PubMed · 10098080
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R C Schenck, R E Hunter, R F Ostrum, C R Perry. 1999. Knee dislocations.. https://pubmed.ncbi.nlm.nih.gov/10098080/
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Measurements of tibial translation in response to an external load are used in clinical and laboratory settings to diagnose and characterize knee-ligament injuries. Before these measurements can be quantified, a reference position of the knee must be established (defined as the position of the knee with no external forces or moments applied). The objective of this study was to determine the effects of cruciate ligament deficiency on this reference position and on subsequent measurements of tibial translation and, in so doing, to establish a standard of kinematic measurement for future biomechanical studies. Thirty-six human cadaveric knees were studied with a robotic/universal force-moment sensor testing system. The reference positions of the intact and posterior cruciate ligament-deficient knees of 18 specimens were determined at full extension and at 30, 60, 90, and 120 degrees of flexion, and the remaining five-degree-of-freedom knee motion was unrestricted. Subsequently, under a 134-N anterior-posterior load, the resulting knee kinematics were measured with respect to the reference positions of the intact and posterior cruciate ligament-deficient knees. With posterior cruciate ligament deficiency, the reference position of the knee moved significantly in the posterior direction, reaching a maximal shift of 9.3 +/- 3.8 mm at 90 degrees of flexion. For the posterior cruciate ligament-deficient knee, posterior tibial translation ranged from 13.0 +/- 3.4 to 17.7 +/- 3.6 mm at 30 and 90 degrees, respectively, when measured with respect to the reference positions of the intact knee. When measured with respect to the reference positions of the posterior cruciate ligament-deficient knee, these values were significantly lower, ranging from 11.7 +/- 4.3 mm at 30 degrees of knee flexion to 8.4 +/- 4.8 mm at 90 degrees. A similar protocol was performed to study the effects of anterior cruciate ligament deficiency on 18 additional knees. With anterior cruciate ligament deficiency, only a very small anterior shift in the reference position was observed. Overall, this shift did not significantly affect measurements of tibial translation in the anterior cruciate ligament-deficient knee. Thus, when the tibial translation in the posterior cruciate ligament-injured knee is measured when the reference position of the intact knee is not available, errors can occur and the measurement may not completely reflect the significance of posterior cruciate ligament deficiency. However, there should be less corresponding error when measuring the tibial translation of the anterior cruciate ligament-injured knee because the shift in reference position with anterior cruciate ligament deficiency is too small to be significant. We therefore recommend that in the clinical setting, where the reference position of the knee changes with injury, comparison of total anterior-posterior translation with that of the uninjured knee can be a more reproducible and accurate measurement for assessing cruciate-ligament injury, especially in posterior cruciate ligament-injured knees. Similarly, in biomechanical testing where tibial translations are often reported for the ligament-deficient and reconstructed knees, a fixed reference position should be chosen when measuring knee kinematics. If such a standard is set, measurements of knee kinematics will more accurately reflect the altered condition of the knee and allow valid comparisons between studies.
Magnetic resonance imaging is the most sensitive, specific, and accurate noninvasive method for diagnosing internal derangement of the knee. During the past 15 years knowledge of pathologic conditions of the knee had evolved significantly. Beyond the basic principles of imaging knee injuries great impact was made on the understanding of indirect or collateral findings, even in rare diseases. In this article the spectrum of disorders of the knee are reviewed and an overview of the current literature is given. This includes considerations about how to achieve a high-standard MR imaging study of the knee, and principles of imaging anterior cruciate ligament and meniscal tears. A focus is put on distinct diseases including intra-articular and intraosseous ganglion cysts, iliotibial band friction syndrome, transient osteoporosis, osteonecrosis, osteochondritis dissecans, and imaging of the articular cartilage.
Female athletes have an increased incidence of ACL rupture. The cause of this increased injury rate is unclear, but it is most likely from a complex interplay between multiple variables. The relative risk of incurring an ACL injury is still low. The increased risk of ACL injury in women compared with men should not discourage female participation in sports. Instead, the focus should be on strategies to prevent injuries. Intrinsic factors are difficult or impossible to change; modifiable risk factors need to identified and prevention strategies should be employed.