X Ray of an affected knee.
Osgood-Schlatter’s Disease
Osgood–Schlatter’s disease is a condition that affects the small growth plate that exists at the ‘bump’ that exists at the very top of the shin bone, directly below the kneecap (patella). The bump is called the tibial tuberosity and it is prominent because the patella tendon attaches to the bone there. The patella tendon is part of the big muscle group called the Quadriceps that exists on the front of the thigh. At about the knee level, the the quadriceps change from being ‘meaty’ muscle tissue to a thick, rope-like tendon that contains the kneecap within it and then runs down to attach to the tibial tuberosity at its bottom end.
Who gets Osgood-Schlatter’s Disease ?
Osgood–Schlatter’s disease occurs in children between the ages of 9–16 years. Around 75% of cases affect boys and occurs in up to 20% of sporty children compared to 4% of a group of all activity levels. In a quarter of cases, both knees are affected and it is more likely to occur around periods of rapid growth. As the condition is due to irritation and damage of the growth plate, it can only occur while the growth plate is present, up to the age of 16 years approximately. Adults cannot get Osgood-Schlatter’s Disease as the growth plate closes over and turns into bone with skeletal maturity.
Why does Osgood Schlatter’s disease occur ?
As the Quadriceps muscle contracts, tensile stress is transmitted to the tuberosity. A good way to think of this is to imagine a rope screwed to a plaster wall. When you pull on it very hard, if everything is solid enough, nothing bad will happen. However, if the fixation to the wall is less strong than the pull exerted on the rope, a chunk of plaster will pull free. In Osgood–Schlatter’s disease, it is the small bump of bone at the tuberosity that pulls loose. In children, the tendon / rope is generally the strongest link in the chain and so a patella tendon injury is less common. This changes in adulthood. A fracture of this sort where the bone is pulled off by a tendon or other soft tissue is called an avulsion fracture. The body’s response to this is to grow extra bone to shore up the area and so, past sufferers of Osgood–Schlatter’s disease will usually have a more prominent bump than others that will last a lifetime.
The pain of Osgood-Schlatter’s Disease is usually experienced when running, jumping, squatting, kneeling and going up or down stairs. It can be reproduced by having the child try to straighten the knee out against resistance.
Mechanical factors play a big role in Osgood–Schlatter’s disease. When the feet are in ‘perfect’ alignment, the Quadriceps muscles, patella tendon, kneecap and tibial tuberosity are all in a line. Any force created by using the thigh muscles transmits to the tuberosity in a direct, front-on direction. A pronated foot will increase the Quadriceps angle in a similar way that a knock kneed position would. The change in the angle of pull can leave the trochanter more vulnerable from an angled pulling force.
How to treat Osgood-Schlatter’s Disease
Osgood–Schlatter’s disease should be initially treated with RICE (Rest, Ice, Compression, and Elevation) and some non-steroidal anti-inflammatory drugs (such as paracetamol) if indicated. It is almost always possible to recommence sport in a month or so, though return to activity should be supervised by a qualified person such as a podiatrist, physiotherapist or experienced adolescent coach. Quadriceps and Hamstrings should be stretched if tight.
A podiatrist is an important part of the treatment team to assess foot function and it’s affect on the mechanical workings of the knee. Orthotics are fairly likely to be used to create a better angle of pull as discussed above.
To learn more about Osgood-Schlatter’s Disease and other podiatric conditions, please use this link to return to Podiatry FAQs.