Metallosis Presenting as Knee Pain 26 years after Primary Total Knee Arthroplasty.
BACKGROUND
Metallosis occurs when periprosthetic soft tissues, synovium, and/or bone is infiltrated by metallic debris secondary to metal-on-metal wear. This debris can cause a chronic inflammatory reaction leading to joint instability, pain, and swelling, and may cause osteolysis, implant looseningand ultimately implant failure.


METHODS
An 81 year old female, with a history of primary left total knee arthroplasty, presented with a 6 month history of left knee pain, swelling, and limited range of motion following a fall. Radiographs and joint aspiration were performed, with results that showed no evidence of periprosthetic trauma or infection but were suspicious for chronic metallosis. The patient underwent revision total knee replacement of the left knee which revealed extensive necrotic black metal debris throughout the joint space. Histopathology confirmed the diagnosis of a foreign body reaction consistent with metallosis.


CONCLUSIONS
This case is a rare example of chronic metallosis presenting 26 years following total knee replacement. Treatment with revision total knee replacement is the consensus management choice to avoid further destruction of the bone and joint capsule that can occur with metal-induced inflammation.
Department of Orthopaedic Surgery, University of California, Irvine. Orange, CA, USA.
Behnam
B
Sharareh
Department of Orthopaedic Surgery, University of California, Irvine. Orange, CA, USA.
Duy L
DL
Phan
Department of Pathology & Laboratory Medicine, University of California, Irvine. Orange.
Wamda
W
Goreal
Department of Orthopaedic Surgery, University of California, Irvine. Orange, CA, USA.
Ran
R
Schwarzkopf
Aseptic loosening; Metal-induced synovitis; bubble sign; cloud sign; metal-line sign; metallosis; severe osteolysis