An avulsion fracture is a

bone fracture A bone fracture (abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a ''c ...

which occurs when a fragment of bone tears away from the main mass of bone as a result of

physical trauma Injury is physiology, physiological damage to the living tissue of any organism, whether Injury in humans, in humans, Injury in animals, in other animals, or Injury in plants, in plants. Injuries can be caused in many ways, including mechanic ...

. This can occur at the

ligament A ligament is a type of fibrous connective tissue in the body that connects bones to other bones. It also connects flight feathers to bones, in dinosaurs and birds. All 30,000 species of amniotes (land animals with internal bones) have liga ...

by the application of forces external to the body (such as a fall or pull) or at the

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

by a muscular contraction that is stronger than the forces holding the bone together. Generally muscular avulsion is prevented by the neurological limitations placed on

muscle contraction Muscle contraction is the activation of Tension (physics), tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in musc ...

s. Highly trained

athletes An athlete is most commonly a person who competes in one or more sports involving physical strength, speed, power, or endurance. Sometimes, the word "athlete" is used to refer specifically to sport of athletics competitors, i.e. including trac ...

can overcome this neurological inhibition of strength and produce a much greater force output capable of breaking or avulsing a bone.

Types

Dental avulsion

Traumatic Trauma most often refers to: *Psychological trauma, in psychology and psychiatric medicine, refers to severe mental and emotional injury caused by distressing events *Traumatic injury, sudden physical injury caused by an external force, which doe ...

complete displacement of a

tooth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tea ...

from its socket in

alveolar bone The alveolar process () is the portion of bone containing the tooth sockets on the jaw bones (in humans, the maxilla and the mandible). The alveolar process is covered by gums within the mouth, terminating roughly along the line of the mandibu ...

. It is a serious dental emergency in which prompt management (within 20–40 minutes of injury) affects the

prognosis Prognosis ( Greek: πρόγνωσις "fore-knowing, foreseeing"; : prognoses) is a medical term for predicting the likelihood or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) ...

of the tooth.

Tuberosity avulsion of the 5th metatarsal

left, Proximal fractures of 5th metatarsal The

tuberosity In the skeleton of humans and other animals, a tubercle, tuberosity or apophysis is a protrusion or eminence that serves as an attachment for skeletal muscles. The muscles attach by tendons, where the enthesis is the connective tissue between the ...

avulsion fracture (also known as pseudo-Jones fracture or dancer's fracture is a common fracture of the

fifth metatarsal The fifth metatarsal bone is a long bone in the foot, and is palpable along the distal outer edges of the feet. It is the second smallest of the five metatarsal bones. The fifth metatarsal is analogous to the fifth metacarpal bone in the hand. As ...

(the bone on the outside edge of the foot extending to the little toe). This fracture is likely caused by the lateral band of the

plantar aponeurosis The plantar fascia or plantar aponeurosis is the thick connective tissue aponeurosis which supports the arch on the bottom (plantar side) of the foot. Recent studies suggest that the plantar fascia is actually an aponeurosis rather than true fasc ...

(tendon). 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. Healing is usually completed within eight weeks.

Tibial tuberosity avulsion

A tibial tuberosity avulsion fracture is an incomplete or complete separation of the

tibial tuberosity The tuberosity of the tibia, tibial tuberosity or tibial tubercle is an elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end. Structure The tuberosity of ...

from the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

. This occurs as a result of a violent

contraction Contraction may refer to: Linguistics * Contraction (grammar), a shortened word * Poetic contraction, omission of letters for poetic reasons * Elision, omission of sounds ** Syncope (phonology), omission of sounds in a word * Synalepha, merged ...

of the

quadriceps muscles The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

, 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.

Treatment

$Avulsion fracture of the left first metacarpal$ If the fracture is small, it is usually sufficient to treat with rest and support bandage, but in more severe cases, surgery may be required. Ice may be used to relieve swelling. Displaced avulsion fractures are best managed by either open reduction and internal fixation or closed reduction and pinning. Open reduction (using surgical incision) and

internal fixation Internal fixation is an Surgery, operation in orthopedics that involves the surgical implementation of Implant (medicine), implants for the purpose of repairing a bone, a concept that dates to the mid-nineteenth century and was made applicable fo ...

is used when pins, screws, or similar hardware is needed to fix the bone fragment.

Other animals

Dinosaurs

In 2001, Bruce Rothschild and other

paleontologists Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

published a study examining evidence for

tendon avulsions An avulsion fracture is a bone fracture which occurs when a fragment of bone tears away from the main mass of bone as a result of physical trauma. This can occur at the ligament by the application of forces external to the body (such as a fall ...

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

dinosaurs. Among the dinosaurs studied,

avulsion injuries Avulsion in general refers to a tearing away. Specifically, it can refer to: * Avulsion fracture, when a fragment of bone tears away from the main mass of bone as a result of physical trauma * Avulsion injury, in which a body structure is detac ...

were only noted among ''

Tyrannosaurus ''Tyrannosaurus'' () is a genus of large theropod dinosaur. The type species ''Tyrannosaurus rex'' ( meaning 'king' in Latin), often shortened to ''T. rex'' or colloquially t-rex, is one of the best represented theropods. It lived througho ...

'' and ''

Allosaurus ''Allosaurus'' ( ) is an extinct genus of theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic period ( Kimmeridgian to late Tithonian ages). The first fossil remains that could definitively be ascribed to th ...

''.

Scars SCARS or S.C.A.R.S. is an acronym that may refer to: * SCARS (military) (Special Combat Aggressive Reactionary System), an American combat fighting system * Severe cutaneous adverse reactions Severe cutaneous adverse reactions (SCARs) are a gr ...

from these sorts of injuries were limited to the

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

and

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

. 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 Deltoid (delta-shaped) can refer to: * The deltoid muscle, a muscle in the shoulder * Kite (geometry), also known as a deltoid, a type of quadrilateral * A deltoid curve, a three-cusped hypocycloid * A leaf shape * The deltoid tuberosity, a part o ...

teres major The teres major muscle is a muscle of the upper limb. It attaches to the scapula and the humerus and is one of the seven scapulohumeral muscles. It is a thick but somewhat flattened muscle. The teres major muscle (from Latin ''teres'', meanin ...

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.Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 331-336.

References

{{DEFAULTSORT:Avulsion Fracture Bone fractures