Biomedical subjects

Keith Kenter

Publications and source records attributed to Keith Kenter.

8 recordsLinked to original sources

PubMed2004

Bipolar and monopolar radiofrequency treatment of osteoarthritic knee articular cartilage: acute and temporal effects on cartilage compressive stiffness, permeability, cell synthesis, and extracellular matrix composition.

The cellular, biochemical, biomechanical, and histologic effects of radiofrequency-generated heat on osteoarthritic cartilage were assessed. Articular cartilage explants (n=240) from 26 patients undergoing total knee arthroplasty were divided based on Outerbridge grade (I or II/III) and randomly assigned to receive no treatment (controls) or monopolar or bipolar radiofrequency at 15 or 30 W. Both potentially beneficial and harmful effects of radiofrequency treatment of articular cartilage were noted. It will be vital to correlate data from in vitro and in vivo study of radiofrequency thermal chondroplasty to determine the clinical usefulness of this technique.

Biomechanical Phenomena↗

PubMed2004

Changes in transcutaneous carbon dioxide, oxygen saturation, and respiratory rate after interscalene block.

BACKGROUND: We used transcutaneous (TC) carbon dioxide (CO2) monitoring to prospectively evaluate changes in respiratory status after interscalene anesthesia in 45 adults (40 successful and 5 unsuccessful blocks). METHODS: TC-CO2 oxygen saturation and respiratory rate were recorded every minute for 5 minutes before block and every 2 minutes for a total of 30 minutes (15 data sets) after injection of the local anesthetic solution. RESULTS: After successful block, TC-CO2 increased from 41 +/- 5 mm Hg to a maximum value of 44 +/- 6 mm Hg (P < 0.0001) and the respiratory rate increased from 14 +/- 2 breaths/min to a maximum of 20 +/- 4 breaths/min (P < 0.001). The increase in TC-CO2 was > or = 5 mm Hg in 11 patients and > or = 10 mm Hg in 4 patients, with a maximum increase of 12 mm Hg. Of the 600 TC-CO2 data points recorded (15 each from the 40 patients with a successful block), 62 (10.3%) showed a TC-CO2 value of 50 mm Hg or greater, with a maximum value of 57 mm Hg. No significant change in TC-CO2 or respiratory rate was seen in the five patients with unsuccessful block. CONCLUSION: After interscalene blockade, we found an increase in respiratory rate and hypercarbia that resulted in no clinically significant effect.

Amides↗

PubMed2004

Assessment of cellular, biochemical, and histologic effects of bipolar radiofrequency treatment of canine articular cartilage.

OBJECTIVE: To assess the cellular, biochemical, and histologic effects of bipolar radiofrequency-generated heat on canine articular cartilage. SAMPLE POPULATION: Articular cartilage explants (n = 72) from 6 canine cadavers and cultured articular chondrocytes from 5 canine cadavers. PROCEDURE: Cartilage explants were randomly assigned to receive no treatment or treatment with focal (3 seconds) or diffuse bipolar radiofrequency. Following treatment, methylene blue permeability assay was performed (n = 12) and remaining samples (60) were cultured. Immediately and 5, 10, and 20 days after treatment, cultured explants were assessed for glycosaminoglycan (GAG) and collagen contents, type II collagen and matrix metalloproteinase (MMP)-13 immunoreactivity, and modified Mankin histologic scores. Liquid culture media were collected every 4 days and GAG content measured. Additionally, cultured chondrocytes were exposed for 3 seconds to media preheated to 37 degrees, 45 degrees, or 55 degrees C. Cell viability was determined via 2 different assays immediately and 24 hours after treatment. RESULTS: Radiofrequency-treated cartilage had reduced permeability and considerable histologic damage, compared with control samples; most treated samples had reduced collagen II staining and increased MMP-13 immunostaining. Compared with other treatments, less GAGs were released from cartilage after diffuse radiofrequency treatment throughout the study period. Cell viability was significantly different between controls and cells treated at 55 degrees C immediately and 24 hours after heat treatment. CONCLUSIONS AND CLINICAL RELEVANCE: In this study, bipolar radiofrequency treatment had detrimental effects on normal articular cartilage cells and extracellular matrix with probable long-term clinical consequences. The usefulness of radiofrequency for treatment of osteoarthritic articular cartilage requires further investigation.

Analysis of Variance↗

PubMed2003

Induction of matrix metalloproteinase 1 gene expression is regulated by inflammation-responsive transcription factor SAF-1 in osteoarthritis.

OBJECTIVE: To identify specific transcription factors that are activated in the cartilage tissue of osteoarthritis (OA) patients and are involved in the expression of matrix metalloproteinase 1 (MMP-1). METHODS: DNase I footprint and electrophoretic mobility shift assays were performed to identify active elements of the MMP1 promoter and the transcription factors that interact with it. The relative abundance of the involved transcription factor in the cartilage was determined by immunohistochemical analysis. The role of serum amyloid A-activating factor 1 (SAF-1) in MMP-1 expression was assessed by transient transfection assay with plasmids containing either a functional or an antisense SAF-1 complementary DNA. RESULTS: A novel promoter element was detected in the human MMP1 gene, and the inflammation-responsive transcription factor SAF-1 was found to interact with it. SAF-1 activity was detected in the chondrocytes of OA cartilage, where most of the cells stained positive for SAF-1. Overexpression of SAF-1 in OA chondrocytes increased the expression of the MMP1 promoter, and interference of endogenous SAF-1 activity by antisense SAF-1 messenger RNA inhibited interleukin-1-mediated MMP1 promoter activity. CONCLUSION: The results indicate that SAF-1 is involved in the regulation of MMP1 gene expression and it is highly abundant in the articular cartilage chondrocytes of OA patients. The data also demonstrate that control of SAF-1 activity can suppress induced expression of MMP-1. Conceivably, SAF-1 could be a potential therapeutic target to control the overexpression of MMP-1 associated with the pathogenesis of OA.

Animals↗

PubMed2003

Interscalene block for elective shoulder surgery.

This study assessed patient experiences with interscalene block anesthesia for elective shoulder surgery. Routine use of interscalene anesthesia was introduced at our institution in 1997. All patients who underwent interscalene anesthesia during the first 3 years of our experience with this regional anesthetic technique were asked to respond to an anesthesia-related questionnaire. Overall patient satisfaction with interscalene anesthesia was 87%, and success rate in achieving a complete motor and sensory block was 79%. The duration of pain relief postoperatively was 10.5 hours for patients with a successful block. Patients consistently reported that having an interscalene block was less painful than anticipated; 90% said they would have interscalene anesthesia again for shoulder surgery. This study demonstrates that interscalene anesthesia for elective shoulder surgery is safe and well accepted in this patient population.

Humans↗

PubMedDate not supplied

Treatment of dogs diagnosed with medial shoulder instability using radiofrequency-induced thermal capsulorrhaphy.

OBJECTIVE: To report clinical findings and outcome in dogs diagnosed with medial shoulder instability (MSI) treated with radiofrequency-induced thermal capsulorrhaphy (RITC). STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n=43) with MSI. METHODS: Medical records from consecutive cases with MSI based on orthopedic examination, palpation of shoulder abduction angles, and arthroscopic findings were used to determine clinical findings and long-term (> or = 1 year) outcome of RITC. RESULTS: Forty-three dogs met the criteria for inclusion; 2 dogs had bilateral MSI. The most common clinical findings were chronic unilateral weight-bearing lameness, large (> 45 degrees) shoulder abduction angles, and spinatus muscle atrophy in the affected limb. Mean preoperative abduction angle (50.7 degrees +/- 4.8 degrees) in affected shoulders was significantly larger than in the unaffected shoulders (32.5 degrees +/- 2.1 degrees). Mean postoperative abduction angle in affected shoulders was not significantly different from unaffected shoulders when measured immediately, 8, 16-20 weeks, and approximately 1 year after surgery. Follow-up evaluation ranged from 1 to 6.2 years. RITC treatment resulted in improved clinical function in 40 cases (93%) with 34 cases (79%) considered excellent; 3 cases (7%) were considered failures. CONCLUSIONS: RITC was a safe and effective method of treatment of MSI in most dogs studied. CLINICAL RELEVANCE: RITC can be considered as a viable option for surgical treatment of selected cases of MSI in dogs.

Animals↗

PubMedDate not supplied

Arthroscopic biceps tenodesis: technique and results in six dogs.

Biceps tenodesis was performed using an arthroscopic-assisted technique on six dogs diagnosed with chronic bicipital tendon pathology. The technique was performed using two different fixation methods (i.e., cannulated interference screw, cannulated screw and tissue washer). All six dogs had successful outcomes in terms of return to full function at a mean follow-up time of 11.7 months after surgery. Arthroscopic biceps tenodesis is a feasible option for surgical management of biceps tendon pathology, and it may have advantages over open tenodesis and open or arthroscopic tenotomy. Further study is needed before definitive recommendations regarding indications, complications, and prognosis associated with arthroscopic biceps tenodesis can be made.

Animals↗

PubMedDate not supplied

Bilateral shoulder arthroplasty in a patient with pseudogout: a case report.

Pseudogout or calcium pyrophosphate dihydrate deposition disease (CPPD) can be a significant cause of morbidity among many patients. The pathophysiology involves the accumulation of calcium pyrophosphate dihydrate crystals and can be confused with degenerative osteoarthritis. Treatment is usually with NSAIDs. There has been little documentation relating CPPD to joint replacement surgery. We present a case report of a patient who underwent staged, bilateral total shoulder arthroplasty and was found to have pseudogout.

Aged↗