[Detritic synovitis and rare skeletal diseases]

Detritic synovitis represents a common finding in routine orthopedic pathology. Microscopically, the synovium displays cartilaginous and bony fragments in the synoviocyte layer or within the subsynovial soft tissues associated with resorptive changes. In the vast majority of cases, detritic synovitis is associated with conditions leading to the destruction of articular cartilage and subchondral bone, such as severe osteoarthritis, collapsed avascular necrosis, diabetes mellitus, Charcot arthropathy or non-union fractures. The objective of this article is to review the literature regarding the microscopic findings in ochronosis, rapidly destructive hip disease and apatite crystal depositions that can enable a confident diagnosis or a limited differential diagnosis of detritic synovitis.