Osgood-Schlatters disease / Syndrome
What is Osgood-Schlatters disease?
Osgood-Schlatters disease is an inflammation of the tibial tubercle, a part of the tibia at the top and front of the bone where the patellar ligament is attached. It is located 2 cm below the kneecap and is caused by the bone being overused, especially during late childhood or adolescence. It is named after Dr Robert Osgood and Dr Carl Schlatter, who first described the disease in 1903.
Normal structure of the knee
The knee is a hinge joint in the lower limb, and consists of the tibia (shin bone), femur (thigh bone), patella (kneecap). The fibula (calf bone) starts below the level of the knee and is not very involved in the joint. The surfaces of the femur and tibia facing each other are covered in articular cartilage, which is extremely smooth and reduces friction. The space between the cartilage is filled with synovial fluid, a fluid which further reduces friction and provides a small amount of cushioning. The synovial fluid is encased in a synovial membrane, which produces the fluid.
There are also a number ligaments involved in the knee joint. Ligaments are strong bands of collagen (a type of protein found in the body) fibres that run between bones. The anterior cruciate ligament sits in front of the articular cartilage and runs from the lateral (outer) part of the front of the femur to the medial (inner) part of the front of the tibia. The posterior cruciate ligament sits behind the articular cartilage and runs in the opposite direction. There are also two collateral ligaments - the lateral collateral ligament runs from the outer side of the femur to the outer side of the fibula, and the medial collateral ligament runs from the inner side of the femur to the inner side of the tibia.
The patella is attached to the knee joint in two ways. It attaches to the quadriceps muscle (a group of four muscles in the thigh) attaches to the patella from above by the quadriceps tendon (tendons are similar to ligaments in structure, however, they attach muscles to bone). The patella also attaches to the tibia at the tibial tuberosity (a raised area near the top of the tibia) by the patellar ligament. It is the forces acting on the tibial tuberosity through the patellar ligament that lead to Osgood-Schlatters disease.
Who can get Osgood-Schlatters disease?
Osgood-Schlatters disease typically affects boys and girls in late childhood or early adolescence, and it has been shown that it is most common between the ages of 11 and 15 years, as the area is particularly vulnerable to very small avulsion fractures in this age group. Bones typically grow faster than muscles and tendons in adolescence and this can result in tightness, thus, making adolescents more vulnerable to Osgood-Schlatters disease. Both boys and girls are equally likely to get Osgood-Schlatters disease but it is more common in boys. This is probably because boys usually do more sports and physical exercise.
It is caused by overuse and excessive force acting on the tibial tubercle, and is more common in athletes. In a retrospective study of young athletes, it was shown that 21.2 % of the athletes had suffered from Osgood-Schlatters disease, as compared to 4.5 % of the non-athletic group, and the condition was present in 12.9 % of all the people involved in the study. Sports that require lots of running, jumping, squatting or kneeling are particularly associated with Osgood-Schlatters disease, and the athletes are often involved in football, basketball, gymnastics, or ballet.
What are the symptoms of Osgood-Schlatters disease
Osgood-Schlatters disease typically causes pain or tenderness in the tibial tubercle, a few centimetres below the kneecap, and can also cause swelling which may be visible. The pain can occur on activity of the knee (especially in activities which involve running, jumping, or climbing stairs and can improve with rest; but it can also be constant, and the severity and duration of the pain can vary between individuals. There may be an associated tightness of the quadriceps or hamstrings (muscles in the thigh, the hamstrings are at the back and the quadriceps are at the front), but it is uncertain as to whether this is a cause or a consequence. It typically only affects one knee.
Osgood-Schlatters disease can be diagnosed clinically and scans are only necessary except to exclude other conditions, however an ultrasound scan can be used to detect Osgood-Schlatter disease in patients who present with slightly different symptoms. This would show fragmenting of the tibial tubercle and swelling of the overlying cartilage. In more advanced cases, the patellar ligament may be affected.
What are the treatments for Osgood-Schlatters disease
The most important treatment is rest and restriction of sporting activities. Knee pads or a knee immobiliser combined with an isometric exercise program, in which the joints do not move, may also help. It can also help to do exercises to increase the flexibility of the hamstrings and quadriceps. Symptoms may reoccur occasionally while the tibial tubercle is healing, a process which can take 18 - 24 months to complete. Ice or cold therapy can help with the pain and inflammation. Knee supports can help by reducing tension on the knee: a simple patella tendon strap will work, but heat-retaining supports are also available that can speed up recovery. Non-steroidal anti-inflammatory agents (such as aspirin or ibuprofen) can also help with the pain, but care must be taken to avoid stomach or kidney problems.
What other conditions are similar to Osgood-Schlatters disease
Front knee pain is common in adolescence and often has no cause despite many investigations. This is known as anterior knee pain syndrome, and settles with time. Isometric exercises and avoiding high-heeled shoes can help.
Sinding-Larsen-Johansson disease is very similar to Osgood-Schlatters disease in that they are both caused by forces acting via the patellar ligament. Sinding-Larsen-Johansson disease typically affects children or adolescents, however the injury is on the lower part of the patella rather than at the upper part of the tibia.
Bursitis is inflammation of the bursa, a sac of lubricant between ligaments and bone. Prepatellar bursitis is the most common type of bursitis, and can cause fluctuating pain, tenderness and swelling in front of the kneecap. Superficial or deep infrapatellar bursitis can cause fluctuating pain, tenderness and swelling just below the kneecap, either in front of (superficial) or behind (deep) the patellar ligament. This can often be caused by kneeling too much and can be resolved by avoiding kneeling and with local corticosteroid injections.
Patellar tendonitis is a condition in which the patellar ligament and the tissues surrounding the patella become inflamed. It is typically caused by exercise and associated with exercises that involve jumping activities, and can also be found in people who participate in football, basketball, or running. It can also occur after injury to the patellar ligament. This condition can cause pain directly around the patella.
Arthritis can cause pain in the knee joint. Osteoarthritis is caused by wearing away of the articular cartilage in the joint, and rarely presents in young people. Rheumatoid arthritis is caused by the body's defences acting against the bone and cartilage in the joint. In addition, the knee can be affected in virtually all types of acute monoarthritis (where only one joint is affected), the exact type of monoarthritis can be worked out by looking at which other joint is affected. The knee is also the most common site for chronic inflammatory monoarthritis.