What does ankylosis mean?
Ankylosis is a medical term describing the abnormal stiffening or outright fusion of a joint, leaving it permanently immobile. It arises when bone or fibrous tissue grows across a joint space, most often as a consequence of chronic inflammation such as rheumatoid arthritis or ankylosing spondylitis, severe trauma, or prolonged immobilisation — though surgeons may deliberately induce it through arthrodesis to relieve intractable pain. Doctors distinguish bony ankylosis, in which the bones themselves unite, from fibrous ankylosis, where dense scar tissue produces the rigidity. The word derives from the Greek 'ankylos', meaning crooked or bent, and entered English medical vocabulary in the early eighteenth century. Though rarely encountered outside clinical settings, it remains essential terminology in orthopaedics and rheumatology, and its familiar '-osis' ending links it to a whole family of medical terms describing abnormal conditions.
nounAbnormal stiffness or fusion of a joint, typically caused by disease, injury, or surgical intervention, resulting in complete loss of mobility at that joint.
- Medicine: abnormal adhesion and rigidity of the bones of a joint, leading to complete immobility of that joint.
"Years of untreated rheumatoid arthritis left her fingers in near-complete ankylosis."
"Advanced ankylosing spondylitis can produce ankylosis of the spine, fusing the vertebrae into a single rigid column."
"After the fracture healed badly, fibrous ankylosis left his jaw unable to open more than a few millimetres."
The plural follows the standard Greek-derived '-es' pattern for '-osis' nouns; in practice, clinicians often refer to 'a single ankylosis' affecting one joint rather than using the plural.
"The examination revealed multiple ankyloses across both hands."
The word comes from the Greek 'ankylos', meaning 'crooked' — the same root that gives us the word for a bent fishhook.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ankylosis
Ankylosis derives from the Greek 'ankylosis', formed from 'ankylos', meaning crooked, bent, or hooked, combined with the '-osis' suffix denoting a condition or process. It was adopted into Latin medical writing and entered English usage in the early eighteenth century as physicians systematised anatomical terminology. The same Greek root underlies 'ankylosing spondylitis', and the '-osis' suffix connects it to numerous other medical terms such as sclerosis and necrosis.
Related word forms
How ankylosis is actually used
A technical term used almost exclusively in medical and anatomical contexts; it carries a clinical rather than everyday register. Clinicians distinguish between bony ankylosis (true union of bone across the joint) and fibrous ankylosis (rigid connective tissue bridging the joint). The related condition ankylosing spondylitis takes its name from this word.
Easily confused with ankylosis
Arthritis is inflammation of a joint, whereas ankylosis is the stiffening or bony fusion of a joint, which may result from chronic arthritis.
Arthrodesis is the deliberate surgical fusion of a joint to relieve pain, while ankylosis usually refers to pathological or spontaneous fusion.