Synovial pseudarthrosis: a clinical, roentgenographic-scintigraphic, and pathologic study.

Seventy-six patients with synovial pseudarthrosis were reviewed. This is a distinct pathologic entity which is a different form of nonunion. The humerus, femur, and tibia were the bones most commonly involved. Routine roentgenograms were not beneficial but 99mTc scans were useful for identifying this entity in 93% of cases. Light and electron microscopy revealed normal synovial lining tissue. Motion and infection may lead to the development of this condition. The results of treatment were a 43% success rate in infected cases and 59% for noninfected cases, which is far different from that of regular nonunion.