Impact of monopolar radiofrequency energy on subchondral bone viability

The purpose of this study was to analyze the impact of monopolar radiofrequency energy treatment on subchondral bone viability. The femoral grooves of six chinchilla bastard rabbits were exposed bilaterally to monopolar radiofrequency energy for 2, 4 and 8 s, creating a total of 36 defects. An intravital fluorescence bone-labeling technique characterized the process of subchondral bone mineralization within the 3 months following exposure to radiofrequency energy and was analyzed by widefield epifluorescence optical sectioning microscopy using an ApoTome. After 2 s of radiofrequency energy exposure, regular fluorescence staining of the subchondral bone was evident in all samples when compared to untreated areas. The depth of osteonecrosis after 4 and 8 s of radiofrequency energy treatment averaged 126 and 942 µm at 22 days (P < .05; P < .01). The 4 s treatment group showed no osteonecrosis after 44 days whereas the depth of osteonecrosis extended from 519 µm at 44 days (P < .01), to 281 µm at 66 days (P < .01) and to 133 µm at 88 days (P < .05) after 8 s of radiofrequency energy application. Though radiofrequency energy may induce transient osteonecrosis in the superficial zone of the subchondral bone, the results of this study suggest that post-arthroscopic osteonecrosis appears to be of only modest risk given the current clinical application in humans

Effects of low-magnitude, high-frequency mechanical stimulation in the rat osteopenia model

In this study, short-term, whole-body vertical vibration at 90 Hz improved trabecular bone quality. There was an improvement of bone quality and density in both osteoporotic and control rats. This treatment may therefore be an attractive option for the treatment of osteoporosis. Aside from pharmacological treatment options, physical exercise is known to augment bone mass. In this study, the effects of whole-body vertical vibration (WBVV) on bone quality and density were evaluated using an osteoporotic rat model. Sixty female Sprague Dawley rats were ovariectomized (C) or sham (SHAM) operated at the age of 3 months. After 3 months, both groups were divided into two subgroups that received either WBVV at 90 Hz for 35 days or no treatment. After sacrificing the rats, we evaluated vertebral bone strength, histomorphometric parameters, and bone mineral density (BMD). Treatment with WBVV resulted in improved biomechanical properties. The yield load after WBVV was significantly enhanced. According to yield load and Young's modulus, the treated OVX rats reached the level of the untreated SHAM animals. In all measured histomorphometric parameters, WBVV significantly improved bone density. Treatment with WBVV demonstrated greater effects on the trabecular bone compared to the cortical bone. The ash-BMD index showed significant differences between treated and untreated rats. Using WBVV as a non-pharmacological supportive treatment option for osteoporosis demonstrated an enhancement of bone strength and bone mass. This procedure may be an attractive option for the treatment of osteoporosis

Musculoskeletal Response to Whole-Body Vibration During Fracture Healing in Intact and Ovariectomized Rats

This study investigated the effect of vibration on bone healing and muscle in intact and ovariectomized rats. Thirty ovariectomized (at 3 months of age) and 30 intact 5-month old female Sprague-Dawley rats underwent bilateral metaphyseal osteotomy of tibia. Five days later, half of the ovariectomized and of the intact rats were exposed to whole-body vertical vibration (90 Hz, 0.5 mm, 4 × g acceleration) for 15 min twice a day during 30 days. The other animals did not undergo vibration. After decapitation of rats, one tibia was used for computed tomographic, biomechanical, and histological analyses; the other was used for gene expression analyses of alkaline phosphatase (Alp), osteocalcin (Oc), tartrate-resistant acid phosphatase 1, and insulinlike growth factor 1. Serum Alp and Oc were measured. Mitochondrial activity, fiber area and distribution, and capillary densities were analyzed in M. gastrocnemius and M. longissimus. We found that vibration had no effect on body weight and food intake, but it improved cortical and callus densities (97 vs. 99%, 72 vs. 81%), trabecular structure (9 vs. 14 trabecular nodes), blood supply (1.7 vs. 2.1 capillaries/fiber), and oxidative metabolism (17 vs. 23 pmol O2/s/mg) in ovariectomized rats. Vibration generally increased muscle fiber size. Tibia biomechanical properties were diminished after vibration. Oc gene expression was higher in vibrated rats. Serum Alp was increased in ovariectomized rats. In ovariectomized rats, vibration resulted in an earlier bridging; in intact rats, callus bridging occurred later after vibration. The chosen vibration regimen (90 Hz, 0.5 mm, 4 × g acceleration, 15 min twice a day) was effective in improving musculoskeletal tissues in ovariectomized rats but was not optimal for fracture healing

Effect of sitagliptin on cardiovascular outcomes in type 2 diabetes

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P = 0.98). There were no significant between-group differences in rates of acute pancreatitis (P = 0.07) or pancreatic cancer (P = 0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events