Lead arthropathy: arthritis caused by retained intra-articular bullets.

The cases of 14 patients seen 6 weeks to 7 years after gunshot wounds with painful, restrictive joint disease and retained intra-articular bullets were reviewed. Twelve patients had radiographic findings characteristic of lead synovitis. The earliest finding was a fine, punctate deposition of radiopaque lead on the articular cartilage that resembled chondrocalcinosis but was of greater density. This was followed by more discrete lead speckling of hypertrophied synovium. The opacities became larger, coarser, and more confluent over time, ultimately outlining the synovium, articular cartilage, and joint capsule. Synovial hypertrophy and diffuse chronic inflammation and fibrosis were seen in seven patients on gross pathologic examination. The lead was deposited extracellularly in the subsynovial layer and within the marrow spaces of subarticular and periarticular bone. Electron-microscopic study suggests that lead is initially incorporated within cells and secondarily deposited extracellularly after cell death. Bullets in joints are not physiologically inert and should be removed when encountered.