A subluxation is a partial dislocation of a joint, where the two bones that normally meet have shifted out of alignment but still remain partially in contact with each other. In a full dislocation, the bones separate completely. A subluxation can be just as painful as a full dislocation, and it can happen in nearly any joint in the body, from the shoulder and kneecap to the small bones in the spine and even a toddler’s elbow.
Subluxation vs. Full Dislocation
The key difference is how far the bones have moved. In a dislocation, the bone is completely displaced from its natural position in the joint, and the two surfaces lose all contact. In a subluxation, the bone slips only partway out. The joint surfaces still overlap to some degree, but the alignment is off enough to cause pain, instability, and sometimes nerve or soft tissue damage. Both injuries can stretch or tear the ligaments, cartilage, and other structures that normally hold the joint in place.
Because a subluxation involves less displacement, some people assume it’s a minor injury. That’s not always the case. A subluxation can damage the same stabilizing structures that tear during a full dislocation, and it carries a real risk of becoming a recurring problem if those structures don’t heal properly.
Where Subluxations Happen Most Often
Shoulder
The shoulder is the most mobile joint in the body, which also makes it one of the least stable. Shoulder subluxations fall into two broad patterns. The first is traumatic and typically one-directional: a hard impact or fall tears the rim of cartilage (called the labrum) that deepens the shoulder socket, allowing the ball of the upper arm bone to slip forward. The second pattern is non-traumatic, often involving naturally loose ligaments and a stretchy joint capsule that allow the shoulder to shift in multiple directions. People with generalized joint hypermobility are especially prone to this second type.
Neuromuscular conditions can also cause shoulder subluxation. When the rotator cuff muscles are weak, such as after a stroke, the weight of the arm can pull the upper arm bone downward and partially out of the socket. Spasticity in certain chest and back muscles can push the bone backward instead.
Kneecap
Kneecap (patellar) subluxation produces a dramatic, painful popping sensation when the kneecap shifts sideways during movement. People with this problem often report swelling, a feeling that the knee is “giving way,” and difficulty going up or down stairs. Many develop avoidance patterns, steering clear of the specific knee positions that trigger the slip. Patellar subluxation can result from previous knee surgery, loose ligaments, or an unusually shaped groove in the thighbone where the kneecap normally tracks.
Nursemaid’s Elbow in Children
One of the most common subluxations in young children is called nursemaid’s elbow. It happens when a pull on a child’s outstretched arm causes a ligament near the elbow to slip over the top of the radius bone and get trapped in the joint. Swinging a toddler by the arms, lifting them by one hand, or even pulling on their arm to prevent a fall can cause it. The child will typically stop using the arm and hold it still against their body. A healthcare provider can usually slide the ligament back into place in seconds with a specific rotation of the forearm, and most children are using the arm normally again within minutes.
Connective Tissue Disorders and Chronic Subluxation
For some people, subluxations aren’t a one-time injury. They’re a recurring feature of daily life. Ehlers-Danlos syndrome (EDS) is a group of inherited conditions that affect collagen, the protein that gives ligaments and other connective tissues their strength. In EDS, the structures that normally hold joints in place are fundamentally weaker than normal. Joint dislocations occur in roughly 75% of all people with EDS, and that number climbs above 95% for the hypermobile type specifically.
Because the ligaments can’t do their job, the muscles and bony shape of the joint aren’t enough to compensate. Joints slip repeatedly, sometimes in multiple directions and during ordinary movements rather than only at the extremes of motion. Over time, chronic subluxation leads to uneven loading of the joint, poor muscle tone, impaired body awareness, and significant pain and fatigue. Many people with hypermobile EDS develop altered shoulder blade movement patterns and reduced muscle mass from years of instability and guarding against injury. The majority eventually pursue surgical stabilization for at least one joint.
How Subluxations Are Diagnosed
Doctors typically diagnose subluxations through a combination of physical examination and imaging. During a physical exam, the provider will try to reproduce the instability you describe. For a kneecap subluxation, for example, the examiner pushes the kneecap sideways while slowly bending the knee. If the kneecap snaps back into its groove with a painful pop that matches your symptoms, the test is considered positive.
X-rays can reveal whether bones are sitting in the wrong position and whether there’s any bone damage. MRI scans show soft tissue injuries like torn ligaments or cartilage that X-rays miss. For subluxations in the upper spine, specific measurements on imaging help determine severity. In adults, a gap greater than 3 millimeters between the first vertebra and the peg-like projection of the second vertebra signals abnormal movement. In children, that threshold is 5 millimeters because their ligaments are naturally more flexible.
Recurrence Risk
One of the biggest concerns after a subluxation is whether it will happen again. The answer depends heavily on age and activity level. Young athletes face the highest recurrence rates. One study of skeletally immature patients (children and teens still growing) found a 100% redislocation rate when the shoulder was treated with a sling alone. Even with surgical repair, recurrence rates in young contact athletes range from 13% to 25%, depending on the surgical technique used. Each repeat episode can further stretch out the joint capsule and damage stabilizing structures, making the next one more likely.
Recovery and Rehabilitation
Treatment for a subluxation depends on which joint is affected and how badly the surrounding structures are damaged. Some subluxations reduce on their own, meaning the bone slips back into position spontaneously. Others need a healthcare provider to guide the bone back. Either way, the real work begins with rehabilitation.
For a shoulder subluxation in an athlete, structured physical therapy typically starts about two weeks after the injury and follows a progressive six-week timeline. The first phase focuses on pain control and gentle rotation exercises using light resistance bands, building early strength in the rotator cuff and the muscles around the shoulder blade. In weeks three and four, the intensity increases significantly, with exercises targeting the deltoid, trapezius, and serratus anterior muscles through a wider range of motion. The final phase introduces plyometric (explosive) movements and heavier resistance to restore full strength and endurance. The goal by the end is equal strength in both arms and a range of motion that approaches or matches the uninjured side.
For people with underlying hypermobility or connective tissue disorders, rehabilitation looks different. The focus shifts toward long-term muscle strengthening and body awareness training rather than a finite recovery timeline. Building muscle around unstable joints serves as a substitute for the ligament support that’s lacking. This is often a lifelong process rather than a six-week program.
The Chiropractic Use of “Subluxation”
If you’ve encountered the word “subluxation” through a chiropractor, it’s worth knowing that the chiropractic definition differs significantly from the medical one. In chiropractic theory, a “vertebral subluxation” refers to a spinal misalignment believed to interfere with nerve function and, by extension, the body’s ability to heal itself. Early chiropractic leaders hypothesized that 90% to 95% of disease processes were related to these spinal misalignments, either as a primary or secondary cause.
This concept has evolved over more than a century, incorporating ideas about reflexes, nerve signaling, and what chiropractors call “dis-ease,” a state of altered function they distinguish from actual disease. The vertebral subluxation remains a foundational concept in some branches of chiropractic practice, but it is not recognized as a diagnosable condition in mainstream medicine. Orthopedic and medical uses of the term “subluxation” refer strictly to a measurable, partial displacement of a joint that can be confirmed on physical exam or imaging.