuries with nondisplaced fractures of the tibial plateau and cautions the physician and patient with respect to future knee function and possible arthrosis.

Adult↗
PubMed2002

Strengthening the supraspinatus: a clinical and biomechanical review.

Rotator cuff weakness has been implicated as a cause of subacromial impingement. Numerous exercises have been advocated to strengthen the rotator cuff, particularly the supraspinatus. The clinical rationale and two exercises advocated for strengthening the supraspinatus, the empty can and the full can, were evaluated. By understanding how these exercises vary from a biomechanical perspective, it is hoped that clinicians can minimize the forces experienced by the supraspinatus during the rehabilitation process.

Biomechanical Phenomena↗
PubMedDate not supplied

Biomechanical analysis of allograft bone treated with a novel tissue sterilization process.

BACKGROUND CONTEXT: Several methods to sterilize allograft bone exist, including gamma irradiation and freeze-drying, which can alter the mechanical properties of the graft. Efforts are under way to develop a method for processing osseous allograft that maintains structural integrity. Herein is presented one such method. PURPOSE: To analyze the mechanical properties, compared with nontreated controls, of a novel sterilization process for allograft cortical bone. STUDY DESIGN/SETTING: A controlled biomechanical evaluation of allograft bone under various types of loading after a novel sterilization treatment. PATIENT SAMPLE: Not applicable; basic science. OUTCOME MEASURES: The load to failure was recorded for both the study and control groups, and statistical analysis of these results was performed. Significance level (alpha) and power (beta) were set to 0.05 and 0.90, respectively. Single-factor analysis of variance (ANOVA) was used to detect significant differences between the treated and untreated groups. A post-experimental power analysis was performed for each of the response variables. METHODS: Cortical tibia and femur samples from seven cadaveric donors (mean age 68.7 years) were treated with Biocleanse and compared with untreated samples with regard to density and strength. All samples were loaded to failure under diametral and biaxial compression, shear, and three-point bending. RESULTS: Statistical analysis was done on the density and failure stress for all modes of loading. ANOVA did not indicate a significant (p>.05) effect of treatment on the density except for the axial and biaxial specimens (p<.05). ANOVA analysis of failure stress demonstrated no significant differences (p>.05) between cortical bone treated with Biocleanse and untreated specimens under all four types of mechanical loading. Post-experimental power analysis revealed power to be greater than 0.9 for each test. CONCLUSIONS: Sterilization of allograft bone with Biocleanse does not significantly alter the mechanical properties when compared with untreated samples. The effect of this sterilization process on the osteoconductive and osteoinductive properties of allograft bone must be determined.

Aged↗
PubMedDate not supplied

Radiofrequency thermal effects on the human meniscus: an in vitro analysis.

PURPOSE: The purpose of this study was to evaluate the thermal effects produced in meniscal tissue with different radiofrequency (RF) energy levels and exposure times using a bipolar device. TYPE OF STUDY: An anatomic in vitro analysis of the thermal effects of an RF device. METHODS: A specially designed jig was used to apply RF energy under a constant force to cadaveric menisci. Three different energy levels were applied for 4 different contact times. RESULTS: The overall mean depth of thermal change was 547 microm (range, 468 to 650 microm). There were no significant differences or trends when contact time and energy were varied. CONCLUSIONS: These data suggest that increased contact times and energy outputs are not associated with increased thermal change in the meniscus. The submillimeter thermal denaturation was consistent with published reports using other thermal devices, such as laser.

Adult↗
PubMedDate not supplied

Radiofrequency thermal effects on the human meniscus. An in vitro study of systems with monopolar and bipolar electrodes.

BACKGROUND: No data exist on the cutting efficiency of monopolar versus bipolar radiofrequency energy application systems on human meniscal tissue. PURPOSE: To compare the effects of monopolar and bipolar thermal energy systems on human meniscal tissue. STUDY DESIGN: Controlled laboratory study. METHODS: Fresh-frozen menisci were cut in cross-section into 180 pie-shaped specimens. A specially designed jig was used to consistently apply radiofrequency energy to the tissue under a constant 30-g force. Three different systems were tested at the low, middle, and high ranges, with application times of 1 and 3 seconds. Thermal effects were measured by image analysis microscopy. RESULTS: No significant differences in thermal effects were found with respect to energy output for each system. Both the individual system tested and the application time had statistically significant effects on thermal damage, with the individual system tested having a greater effect. The mean depths of thermal change produced by the Mitek (bipolar) device were 564 and 648 microm at 1 and 3 seconds applications, respectively. The Arthrocare device (bipolar) produced depths of 1444 and 1697 microm at 1 and 3 seconds. The Oratec device (monopolar) produced depths of 895 and 1057 microm, respectively. CONCLUSIONS: A differential thermal effect was created in the meniscal tissue by three commercially available radiofrequency systems. Within the parameters of the experiment, all three systems limited thermal damage to a depth of less than 2 mm. The results appeared to depend more on the particular system used, not whether it had monopolar or bipolar electrodes. CLINICAL RELEVANCE: These data imply reasonably safe (less than 2 mm) thermal changes in the meniscus after radiofrequency energy application from these three systems.

Aged↗
PubMedDate not supplied

Allograft transplantation in the knee: tissue regulation, procurement, processing, and sterilization.

Use of musculoskeletal allografts has become increasingly popular, with widespread use among knee surgeons. The advantages and disadvantages of their use have been documented. In the knee, allografts are used for ligament reconstruction, meniscal transplantation, and articular surface reconstruction. The purpose of this review is to present issues surrounding the allograft industry, including regulation of tissues and tissue banks and procurement, processing, sterilization, and storage of allograft tissue. Tissue bank regulation is ultimately under the jurisdiction and authority of the Food and Drug Administration; some individual states regulate tissue banks. The American Association of Tissue Banks is a scientific organization that encourages education, research, and voluntary accreditation of tissue banks. It promotes safety and standards for retrieval, processing, storage, and distribution of transplantable human tissue. Allograft tissues are generally harvested and processed aseptically, which may not prevent contamination. Tissue sterilization is difficult and controversial. Tissue banks historically have used one of two methods of sterilization, ethylene oxide or gamma radiation. Both methods have risks and benefits. Newer methods of sterilization are being developed. Allograft tissue that is not transplanted fresh can be freeze-dried or deep frozen for storage. Ultimately, allograft transplantation in the knee facilitates knee form and function and enhances the patient's quality of life. Orthopaedic surgeons who use allograft tissue must understand the tissue banking process to provide safe and effective tissues to their patients.

Cartilage, Articular↗