Age / Sex : 53 / F

Age / Sex : 53/F

Chief complaint : Knee pain

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to In Sook Lee, MD ([email protected])

Courtesy :

Stress fracture

Discussion

Findings:

A sclerotic line is seen at the proximal portion of the medial condyle of tibia with step off of the adjacent cortex.

A fat-suppressed proton density-weighted coronal image of the corresponding knee portion reveals a low signal line, which is perpendicular to the cortex. Extensive edema is seen around the low signal line.

Differential Diagnosis:

None.

Diagnosis:  

Stress fracture of medial tibial condyle

Discussion:

Bone stress injuries resulting from overuse are frequent not only in athletes and in military trainees but also in healthy people who have recently started a new or intensive physical activity. The clinical diagnosis of bone stress injury is difficult, and plain radiographs can produce false-negative findings. In bone scans, false-positive cases are common, especially in the knee area, where osteonecrosis, osteochondritis dissecans, or ligamentous injury can result in abnormal uptake. One of the first choice diagnostic modalities for stress-related bone changes and for the internal derangement of the knee joint is MRI. A study reported that high proportion had a bone stress injury in the knee as a cause of exercise-induced knee pain. And other reports also stated that substantial proportion of stress injury is associated with knee. Among others medial tibial condyle is considered the most common location of stress fracture. This preponderance is considered to be associated with the fact that the weight bearing stress in the proximal tibia is thought to be greatest in the medial and posterior parts of the bone. In the shaft, the thick cortex handles most of the stress, whereas in the ends of the long bones, the cancellous trabeculae handle much of the weight bearing stress.

References:

Niva MH, Kiuru MJ, Haataja R, Pihlajamäki HK. Am J Sports Med. 2006 Jan;34(1):78-83