Many runners will experience a knee injury at some point. Here’s an introduction to the most common sources of the pain.
Knee injuries with running may seem like death and taxes—inevitable. Many runners have stopped running because of knee pain or the worry that the constant impact will lead to a knee replacement or other problems down the road.
But don’t join your local aqua-aerobics class just yet. Despite the fact that studies show 30 to 50 percent of runners will suffer from an injury in a training year, they are neither inevitable nor untreatable when they do occur. Of the running injuries that do occur, one out of four involves the knee, making it the most commonly injured joint among runners.
The likelihood of an overuse injury occurring is influenced by outside factors such as training issues and running surface, as well as internal anatomic factors that are specific to each runner. Research on the risk factors for injury among runners shows that more experienced runners are at less risk for developing problems. Why? Because they were more likely to listen to their bodies and were less likely to make the training mistakes that contribute to many overuse injuries. Additionally, these more seasoned runners were conditioned to the impact and stress of running.
Research indicates another factor strongly associated with injury risk; a history of previous injury. As a prior running injury can lead to continued risk of future problems, research in Current Sports Medicine Reports stated, “The recovery and rehabilitation of these injuries clearly play a role in the subsequent risk of new running injuries.” Therefore, taking the time to fully rehabilitate from a knee injury and avoiding common training mistakes are crucial in avoiding the repeated cycle of injury.
Kneecap/Patellofemoral Pain/Runner’s Knee
So called Runner’s Knee or kneecap pain is the scourge of many runners. The patellofemoral, or kneecap joint, is formed by the patella/kneecap and the underlying groove of the femur. The kneecap plays a critical role in lengthening the lever arm of the quads, but in doing so is subjected to impact of up to eight times your bodyweight when running. Of the running injuries to the knee, kneecap pain is the most common, constituting a quarter of all knee injuries among runners.
Weak quads and outer hip muscles have both been linked to the development of kneecap pain. An increase in the angle of the hip and knee, known as the “Q-angle,” through excessive pronation or “knock-kneed” gait is also a risk factor.
Those with kneecap pain will usually experience a gradual onset of pain around the edge or underneath the kneecap during or after running. Other than running, this soreness can be aggravated by squatting, descending stairs or hills and sitting for long periods. Occasionally, mild swelling around the kneecap might be present but not the large amount of swelling present after a more traumatic knee injury. Frequently, there is an increase in the popping and cracking of the kneecap when bending and straightening the knee.
Many researchers have found that those who suffer from kneecap pain have decreased quad and outer hip strength. As complete isolation of any one portion of the muscle has proven to be difficult to attain, the emphasis of quad strengthening exercises should be regaining overall quad muscle strength rather than complete isolation of any one portion of the muscle.
Research in Medicine and Science in Sports and Exercise found that female runners with kneecap pain had significantly less outer hip/hip abductor muscle strength in their injured leg. Other studies have shown the importance of hip strengthening as a significant piece of recovery from kneecap pain. The addition of orthotics to address alignment of the foot and leg can also be helpful in treating kneecap pain.
Iliotibial Band Inflammation
The Iliotibial Band is a thick band of connective tissue that runs from the outer hip to an attachment just below the knee. According to the most recent running injury surveys, IT Band injuries may have overtaken kneecap pain as the most common injury among runners. Like other overuse running injuries that generally result from the constant repetition of the running motion, Iliotibial Band Syndrome (ITBS) is hypothesized to result from the friction of the IT Band sliding over the end of the femur near the knee. It is the most common cause of lateral knee pain among runners.
Weak outer hip muscles and decreased strength of the quad and hamstrings are risk factors for the development of ITBS. Other factors, such as “bow legs” and excessive running on banked surfaces have been postulated to increase the risk of ITBS.
ITBS pain will usually come on after a specific distance or time spent running and consists of pain on the outside portion of the knee. Initially, these symptoms will subside after finishing the run, but frequently will return with subsequent training. This pain can progress to the point where it is present with daily walking and stairs. Inflammation and mild swelling can also be present in the area. It is distinguished from other types of lateral knee pain as the pain is usually slightly above the knee joint.
Dr. Michael Fredericson, an expert in running-related injuries at Stanford, found that runners with ITBS were more likely to have weakness in the outer hip muscle and recommends strengthening of this area to treat the condition. Those with ITBS can also benefit from general quad and leg strengthening exercise. A comprehensive hip and IT Band stretching program has also been successful in improving ITB flexibility. Additionally, many sports medicine professionals use self-massage with a foam roll to address the soft-tissue mobility of the ITB.
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While not thought of as a running injury, meniscus and knee cartilage injuries are a growing source of knee pain in runners, perhaps due to the rising average age of runners. While meniscus tears can be the result of a slip, fall or sudden twist, runners generally experience age-related degenerative tearing of the meniscus.
The meniscus is a washer-like structure between the femur and tibia that weakens with age. The meniscus and cartilage of the knee serve as shock absorbers and, when damaged, compromise the ability of the knee to dampen the impact of running. Highlighting the importance of diagnosis and treatment, those who suffer from meniscal injuries are at greater risk of arthritis in later years.
While cartilage injuries can occur with running, running does not appear to lead to an increased risk of developing arthritis later in life. A review of arthritis research in Physical Medicine and Rehabilitation concluded that “runners appear to have no more risk of developing osteoarthritis than non-runners.”
Pain and joint swelling are the hallmarks of a meniscus tear. The pain is usually along the joint line on one side of the knee and can coincide with a locking sensation of the knee. This locking or catching sensation, caused by a torn piece of meniscus lodging inside the joint, is a serious complication and consultation with an orthopedic surgeon should be sought. If pain and swelling persist, surgical intervention may be needed as meniscus tears generally do not heal.
Depending on the severity and location of the tear, conservative treatment can be successful for those with small degenerative tears of the meniscus. Relative rest from running and cross-training should be used until pain and swelling has subsided.
While pain at the front of the knee is most likely to be caused by kneecap pain, overuse conditions of the patellar tendon, the tendon that connects the kneecap to the lower leg bone, are also a frequent source of injury among runners. While there is an ongoing debate over the correct term to refer to patellar tendon conditions (tendinitis vs. tendinosis vs. tendinopathy), experts do agree that it is caused by repetitive strain to the tendon. Additionally, German researchers reported in the Journal of Biomechanics that “Forefoot running appears to be a major factor in the development of patellar tendinopathy.” In other words, a barefoot/minimalist style of running may be a risk factor for developing patellar tendon pain.
As both patellar tendinopathy and kneecap pain cause pain in the front of the knee, identifying the source of pain can be difficult. Patellar tendinopathy can be differentiated from kneecap pain as the pain is directly on the tendon or its connection to the bone, while kneecap pain is usually located around or underneath the kneecap. Patellar tendon pain is usually insidious and often is related to an abrupt change in training. As the condition progresses, pain will be present while running and often with daily activity. It is important to note that mild tenderness of the tendon is normal in many runners.
A Sports Medicine article reviewing treatment of patellar tendon injuries recommends a focus on strengthening exercise, particularly of the quads. The article highlights the need for relative rest from running but stresses that complete rest may actually make the problem worse. Therefore, a careful balance between strengthening exercises and safe cardiovascular training should be the goal of a conservative recovery program.
If one wanted to establish a theme that runs through virtually every sports medicine article on knee injuries, it would be this: train smart. Overtraining is a major risk factor for injury and can be summarized as too many miles, too much intensity and too soon. Many running injuries suffered by both rookie and seasoned runners can be avoided by embracing the principles of cross-training, leg strengthening and a well-planned training program. Increases in volume and intensity should always be gradual and should never exceed more than 10 percent over the previous week or month.
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“As running injuries are usually the result of a combination of factors, many can benefit from a comprehensive analysis of gait, shoe wear patterns and muscle strength and flexibility” says Dr. Fredericson, director of Stanford’s Run Safe Clinic.
Although many studies note the high risk of injury with running, most also observe that the groups of runners studied were generally healthier than their counterparts that did not exercise. So run smart and run long.