On the fracture toughness of equine metacarpi.
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Biomedical subjects
Publications and source records attributed to M H Pope.
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With a knee-testing device we measured the valgus stiffness of the medial musculoligamentous complex of the knee in five volunteers. Tests were done with the muscles quiescent and with contraction of the sartorius and vastus medialis. Contraction of those muscles substantially increased the valgus stiffness. In eight subjects the voluntary reaction times were measured. With either a visual or a tactile impulse for prophylactic muscle contraction, the muscles acted too slowly to augment the stiffness of the knee so as to prevent injury. In fifty-one volunteers we applied the maximum torque to the leg, just short of eliciting pain, and showed that even then the muscle contraction would occur too late to protect the knee in typical sports situations.
Trauma plays an important role in the production of low back pain. This review emphasizes how the forces to which the spine is subjected are modified by many factors. Attention is directed to the role of mechanical stress in the etiology of spondylolisthesis, subtle spinal fractures, as well as the relevance of stress to the degenerative process. It is suggested that trauma plays a very major role in low back pain but, at present, the problems in diagnostic technology create difficulty in establishing the precise degree of that role. The drawbacks of over-reliance on plane radiography are emphasized. It is suggested that improved diagnostic techniques may result in more accurate treatment and perhaps less disability resultant from the ubiquitous problem of low back pain.
Fractures of the fibula were produced in rats with sciatic denervation. The denervated rats exhibited more rapid fracture healing than controls. Fifteen days following injury, enhanced union was measured by histologic assessment (p less than 0.001), and biomechanical testing including fracture stress (p less than 0.005), elastic modulus (p less than 0.005), strain at failure (p = 0.01) and energy to failure (p = 0.05).
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A compression testing machine was used to transmit increasing loads at various strain rates across twelve canine and twelve human cadaver knees. The specimens were originally evaluated with both menisci intact and the same tests were repeated with one meniscus removed and then with both menisci removed. This investigation showed that the menisci perform a load-transmitting and energy-absorbing function in the knee joint. The stress acting across the joint increased significantly after meniscectomy. The intact meniscus was deformed during compressive loading rather than being passively pushed away, thus demonstrating the presence of hoop stresses within the meniscus.
Frequently, the diagnosis of disease of the low back is a difficult matter due to the multitude of factors affecting the patient's symptoms. In this report an attempt is made to use biomechanical testing to objectify certain aspects of the diagnostic process. Our philosophy is that a biomechanical assessment is one of the disciplines that should be brought to bear on the low-back pain patient. A group of biomechanical tests has been developed by adding quantitative measurement techniques to certain standard clinical maneuvers: muscle testing, range of motion testing, and straight leg raising testing. Moire fringe topography is employed for studying posture. Results of application of these techniques to 117 patients and 10 controls indicate potential utility in the method for epidemiologic and clinical research.
A prospective study of all tibial shaft fractures produced during a single ski season in a Northern Vermont area is presented. Very little previous work concerning skiing-induced tibial fractures was present in the literature. Younger, lighter, and less skilled skiers are more frequently so injured. Spiral fractures account for 41.9% and boot top fractures for 37.9% of the total. Spiral fractures occurred by an internal rotation mechanism just as frequently as by external rotation, and were observed more frequently in slower moving skiers who were using shorter skis and lower, softer boots. Associated fibular fractures were commonly not observed in children. Tibial fractures occurring in skiing are the result of relatively low energy trauma. The level and type of fracture had little effect on healing time. With rare exceptions these fractures heal satisfactorily with nonsurgical techniques.
During the past four ski seasons, all 1,141 ski injuries which occurred in a large northern Vermont ski area were evaluated prospectively. Of these injuries, 21.6% involved knee ligaments and 18.6% involved sprains of the medial collateral ligament. Females sustained a disproportionately high incidence of Grade I medial collateral sprains, but suffered the more severe sprains at a rate similar to that of males. Individuals who were smaller, younger, less experienced, and less skilled sustained a higher incidence of Grade I injuries. Skiers suffering complete tears of the medial collateral ligament were no smaller, younger, or less skilled or experienced than our control population. Medial collateral sprains are produced primarily by external rotation and valgus forces. Two-mode release bindings are insensitive to several loading configurations which could produce knee sprains. Bindings which allow release in roll, shear, and twist at the heel, as well as twist at the toe and forward lean, appear to be necessary to protect the knee.
A device is described that measures the mechanical impedance of the human knee in vivo. The device and method were tested in a reliability study, on a normal control population, and in a follow-up test of previously injured subjects. Finally, impedance measurement was compared with the clinical examination, the currently employed test for ligament injuries. This impedance method to measure ligament stiffness was found useful in diagnosing acute injuries.