KNEE ANTERIOR CRUCIATE LIGAMENT RUPTURE INTERNAL FEMORAL ROTATION
Knee Anterior Cruciate Ligament Rupture Internal Femoral Rotation demonstrative evidence graphics
An intact anterior cruciate ligament is vital for knee stability and durability over time. Excess stretching forces applied to the anterior cruciate ligament can cause a partial tear or complete rupture of this ligament. A common mechanism of anterior cruciate ligament tearing is excessive internal femoral rotation, which can tear the medial collateral ligament and then the anterior cruciate ligament and the medial meniscus, such as during a side-step with the foot planted on the ground. Knee Anterior Cruciate Ligament Rupture Internal Femoral Rotation demonstrative evidence graphics.
A stretched or ruptured anterior cruciate ligament results in an unstable knee that leads to increased stresses on the other supporting structures in the knee and their accelerated wear and tear. This can cause articular cartilage fissuring, erosions and osteo-arthritis, and menisci degeneration, stiffening and tears. Knee Anterior Cruciate Ligament Rupture Internal Femoral Rotation demonstrative evidence graphics.
The fibres of the cruciates have different lengths and direction, so that during knee movements, they are not all stretched at the same time. The anterior cruciate ligament posses very little inherent elasticity. Application of a force straining it by more than 5% of its resting length will result in rupture. This rupture may be complete and obvious on gross inspection, or it may be partial, demonstrating failure in continuities. The anterior cruciate ligament is able to resist force of 1700N before failure.
Functional instability is usually the result of acute ligament disruption or chronic attenuation superimposed on an acute injury. Nevertheless, the patient assessment must rule out the other causes that either contribute to the athlete's problem or may be the sole causes. They include meniscal lesions, chondral damage, osteo-chondral fragments, loose bodies, and patellar subluxation and dislocation. Acute and chronic injuries are discussed, but it must be realized that the acute injury is complicated by pain, and the chronic injury by internal derangement and attenuation of multiple secondary restraints.
A history of pain is not always a good guide to these injuries. Some of the serious injuries may be no more painful than some of the minor injuries. Indeed, there are circumstances where partial ligament tears may produce more pain than complete third degree tears.
With acute injuries, the key points are the feeling or hearing of something 'pop' or rip, the sensation of the knee going out of joint and the subsequent inability to weight bear. The report that the knee felt wobbly when attempting to walk or run is also ominous. Eight percent of individuals experiencing a painful significant pop as their knee gives way have an anterior or posterior cruciate injury or a meniscal lesion.
In the presence of trauma, the main thrust of the history should be establishing whether the person complains of an effusion or hemarthrosis. An effusion is the method by which the knee joint reacts to all stress and usually takes several hours to accumulate. By contrast, an acute hemarthrosis is usually well formed after 1 to 2 hours, leaving a tense, inflamed knee. It has been shown that more than 8 percent of individuals presenting with an acute hemarthrosis have a surgically treatable lesion, the most common of which is a partial or complete tear of the Anterior Cruciate Ligament (ACL). Two thirds of these ligamentous lesions are associated with meniscal damage. The other diagnoses compatible with acute hemarthrosis are peripheral meniscal tears, osteochondral fracture or posterior cruciate injuries. It is important to stress that, whereas a hemarthrosis usually accumulates rapidly, the absence of tense swelling after the first few hours does not rule out significant injury. Occasionally the hemorrhage is contained within the synovial sheath surrounding the cruciate ligaments, particularly with partial tears. Furthermore the main vessels of the cruciates may bleed slowly due to vessel constriction followed by clotting. Hence the report of swelling delayed 24 to 48 hours must still be taken seriously. Furthermore, associated chondral fractures and mid-substance meniscal tears may produce slowly accumulating effusions rather than tense hemarthrosis. demonstrative evidence graphics.
This information is taken from I.A. Kapandji's The Physiology of the Joints Volume Two the Lower Limb, D.C. Reid's Sports Injury Assessment and Rehabilitation, and the Oxford Textbook of Sports Medicine.
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| Science & Technology | Upload TimePublished on 20 Dec 2011 |
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