The stages of human life

From 'Atlas of human anatomy and surgery,' 1831-1854

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Myositis Ossificans (MO)

It's a type of heterotopic ossification that develops within a muscle and is known to occur following muscle injury or bone fracture. It remains unclear why MO occurs, but it can develop at any site of muscle injury.

MO may be palpable as early as four to five days after a quadriceps contusion but may take several weeks to develop. Early symptoms include persistent pain and swelling that does not appear to be resolving. Later symptoms include a worsening of pain with activity or swelling, early morning or night pain, and decreasing range of motion after two to three weeks. If MO is suspected, plain radiographs or ultrasound should be obtained. Two to four weeks are typically needed for MO to become visible on plain radiographs.

It's histology is similar to osteosarcoma, even though it's benign and does not evolve into a malignant tumor. It's one of those "don't touch" lesions that are diagnosed radiologically & clinically alone, and don't need a histopathological study because it will only confuse you more.

Also called skeletal "leave alone" lesions. They are so characteristic radiographically, that further diagnostic tests such as a biopsy are unnecessary and can be frankly misleading and lead to additional unnecessary surgery. Thus a radiologic diagnosis should be made without a list of differential possibilities.

The knee is stabilized mainly by the quadriceps tendon in front and the tendon of the semimembranosus muscle on the rear of the thigh. Developing strength in these muscles therefore reduces the risk of knee injury.

Look for the collateral ligaments, menisci, and the cruciate ligaments. These are very important in knee stabilization and are common sites for knee injury.

Although the knee can bear a lot of weight, it is highly vulnerable to rotational and horizontal stress, especially when the knee is flexed (as in skiing or running) and receives a blow from behind or from the side. The most common injuries are to a meniscus or the anterior cruciate ligament (ACL).