Avulsion fracture

Traumatic complete displacement of a tooth from its socket in alveolar bone. It is a serious dental emergency in which prompt management (within 20–40 minutes of injury) affects the prognosis of the tooth.[1]

Proximal fractures of the fifth metatarsal bone:
- Proximal diaphysis, typically stress fracture.[2][3]
- Metaphysis: Jones fracture[4]
-Tuberosity: Pseudo-Jones fracture[5] (avulsion fracture).[6]
Normal anatomy:
- Apophysis: Normal at 10 - 16 years.[7]
- Os vesalianum, an accessory bone.[8]

The tuberosity avulsion fracture (also known as pseudo-Jones fracture or dancer's fracture[9] is a common fracture of the fifth metatarsal (the bone on the outside edge of the foot extending to the little toe).[10] This fracture is likely caused by the lateral band of the plantar aponeurosis (tendon).[11] Most of these fractures are treated with a hard-soled shoe or walking cast. This is needed until the pain goes away and then the patient can return to normal activities.[10] Healing is usually completed within eight weeks.[12]

X-ray of a 15 year old male, showing an older avulsion fracture of the tibial tuberosity.

A tibial tuberosity avulsion fracture is an incomplete or complete separation of the tibial tuberosity from the tibia. This occurs as a result of a violent contraction of the quadriceps muscles, most often as a result of a high-power jump. Incomplete fractures are usually treatable with the traditional RICE (rest, ice, compression, elevation) method, but complete/displaced fractures will most often require surgery to pin the tuberosity back in place. Tibial tuberosity avulsions occur most often in teenagers that engage in a large amount of sporting activities, and many studies have shown a history with Osgood-Schlatter's disease to be linked to the fracture.

In 2001, Bruce Rothschild and other paleontologists published a study examining evidence for tendon avulsions in theropod dinosaurs. Among the dinosaurs studied, Avulsion injuries were only noted among Tyrannosaurus and Allosaurus. Scars from these sorts of injuries were limited to the humerus and scapula. A divot on the humerus of Sue the T. rex was one such avulsion. The divot appears to be located at the origin of the deltoid or teres major muscles. The localization in theropod scapulae as evidenced by the tendon avulsion in Sue suggests that theropods may have had a musculature more complex and functionally different from those of their descendants, the birds.[14]