Fibrous ankylosis is a fibrous connective tissue process which results in decreased range of motion. Symptoms present as bony ankylosis, in which osseous tissue fuses two bones together reducing mobility, which is why fibrous ankylosis is also known as false ankylosis.
Pathology may be the result of trauma, disease, chronic inflammation, or surgery.
Some research suggests fibrous ankylosis may precede the development of bony ankylosis
References
Fibrous ankylosis Wikipedia(Text) CC BY-SA