Clinical orthopaedics and related research
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Clin. Orthop. Relat. Res. · Aug 1993
Comparative StudyMechanical performance of Ilizarov circular external fixators in comparison with other external fixators.
The fundamental difference of the Ilizarov fixator is the type of pins used for bone fixation, i.e., Kirschner wires 1.5 mm and 1.8 mm in diameter, pretensioned from 50 to 130 kg before being affixed to the rings that are connected and fixed by threaded rods. The mechanical characteristics of external fixators may influence the biologic environment at the fracture site and ultimately decide the outcome of a surgical procedure. Thus, knowledge of the mechanical properties of the Ilizarov fixator is essential to a surgeon using it in clinical practice. ⋯ Torsional stiffness increased significantly under coupled axial compression applied through the bone ends. All four-point bending tests demonstrated two distinct stiffness curves that were probably due to slippage of the bone model on the wires. This information should help to understand the mechanical behavior of the Ilizarov device and thereby improve its clinical performance.
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Clin. Orthop. Relat. Res. · Aug 1993
Mechanical monitoring of fracture healing using ultrasound imaging.
Ultrasound scanning is based on biologic noninvasive use of high-frequency sonic vibration ultrasounds to obtain images of diagnostic relevance in vivo. Ultrasound scanning was used as an additional parameter in evaluation of healing of long bone fractures in patients treated by external fixation devices. ⋯ Strain-recorded maximal values variations are synchronous with the variations of reflected echo demonstrating a correlation between the ultrasound image and mechanical status of external callus. In the current state-of-the-art, no quantitative evaluation of mechanical status of fracture site is possible by ultrasound technique alone.
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There have appeared no objective means by which preoperative risk in patients with fractures of the hip can be quantitatively predicted. The developed risk's core is based on medical history, physical examination, chest radiograph, and screening laboratory data. This system reproducibly assigns patients into one of three groups. ⋯ The medical complications in Group I were 12.6%; in Group II, 28.6%; and in Group III, 67.6%. The difference for each group was significant. This preoperative risk assessment appears effective in more accurately identifying patient risk.
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Clin. Orthop. Relat. Res. · Aug 1993
Randomized Controlled Trial Comparative Study Clinical TrialTibial external fixation, weight bearing, and fracture movement.
Axial fracture movement and loading has been measured during weight bearing in 45 patients with tibial diaphyseal fractures treated with unilateral external skeletal fixation. Mean axial fracture displacement reached a maximum of 0.6 mm between seven and 12 weeks postfracture. Very little movement occurred during the first five weeks after fracture. ⋯ Weight bearing was not decreased by any biofeedback mechanism. A randomized prospective clinical study of diaphyseal tibial fractures treated with external fixation showed a significant reduction in time to healing when micromovement was imposed. Controlled fracture site movement can be imposed very early after fixator frame application when mechanical stimulation may be most effective, and the active loading by the patient is least.
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Clin. Orthop. Relat. Res. · Aug 1993
Clinically inapparent hypoxemia after skeletal injury. The use of the pulse oximeter as a screening method.
The efficacy of the pulse oximeter was evaluated in lieu of multiple arterial blood gas (ABG) determinations as a screening method for the early diagnosis of hypoxemia and clinical fat embolism syndrome. A prospective analysis was performed on 43 patients with long bone and pelvic fractures without any associated chest wall, head, or intraabdominal trauma. A standard pulse oximetry reading was obtained initially within 12 hours of injury and at 24-hour intervals thereafter until the patient had been observed for 72 hours. ⋯ These patients were subsequently managed with an intensive pulmonary care regimen. Hypoxemia resolved in all patients within 48 hours of the initiation of treatment. The pulse oximeter is an efficient and reliable screening device to identify patients with clinically unrecognized hypoxemia.