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פורסם במקור על ידי shikoLM
אין טעם להפוך את זה לעוד וויכוח על וינגייט, אתה מוזמן לפתוח ספרות מקצועית בתחום (Basic Biomechanics of the Musculoskeletal System, ובמיוחד הייתי ממליץ לך על Kinesiology of the Musculoskeletal System של ניומן) ולגלות שמדובר בדברים מבוססים שנדונים בהרחבה ומגובים ברפרנס. לעומת הספר של ריפטו שעם כל הכבוד פונה לקהל הרחב וככל הנראה, במקרה הטוב, דבריו של אותו פרופסור לקינזיולוגיה עברו עריכה רצינית בכדי לפשט את העניין.
בכל מקרה הדיון המקורי שלנו באותו שירשור נגע למידת הפעילות של האמסטרינגס ומידת ההשפעה שלו במקרה הזה (דרך המפרק הטיביו-פימורלי) על המפרק הפטלו-פימורלי.
צירפתי לך מחקר שעוסק בנושא המדובר, בנוסף צירפתי מחקר על העומס הפועל על המפרק הטיביו-פימורלי.
אני אחפש בשבילך בנוסף מחקר שראיתי בנוגע לעומסי הגזירה על ACL.
אם זה מעניין אותך אני יכול להסביר בצורה קצת יותר נרחבת על מה שמתרחש במפרקים השונים בברך בעת כפיפה.
The effect of tibiofemoral joint kinematics on patellofemoral contact pressures under simulated muscle loads
G. Li 1 *, L. E. DeFrate 2, S. Zayontz 1, S. E. Park 1, T. J. Gill 1
1Orthopaedic Biomechanics Laboratory, Massachusetts General Hospitall Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02114, USA
2Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Funded by:
Whitaker Foundation and the Orthopaedic Education and Research Foundation
Abstract
Altered patellofemoral joint contact pressures are thought to contribute to patellofemoral joint symptoms. However, little is known about the relationship between tibiofemoral joint kinematics and patellofemoral joint contact pressures. The objective of this paper was to investigate the effect of tibiofemoral joint kinematics on patellofemoral joint pressures using an established in vitro robotic testing experimental setup. Eight cadaveric knee specimens were tested at 0°, 30°, 60°, 90°, and 120° of flexion under an isolated quadriceps load of 400 N and a combined quadriceps/hamstrings load of 400 N/200 N. Tibiofemoral joint kinematics were measured by the robot and contact pressures by a TekScan pressure sensor. The isolated quadriceps loading caused anterior translation and internal rotation of the tibia up to 60° of flexion and posterior translation and external rotation of the tibia beyond 60°. The co-contraction of the hamstring muscles caused a posterior translation and external rotation of the tibia relative to the motion of the tibia under the quadriceps load. Correspondingly, the contact pressures were elevated significantly at all flexion angles. For example, at 60° of flexion, the hamstrings co-contraction increased the posterior tibial translation by approximately 2.8 mm and external tibial rotation by approximately 3.6°. The peak contact pressure increased from 1.4 ± 0.8 to 1.7 ± 1.0 MPa, a 15% increase. The elevated contact pressures after hamstrings co-contraction indicates an intrinsic relation between the tibiofemoral joint kinematics and the patellofemoral joint biomechanics. An increase in posterior tibial translation and external rotation is accompanied by an increase in contact pressure in the patellofemoral joint. These results imply that excessive strength conditioning with the hamstring muscles might not be beneficial to the patellofemoral joint. Knee pathology that causes an increase in tibial posterior translation and external rotation might contribute to degeneration of the patellofemoral joint. These results suggest that conservative treatment of posterior cruciate ligament injury should be reconsidered. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Contact stresses in the knee joint in deep flexion.
Thambyah A, Goh JC, De SD.
Department of Orthopaedic Surgery, National University of Singapore.
The contact stresses in the knee that arise from activities involving deep flexion have not been given due consideration in view of social and cultural practice amongst many Asians that frequently cause the engagement of these activities. Excessively large stresses (>25 MPa) can cause cartilage damage and may be the precursor to the development of degenerative disease of the joint. In this study, forces in the knee derived from previous studies of human walking and squatting were applied to five cadaver knees that underwent quasi-static mechanical testing. This was conducted using a materials-testing machine and a custom-made apparatus that allowed secure and consistent loading of the knee specimen in flexion beyond 120 degrees. A thin-film electronic pressure transducer was inserted into the cadaver tibiofemoral joint space to measure force and area. Throughout the various positions simulating specific phases of walking, it was found that stresses peaked to 14 MPa (standard deviation was 2.5 MPa). In deep flexion, the peak stresses were significantly larger by over 80%, reaching the damage limits of cartilage. The results from this biomechanical study suggest that the adequacy of articular cartilage to support loads in the knee joint during deep flexion may be questionable.
PMID: 15823474 [PubMed - indexed for MEDLINE]
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