What does anchylosis mean?
Anchylosis refers to the abnormal stiffening or complete immobility of a joint, typically caused by the fusion of the adjacent bones into a single rigid mass. Physicians distinguish true anchylosis, in which the bones themselves unite, from false anchylosis, where stiffness arises from structures around the joint such as contracted muscles, tendons, or scar tissue. The condition may result from chronic inflammation, infection, trauma, or prolonged disuse, though surgeons can also deliberately create it — a procedure called arthrodesis — to stabilize a painful, destroyed joint. The word derives from the Greek 'ankylos', meaning bent or crooked, and shares that root with the name of the armored dinosaur Ankylosaurus. Today it appears chiefly in medical and historical contexts, where the spelling 'ankylosis' has become standard, making 'anchylosis' a form readers are most likely to meet in older clinical literature.
nounAbnormal stiffness or immobility of a joint resulting from the fusion of the bones that form it, whether caused by disease, injury, surgery, or prolonged immobilization.
- True anchylosis: permanent union of the bones of a joint, eliminating movement entirely.
- False anchylosis: stiffness of a joint caused by factors outside the joint itself, such as contracted muscles, tendons, or scar tissue.
"The patient's long-standing rheumatoid arthritis had led to complete anchylosis of the knee."
"After years of untreated infection, the vertebrae had fused in a state of bony anchylosis."
"Surgeons sometimes deliberately induce anchylosis through arthrodesis to relieve pain in a destroyed joint."
The plural follows the standard -is → -es pattern for Greek-derived medical nouns, matching terms like 'necrosis' → 'necroses'. It is uncommon, since clinical writing usually discusses a single affected joint.
"The examination noted anchyloses at both the elbow and the wrist."
The word traces back to the Greek for 'bent' or 'crooked' — the same root that names the tank-like dinosaur Ankylosaurus, whose fused armor plates made it a living embodiment of the term.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of anchylosis
Anchylosis comes from the Greek 'ankylosis', derived from 'ankylos', meaning bent, crooked, or hooked. The term entered European medical vocabulary in the early modern period, appearing in English medical writing by at least the seventeenth century as physicians adopted Greek terminology for describing joint disease. Its Greek root also underlies the name Ankylosaurus, the heavily armored dinosaur named in the twentieth century for its fused, rigid bony plates. Over time the spelling gradually shifted toward 'ankylosis', which is now the preferred modern form.
How anchylosis is actually used
A formal medical term used almost exclusively in clinical, anatomical, and historical medical writing. In contemporary medicine the spelling 'ankylosis' has largely displaced 'anchylosis', which survives mainly in older texts and British literature. The word carries no informal register and would rarely appear outside professional contexts.
Easily confused with anchylosis
Ankylosis is simply the modern standard spelling of the same word; 'anchylosis' is the older British form, so the two refer to the identical condition rather than different things.