Take A Knee: ACL Tears, Knee Pain and Injuries


One of the important functions of the patella is to act as a pulley for the large, powerful quadriceps muscles. As the quads come down from the hip, they narrow to form the quadriceps tendon, which runs over the kneecap before attaching to the tibia. The kneecap, by acting as a pulley, gives the quadriceps better leverage, allowing one to walk, run, jump squat and lift better. Overuse and over-stress of the quadriceps on a regular basis puts excess pressure on the kneecap, causing the cartilage on the patellar under-surface to wear down.

Another factor that leads to erosion of the knee cartilage is improper tracking of the kneecap. The underside of the kneecap has a central ridge that slides up and down along a groove located on the femur. That ridge happens to be the only area of bone coated with cartilage. When the patella goes off track, as it does with many people, it becomes like a train that has only one set of its wheels on the track. The set that’s dragging begins to wear away. A partially eroded kneecap will cause pain, because it’s unable to dampen the forces exerted on the underlying bone by the quadricep muscles. Depending on how advanced the condition is, it may hurt only at specific times, causing a quick twinge; or it may cause inflammation and hurt for sustained periods of time.

If the knee is aggravated, it will likely hurt during times of activity like running, squatting or going up and down stairs. Once the patellofemoral joint gets inflamed, it may even hurt when sitting, at rest, or driving with the knee bent. During times of inactivity, blood flow to the area is reduced and inflammation accumulates, resulting in pain.

Possible causes of patellofemoral pain include; chondromalacia patella, muscular imbalance and poor foot biomechanics. Chrondromalacia patella is a condition in which the cartilage behind the kneecap softens. Muscular imbalance is when two quadriceps muscles that attach to the knee, the vastus lateralis and the vastus medialis oblique, each pull on the kneecap from opposite directions in an effort to keep it properly centered as it moves along the groove of the femur. Most often it’s the vastus medialis oblique that’s weaker, allowing the kneecap to track too much toward the outside. If the lateral structures on the outside of the knee are too tight, the effect is the same, the kneecap tracks toward the outside. That can cause the equivalent of a partial dislocation, or subluxation, and subsequent pain and degeneration of the knee. Poor foot biomechanics like over pronation can cause mechanical problems that result in patellofemoral pain.

If the problem is chronic, consider strengthen and flexibility exercises to help smooth out cartilage. The best measures are preventive; at the first sign of patella pain, refrain from activities that place high compressive forces on the knee like stair climbing, squatting, running and heavy-resistance biking. Consider cross-training and substitute exercises that place less stress on the knee. Good substitutes are the cross-country ski machine, walking, pool running and low-resistance biking. Proper footwear to control over pronation and shock absorption are critical. Strength the muscles that protect the patella so they can perform as better internal shock absorbers, where less force is transmitted to the inflamed cartilage. Treat inflammation with cold therapy for 20 minutes after activity.

A sprain or rupture of the anterior cruciate ligament (ACL) is a very common knee injury. A tear of the ACL is caused by twisting of the knee with the foot planted, or by trauma, such as a front or side tackle. This injury is extremely common in skiing and may occur when one ski gets caught in the snow while the rest of the body keeps moving. Even though ACL injuries are serious, pain and swelling may not be immediately evident. What is noticeable is the feeling that something has popped and that the joint is inherently unstable. The injured joint should be iced, compressed and elevated immediately. The ligament rupture may require surgical reconstruction, as the ACL is unable to heal on its own due to insufficient blood supply. Surgical reconstruction involves using a tendon from another part of the body, such as the hamstring tendon or patellar tendon, to fashion a substitute ACL. Rehabilitation from an ACL injury can take up to 8 months.

A sprain or rupture of the posterior cruciate ligament (PCL) is not as common as an ACL tear. PCL injuries generally occur when the tibia is hit from the front while the knee is bent, like in a car accident where the knee hits the dashboard and the tibia is forced backward. PCL sprains can also occur when the knee is hyperextended.

Meniscal tears is any shearing or twisting of the knee beyond its normal range of motion that damages the medial or lateral meniscus. As with sprains and ruptures of the ACL, meniscal tears commonly occur when a person plants the foot with the toes pointed outward while twisting the upper body inward, or they are being tackled or hit on the outside of the leg or knee like in football. Often, there’s a combination of twisting and impact. As the meniscus ages, it can get brittle and may crack with minor trauma or simple repetitive use. Pain and swelling occur on the inner part of the knee; the pain is most noticeable when the knee is bent. People with torn menisci can develop a trick knee, in which the joint periodically locks or catches as a result of a torn edge of cartilage that gets caught in the hinges of the joint.

Where the meniscus is concerned, an accurate and detailed diagnosis is especially important, because the cartilage won’t heal on its own and can’t be replaced. If the tear is clean rather than jagged and uneven, and if it occurs along the outer edge, close to a blood supply, then the meniscus can be surgically repaired. The advantage of surgery is to retain the entire shock-absorbing meniscus; however, rehabilitation can take upwards of 6 months. If the meniscus cannot be repaired, then a partial menisectomy will be performed. Only the torn part of the meniscus is removed and as much intact meniscus as possible is left in the joint to maximize the remaining shock-absorbing capabilities of the knee.

The most common knee injuries include; ligament sprains, patellar tendinitis, patellofemoral pain syndrome and meniscal tears. Ligament sprains occur most frequently in the ACL. Patellar tendinitis is inflammation of the tendon just below the kneecap, where it connects to the lower leg. Patellofemroal pain syndrome is pain beneath the knee cap, caused by a number of factor and finally, meniscal tears, is damage to the special shock-absorbing pads that cushion the space between the thigh bone and the lower leg bone.

Patellar tendinitis, or jumper’s knee, is inflammation of the thick tendon that runs under the kneecap, connecting the quadriceps to the lower leg. Heavy squatting, jumping and sprinting all place a lot of stress on the patellar tendon and cause a series of small tears along the tissue, and ultimately a partial or even complete rupture. The damage usually begins before symptoms are felt and results from the knee not having enough time to recover between bouts of exercise an activity. The pain can be felt just below the kneecap, right on the tendon. Since this is primarily an overuse condition resulting in inflammation, rest from aggravating activity is vital. Once the pain has subsided, a gradual return to regular activities should be accompanied by stretching and strengthening exercises.

Bursitis of the knee is also know as water on the knee. The prepatellar bursa, a fluid-filled sac located right over the kneecap, becomes inflamed, causing pain, swelling and a feeling of radiating heat around the joint. Knee bursitis can be precipitated by one incident, such as landing or falling on the knee, or can result from cumulative, hard impacts from running or jumping. RICE therapy; rest, ice, compression and elevation help encourage recovery.