Cruciate Ligaments Sprain - Essay Example

CRUCIATE LIGAMENT SPRAINS Introduction The knee joint is a complex structure that is susceptible to a variety of injuries through an individual's routine participation in athletic activities both professionally as well as on a normal fitness level and it is not limited to any particular age group although in some cases of older individuals it may be due to a degenerative process such as arthritis (Chester Knee Clinic). According to the Seattle Orthopaedic Fracture Clinic, a sprain is a term that refers to a partial or complete tear of ligament matter. In minor or low-grade sprains only a few fibres are torn and though there is pain, there isn't much instability from a loose ligament. However, in complex sprains a large segment of the fibres are torn and the ends of the ligament may have separated from each other. This would result in immense pain as well as instability of the joint and it may require surgical treatment. Rouzier indicates that sprains may be graded according to their severity: Grade I sprain: pain with slight stretching or micro-tearing of the ligament Grade II sprain: more ligament disruption and mild looseness of the joint Grade III tear: complete tearing of the ligament and the joint is unstable. The Anatomy of the Knee According to the Chester Knee Clinic, the knee is a well exposed structure that consists of two joints and made up of three bones namely, the femur, tibia and the patella. They further go on to describe its anatomy in greater detail: The tibio-femoral joint has medial and lateral compartments. The medial and lateral femoral condyles articulate with the medial and lateral tibial plateaus. The patella covers the front of the knee. The patello-femoral joint is the articulation of the patella with the femoral trochlea. All joint surfaces are covered with hyaline articular cartilage. This anatomy of the knee joint offers no real support to the joint's stability. Thus, ligaments are essential in regulating the movement of the knee joint and maintaining its stability. Various stabilizing configurations are brought into play as the knee moves through its full range of motion, giving dynamic stability to the joint (Smith and Moran 1). Avery describes the knee joint as consisting of four essential ligaments that aid in its stabilization. The sides of the joint consist of the medial and lateral collateral ligaments which aid in the side-to-side stability of the joint. In the front of the joint is the anterior crusiate ligament (ACL) which serves to prevent the tibia from sliding forward and rotating during various agile activities such as jumping. Opposite to the ACL is the posterior crusiate ligament (PCL) which prevents the tibia from sliding back. The crusiate ligaments regulate movement as the centre of rotation changes during movement. The presence of the menisci is another important feature for not only do they act as shock absorbers, but they also aid in weight distribution (ehealthMD 1). Incidentally, the crossing of the ACL and PCL in the centre of the knee is what gives rise to the term "crusiate". Representations of these structures courtesy of the Journal of the American Medical Association are as seen in Figures 1 and 2 below. Figure 1: Anatomy of the Right Knee Figure 2: Anatomy of the right knee with ligaments cut. Knee Biomechanics As Elliot explains, clinical biomechanics refers to the research conducted on the actions of walking, tissue mechanics, neuromuscular control and the evaluation of movement when an individual is undergoing rehabilitation when recovering from disease or injury (1). The Chester Knee Clinic provides a comprehensive understanding of the biomechanics of the knee. The bones of the knee joint, unlike the hip joint, are not a close fit to one another. This variation allows for a wider range of motion to occur in order for an individual to carry out daily activities. However, this range of motion is still limited in its inherited stability due to the bony structure of the joint. According to the KneeDoc, "the lack of conformity between bony surfaces allow 6 of freedom of motion about the knee including translation in three planes (medio-lateral, antero-posterior, proximo-distal) and rotation in three planes (flexion/extension, internal/external, varus/valgus)". They go on to relate that the function of the cruciate ligaments is to allow the knee to roll and slide at an angle of maximum motion while allowing for contact and stability. The medial and lateral collateral ligaments provide stability for side-to-side motion while the menisci increase surface area contact between the round femoral condyles and the flatter tibial plateau on the medial side and the convex tibial plateau on the lateral side. Thus, the menisci are of pivotal importance in transmission of loads. Explaining the biomechanics of the knee in a more extensive light, let us look at the mechanics of gait as according to Stewart and Hall as well as Hungerford et al. Walking is divided into two phases, the stance and the swing phase and each of these phases begin and end with double support. The stance phase can also be sub-divided into four stages, namely heel-strike (HS), flat-foot (FF), heel-off (HO) and toe-off (TO). Starting off with the HS stage, the heel strikes in contact with the ground and this produces a flexion movement at the hip as well as an extension movement at the knee which is resisted by the hamstring muscle. In this position the knee is at its maximum extension with a load of about two to four times of body weight impacting on the joint. This is mainly due to the various muscle forces that act to stabilise the knee. Stewart and Hall (4) identify that that the most stable position of the knee is when the heel hits the ground. This depends on the static and dynamic factors which can be classified as follows: 1. Static factors are divided into two main areas. These are: a) The bony stability which is provided by the medial/lateral spading of the femoral condyles. In this position, the condyles are tightened against the intercondylar notch (tibial spine). b) The large radius of curvature of the femoral condyles and the tibial plateau which is sloped anteriorly and these two combine to pull the collateral ligaments taught during extension. The other ligaments that are involved in the stability of the knee joint also include the medial and lateral collateral ligaments, anterior and posterior cruciate ligaments, oblique popliteal and arcuate ligaments.The ilio-tibial band is also considered a static factor. 2. The dynamic factor responsible for the stable position of the knee is the muscle forces and this includes all the muscles and their aponeuroses such as the quadriceps femoris, popliteus and semi-membranosis among others (the Kneedoc). As the individual progress, between the stages of HS and FF, the knee undergoes a flexion of 20 before extending back to 0 as the motion continues. During this stage of mid-stance, the knee is less stable since the spacing of the medial/lateral femoral condyles is larger and do not lock against the intercondylar notch anymore. Stewart and Hall (5) further explain the last two stages of the stance phase as follows: As walking continues the knee flexes once again. Rolling occurs up to 20 flexion until at which time the posterior translation of the femur relative to the tibia that occurs during the rolling action is restricted by the anterior cruciate ligament which acts like an anchor preventing posterior translation. As flexion continues and the condyles can no longer roll backward on the tibia the motion between the femoral and tibial surfaces changes from rolling to sliding. This change occurs initially with the medial condyle and then the lateral condyle resulting in a natural external rotation of the knee. At toe-off (about 50 flexion) the quadriceps calf muscle (gastrocnemius) act to both stabilize the knee joint and produce plantar flexion of the ankle joint which accelerates the body forward resulting in a vertical joint reaction force of two to four times of body weight. This is merely one aspect of the biomechanics of the knee that serves as an example and further reading is recommended for additional information. The injuries that are attributed to the crusiate ligaments are usually due to a sudden forceful blow to the front of the knee joint. This is accompanied with pain, swelling and generally a sense of the looseness of the knee joint or the knee 'giving out' during normal activities (Avery). The general signs and symptoms of crusiate ligament injuries are seen above. However, specific aspects of the injuries to each of the crusiate ligaments will be discussed. Anterior Crusiate Ligament Causes As has been discussed previously, the anterior cruciate ligament is the main stabilizer of the knee especially during physical exertion, preventing the tibia from sliding forward when the knee is positioned straight. Since it is involved in most of an individual's activities, studies conducted by Nawabi et al. demonstrate that sprains of the anterior cruciate ligament and the medial collateral ligament account for 90% of all injuries in active and young individuals (1). It has also been proven that the spontaneous healing potential of the ACL is very rare and limited and thus most athletic individuals who suffer such injuries resort to surgical reconstruction. The anterior cruciate ligament may be sprained in a number of ways as stated by the Merck Manual, the most common being an inward or outward force which is accompanied by the rotation or twisting of the knee or lower leg. A good example of such an action would be in the sport of football when a player is has to slow down quickly and conduct a quick turn in order to change direction and in such a situation the knee is subjected to sudden twists and stretches. Another example is the case of a gymnast who lands after a dismount with the feet striking the ground while the knees are straight. Extending the knee 10 degrees beyond the normal limits of its extension (hyperextension) can also lead to sprains of the cruciate ligament as it forces the lower leg forward at a greater degree than compared to the upper leg. An example of such an injury would be in the case of a baseball player who slides into a base with a hyperextended knee and additional force being exerted on it. The leg would then come to an abrupt halt while in this position, thereby causing a sprain in the anterior cruciate ligament. The severity of any such injuries described above would largely depend on the direction and force of the blow as well as the position that the knee was in. As seen by the example above, it is mostly athletes who suffer from injuries to the ACL. However, non-athletes may also suffer from similar injuries through circumstances such as repeated trauma to the knees, vehicular accidents or any sudden blow to the knees. A graphic representation of a tear in the ACL is as shown in Figure 3 below, courtesy of ehealthMD. Figure 3: Torn ACL as viewed through an arthroscope Signs and Symptoms The first sign that an individual has sprained their ACL is usually an audible 'pop' sound together with a significant amount of pain and swelling of the knee. This swelling, also known as an effusion, consists of blood that has collected in the knee joint (Rouzier). In the case of a Grade I or Grade II sprain, there might be a slight tearing and looseness of the ligament. However, in the case of a Grade III sprain, the ACL is torn completely and there may be no sign of an effusion since such a tear would result in the opening of the joint capsule and blood can then exit the joint. (Avery, Merck Manual) The Posterior Cruciate Ligament Causes As was explained initially, the posterior cruciate ligament extends at the back of the leg from the tibia to the femur and its purpose is to prevent the tibia from sliding backwards. Posterior cruciate ligament injuries are usually far less common as compared to anterior cruciate ligament injuries. However, the pain that is caused by such an injury is equally painful. Injuries to the posterior cruciate ligament occur due to hyperextension or hyperflexion of the knee. Avery points out that the most common of the PCL injuries is during a car accident where the knee hits the dashboard. Such a blow to the upper tibia while the knee is bent and the foot is planted will force the lower leg backwards, thus tearing the ligament. In the case of sports such as hockey, athletes may injure their posterior cruciate ligament when they fall on a bent knee with their foot pointed downwards (MayoClinic). Signs and Symptoms A minor tear or sprain of the PCL usually is less sore and swollen. The pain is localized to the back of the knee aggravated with activities such as kneeling, squatting or walking up and down inclines. As with the injuries to the ACL, there is a feeling of instability in the knees as well as the occurrence of swelling in the joints (Avery, MayoClinic, Rouzier). In addition, sprains of the PCL usually occur concurrently with other major knee injuries. REFERENCES "Anterior Cruciate Ligament (ACL) Injuries". Chester Knee Clinic.14th October 2007 "Athletic Injuries". 2006. Seattle Orthopaedic Fracture Clinic.. 14th October 2006 Avery, F. L. "Knee Ligament Anatomy". Orthopaedic Associates of Portland. 16th October 2007. Elliot, B. "Sir William Refshauge Lecture 1998: Biomechanics: An integral part of sport science and sport medicine". Journal of Science and Medicine in Sport Volume 2, Issue 4, December 1999, Pages 299-310. ScienceDirect. 19th October 2007. Hungerford, D. S., Kenna, R. V. and Haynes, D.W. "Relevant Biomechanics of the Knee for Knee Replacement". Physician Topics. About Joints. 20th October 2007. "Knee Joint Stabilisation". The KneeDoc. 19th October 2007. "Knee Pain". Jama Patient Page. The Journal of the American Medical Association. April 18, 2007-Vol 297, No. 15. 18th October 2007. "Knee Sprains and Meniscal Injuries". November 2005. The Merck Manuals Online Medical Library. 14th October 2007. Nawabi, D.H., Patel, R.V., Hall-Craggs, M., Haddad, F.S. "MRI-Confirmed Tear and Spontaneous Healing of the Anterior Cruciate Ligament". Injury Extra (2006) 37, 125-128. ScienceDirect. 15th October 2007. "Posterior Cruciate Ligament Injury". March 29 2007. MayoClinic.com 17th October 2007. Rouzier, P., M.D. "Anterior Cruciate Ligament (ACL) Sprain". 2002. University of Michigan Health System. 14th October 2007. Smith, A. and Moran, C. "Soft Tissue Injuries of the Knee". Orthopaedic II: soft tissue, metabolism and malignancy. Surgery 24:11. ScienceDirect. 15th October 2007. Stewart, T.D. and Hall, R.M. "Basic biomechanics of human joints: Hips, knees and the spine" Current Orthopaedics (2006) 20, 23-31. ScienceDirect. 19th October 2007. "What Is The Anterior Cruciate Ligament" July 2004. ehealthMD: 1. 16th October 2007. "What Causes An ACL Tear" July 2004. ehealthMD: 2. 16th October 2007. Read More