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Anterior Cruciate Ligamentous Injury Analysis

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Introduction

The most common ligamentous injury to the knee is injury to the anterior cruciate ligament (ACL) (Teske 2010), and it is the second most common injury in the lower extremity. It has become so common of an injury that 1 in 3000 individuals in the United States will be affected with an ACL tear (Micheo 2010) and there are 200,000 new cases per year (Wilk 2012). It is most commonly seen in people 15-30 years of age (Teske 2010). It is also more common in females than males (Fayad 2003, Teske 2010, Bowerman 2006). This is due to increased joint laxity in post-pubescent females compared to post-pubescent males (Bowerman 2006) and differences in muscle activation. Males tend to have a more balanced quadriceps to hamstrings ratio …show more content…

It is a modified hinge joint that allows flexion and extension, as well as anterior and posterior gliding and minimal rotation. The bony articulations of the knee include medial and lateral tibio-femoral articulations and a patello-femoral articulation. There is also an articulation between the head of the fibula and the tibia, but the fibula does not bear weight and is not considered part of the knee joint itself. The afore-mentioned articulating surfaces are incongruous, and the stability of the knee relies mostly on the integrity of the supporting muscles and ligaments. The muscles that span the knee are the quadriceps anteriorly, the hamstrings and gastrocnemius posteriorly, and the tensor fascia latae (iliotibial band) laterally (Moore 2014).
The quadriceps are comprised of four muscles: vastus lateralis, vastus medialis, vastus intermedialis, and rectus femoris. These muscles attach proximally at differing locations along the shaft of the femur and on the hip bone (rectus femoris only). They span the length of the femur and converge on the quadriceps tendon on the superior aspect of the patella and continue to the tibial tuberosity via the patellar tendon. The quadriceps are responsible for extending the knee, assisting in proper tracking of the patella, and preventing posterior translation of the tibia on the femur (Moore …show more content…

If a knee is hit from the outside, especially while the foot is planted, it will be forced into genu valgus. This puts several structures at risk, namely the ACL, MCL and joint capsule. These structures specifically prevent valgus forces and are expected to be damaged when subjected to excessive genu valgus. The nature of the force can also damage the bones because valgus will cause the lateral condyles of the femur and tibia to be compressed while the medial condyles will be distracted. This can result in bruising of the bone or damage to articular cartilage of the compressed side. In addition, the menisci can be involved depending on the direction of the force, especially if rotation occurs. The lateral meniscus can be damaged without rotation if it is compressed between the condyles or with rotation by getting torqued between the condyles. The medial meniscus is at a lesser risk of being damaged due to compression because the medial condyles are being distracted from one another. However, because it has attachments to both the ACL and MCL, if one or both of those are damaged, the medial meniscus is at risk. Therefore, a 20 year-old male rugby player who was side tackled may very well present with a torn ACL, MCL, and medial

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