Biomechanical effects of rockers on walking in a plaster cast

Rockers are applied to lower limb casts to assist walking but there is little information on their biomechanical effects. The performances of 10 commercially available rockers were compared. They were applied to a below-knee cast worn by a normal subject who was also tested walking in the cast alone. Gait analysis was used to evaluate kinematic and kinetic data. The design of rocker had no effect upon the kinematics of walking. However, using new criteria for kinetic assessment of rocker function (tibial floor angular velocity and centre of pressure progression), most designs had a deleterious effect on the biomechanics of gait. Only two rockers approached the ideal kinetic criteria.     

The effect of steam sterilization on plaster casting material

Plaster-impregnated gauze was autoclaved as a preventative measure against infection. The mechanical properties and the hardening time of casts made with autoclaved plaster were investigated by measuring flexural yield stress and flexural modulus of elasticity. A cantilever bending test was used to determine the time required to harden. The average yield stress in bending was reduced by an average of 8% and the modulus of elasticity was unchanged by the steam sterilization. The time required for the plaster splint to harden was increased by a factor of 5.6 after steam sterilization. Although the reduction in the yield strength was not prohibitive, the increase in hardening time was unacceptable. The use of gas sterilization is recommended when a sterile cast is necessary because gas sterilization does not increase hardening time.     

Evaluation of pressure beneath a split above elbow plaster cast

It has previously been shown that splitting a plaster cast after manipulation of, or surgery on, a limb leads to a decrease in pressure beneath the cast by accommodating the swelling that may occur. However, it is not known whether the axis along which the cast is split influences the amount of swelling that can occur before a critical pressure is reached. We investigated this with reference to above elbow plaster casts.     

Mechanical stimulation of venous blood flow in below-the-knee plaster cast

Physical methods became recently more important as an alternative to anticoagulation for prophylaxis of thromboembolism and were studied for their efficacy. The AV-impulse-system proved efficient in reducing thromboembolic complications in patients undergoing hip surgery by increasing the return of venous blood in the deep veins of the leg. In a preclinical trial we studied the influence of the AV-impulse-system and of active forefoot movement on venous blood return in 12 lower extremities of 6 healthy individuals immobilized in below the knee plaster casts. Our results show a significant increase in venous blood flow caused by the AV-impulse-system (p < 0.05) and by active forefoot movements (p < 0.05). Prevention of thromboembolic complications in trauma and orthopaedic patients immobilized in plaster cast seems possible by using the AV-impulse-system which significantly increases the venous blood flow independent from patient compliance.     

The effect of water intake on body temperature during rugby matches

The effect of drinking up to 1 litre of fluid on water deficit, sweat loss and rectal temperature was determined during three separate rugby matches played in thermoneutral environments. Each player was allotted a litre of fluid and encouraged to drink 500 ml before the start of the game and a further 500 ml at half-time. The players were weighed and rectal temperatures determined before and after the matches. Rectal temperatures were markedly elevated after all three matches and reached levels which may have been high enough to have impaired performance towards the end of the game. The volume of fluid ingested by the players had no influence on final rectal temperatures. The majority of the players had sweat rate/rectal temperature relationships similar to those of heat-acclimatized subjects. It is concluded that, in a thermoneutral environment, the ingestion of volumes of fluid up to 1 litre has no significant beneficial effect on thermoregulation during rugby games, and that the role of the clothing worn may have a greater influence on thermoregulation than was hitherto envisaged.     

石膏绷带外固定治疗耳廓假性囊肿66例

目的:观察石膏绷带外固定治疗耳廓假性囊肿的临床效果。方法:对66例耳廓假性囊肿患者采用穿刺抽液后石膏绷带外固定,观察其治疗效果。结果:全组患者中64例(占97%)经一次性治愈,2例(占3%)经二次治愈,无一例感染及复发,总治愈率100%。结论:石膏绷带外固定治疗耳廓假性囊肿,取材方便、操作简单,疗效可靠。     

Treatment of isolated distal ulnar shaft fractures with below-elbow plaster cast

In a prospective study 52 patients with an isolated fracture of the distal ulna were treated with a below-elbow plaster cast. The histories of 46 patients were reviewed after a mean follow-up of 3.5 years (ranging from 10 months to 7 years). Forty-three fractures united. There were two non-unions. One fracture displaced while in the plaster, so that there was no longer any bone contact between the fragments. The fracture was consequently treated by open reduction and internal fixation. The type of fracture, the initial displacement (all fractures had bone contact) or the initial angulation (maximum 10 deg) was not found to influence the final clinical results. Below-elbow plaster cast appeared to produce satisfactory results in 89% of the patients.     

The effects of hydration on core temperature in pediatric surgical patients

BACKGROUND: Reduced vascular volume might influence body temperature by diverting heat flow from peripheral tissues to the central organs. We therefore tested the hypothesis that mild hypovolemia helps to prevent intraoperative hypothermia in pediatric patients. METHODS: Twenty-two pediatric patients (aged 1-3 yr) undergoing prolonged minor surgery were randomly assigned to conservative (n = 12) or aggressive (n = 10) perioperative fluid management. The conservative group fasted 8 h before surgery and received a crystalloid at 1 ml. kg-1. h-1 during surgery. The aggressive group was allowed to drink liquids until 3 h before surgery and was given a maintenance crystalloid at 8 ml. kg-1. h-1. Anesthesia was induced and maintained with halothane in nitrous oxide. Ambient temperature was kept near 25 degrees C, but the patients were not actively warmed. During recovery from anesthesia, additional fluid was given to the conservative group so that perioperative fluid totaled 9.5 ml. kg-1. h-1 in both groups. RESULTS: Intraoperative body weight remained unchanged in the aggressive group and decreased only 1% in patients managed conservatively. Heart rate was slightly greater in the conservative group (107 +/- 9 vs. 95 +/- 4 beats/min, P = 0.002), but blood pressure was similar. Esophageal temperature in patients whose fluid was managed conservatively increased significantly, by 0.4 +/- 0.3 degrees C, to 37.1 degrees C; in contrast, temperature in the aggressive group decreased significantly, by 0.4 +/- 0.2 degrees C, to 36.4 degrees C (P < 0.001 between groups). Temperatures remained significantly different 1 h after surgery. CONCLUSIONS: Conservative fluid management, which decreased body weight by only 1%, prevented reduction in core body temperature, presumably by reducing dissipation of metabolic heat from the core thermal compartment to peripheral tissues.     

The effect of the patellar tendon-bearing cast on loading

We assessed the unloading effect of the patellar tendon-bearing (PTB) cast in five healthy volunteers using a new system for analysis of dynamic plantar pressure. We devised a method to improve the unloading effect of the PTB cast, and tested this using the same system. Our findings showed that the conventional PTB cast only achieved unloading of 30% of the body-weight and that the part of the cast on the leg had a more important role in the unloading than that which was in contact with the patellar tendon. When the depth of the free space under the foot inside the PTB cast was 1, 2 and 3 cm, the unloading effect was 60%, 80% and 98%, respectively. The unloading effect of the conventional PTB cast was disappointing at only 30% of body-weight. It was improved by producing a space between the sole of the foot and the cast, and was adjustable by altering the depth of this space.