Effect of mitomycin-C on post-operative adhesions in tendon surgery: an experimental study in rats.

We investigated the effect of mitomycin-C on the reduction of the formation of peritendinous fibrous adhesions after tendon repair. In 20 Wistar albino rats the tendo Achillis was cut and repaired using a modified Kessler technique. The rats were divided into two equal groups. In group 1, an injection of mitomycin-C was placed between the tendon and skin of the right leg. In group 2, an identical volume of sterile normal saline was injected on the left side in a similar fashion. All the rats received mitomycin-C or saline for four weeks starting from the day of operation. The animals were killed after 30 days. The formation of peritendinous fibrous tissue, the inflammatory reaction and tendon healing were evaluated. The tensile strength of the repaired tendons was measured biomechanically. Microscopic evidence of the formation of adhesions and inflammation was less in group 1. There was no significant difference in the tensile load required to rupture the repaired tendons in the two groups. Mitomycin-C may therefore provide a simple and inexpensive means of preventing of post-operative adhesions.

Prosthetic radial head components and proximal radial morphology: a mismatch.

A morphometric study of the proximal radius was performed with magnetic resonance imaging scans to measure the anatomic dimensions of the radial head and neck. These dimensions were then compared with the manufacturer's size specifications of commercially available titanium prosthetic radial head components to determine whether these designs adequately match the morphologic characteristics of the proximal radius. A cadaveric correlation was performed to validate the accuracy and reliability of measurements obtained from the magnetic resonance scans. The narrow intramedullary dimensions of the radial neck negated fitting of even the smallest available metallic prosthetic component stem in 18 (39%) of 46 scans reviewed (confidence interval 26% to 53%). Of the 31 male patients who underwent scanning, 4 (13%) would not be able to be fitted with a prosthetic component according to the manufacturer's technique guide (confidence interval 0% to 29%). Of the 15 female patients who underwent scanning, 14 (93%) would not able to be fitted with a prosthetic stem (confidence interval 70% to 99%). In those patients in whom the radial neck could accommodate a prosthetic stem (n = 26), there was ineffective restoration of proximal radial head length in all cases (100%, confidence interval 87% to 100%). The average shortening was 4 mm of proximal radial length (range 1 to 7 mm). Our findings reveal that the commercially available metallic radial head design may overestimate the dimensions of the radial neck. Inadequate sizing of radial head prostheses may lead to an inadvertent change in proximal radial length, with potentially adverse effects on elbow, forearm, and wrist mechanics. Newer designs taking into account these anatomic dimensions may lead to an improvement in function after reconstruction.

Microcirculatory response to halothane and isoflurane anesthesia.

Microcirculatory hemodynamics are often used to monitor tissue and organ survival. This study investigated the effect of halothane and isoflurane anesthesia on peripheral microcirculation using the cremaster muscle during intravital microscopy. Twenty-three Sprague-Dawley rats were studied in four groups. Two groups served as controls and did not undergo flap isolation but did receive halothane (N = 6) or isoflurane (N = 5). After induction with a single dose of intraperitoneal pentobarbital (40 mg per kilogram), rats were ventilated with either 2 minimum alveolar concentration (MAC) halothane or 2 MAC isoflurane. Esophageal temperature, electrocardiography, central venous pressure, mean arterial pressure, and blood gases were measured over 4 hours. In groups receiving surgery with either halothane (N = 6) or isoflurane (N = 6), the cremaster muscle was isolated on the neurovascular pedicle. Microcirculatory responses to both halothane and isoflurane anesthesia were evaluated by measuring red blood cell (RBC) velocity, vascular diameters in arterioles (A1, A2-1, A2-2, and A3) and the main venule (V1), functional capillary perfusion, and leukocytic endothelial interactions in postcapillary venules (rolling, adherent, and transmigrating leukocytes). Hemodynamic variables were compared among all four groups, and microcirculatory variables were compared between the two surgical groups. During isoflurane anesthesia in animals with flaps, significantly higher (p < 0.05) RBC velocities were recorded in arterioles A1 (24.4%), A2-2 (28.2%), and A3 (17.4%). Capillary perfusion was significantly higher in animals with flaps and halothane anesthesia (17.8%; p < 0.05). The number of rolling leukocytes (39.4%) was significantly higher during isoflurane anesthesia in animals with flaps (p < 0.05). Better flow hemodynamics in the peripheral microcirculation were seen during halothane anesthesia, and were confirmed by greater functional capillary perfusion and fewer activated leukocytes. In the isoflurane group, RBC velocity alone cannot serve as an indicator of microcirculatory function.

Harmful effects of invasive animal monitoring on muscle flap microcirculation.

In this study, peripheral microcirculatory response to arterial and venous cannulation was studied. Eleven Sprague-Dawley rats were evaluated in two groups. Group I was the control group and received no cannulation (N = 6). After cremaster muscle isolation, the following parameters were evaluated at the microcirculatory level: vessel diameters, red blood cell (RBC) velocities, capillary density, and leukocyte and lymphocyte behavior (rollers, stickers, transmigrating white blood cell [WBC]). In group II, vessel cannulation was performed (N = 5). Before cremaster muscle isolation, the right femoral artery was cannulated for mean arterial blood pressure measurements; the right carotid artery was cannulated for arterial partial oxygen pressure (PaO2), arterial partial carbon dioxide pressure (PaCO2), and pH measurements; and the left jugular vein was cannulated for central venous pressure evaluation. Microcirculatory measurements as in group I were also taken. In the cannulated animals, arterial RBC velocity was 18.1% faster, whereas venous RBC velocity was 15.7% decreased (p < 0.05). In addition, leukocyte activation increased and was confirmed by a 254.6% rise in rolling leukocytes, a 59.7% increase in rolling lymphocytes, and a 67.2% increase in leukocyte "stickers" (p < 0.05). In group II, functional capillary perfusion was decreased by 44.9%, and 4.8% higher endothelial edema indexes were found (p < 0.05). In conclusion, this study has proven that, despite its clinical importance during vital signs monitoring, cannulation procedures may significantly impair peripheral microcirculatory hemodynamics. For this reason, cannulation procedures should be designed with caution and should be reported in experimental methods.