Anatomy of the Knee
In order to effectively examine injuries to the Anterior Cruciate Ligament (ACL) and their effects, one must first be able to understand the basic anatomy of the knee. The functions of the ACL inside the knee will also be examined. The knee is a hinge joint (Marx &Myklebust, 2012). That means that it connects the upper and lower parts of the leg in order to provide the ability for movement. However, the physical structure of the knee does not provide the perfect conditions for stability. When compared to the hips’ ball and socket structure, the knee is far more inferior. This is where the ligaments in the knee come into play (2012). The knee ligaments essentially bind two large bones together (Marx & Myklebust, 2012).
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The ACL begins at the lateral, or outside, part of the end of the femur, through the middle of the knee, and then connects to the anterior, or front, part of the tibia. Due to the fact that the ACL lies within the knee, the blood flow to it is not as rich as other ligaments in the knee. This can lead to less effective healing compared to other structures of the knee. The ACL is responsible to prevent the anterior tibial translation on the femur, which means the ACL provides support to the tibia so that it cannot slide forward in front of the femur. The ACL also controls the hyperextension of the knee (Andrews, Harrelson, & Wilk, 1998). The varus stress, which would be thought of as a bow-legged appearance, and the valgus stress, which would be thought of as a knock-kneed appearance are also controlled by the ACL. The ACL is put under a lot of strain due to its many functions in the knee (Marx & Myklebust, …show more content…
This mechanism is a system of muscles, tendons, and other tissues that work together outside the knee to provide stability and the movement of straightening the knee (Marx & Myklebust, 2012). The extensor mechanism begins with the quadriceps muscle, which sits on the front side of the femur. This large muscle is connected to the patella tendon, the tendon that connects the kneecap to the lower leg, by the quadriceps tendon. This mechanism could not work without the presence of the kneecap. The kneecap, or patella, sits within the patellar tendon and provides leverage for the quadriceps muscle
Flexion is the bending of a joint so that the angle between the two bones decreases. The primary muscles that flex the knee are a group collectively known as “hamstrings.” The hamstrings consist of the biceps femoris, semitendinosus, semimembranosus. The muscles that assist in flexion are the sartorius, gracilis,...
The anterior cruciate ligament (ACL) is one of the most important of your four major knee ligaments. The function of the ACL is to provide stability to the knee and minimize stress across the knee joint. It restrains excessive forward movement of the lower leg bone (the tibia) in relation to the thigh bone (the femur). It also limits rotational movements of the knee. “Greater external knee valgus and internal rotation moments have been shown to increase loading on the ACL in vitro and are thought to be associated with the increased risk of noncontact ACL injury” (Effects 2011). A tear to the anterior cruciate ligament results from overstretching of this ligament within the knee. It’s usually due to a sudden stop and twisting motion of the knee, or a “...
In order for athletes to save their active lifestyles they need understand the ACL. The ACL is the most important ligament in the knee because it provides stability to the knee. Athletes have to be aware of the importance of the ACL and know its functions in order to preserve the ligament. The ACL otherwise know as the anterior cruciate ligament is the ligament in the knee that connects the upper leg bone which is the femur to the lower leg bone which is the tibia. The anterior cruciate ligament crosses with the posterior cruciate ligament inside the center of the knee joint to stabilize to the knee in movement.
The most common knee injury in sports is damage to the anterior cruciate ligament (ACL) through tears or sprains. “They occur in high demand sports that involve planting and cutting, jumping with a poor landing, and stopping immediately or changing directions” (University of Colorado Hospital). The ACL is a ligament that runs diagonally in the middle of the knee and found at the front of the patellar bone. Its function involves controlling the back and forth motion of the knee, preventing the tibia from sliding out in front of the femur, and providing rational stability to the knee. Interestingly, women are more prone to ACL injuries than men. The occurrence is four to six times greater in female athletes.
To understand the importance of the ACL, the knee as a whole must be examined. The knee is formed by the femur, the tibia, and the patella. Several muscles and ligaments control the motion of the knee and protect it from damage at the same time. Ligaments are dense structures of connective tissue that fasten bone to bone and stabilize the knee. Two ligaments on either side of the knee, called the medial and lateral collateral ligaments, stabilize the knee from side-to-side. The ACL along with the posterior cruciate ligament are of a pair of ligaments in the center of the knee joint that form a cross. T...
The Anterior Cruciate Ligament (ACL) attaches the femur, which is the thighbone, and the tibia, which is the shin, together (northstar). A torn ACL is one of the most excruciating experiences in an athlete’s life. It is the first thing that comes to mind when they hurt their knee on the field; for many it is their greatest fear. A torn ACL can sometimes mean the end of an athlete’s career. It can mean losing the chance to get that scholarship for young athletes, and it can also mean the end of those million dollar paychecks for those who have gone professional. A torn ACL can result in numerous surgeries, months of vigorous exercise and rehabilitation, and a sufficient amount of pain. It requires complete patience, for pushing too hard can result in further, more painful injury. Even after all that, an athlete is not guaranteed he or she will ever be able to play sports again.
The surfaces of the joint are organised to allow only back and forth motion such as bending and straightening. This type of joint can be found between your upper arm and your lower arm, in the elbow. This type of joint is incredibly important as it allows an up and down movement, without this type of joint, we wouldn’t be able to move our arm up and down. Muscles are attached to this type of joint by tendons to allow it to contract and relax and be able to move the bone within this joint. Ligaments attach the bones in a hinge joint together, for example, the humerus and the tibia are joined by ligaments but they also have antagonist muscle pairs attached to them by tendons which allow the bone to move by contraction and relaxation of the muscles. This type of joint mainly includes long bones as it’s necessary for movement in the skeletal
“The anterior cruicate ligament is a strong band that arises from the posterior middle part of the lateral condyle of the femur, it passes anteriorly and inferiorly between the condyle, and is attached to the depression in front of the intercondylar eminence of the tibia (Mosby‘s page. 105).” The tear of the A.C.L is described as a partial or complete rupture of the anterior cruciate ligament. The A.C.L. does not repair by itself. It is so important to an athlete in most sports because an athlete has to be able to rotate the knee in specific directions. The tear happens more frequently in soccer, basketball, and volleyball. Athletes who started participating in a sport while they were young have a greater chance of sustaining a tear. Women are more susceptible to this injury than men. Theories for this include hormonal, environmental, and biomechanical factors. “Women‘s muscles react differently in landing. Doctors say that women land with straighter legs than men do; thus, they pass their shock to the A.C.L. resulting in a tear. Environmental factors are shoes and playing surfaces.” (Patrick, Dick)
...cient knee during activities of daily living, as they have yet to be determined ⁷². In understanding the factors contributing to the mechanism of non-contact ACL injury, investigators should consider whether the kinematics, kinetics and muscle activation strategies observed are the cause of increased ACL strain or compensation for other kinetic chain insufficiencies ²⁹. Further knowledge on how movement patterns and other kinetic chain structures affect ACL loads prove critical in enhancing future prevention strategies ²⁹ ³⁴. As with reconstruction, rehabilitation should aim to aid the knee in attaining its near-normal function ⁵⁵. Through producing rehabilitation programmes built around existing knowledge on the biological and mechanical properties of the ACL, objectives such as reduced pain, greater ROM and improved muscle function can be achieved ⁵⁵.
The purpose of the squat is to train the muscles around the knees and hip joints, as well as to develop strength in the lower back, for execution of basic skills required in many sporting events and activities of daily living. Because a strong and stable knee is extremely important to an athlete or patient’s success, an understanding of knee biomechanics while performing the squat is helpful to therapists, trainers, and athletes alike (11). Because most activities of daily living require the coordinated contraction of several muscle groups at once, and squatting (a multi-joint movement) is one of the few strength training exercises that is able to effectively recruit multiple muscle groups in a single movement, squats are considered one of the most functional and efficient weight-bearing exercises whether an individual’s goals are sport specific or are for an increased quality of life
Everyday an athlete goes to practice or game, putting on a possibility of getting injured. A common one of those injuries is the tear of the anterior cruciate ligament, better known as the ACL. When sports that require quick pivoting and harsh landings became more popular such as soccer and basketball, ACL injuries quickly multiplied. Since kids, teens, and even adults usually focus on one sport it often occurs that they can overuse and exert their body causing injury to the ACL (Young Athletes 10).
In order to understand how the menisci can be injured, you must understand the basic anatomy of the menisci and why they are important. The menisci are two oval (semilunar) fibrocartilages that deepen the articular facets of the tibia and cushion any stresses placed on the knee joint. They enhance the total stability of the knee, assist in the control of normal knee motion, and provide shock absorption against compression forces between the tibia and the femur (Booher, 2000). Articular cartilage covers the ends of the bones that make up the joint. The articular cartilage surface is a tough, very slick material that allows the surfaces to slide against one another without damage to either surface. This ability of the meniscus to spread out the force on the joint surfaces as we walk is important because it protects the articular cartilage from excessive forces occurring in any one area on the joint surface, leading to degeneration over time (Sutton, 1999).
“Doc, I fell and twisted my knee. I heard a pop. It hurt briefly. When I stood up, the knee felt as if it was not underneath me, and the knee gave way. It swelled up by the next day and ever since feels as though it would pop out when I twist or even cross the street quickly.” In almost all cases the above complaints occur due to an injury to the ACL (Anterior Crucial Ligament) of the knee. The ACL is a very important ligament in the knee that controls the pivoting motion of the knee. This joint guides the femur and tibia through a regular range of motion. It is the most common and serious of injury sustained to the knee (Duffy, f9). How this injury happens, who is most susceptible, and how it is treated are a few questions athletes are becoming heavily concerned with.
The ACL is a dynamic structure whose main function is to provide primary restraint to anterior tibial subluxation. It provides secondary restraint limiting internal rotation and restraint with the knee in full extension. Along with the posterior crutiate ligament, it provides the axis for knee rotation and links rotation with flexion and extension.
ACL injury is quite prevalent in the United States. About every 1 in 3,000 people suffer from an ACL injury in their lifetime, and approximately 95,000 new incidences of ACL injury occur each year. The largest amount of these injuries occurs during sports which involve twisting, cutting, jumping and deceleration. The mechanisms that can cause an ACL injury are excessive valgus (outside of knee) stress, forced hyperextension, or forced external rotation of the femur on the a fixed tibia (Evans, 2001). Many associate the tearing of the ACL with a large impact or collision, however 80% of all ACL injuries are non-contact injuries. This statistic shows that ACL injuries are mostly caused by the individual themselves as opposed to an opponent or other person. The exact mechanism of noncontact ACL tears consists of poor knee positioning (e.g. landing with an extended knee) and a strong, unopposed quad contraction (Murray, 2013).