Studies indicate that females engaged in sporting activities experience more injuries that males. They experience low extremity injuries such as the iliotibial band friction syndrome, tibial, rupture of the anterior cruciate ligament, femoral pubic, patella femoral pain syndrome and metatarsal stress fracture. The topic is off are interest to researchers and athletes as well as health practitioners. Studies indicate that the rate of these injuries to females more than males is attributed to the structural differences that have led to altered ways of movement between the two which contribute to gender bias. Female runners were found to have a bigger hip adduction, external tibial rotation, knee adduction and hip internal rotation as compared to their counterparts. Researcher established that this caused the need for greater demands on the lumo-pelvic musculature (otherwise known as the core) of females. Todays scientists are widening the scope of their research to focus on assessing the joint mechanic proximal and the distance to the respective sites where injuries are common. The inadequate so because of the nature of athletics which is normally closed chain.
This section aims to provide a review of the literature on the risk factors for lower extremity injuries. Prevention has become a focal point for health practitioners to also to the researcher. However, before this is done there is knee to identify clearly the risk factor for these injuries. This paper examines knee valgus as a risk factor to lower extremity injuries. Knee valgus is commonly associated with injuries that involve anterior cruciate patellofemoral. It is, however, also related to other injuries to the leg such as damage to the knee cartilage and meniscus, patellofemoral pain syndrome, sprain of medial collateral ligaments and also knee osteoarthritis. Despite the intensive research that has been done in this area, researchers havent quite been able to explain conclusively causes of knee valgus. Researchers have offered various explanations such as a decrease in the gluteal activation and strength, decrease on the ankle dorsiflexion range of motion and an increase in the hip adduction activation. It was observed that subjects that showed knee valgus had ankle-dorsiflexion which was lower than the controls by 20%.
Studies investigate the risk factors of injuries among athletes for lower extremity, ankle, knees and all others lower extremity injuries. They are based on a clear articulated hypothesis that was used to determine the relationship between knee valgus risk factor and the injuries.
1.1 Aims and Objectives
This paper aims to support the development of the understanding of the mechanisms and causes of knee valgus during athletic endeavor via searching for a consensus within the literature. It also aims to conduct a systemic literature review relating the implications of knee valgus moments on key lower extremity knee injuries Identify relationships, contradictions, gaps and inconsistencies within the research.
2.0 Impact of Knee Valgus on Lower Extremity Injury Risk
Knee valgus is a condition in which the knee experiences abduction and external rotation. This occurs because of abduction and simultaneous internal rotation of the hip (Contrerus, 2013). The knee, therefore, buckles inwards in the presence of a load. During the valgus collapse, the opposite pelvis will characteristically drop whenever the subject stands on one leg. This form abnormal condition may lead to other lower leg injuries including patellofemoral (knee) pain, anterior cruciate ligament (ACL) and medial collateral ligament tears and even iliotibial band syndrome (Brookbush, 2015). There are also proven cases of knee valgus are also causing ugly squat syndrome common in some athletes.
Knee valgus is more common in women than in men. This is due to the presence of relatively wider hips, the lower strength of the hips and increased Q-angles (Huberti, 1984). However, a significant number of cases have also been reported involving men. Sportsmen are the most affected by the deformity especially in sports that involve rapid movement and change in direction and also those that impose intensive weight on hips, knees and ankles such as weight lifting, boxing, and basketball among others (Heatrick, 2015).
The condition usually occurs to people in an upright position when engaged in activities that require the use of hip extensors. The upright posture leads to a significant variation in mechanical torque required during adduction and internal rotation due to the presence of gravity opposing the upward motion and aiding the downward motion. The hips must act accordingly to stabilize the femur by absorbing the differential torque failure to which results to the valgus collapse. It is thus typical for one to experience knee valgus during squatting, walking, jumping and even running (Hollman, 2009).
The exact causes of valgus collapse have not been identified with satisfactory scientific certainty despite intensive research on the subject (Beardsley, 2012). However, few theories have been held as probable causes. One of the common theories is that an increase in the degree of internal rotation of the hip and its resultant rotation of the tibia is caused by a considerable decrease of gluteal activity. This then results to knee valgus. Some other possible causes of knee valgus agreed upon by most sports medicine professionals and scientists include:
Weak gluteus muscles
All the three gluteus muscles namely gluteus minimus, gluteus medius and gluteus maximus along with the external rotator muscles of the hip should be strong enough to support hip activity (Crow, Buttifant, Kearny, & Hyrsomallis, 2012). The inadequate strength of these muscles can consequently lead to stability issues in the femur. Since the gluteus maximus is responsible for hip and thigh movement, it is a tensor to the fascia lata and should stabilize the femur during standing. The lower part of gluteus maximus provides abductor and external rotator function to the limb while upper fiber part is the responsible abduction of the hip joint. It is thus unhealthy for adductors to have significantly increased activity compared to the external rotator. The difference in activity, in most cases valgus collapse.
Ankle mobility issues
Ankles have two functions namely plantarflexion and dorsiflexion (EDGE Magazine, 2015). If the ankle cannot sufficiently perform dorsiflexion (pushing the heel downwards i.e. towards the ground), the overall effect will be a restrained movement of the tibia and knee. The limb will, therefore, overcompensate by allowing for increased forward movement of the knee making the tibia rotate internally. This will subsequently cause internal hip rotation and adduction which may lead to knee displacement.
Lower body mechanics has been linked to knee valgus by several researchers (Murphy, Connolly, & Beynnon, 2003). The body can adjust the gluteus muscles for advantage mechanical purposes. When the gluteus medius is unable to perform its function as a hip abductor during squatting properly, the hip can experience internal rotation to allow the gluteus medius to regain it leverage. However, doing so makes the gluteus maximus unable to perform properly (weakens) its function as a hip extensor. This reflex action designed to aid properly the movement of the lower body ends up having counteractive result leading to caving out of the knee hence knee valgus.
Weak hamstring and quadriceps muscles
The quadriceps femoris is large extensor of the knee. The quad comprises of the rectus femoris vast lateral, vastus medialis and vastus intermedius muscles that connect to the tibia and provide stabilization to the knee. This extensor of the knee function aids walking, running, squatting and also jumping activities. Weaker quad may cause knee collapse (Hewett, Stroupe, Nance, & Noyes, 1996).The hamstring muscles are primarily responsible for walking, running, jumping and also trunk movement in the trunk. They provide an antagonist role to the quad during decoration of the knee extension. The hamstring is a large tendon found in the knee area. Weakened hamstring muscles (biceps femoris, semimembranosus and semitendinosus) can lead to failure of the hamstring to compliment the quad and thereby causing the internal rotation of the hip and consequently knee valgus.
Anatomy of individuals
Medial knee displacement has been, in some cases, linked to the anatomy of the subject (Jones & McCulloch, 2014). The shape of the lower body including the pelvis, knee and ankle, femur, tibia, acetabulum and the relevant ligaments and tendons seem to play a role. As stated, the gender also plays a role thus giving credence to the theory that the body anatomy of the human being has a direct link to valgus collapse making some people likely to experience medial knee displacement than others.
Link between knee valgus and lower extremity injury
As earlier stated knee valgus known to cause lower extremity injury if not corrected promptly. The problems and specific areas affected by medial knee displacement are discussed below:
Anterior Cruciate Ligament (ACL) Tear
The ACL is one of the two cruciform ligaments located in the knee. The other is the posterior cruciate ligament (PCL). The ACL is one of the four major ligaments that connects the femur to the tibia and is known to provide about 80% of the force that restrains the anterior tibia during displacement of the knee flexion at about 30o and 90o. The ACL, therefore, ensures that the tibia moves by the movement of the femur and does not undesirably move out of position. It also provides stability to the knee during knee rotation.
The ACL is the most often injured ligament in the knee (Boden BP, 2000). The injury mechanisms are, when the knee is hyperextended (straightening beyond the knee limits), forced to twist or bend beyond the structural limits allowed. It typically occurs at about 10 o external rotations of the tibia and about 30 o knee flexion positions. The tear of the ligament can be partial or complete. The causes of the injury range from a quick change of direction, abrupt stops, landing and after jumps from fairly large heights. In most cases, ACL injuries will occur in non-contact activities (Hewett, Meyer, & Ford, 2005).
Knee valgus may cause the ACL to tear. During a valgus collapse, the knee can be rotated by about 10o to 30o of flexion, increasing the ligament laxity. Force acting medial to the knee joint (such as gravity when one is upright) is then forcefully absorbed by the ACL, which is already experiencing a strain involving resisting the femur movement that is not in line with the tibia. This valgus knee position (as the knee starts to fall medially to the hip and foot) and the knee rotation cause the ACL to rupture. In most cases, this type of ACL tear is partial.
Medial Collateral Ligament
The MCL is a relatively thick band of tissues that connect the femur to the tibia and prevents the leg from extending beyond its structural limits inwards (over-bending). It also provides stability to the knee joint and allows for its rotational activities (The Journal of Bone and Joint Injury, 2010). These injuries mostly occur in sportsmen (Chen, Kim, Ahmad, & Levine, 2008).
MCL injuries at times occur simultaneously with ACL injuries.it may be caused by intense contact on the outer part of the knee and valgus collapse. Since the MCL is located on the inner side, adjacent to the opposite knee, knee valgus can directly be the source of stress to the MCL. During the patterned collapse of the knee, where the knee collapses medial to the hip and foot, the weight of the upper side o...
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