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Common Conditions of the Knee
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MENISCAL TEARSThere are two kinds of cartilage in the knee that protect the surfaces of the bones during weight bearing. Articular cartilage covers the ends of bones in the femur (thigh bone), tibia (lower leg bone), and patella (knee cap) much like the white, shiny ends of a chicken bone. Menisci are the two c-shaped fibrous cartilages that look like washers in between the knee bones and act as shock absorbers.
Injuries to the meniscus cartilage can occur with twisting injuries of the knee. Patients more commonly incur tears of the inside (medial) meniscus. A tear in the meniscus disrupts the normal frictionless system of the knee, and may cause the knee to click, catch, pop, or feel like it’s unstable. If the tear is large enough or in a complex pattern, it can flap inside the knee as you try to move it and cause it to lock up. Pain is especially noted with twisting or squatting and a variable amount of swelling may be present from fluid that accumulates in response to injury and friction in the knee. Suspicion and diagnosis of a meniscal tear is usually made with a careful history and physical examination. Since an injury is often reported, x-rays are usually taken to exclude the presence of any fractures and an MRI is often recommended to confirm mensical and/ or any additional soft tissue injury. The meniscal cartilage does not have a rich blood supply and therefore meniscal tears do not repair themselves. A torn meniscus in the knee creates unwanted friction on the articular cartilage increasing the risk and rate of arthritis development. In addition, leaving a torn meniscus in the knee can cause continued mechanical problems with movement, and even larger, more complex tears or loose fragments in the knee. For these reasons, a torn meniscus is usually not treated conservatively, but rather surgically using a procedure called Knee arthroscopy. During this procedure the torn part of the meniscus will be removed and the edges smoothed to prevent further tearing. LIGAMENT TEARSWhile cartilage provides the “cushion” in the knee, ligaments provide the stability. There are four ligaments in the knee: collateral ligaments are situated outside and inside of the knee and cruciate ligaments are within the knee itself. Collateral ligaments provide stability for the knee in the sideways movements, away and towards the body, whereas cruciate ligaments provide stability for the knee in the forward and backwards movements. A collateral ligament injury is usually not as serious as a cruciate ligament injury, although both types of ligaments can be injured at the same time. The medial collateral ligament (MCL) is the most common collateral ligament injury. It can occur when stress is placed against the outside of the knee forcing it towards the body, as with clipping in football. A lateral collateral ligament injury is less common and occurs when a force is placed against the inside of the knee forcing the knee away from the body. Injury to the collateral ligaments produces pain, but not usually to the point of completely impairing activity. The injured ligament may be tender anywhere along its course if pressed. Stiffness and swelling are common, but there are rarely any mechanical symptoms such as clicking, popping, locking, unless you also have a meniscal tear. The cruciate ligaments provide the most stability for the knee and injuries to these ligaments are usually considered more severe than injuries to the collateral ligaments. Anterior cruciate ligament (ACL) injuries usually occur with activities that require brisk deceleration or plant- pivot-twist maneuvers. In acute injury, an audible “pop” is often heard followed by significant swelling that causes pain and decreased mobility. More chronic problems of laxity in the ACL causes the knee to feel unstable with activity. The posterior cruciate ligament (PCL) is twice as strong as the ACL and thus, is much less commonly injured. However, when an injury to the PCL does occur it is usually as a result of a direct blow to the front of the knee just below the kneecap. Suspicion and diagnosis of all ligament injuries begins with a careful history and physical examination. As with all injuries, x-rays are usually taken to exclude the presence of any fractures. A MRI is often recommended to confirm the nature of internal derangement in the knee because ligament injuries often have other associated injuries, such as meniscal cartilage tears. Collateral ligaments are more likely to heal on their own, and thus the treatment for these injuries is usually non-operative, unless there are other associated problems that require surgery (such as a meniscal tear). Treatment might involve the use of crutches, immobilization or the use of a hinged knee brace for a period of time, followed by a course of physical therapy to aid in mobility and strengthening of the quadriceps and hamstring muscles. The required length of immobilization and the time required to return to normal activities is based on the severity of the torn or stretched ligament. The cruciate ligaments are not as likely to heal on their own. This is thought to be because they are within the joint, where the joint fluid insulates the ligaments from access to the immune system cells that help to recruit more cells that aid in ligament repair. Treatment of ACL injuries varies considerably depending on the severity of the tear and the physical expectations and demands each individual patient faces. Arthroscopy only may be recommended to remove the torn portion of the ligament followed by aggressive physical therapy for strengthening and stabilizing the knee. Bracing for pivoting sports or other strenuous activities may be recommended. ACL reconstruction is a rigorous procedure where a “new” ligament is grafted into place in the knee. The replacement ligament can come from a variety of sources, including from within the patient’s own body. Physical therapy after this procedure is extensive, aggressive, and vital to the outcome of the reconstruction. Reconstruction of the PCL is not common, as it is much harder to reproduce a positive outcome as with the ACL reconstruction procedures. However, surgery may be recommended if there is an associated fracture, cartilage injury, or need for ligament debridement. Aggressive physical therapy is usually utilized in the case of PCL injuries. OSGOOD SCHLATTER’SOsgood Schlatter’s condition usually affects young, active children who are still growing. There is usually no real history of injury, but pain over a period of time occurs right below the knee over the bony prominence of the shin bone (called the tibial tubercle). Since conservative treatment is not as effective for patients whose bones are mature and who have stopped growing, surgery is more likely to be recommended.
OSTEOCHONDRITIS DISSECANSThere are two kinds of cartilage in the knee that protect the surfaces of the bones during weight bearing. One type, called articular cartilage, covers the ends of bones in the knee much like the white, shiny ends of a chicken bone. Osteochondritis dissecans is a condition where the bone under the articular cartilage (called subchondral bone) looses its blood supply. When this happens, the affected part of the bone can weaken, possibly die, and sometimes even break loose. The most common sites for this problem occur on the end part of the femur bone, especially on the medial femoral condyle (see picture below) near the center of the knee. Other common body sites are in the ankle or the end of the humerus where it forms the elbow. The cause of osteochondritis dissecans is unknown, but it is thought to be related to repetitive small stresses that disrupt the blood supply in the affected area. It is most common in developing boys ages 10 to 20 years old.
Suspicion of osteochondritis dissecans is made with a careful history and physical examination. X-rays of the knee in a variety of positions can help your physician see the quality of bone areas where osteochondritis dissecans is likely to occur and helps to exclude other causes of knee pain. An MRI is a study that primarily looks at the soft tissues to exclude internal derangement in the knee, but can also confirm the presence of poorly vascularized bone, as found with osteochondritis dissecans. Treatment of osteochondritis dissecans depends on whether or not the articular cartilage over the affected bone is loose or intact and also the growth status of the patient. Knee arthroscopy is beneficial for removing any loose cartilage and/ or for drilling any poorly vascularized bone to stimulate return of the blood supply to that area. After surgery, weight bearing is restricted while the blood supply is allowed to restore itself to the affected area. Physical therapy will help with recovery and the advance of activity. Non-operative treatment involves a dramatic reduction in activity for several months with the avoidance of running and jumping activities. Full weight bearing may be restricted, and crutches may be recommended for walking. Since conservative treatment is not as effective for patients whose bones are mature and who have stopped growing, surgery is more likely to be recommended. PATELLAR CONDITIONSThe knee cap, or patella, is a small bone that is suspended by two tendons over the knee. Conditions affecting the knee cap are either acute or chronic. Acute problems usually relate to injury, such as rupture and/ or fracture or bursitis, whereas chronic problems of pain and discomfort are often related to conditions such as malignment, instability and/ or dislocation, tendonitis, or arthritis.
A brief description of the common patella conditions is listed below: - Bursitis: There are several fluid filled sacs about the knee, called bursas, which can become inflamed or infected if there is some kind of direct trauma or blow to the area. The most common bursa to experience problems is the pre-patellar bursa which sits directly over the knee cap. Bursitis usually causes an obvious swelling or inflammation in the affected area which can cause pain with bending the knee. An ACE bandage can be worn to decrease the swelling and the avoidance of kneeling activities is recommended. Aspiration of the bursa fluid provides temporary relief, but recurrence is common so surgical removal of the bursa is often recommended for long-standing problems. If the fluid becomes infected, the knee can become red and warm, or even drain out the leg. Infected bursas are concerning because they can extend into the entire knee joint and so hospitalization and the administration of antibiotic medications, and possibly even surgical removal are often recommended. - Patella tendon rupture or fracture: Rupture and/ or fracture of the patella is almost always related to an acute injury, such as with a fall on a bent knee. The tendons around the patella are strong, so it is not uncommon for part of the patella bone to break off if the tendon ruptures. Patients with this injury often have a conglomeration of signs and symptoms such as history of injury, instability with walking, weakness or inability to straighten the affected leg, significant swelling, and/ or an obvious defect. Since the patella tendon rarely partially tears and associated fractures are not uncommon, surgical repair is usually recommended for these injuries. - Malignment: This refers to abnormal tracking of the knee cap with movement of the knee. Usually malignment occurs to the outside of the knee and it is usually a result of individual differences or predispositions in patient anatomy. Patients who might be predisposed to malignment might have a knee cap that is “higher” than normal, or knees that are more hyperextended than typically seen (causing tissues around the knee cap to be more lax or loose). Malignment can cause pain under the knee cap, especially with stairs or prolonged sitting or standing. Significant malignment can be seen with physical examination of the knee as well as on x-ray. - - Instability / Dislocation: This refers to a spectrum of problems from chronic abnormal tracking to partial or complete dislocation. Acute events of instability or dislocation almost always involve the knee cap slipping to the outside of the knee (versus to the inside). Girls tend to have more problems with instability and dislocation, because their ligaments are generally more lax or loose. Initial episodes are usually very painful, but recurrent, milder episodes often follow. Straightening the knee or manipulating the knee cap often causes apprehension. True dislocation results in significant swelling and tenderness around the knee cap. Dislocated knee caps usually go back into place spontaneously when the knee is straightened, but this may be helped with the use of an ACE bandage or some type of immobilization of the knee. - Patella Femoral Syndrome: Pain in the front part of the knee that increases with overuse or overloading of the joint, such as with activities like running, climbing stairs, kneeling, squatting, or prolonged sitting. This is considered when causes for symptoms from an acute injury, malignment, instability, or arthritis have been eliminated. - Patellar tendonitis: Tendonitis about the knee cap, or “jumper’s knee” is a condition related to overuse or overloading of the group of muscles and their tendons that help the knee to straighten. This is often called “jumper’s knee” because it is usually related to jumping sports, or a strain in the knee related to erratic or changed exercise habits, lifting, or weight gain. Pain is usually felt at the end of activity and felt mostly in the areas where the tendons that support and suspend the knee cap insert into bone.. - Arthritis: The patella sits in a groove over the femur called the trochlea. Both the femur and the undersurface of the patella are covered with cartilage that aids in a smooth, frictionless contact between the bones as the knee moves. When there are poor mechanics in the knee, or structures in the knee are not aligned properly, there is increased friction generated with movements that can cause wear-and-tear (arthritis). Patients with arthritis specifically on the undersurface of the patella have pain when direct pressure is placed over the knee cap. They also might have problems during movements such as squatting, getting up from a chair, or climbing stairs. With the exception of acute injuries that need repair or immediate intervention, treatment is often similar amongst many patellar conditions. Often a period of rest from aggravating activities with the use of anti-inflammatory medications is helpful in settling down acute flare ups. In addition, physical therapy is often recommended for stretching the muscles around the knee effectively as well as strengthening and tightening the support structures around the knee. The use of a brace or immobilization device can also help to stabilize and support the knee during activities, causing the structures to stay tight and in place appropriately. If these methods fail and symptoms persist, there are several surgical options that can help re-align the patella and create the proper mechanics in the knee to alleviate many of the problems described above. ARTHRITISThe knee has two kinds of cartilage to enable smooth, frictionless movements and cushioning with force. There are multiple kinds of arthritic processes that can affect the knee, the most common being osteo-arthritis (wear-and-tear in the cartilage that covers the ends of the bones like the shiny ends of a chicken bone, called articular cartilage), rheumatoid arthritis (an autoimmune process of joint destruction and deformity), and post-traumatic arthritis (after an injury). Wear-and-tear arthritis is perhaps the most common form of arthritis in the knee seen in the orthopedic setting. There are three main areas in the knee where wear and tear can cause problems, called compartments. Osteo-arthritis in the knee most commonly develops in the inside, or medial compartment. Patients with arthritis often experience a gradual onset of problems in the knee. A variety of common complaints including stiffness and decreased motion, swelling, buckling or giving way, locking or catching, or pain with normal activities such as walking or climbing stairs. Click here fore more information on the general process, diagnosis, and treatment of arthritis conditions. |
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