Dislocation: what it is, how a dislocated leg, arm and hip manifest

A dislocation happens suddenly: a fall, a blow, a yank on a child's arm — and the joint is no longer the same. Below are reference facts on how to recognize a dislocation of the arm, leg and hip joint and how it differs from a sprain or fracture.

What a dislocation and subluxation of a joint are

A dislocation is a disruption of the congruence of the articular surfaces of bones: they stop contacting each other correctly. Displacement occurs either under the action of mechanical forces (trauma) or due to destruction of the joint in arthrosis and arthritis. The dislocated part is considered to be the distal part of the limb, the one farther from the trunk.

In a complete dislocation the articular ends separate completely, while in an incomplete one — a subluxation — they remain in partial contact. Congenital and acquired dislocations are also distinguished: traumatic and pathological, which arise without noticeable external force.

Causes of dislocations

Most often the cause is a fall or a blow, sometimes contact sports. Traumatic dislocations in most cases result from indirect trauma: for example, when falling on the hand of an outstretched arm, the shoulder joint is displaced. Less often — from direct trauma, a blow to the joint area.

The cause can also be a sharp muscle contraction that takes movement beyond the limits of normal joint mobility. In children aged 1–3 years, "pulled dislocations" occur — from a sharp yank on the child's arm. With dislocations, the joint capsule almost always ruptures; tendons, muscles, bones, vessels and nerves may be affected — such dislocations are called complicated.

Dislocated arm: how it manifests

A shoulder dislocation is a condition in which the upper part of the humerus comes out of the glenoid cavity. The arm does not move, the shoulder looks displaced or changes shape, and pain, swelling and bruising appear. The diagnosis is confirmed by X-ray, and reduction is performed by a doctor under local anesthesia or sedation.

Recovery after a shoulder dislocation usually takes 6–12 weeks, full return to some sports — up to 16 weeks, and in some people longer. After the first dislocation the risk of recurrence is higher; it depends on age and on how well the joint has healed.

Dislocated leg: signs and possible consequences

The ankle, knee and patella can be dislocated. The typical signs are common to all joints: pronounced pain, swelling, visible deformity and inability to move the limb. After reduction, with proper treatment, the joint usually works normally again within a few weeks.

A separate feature is habitual dislocation: due to stretching of the joint capsule and ligaments or without proper treatment, the joint is displaced repeatedly even with slight effort. This occurs most often in the shoulder joint, but the risk of recurrent dislocation also exists after displacement of the patella.

Dislocation and subluxation of the hip joint

Congenital dislocation of the hip joints occurs in 2–5 newborns per 1000. In an infant it manifests as asymmetry of the folds on the inner surface of the thighs and limited abduction of the leg; when the child begins to walk — lameness and relative shortening of one leg, and with bilateral dislocation — a "duck" gait.

Reduction of a hip dislocation is difficult to perform without muscle relaxants or physically strong assistants: the muscles around the hip joint are the most massive. Prevention of congenital dislocation is an orthopedic examination of newborns.

How a dislocation is diagnosed and when urgent help is needed

The doctor examines the joint and usually orders an X-ray to confirm the dislocation and rule out bone damage. Reduction is performed only by a doctor, and sometimes surgery is needed for this. Next comes immobilization and rehabilitation.

• Pain, swelling and visible deformity of the joint
• Inability to move the limb
• The joint looks displaced or has changed shape
• Limited abduction of the leg in an infant

By itself it is not a reason to call an ambulance; 103 or 112 — if after a joint injury you cannot move your arm or leg, the joint looks displaced, there is severe pain, bruising and swelling, and you cannot get to the hospital on your own.

The prognosis with adequate treatment is favorable: working capacity is usually restored fully. But this is reference material, not a substitute for a doctor's consultation — in case of a joint injury, the decision is made by a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer