Biomedical subjects
Publications and source records attributed to W D McLeod.
An epidemiologic survey of the literature on high school football injuries revealed methodologic problems. These numerator-denominator inconsistencies and other confounding factors are discussed. The authors suggest a more reliable system of reporting these parameters to further reduce the risk of high school football injuries.
The osseous tunnel technique of anterior cruciate ligament (ACL) reconstruction was compared to the over-the-top (OTT) technique in vivo. A prosthesis replaced the ACL in 35 dogs by one of three methods: double osseous tunnels, OTT, or a combined method utilizing the unique Y shape of the prosthesis by placing one fork through a femoral osseous tunnel and the other fork over the top of the femoral condyle in the same stifle. Rupture occurred in all prostheses placed in double osseous tunnels and in one of 12 prostheses placed by the OTT technique. When rupture occurred in only one fork of prostheses placed in the combined method, all occurred in the tunnel-placed fork. If the results of the three groups are combined, rupture occurred in 16.7% of all OTT-placed prostheses versus 91.3% rupture of all osseous tunnel-placed prostheses. Objective assessment of the in vivo testing clearly indicates that the OTT technique is superior to the tunnel technique under the conditions of this study. The relationship between placement technique and rupture of other prostheses should also be tested in vivo.
In this article, we discuss our review of 284 shoulder injuries that were seen and treated arthroscopically during a five-year period. All of the injuries were related to the athletes' particular sport. We describe the biomechanical basis for these injuries and review the data gathered on the forces involved in the act of throwing.
The primary function of the anterior cruciate ligament has been described as one of restraining anterior motion of the tibia. The passive structures that offer secondary support for the anterior cruciate ligament are the collateral ligaments, the mid-third capsular ligaments, the menisci, and the iliotibial band. In this article, the biomechanics and function of these structures, as well as their effectiveness in providing back-up support for the anterior cruciate ligament, are discussed.
Inasmuch as this special issue of the knee is dedicated to the clinician, the clinical approach to biomechanical analysis has been presented. Through the use of biomechanical analysis, the clinician can select positions of exercise that stress certain structures while minimizing stress to other structures.
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A logical definition of the anatomy of the tibial surface, based on the shape of the tibial surface as measured in the laboratory, is presented. The relevance of these data to a better understanding of normal and pathological knee joint function is discussed. The thesis that the spine of the tibia is the major weight-bearing portion of the tibial surface can be supported by this contour study. The significance of the lateral plateau contour relative to the static stability of the joint contributed by joint apposition has been indicated. In addition, the path followed by the lateral femoral condyle during the "screw home mechanism" and caused by joint contour has been clearly demonstrated. We hope that this experimental evidence will establish itself as the basis for understanding the anatomy of the proximal tibial surface and that the nomenclature can be accepted to provide a common base for discussion of the tibial surface.
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The clinical records were reviewed of 142 men and 7 women (average age 26.8 years; range, 15 to 58 years) who had surgical reconstruction for anteromedial rotatory instability of the knee. All were treated consecutively at the same clinic during a 15-year period (1960 to 1975). Preoperative and postoperative symptoms were rated both subjectively and objectively by devised scales and analyzed by a computer program. Comparison of the three major surgical procedures show that the subjective success rate was 87% for the pes anserinus transfer, 70% for the posterior oblique ligament reconstruction, and 72% for the combination procedure. Of the 149 patients, 130 had been injured in sportive activities and 110 were able to return to some degree of athletics. Accurate and detailed recording of clinical data allowed construction of subjective and objective rating systems for computer analysis in review of a large series over a period of years. This approach enhanced our ability to obtain correlation and objective evaluation of the data. Commercial equipment for evaluating the quadriceps and hamstrings is beneficial in determining that a patient has achieved complete rehabilitation or if there will be a permanent decrease in function after surgical intervention.
The bicycle provides quadriceps rehabilitation while controlling the stresses to the knee ligaments. With pedaling on the bicycle, forces are applied to the anterior cruciate ligament, the capsular ligaments, and the posterior structures of the knee joint as the tibial plateau is posteriorly tilted. The knee muscles can modify their forces. Therefore, by controlling the mode of cycling with varying seat heights and pedal positions, the ligaments can be relieved from these forces during the initial stages of the rehabilitative process. An exercise program can then be designed to apply controlled stress to these structures to enhance the healing and recovery processes.
Standards for performance have been derived from the preseason assessment of the high school athlete. The performance of 3,174 athletes during five performance tests was measured. The tests included dips, sit-ups, and pull-ups, in addition to grip strength measurement and vertical jump capability. Measurements were converted to the amount of work done or force developed. Nondimensional ratios were determined using the tables and empirical equations presented in this paper. These quantities were then compared to the percent body fat. The average performance of the athletes as determined by the testing procedures described herein decreases dramatically as the body fat increases above 10% in males and 19% in females.
Tears of the glenoid labrum were observed in 73 baseball pitchers and other throwing athletes who underwent arthroscopic examination of the dominant shoulder. Most of the tears were located over the anterosuperior portion of the glenoid labrum near the origin of the tendon of the long head of the biceps muscle into the glenoid. At arthroscopy, the tendon of the long head of the biceps appeared to originate through and be continuous with the superior portion of the glenoid labrum. In many cases it appeared to have pulled the anterosuperior portion of the labrum off the glenoid. This observation was verified at arthroscopy by viewing the origin of the biceps tendon into the glenoid labrum as the muscle was electrically stimulated. With stimulation of the muscle, the tendinous portion became quite taut, particularly near its attachment to the glenoid labrum, and actually lifted the labrum off the glenoid. Three-dimensional high-speed cinematography with computer analysis revealed that the moment acting about the elbow joint to extend the joint through an arc of about 50 degrees was in excess of 600 inch-pounds. The extremely high velocity of elbow extension which is generated must be decelerated through the final 30 degrees of elbow extension. Of the muscles of the arm that provide the large deceleration forces in the follow-through phase of throwing, only the biceps brachii traverses both the elbow joint and the shoulder joint. Additional forces are generated in the biceps tendon in its function as a "shunt" muscle to stabilize the glenohumeral joint during the throwing act.(ABSTRACT TRUNCATED AT 250 WORDS)
An epidemiologic survey of the literature on high school football injuries revealed methodologic problems. These numerator-denominator inconsistencies and other confounding factors are discussed. The authors suggest a more reliable system of reporting these parameters to further reduce the risk of high school football injuries.
This study was designed to compare the displacement patterns of an isometer, used to determine graft placement during reconstruction, with the actual tensions on an anterior cruciate ligament substitute. In cadaveric specimens, a Kevlar anterior cruciate ligament substitute was implanted in three separate femoral sites, each of which was subsequently fixed to two different tibial sites. The initial tension of the Kevlar substitute was set to 22 or 33 N at 20 degrees of knee flexion. The displacement patterns for each position were recorded during passive flexion-extension using the isometer. Using a custom-designed tensiometer, the tensile forces on the substitute after rigid fixation at the tibia and femur were measured. During passive flexion-extension, the maximum change in tension of the anterior cruciate ligament substitute, measured by the tensiometer, was correlated with the maximum change in displacement between attachment sites, measured by the isometer. The coefficient of determination was equal to 0.15, indicating that the isometer may not accurately predict the tensions developed in the substitute.