The knee is a very large joint that carries an important role in weight bearing and proper movement mechanics. The main component of the knee involves the articulation between the femur (thigh bone) and the tibia (shin bone). In between these two bones you have a medial and lateral meniscus – a big piece of fibrocartilage that acts as a cushion in the joint. In addition to that you have 4 major ligaments that provide stability; the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). In the front of the knee sits your patella or knee cap. This bone “floats” as it is embedded in the quadriceps tendon and sits on top of a groove in the femur. The articulation between the patella and femur is called the patellofemoral joint. On the outside of the knee, there is an articulation between the fibula and the tibia which is called the proximal tibiofibular joint. This joint is not a common source of pain or movement dysfunction but it does happen on occasion.
Muscles and joints of the knee can be common sources of pain (see Muscle & Joint Pain page). In addition to those, here are some other conditions that physical therapy can help you with:
Patellofemoral Pain Syndrome – Also known as Runner’s Knee this is a condition presenting with pain in the front of the knee around the knee cap. Other terms used for this condition may include retropatellar pain or chondromalacia patella. This problem may develop from several factors but tight and weak quadriceps as well as weak gluteal muscles are a common cause. The thought it that muscle imbalances in the lower body lead to abnormal tracking of the patella in the groove of the femur which leads to irritation and wear and tear under the knee cap. This condition can vary from mild to severe in intensity but rarely involves swelling. This is an overuse condition with a gradual onset and does not generally start from a trauma.
Patellar Tendinitis – Also known as Jumper’s Knee this condition also presents with pain in the front of the knee but it is specifically located in the patellar tendon. This tendon connects the knee cap to the shin bone. The onset and cause of patellar tendinitis is similar to that of patellofemoral pain in that it is usual a gradual onset due to overuse and muscle imbalances. This problem is more likely to occur in individuals who do repetitive jumping activities like basketball or volleyball as compared to runners who are more likely to get patellofemoral pain.
Iliotibial Band Syndrome – IT Band syndrome can present as pain on the outside of the knee or outside of the hip based on where it attaches. The IT Band is a large piece of connective tissue that spans down the outside of the leg from the hip to the knee. Weak hip and leg muscles, asymmetrical pelvic rotations, or lower extremity tightness can lead to development of IT band syndrome. Runner’s who get this problem generally run upwards of 20 miles per week so it is uncommon to see in beginner runners. An important thing to understand in this condition is that the IT band is a very thick fibrous tissue. This means that it is not easily stretched. Many people believe their IT band is tight but this is rarely the main factor in development of problems. Yes, foam rolling and stretching can provide some relief and be beneficial but it is NOT because you are lengthening the IT band.
ACL Tear – ACL ruptures are a common knee injury sustained by men and women athletes of all types. This is a traumatic injury that often results from non-contact cutting and pivoting movements. A force that results in hyperextension of the knee can tear the ACL. Forces coming from the outside of the knee (valgus) along with excess rotation are also common mechanisms of injury. An ACL tear is often accompanied by a “pop” sound followed by swelling within 24 hours. These injuries should be evaluated by a physician to determine the need for surgery.
Meniscus Tear – As mentioned above, the meniscus acts as a cushion in the knee and reduces friction in the joint. Traumatic injuries to the meniscus can occur with similar mechanisms as an ACL tear but in addition, these occur with a heavy weight-bearing rotational movement to the knee especially when it is bent. Rotational forces to the knee while in a squatting position places a lot of stress to the meniscus. Tears occur in both the medial and lateral meniscus and are managed based on their size, type, and location. It is important to be aware that you don’t need trauma to tear the meniscus. Degenerative tears of the meniscus can occur as well. This is thought to be due to wear and tear of the fibrocartilage (like a used tired) as we age.
Patellar Discloation – This occurs when the knee cap forcefully slips out of place resulting in rupture of the ligament on the inside of the knee that anchors it in place – the medial patellofemoral ligament. This can above from non-contact or contact injuries to the knee that result in the femur going in and the patella going out. After a knee dislocation, individuals may complain of repetitive patellar subluxations and knee pain due to the instability without the ligament in place. A subluxation involves the knee cap sliding out of place briefly but then returning to its normal position. This problem may require surgical intervention.
Quadriceps Tendon Rupture – The quadriceps tendon sits above the knee cap and is an extension of the quadriceps muscle. This is a rare but serious injury. It is caused by forceful trauma to the knee as can occur in motor vehicle accidents, sports injuries, and falls. A rapid and forceful bending of the knee can cause the quad tendon to tear. This requires surgery to fix followed by extensive rehab to return to normal function.
Patellar Tendon Rupture – Similar to the quadriceps tendon rupture, this occurs from forceful trauma to the knee. It is even more rare than the quadriceps tendon rupture and also more serious. This injury also requires surgery to fix followed by extensive physical therapy.
MCL, LCL, and PCL tears – The other 3 major knee ligaments are also causes for knee pain and disability when injured. MCL tears are far more common than LCL or PCL tears but any of them can result in pain, swelling, loss of motion, and weakness. MVAs, sports injuries, and falls contribute to most of these knee ligaments tears. Some injuries can be managed with physical therapy alone while others require surgery then rehab.