Dislocation vs. Subluxation

The key distinction

Both dislocations and subluxations are injuries where a bone slides out of its normal position in a joint. The difference is location and duration:

• Dislocation — the bone is completely out of the socket and stays out. It won’t move back into place on its own; it requires a doctor to “reduce” (manually reposition) it.
• Subluxation — the bone partially or temporarily slips out of the socket and spontaneously pops back in, usually within seconds or minutes. The person may not even see a doctor because it’s already relocated.

Both are traumatic joint injuries. Both involve damage to ligaments, and sometimes to the cartilage or the bony socket itself. But the history—did it pop back in on its own?—changes the diagnosis and urgency.

Common dislocation sites

Shoulder is by far the most common joint to fully dislocate. The shoulder is a shallow socket with a mobile ball (the humeral head), making it inherently unstable. A fall, a collision, or a forceful throw can pop it out. Anterior dislocations (the arm shifts forward) account for >95% of shoulder dislocations.

Fingers and thumb dislocate frequently, especially at the MCP (knuckle) or PIP joints. A blow or a catching injury can cause the finger to jam and dislocate. These are often reduced in the emergency department or clinic without surgery, but the ligament damage may be severe.

Knee dislocations are less common but more serious. They usually occur from high-force trauma (car crash, fall from height) and often damage multiple ligaments (ACL, MCL, PCL) and can injure the popliteal artery (the main blood vessel behind the knee), making them orthopedic emergencies.

Hip dislocations are rare and typically from high-energy trauma. Posterior dislocations (the femur shifts backward) are more common than anterior.

Ankle dislocations are uncommon; most ankle injuries are sprains.

Common subluxation sites

Shoulder subluxations happen in athletes, especially throwers or swimmers. The shoulder slips forward during overhead motion, then pops back. The patient may report the shoulder “going out” but by the time they reach a doctor, it’s back in place. Recurrent shoulder subluxations are a real problem; each event damages more ligaments and cartilage.

Patella (kneecap) subluxations or dislocations are common in younger patients, especially females. The patella can slip to the outside (lateral) during a deceleration or twist. It either pops back in on its own (subluxation) or stays out (dislocation). Even a subluxation can tear the medial patellofemoral ligament (MPFL) and cartilage, leading to recurrent instability.

Radial head in children can subluxate (slip out of the radial notch of the ulna). This happens from a forceful pull on the arm (being swung by the wrist by a parent, caught under a door). The radial head can usually be relocated by the doctor, but it may need imaging to rule out fracture.

Immediate management: dislocation

A true dislocation is an emergency. The person typically has severe pain, the joint is immobilized in an abnormal position, and they cannot move it. The goals are:

• Reduce (relocate) the joint — a doctor uses specific maneuvers to guide the bone back into place. Pain relief or sedation is usually needed.
• Assess for other damage — X-rays to rule out fractures; for knee dislocations, vascular imaging to ensure the blood supply is intact.
• Immobilize and ice — after reduction, the joint is typically immobilized in a sling, brace, or cast for 3–6 weeks depending on which joint and the extent of ligament damage.
• Rehab — once acute pain settles, physical therapy restores strength and proprioception (joint sense) to prevent recurrence.

Recurrent dislocations and subluxations

Once a joint has dislocated or subluxated, the risk of recurrence is high. The ligaments are stretched or torn, the joint capsule is lax, and the patient may have lost confidence in the joint. Recurrent shoulder instability is a classic problem in overhead athletes. Recurrent patellar dislocations happen in >50% of patients after the first event.

When dislocations or subluxations recur despite conservative management (bracing, physical therapy), surgery to tighten ligaments or reconstruct damaged structures becomes the right choice. For the shoulder, this might be a Bankart repair (tightening the labrum and ligaments); for the patella, a medial reefing or MPFL reconstruction.

Key takeaway

A dislocation requires urgent medical attention to relocate the joint. A subluxation self-reduces but still represents significant ligament injury and carries a high risk of recurrence. Either way, early imaging, proper immobilization, and rehabilitation are essential. If dislocations or subluxations keep happening, surgery may be necessary to restore stability and prevent chronic joint damage.

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