The knee is the largest and most vulnerable joint of the body. Made of bones, tendons, ligaments and cartilage, the knee brings together different components that are susceptible to injury. In the knee, three bones—femur (thigh bone), tibia (shin bone) and patella (knee cap)—meet to form the knee joint. The ends of the femur and tibia and the back of the patella are covered with articular cartilage—a slippery substance the keeps the knee bones gliding smoothly across each other as the leg is straightened or bent. A tough, rubbery wedge-shaped cartilage called the meniscus is located between the tibia and femur to absorb shock between the bones and stabilize and cushion the joint.
The bones of the knee are connected to each other through four ligaments, which are strong string-like structures holding the bones of the knee and keeping the joint stable. On the sides of the knee are collateral ligaments—lateral collateral on the outside and medial collateral on the inside—that control sideways motion of the knee and prevent unusual motion. The cruciate ligaments (anterior cruciate in front and posterior cruciate in the back) are found inside the knee, crossing each other and controlling the back and forth movement of the knee. The bones of the knee are connected to muscles through tendons, which allow for support of the muscles and enable motion.
So what is the most common knee injury?Ligament sprains are the most common knee injury accounting for more than 45-percent of knee injuries. Ligament injuries occur when the knee is overextended or moved unnaturally and the ligaments are unable to support the movement. Since ligaments help to keep the knee in place, when they are forced too much they lose their ability to perform their function and stretch or tear.
When a ligament is torn or stretched, the knee joint becomes unstable, leading to difficulty with activities like standing on one leg, moving from side to side, stopping and starting movement, squatting, and going up and down steps. A ligament that is completely torn does not heal on its own.
Anterior Cruciate Ligament (ACL) Injury
Anterior cruciate ligament injuries are the most frequent knee ligament injuries. They account for about 40% of all sports-related injuries. Actually, athletes in high-demand sports like soccer, basketball and football are more likely to injure their ACL at some point during their career. ACL joins the lower and upper leg bones together and keeps the knee stable. It can be torn or injured when the lower leg extends forward too much (hyperextended), beyond the typical end range of movement. But ACL injury may also occur when bones of the lower and upper leg twist in opposite directions while the foot is on the ground.
For most players, ACL injuries occur when changing direction rapidly or landing from a jump—though 80% of ACL injuries occur in non-contact situations while the rest are caused by a direct blows to the knee joint. An ACL injury may be just a small tear (partial) or a severe injury, such as when the ligament is completely torn or fully separated from the bone. Treatment for ACL injury depends on the severity of the tear, with physical therapy and orthopedic rehabilitation often applied in most cases and surgery recommended in very severe situations.
Posterior Cruciate Ligament (PCL) InjuryMore than 50% of anterior cruciate ligament injuries occur along with damage to other knee structures, such as other ligaments, cartilage or meniscus. For instance, a blow to the knee when it is bent can lead to both ACL and PCL injury. The posterior cruciate ligament is located at the back of the knee and connects the femur to the shinbone, ensuring that the shinbone does not move too far backwards. PCL injuries frequently occur in motor-vehicle crashes and sports-related contact, but are usually partial tears with the potential to heal on their own. Actually, if the damage is only on the PCL, treatment is usually non-surgical physical therapy and orthopedic rehabilitation.
Collateral Ligament TearsInjuries to collateral ligaments are often caused by a force that pushes the knee to move sideways. Hence collateral ligament injuries are usually contact injuries and sports-related. Injuries to the medial collateral ligament are caused by direct blows to the outside of the knee and are linked to sports. The medial collateral ligament is easily torn when the lower leg is forced to move sideways.
Blows to the inside of the knee that push the knee outwards tend to injure the lateral collateral ligament, but such injuries are less frequent than the other knee injuries. Collateral ligament injuries are treated using physical therapy and orthopedic rehabilitation techniques, though surgery may be necessary if other structures of the knee are involved.
Meniscal tearsSudden meniscal tears usually occur alongside ACL injuries during sports. In fact, in sports that involve jumping, pivoting, twisting, tackling and other forms of contact, meniscus injuries are very common. Basically, just an awkward twist or abrupt change of direction while running can cause a meniscus tear. Depending on the extent and severity of meniscal injury, surgery may be necessary.
Patella fracturesThe patella shields and protects the knee joint from damage and injury during a fall or high-impact. But that also makes the patella the most commonly broken bone around the knee. When patella fractures occur, they are very serious injuries that require immobilization and in some cases can only be corrected surgically. Apart from patella fractures, high energy trauma can also cause fractures at the ends of the femur and tibia where they form the knee joint.
Tendon tearsThe tendon (patellar tendon) works together with knee muscles of the front thigh to straighten the leg. When the quadriceps and patellar tendon are overly stretched, especially when jumping or running, they can get torn. While anyone can have a tendon injury, tears are more commonly seen in middle-aged people, particularly in jumping or running sports activities. Tendon tears occur when people fall, land awkwardly from a jump or direct a force to the front of the knee. Most tendon tears are partial and typically require rest, physical therapy and orthopedic rehabilitation to heal. But complete tears are disabling and require surgery to restore complete function.
DislocationsDislocations occur when bones of the knee are either partially or completely out of place. For example, the patella can be forced to slip out of place while the femur and tibia may move out of a ligament. Knee dislocations are commonly caused by high-energy trauma, such as high-speed impact, car crash, falls, and sports-related contact. They also occur when the knee twists while one foot is planted on the ground.
When they occur, knee dislocations require relocations. In some cases, the kneecap spontaneously returns to its proper position without intervention. But in most cases, a mild sedative is necessary to allow the doctor to restore the knee without a lot of discomfort. It takes roughly one week for a knee to fully heal after relocation of a dislocated knee.
If you have suffured a serious knee injury or experience intense knee pain, it is important to see an orthopedic specialist as soon as possible for a diagnosis and treatment plan that will get you back on track.
At FYZICAL Lakewood Ranch, you can find knee specialists who will help you determine the type of knee injury you have and recommend appropriate treatment for quick relief. We provide tailored physical therapy plans consisting of effective stretches and exercises to strengthen muscles around the knee joint and restore knee function. For more information about our services, visit the FYZICAL website or stop by one of our locations near you.