Knee problems result from damage to the muscles, tendons and ligaments surrounding the knee joint. This joint is comprised of the articulation of one thigh bone and two shin bones, and the knee cap supports and assists the body in coordinated movements of several joints. The ACL or anterior cruciate ligament, is a strong rope-like material that attaches the femur head to the tibia below. The ACL is the last stabilizing tool for the knee joint in the event that muscle, tendons and other ligaments are damaged. The ACL can tear, sever and wear away from the bones. When the knee joint is turned, twisted or jammed while the foot is planted, injury can occur from tears the tissues supporting the joint.
Anterior Cruciate Ligament Tear
The muscles of the three bones--femur, tibia and fibula--and the knee cap are surrounded by muscle that is reinforced with tendons that attach to ligaments. The ligaments attach to the surfaces on the bones on the back, side and front of the knee, adding additional stability to hip and ankle movement. The ACL is protected and surrounded by muscle on the top, side and back of the knee. In the event that any of these muscles or attaching tendons is torn from the femur or tibial head, the ACL still stabilizes the knee joint. This ligament allows the knee, leg and ankle to move in stop-and-start, side-to-side, twisting motions. If however, the muscles and tendons are not intact, the ACL may tear from sudden impact or cumulative micro-tears. Often described as a sharp pull, the ACL tear may take months to heal. A tear in the ligament is similar to a tear in material; the threads pull apart, causing mild and medium inflammation and discomfort when engaging in weight bearing activities on the affected knee. This type of injury may be evident when the knee appears to "give out" without notice or particular activity. The ACL is subject to more damage as a result of the tear, because it is difficult to know when or what activities will cause the knee joint to malfunction.
Anterior Cruciate Ligament Separation
The knee is a complicated structure that works in conjunction with other joints; therefore, ACL injury types and severity may vary. A range of bone, muscle, tendon and ligamental tissue damage can exacerbate and cause ACL tears. An anterior cruciate ligament separation will be evident by an immediate popping sound followed by inflammation of the tissue and muscle surrounding the knee.The injury forces the knee joint out of alignment, and the joint will not support the weight of the body on the affected area. Reports on both the Merck Manual and Mayo Clinic websites note that some people with ACL injuries hear and feel a loud popping sound just prior to inflammation, mild pain and inability to continue weight bearing on the knee joint. Also the Merck article "Knee Sprains and Meniscal Injuries" indicates that patients may have accompanying muscle spasms and locking or inability to move the knee joint.
ACL and Meniscal Damage
The meniscus is a shock-absorbing tissue that sits between the femur and tibia; when it is damaged, the ligaments of the knee can be weakened. Not only athletes fall victim to knee injuries; assembly line factory work of a repetitive nature and other job-related knee-twisting motions can cause knee problems. The constant coiling and torque movements can cause wear to the meniscus sheath. Once worn, the outer aspects of bone can grind as in osteoarthritis. A few extra pounds on the hips or waist and years of standing, rocking motion at work on cement floors is a recipe for knee tissue wear. The specific movements that cause strain and eventual damage to the knee joint are repetitive, twisting, side-to-side motions with abrupt stopping and starting maneuvers that force torque to the ankle joint while the foot is planted. This action pulls the muscles, tendons and ligaments of the anterior thigh to the back and sides of the knee capsule while alternately pulling the muscles of the posterior thigh in the opposite direction. The knee joint can support these movements when muscle fibers are toned and stretched. However, continuous micro-tearing of the fibers surrounding this joint can wear away the meniscus, leading to ACL knee injuries.
