Follow Dr. Win Huang to Learn Clinical Diagnosis (Case 11)

Pain Below the Knee Is Not Always a Strain – A Cause You May Not Know

A few days ago, a young patient came to my clinic. He was an 11-year-old boy, and the reason for the visit was pain just below his right knee.

According to his parents, about four weeks earlier, he felt pain in the knee while running and suddenly turning. At the time, the family assumed it was simply a sports strain and expected that a few days of rest would solve the problem.

However, after several days the pain did not improve. During normal walking he felt relatively fine, but running, jumping, going up and down stairs, or squatting would clearly trigger pain below the knee. More importantly, the area below the knee had become noticeably swollen.

The parents later took him to the hospital, where an X-ray examination was performed. The doctor suggested that it might be a mild strain, but the radiology report also mentioned bony enlargement of the tibial tuberosity. No specific treatment was given, except advice to avoid running.

After several more weeks, the symptoms still had not improved and seemed to be getting slightly worse. Eventually, through a friend’s recommendation, the parents brought him to try acupuncture treatment.

During my examination, I noticed that the right tibial tuberosity was clearly larger than the left, and the area was very tender to pressure. There was also visible local swelling just below the patellar tendon.

At first glance, it would be easy to interpret this case as a simple knee strain caused by exercise. But after carefully analyzing the situation, I felt that explanation was not entirely convincing.

First, the pain occurred when the child turned while running. Although such a movement could trigger discomfort, it is not a particularly severe injury mechanism. To attribute the entire problem solely to that single movement seems somewhat forced.

Second, the X-ray had already shown bony enlargement of the tibial tuberosity. This type of change is usually not a feature of an acute injury, but rather suggests chronic traction over time. In other words, the underlying process was probably developing gradually long before this episode of pain.

Third, the clinical course also does not resemble a typical soft-tissue strain. In most mild strains, symptoms gradually improve with rest. In this child’s case, however, the pain did not improve after several days of rest and instead developed progressive swelling and significant tenderness.

Considering all these factors, I was more inclined to think of a condition that is relatively common in adolescents:
tibial tuberosity traction apophysitis, also known as Osgood–Schlatter disease.

This condition is most commonly seen in children between 10 and 14 years of age, especially those who are physically active. During this stage of growth, the tibial tuberosity growth center has not yet fully matured. The quadriceps muscle repeatedly pulls on this area through the patellar tendon, and over time this repetitive traction can lead to local inflammation and pain.

Therefore, the pain that appeared when the boy turned while running was most likely a triggering event, rather than the true underlying cause of the condition.

From a clinical perspective, recognizing this distinction is very important.

Although the pain can be quite noticeable, this condition is essentially a self-limiting problem related to growth and development. As the child grows older and the growth plate gradually matures and closes, the traction inflammation usually improves and eventually resolves in many patients.

For this reason, while planning treatment, I also took time to explain the situation carefully to the parents. The problem is not a serious structural injury, and it does not mean that the knee joint itself is damaged. With reduced high-impact activities such as running and jumping, and by avoiding repeated squatting, most children will gradually improve with time and appropriate management.

In many cases, the value of a correct diagnosis is not only in choosing the right treatment, but also in giving both the parents and the child a sense of reassurance and clarity.