ankylose

Ankylosis, sometimes written ankyloses, refers to the pathological stiffening and fusion of a joint, resulting in restricted or absent movement. It can involve fibrous tissue, bone, or both, and may be congenital or acquired. While any joint can be affected, ankylosis most commonly involves the temporomandibular joint, knee, elbow, shoulder, hip, or spine.

Classification and causes: Ankylosis is commonly categorized into fibrous ankylosis, osseous (bony) ankylosis, and pseudo-ankylosis. Fibrous ankylosis involves scar tissue across the joint; osseous ankylosis involves actual fusion of the articular surfaces by bone. Pseudo-ankylosis describes restricted movement due to periarticular structures such as muscle contractures or severe deformities rather than true joint fusion. Causes are diverse and include trauma, infection (notably tuberculous or septic arthritis), inflammatory arthritis (for example rheumatoid arthritis), congenital joint abnormalities, tumors, prior surgery, and degenerative disease.

Clinical features and diagnosis: The hallmark is a markedly reduced range of motion at the affected joint, with functional impairment and potential deformity. Symptoms may include pain or discomfort, depending on the underlying cause and joint involved. Diagnosis relies on clinical examination supported by imaging. X-ray and computed tomography can demonstrate bony fusion in osseous ankylosis, while MRI may reveal soft tissue involvement. Classification by site and the degree of motion loss help guide treatment.

Treatment and prognosis: Management depends on the site, cause, and degree of immobility. Goals are to restore function and alleviate disability while addressing the underlying condition. Surgical release of the fused joint (ankylosis release) with interpositional grafts or prosthetic options is commonly used for functional restoration, followed by rigorous postoperative therapy to prevent recurrence. Fibrous ankylosis and pseudo-ankylosis may require less extensive intervention. Recurrence after treatment is a recognized concern, particularly when the underlying disease is not controlled or rehabilitation is incomplete.