Joint dislocation

A dislocation (Latin luxare " crick ", English: dislocation ) or dislocation (verb dislocate dislocate or dislocate ) is a complete or incomplete ( subluxation ) loss of contact joints forming bone ends. It is another medically defined shape of the dislocation with temporary or permanent deformity of the articulating bones. As luxated bones of the body distant bone is always referred to.

A dislocation is basically a serious injury to a joint dar. In children, it is possible that the joint is stretched far beyond the normal range. In addition, the growing skeleton near the joint fractures ( fractures ) are much more common than dislocations. The classification is usually the cause of dislocation.

While traumatic dislocations can be put right ( fall or sudden overstretching ) usually rapidly, requiring congenital or chronic dislocations prolonged treatment.

A special form of traumatic luxation is the dislocation, in which a partial or complete dislocation associated with a fracture of the articulating parts of the bone.

Traumatic dislocation

The cause is usually an indirect trauma such as a fall on the arm. Most commonly, the shoulder dislocation, which makes up more than 50 % of all traumatic dislocations, followed by the elbow dislocation. Almost all joints can be affected ( also Kieferluxation ). At the finger joints usually hyperextension injuries lead to dislocation, often in handball and volleyball. The acromioclavicular dislocation occurs most frequently during bicycle crash (see image ). Rarely can also direct train cause a dislocation, as in the child's radial head by train on the extended pronated arm ( Pronatio dolorosa Chassaignac ).

In the investigation made ​​a posture with loss of function and pain, occasionally swelling and a bruise. So-called "safe" Luxationzeichen are a visible deformity, a recognizable empty socket and abnormal position of the condyle ( on the shoulder often visible) and a resilient fixation. But even with an apparently intact joint function may be a dislocation.

Proving, radiographs taken in two planes, which are rare forms (such as the posterior shoulder dislocation ) and filial dislocations and thereby difficult to detect. Then help a computed tomography ( CT ), magnetic resonance imaging (MRI) or arthrography ( special x-ray technology with the introduction of a contrast medium into the joint ). In children dislocations in ultrasound are well represented.

Traumatic dislocation of an immediate reduction ( righting ) is required. This should always be done gently and not abruptly or with great force, otherwise can result in the risk of nerve and blood vessel damage and injury to the joint. Is not possible to relaxation, the reduction occurs in conscious sedation or general anesthesia. Subsequently, the reduction must be documented in the X-ray, after immobilization takes place ( at the shoulder, for example, in Gilchristverband ) and possibly further investigations to rule out injury to the parts of the bone, the joint capsule, the labrum and the surrounding ligaments.

If closed reduction is not possible or is a combination with a broken bone ( fracture-dislocation ), which is surgical repositioning with the opening of the joint ( arthrotomy, so-called open or bloody reduction ). Undergo surgical treatment usually also injured ligamentous structures (eg sidebands ) and accompanying fractures. Complications are primarily joint instability by tearing of the capsule and the surrounding bands. This can further dislocations result, to the habitual dislocation (see below). Also an avulsion of the labrum ( at the shoulder: the Bankart lesion) can lead to joint instability, often associated with a feeling of uncertainty and fear, to dislocate the joint again. Instability and repeated dislocations lead to premature osteoarthritis. It can also occur concomitant fractures, such as the depressed fracture back of the humeral head ( Hill-Sachs lesion) or dislocations. By a violent reduction also damage blood vessels and nerves can occur.

A special form of traumatic dislocation of the hip is the central dislocation of the hip. With strong, axial force acting on the thigh, such as car accidents with high speed and falls from height of the femoral head is driven through the shattered pan and into the pelvis. As with the dislocations surgical repair is necessary.

Habitual dislocation

Usually due to traumatic Erstluxation, it comes with remaining instability with less force, finally without further accident mechanism to repeated dislocations, a so-called habitual dislocation. Most commonly this is after a shoulder dislocation and after a dislocation of the patella. Occasionally, the joint can be dislocated at the request and automatically repositioned ( put right ) (so-called arbitrary dislocation).

Congenital dislocation

Here, the dislocation is present at birth before or develops from a congenital Gelenkdysplasie. The most common is hip dysplasia of newborns and congenital hip dislocation at about 0.1 % of all newborns at about 1-2%. Much less common is the innate Kniegelenkluxation. All joints can be affected, but this is very rare, but is inter alia as part of the Larsen syndrome with multiple dislocated joints before.

Chronic dislocation

Due to chronic diseases or deformities there is an increasing joint destruction (destruction ) that a subluxation to complete dislocation leads insidiously ( Destruktionsluxation ). This is not painful than the disease or deformity actually underlying. A sole reduction is usually not possible and not useful, since it comes immediately to re- dislocation in the absence of stability. All joints can be affected. Typical examples are:

• With hallux valgus foot deformity and contractures of the little toes ( hammer toes, claw toes )
• Through a joint infection (septic arthritis) caused destruction of the joint - ligament apparatus
• Rheumatoid arthritis caused by destruction of the sidebands, the suspensory apparatus and the joint capsule (typically on hands and feet)
• When flaccid and spastic paralysis gradually increasing deformity to the dislocation; in spasticity of the adductor muscles often progressive hip subluxation
• As a result of periarticular tumor
• In osteonecrosis with subsequent deformation of the adjacent joint esp. in femoral head necrosis. Usually it comes only to the subluxation. The more serious problem is usually osteoarthritis.
• Outdated traumatic, not repositioned dislocation (most common radial head in children)

Linsenluxation

The lens luxation is a full ( Linsenektopie; ektopos = shift ) or partially ( Linsensubluxation ) displacement of the lens (eg, in the anterior chamber ). It can be congenital acquired (eg, Marfan syndrome) or by an accident.

Zahnluxationen

In dentistry is called a dislocation traumatic abnormal change in position of a tooth called ( luxation, subluxation, lateral luxation ... ).

Also, the movements, with the help of the dentist removed a tooth, as " Luxationsbewegungen " means.

Swell

• K. L. Krämer, M. floor. M. Winter: Clinic Guide orthopedics. Gustav Fischer Verlag, Ulm 1997 ( 3rd edition )
• AM Debrunner: Orthopaedics - Orthopaedic Surgery. Verlag Hans Huber, Bern, 1994 ( 3rd edition )