Dislocations are injuries in which the normal articulating surfaces of a joint become completely separated from their usual anatomical relationship. A joint consists of interacting structures including bones, articular cartilage, a capsule, ligaments and often tendons, muscles and other stabilising tissues. During a dislocation, the forces acting on the joint exceed the capacity of its stabilising structures, allowing one bone to move out of its normal articulation with another.
Dislocations can result from falls, collisions, sports injuries, motor vehicle trauma or other high-energy events, although some joints can dislocate after relatively modest forces when substantial ligamentous or structural instability already exists. Common examples include shoulder, elbow, finger, hip, patellar and certain spinal or jaw dislocations. A partial displacement is generally called a subluxation rather than a complete dislocation. The term may also be used for recurrent or chronic conditions in which the joint repeatedly loses normal alignment. Because dislocation can damage ligaments, cartilage, nerves, blood vessels, tendons and nearby bone, it is not simply a problem of joint position; associated tissue injury determines much of the clinical significance.
The mechanism and anatomical direction of a Dislocation are important for diagnosis and treatment. Shoulder dislocations commonly occur anteriorly, often after a combination of abduction, external rotation and trauma, although posterior dislocations can occur in particular circumstances and may be more easily missed. Hip dislocations are usually associated with substantial trauma and can threaten the blood supply to the femoral head. Elbow dislocations may stretch or rupture multiple stabilising ligaments and can be associated with fractures.
Patellar dislocations commonly involve lateral displacement and may injure the medial stabilising structures and articular cartilage. Some dislocations are simple, meaning that no major associated fracture is present, while fracture-dislocations involve both loss of joint congruence and a fracture. Congenital or developmental instability and connective-tissue disorders can predispose certain individuals to recurrent dislocations, while neurological or muscular disorders can alter joint control. Traumatic dislocations can also produce small avulsion fractures where ligaments or other stabilising structures pull on their bony attachments.
Clinical features of Dislocations commonly include severe pain, obvious or subtle deformity, restricted movement and protective muscle spasm. The affected limb or joint may appear to have an abnormal contour, although swelling can obscure the deformity. The patient may be unable or unwilling to move the joint normally. A critical part of assessment is examination of distal circulation and neurological function because displaced bones can compress or injure nearby vessels and nerves.
This is particularly important in major-joint dislocations and should be assessed before and after reduction. Plain radiographs are generally used to confirm the direction of displacement and identify associated fractures, although imaging protocols vary by joint and clinical circumstance. Computed tomography can provide additional detail when complex fracture-dislocations are present. Magnetic resonance imaging can be useful for assessing associated soft-tissue damage after the acute problem has been stabilised. In some circumstances, recurrent instability is evaluated with specialised imaging or functional assessment.
Treatment of Dislocations generally requires reduction, meaning restoration of the normal relationship between the joint surfaces. Reduction should be performed using an appropriate technique by a trained professional, with attention to analgesia, sedation where necessary and the possibility of associated fractures or neurovascular injury. Forceful or repeated untrained attempts at reduction can cause additional damage. Once reduced, the joint is reassessed clinically and often radiographically to confirm alignment and identify previously unrecognised injuries.
Immobilisation may be used for a period appropriate to the particular joint and injury, followed by rehabilitation aimed at restoring range of motion, strength and dynamic stability. The optimal duration of immobilisation differs substantially between joints; excessive immobilisation can produce stiffness and muscle loss, while insufficient protection can permit recurrent instability. Surgery may be required when closed reduction fails, when a fracture prevents stable reduction, when major soft-tissue damage is present or when recurrent instability persists despite appropriate conservative treatment.
Shoulder Dislocations illustrate the distinction between restoring alignment and restoring long-term stability. The shoulder has a large range of motion but relatively limited inherent bony constraint, so it relies substantially on the labrum, capsule, ligaments, rotator cuff and coordinated muscular control. Following a traumatic anterior shoulder dislocation, associated injuries can include labral tears, impaction defects of the humeral head, rotator cuff damage and nerve injury.
Younger or highly active individuals can have substantial recurrence risk after certain traumatic shoulder dislocations, although recurrence depends on age, mechanism, associated structural lesions and activity. Rehabilitation emphasises restoration of movement, rotator-cuff and scapular strength, proprioception and controlled exposure to positions that previously produced instability. Some patients with recurrent instability or significant structural damage undergo stabilisation surgery. The shoulder therefore demonstrates why treatment of a Dislocation cannot be reduced to the single act of putting the joint back into position; the underlying stabilising structures and future functional stability also require consideration.
Hip Dislocations and other high-energy Dislocations require particular urgency because associated tissue damage can be severe. Traumatic hip dislocation can compromise the vascular supply to the femoral head, increasing the risk of avascular necrosis if reduction is delayed or blood supply has been severely disrupted. It can also involve acetabular or femoral fractures and sciatic nerve injury.
Knee dislocation is another particularly serious injury because it can disrupt multiple ligaments and potentially injure the popliteal artery even when the joint spontaneously reduces before medical assessment. Consequently, the term "dislocation" does not imply a uniform level of severity. A finger dislocation may sometimes be managed relatively simply after appropriate reduction and assessment, whereas a major-joint dislocation after high-energy trauma can represent a limb-threatening injury. The anatomical context, mechanism and neurovascular findings are therefore central to determining urgency.
Recurrent Dislocations can result from persistent ligamentous laxity, structural defects, inadequate healing, altered joint geometry or insufficient neuromuscular control. Repeated episodes may progressively damage cartilage and other joint structures and can produce apprehension, pain and functional limitations. Rehabilitation seeks to improve dynamic stabilisation by strengthening relevant muscles and retraining coordinated movement. Where structural instability remains substantial, surgical stabilisation may be considered.
Recurrent dislocation should be distinguished from voluntary or habitual joint movement without traumatic injury, although the underlying anatomy and tissue properties can overlap in some cases. Some people have generalised joint hypermobility without experiencing pathological dislocations, so increased range of motion alone does not establish joint instability. Conversely, recurrent instability can occur even when the joint appears normal between episodes. Accurate history is therefore important when determining whether symptoms represent a true dislocation, subluxation, instability episode or another mechanical problem.
Dislocations differ from fractures and sprains but commonly coexist with them. A fracture is a break in bone, a sprain is an injury to a ligament, and a dislocation is a loss of normal joint congruence. A fracture-dislocation combines the latter two mechanisms and can be particularly complex. Dislocations can cause secondary cartilage injury that may increase later risk of degenerative joint disease.
Acute complications include nerve compression, vascular injury, skin compromise and associated fractures, while later complications include stiffness, chronic instability, recurrent dislocation and post-traumatic arthritis. Prognosis depends strongly on the joint involved, duration of displacement, associated structural injury, patient characteristics and quality of rehabilitation. Prompt professional assessment is particularly important after major trauma or when deformity, severe pain, numbness, weakness, absent or diminished pulses or an inability to move the limb occurs.
