metallosis involving the knee joint most often results from metal - on - metal contact late in the life of a failing implant following polyethylene wear . we report a case of acute metallosis following knee arthroplasty in a previously healthy 59-year old male . in june 2011 , the patient underwent left knee arthroplasty for severe osteoarthritis with necrosis and bone edema in the medial femoral condyle and tibial plateau . nine months later , because of persistent pain and swelling in the joint , revision arthroplasty was undertaken along with partial synovectomy . examination revealed pristine prosthetic implants in the absence of loose fragments of bone or glue . synovial pathology exhibited marked chronic inflammation and hyperplasia with extensive finely granular foreign material resembling metallic debris . laboratory analysis of synovium revealed a predominance of iron , the principal component of the saw blades . we hypothesize the patient experienced acute metallosis resulting from deposition of metallic fragments from three saw blades used during arthroplasty . we believe the increased density of the patient s bone that required use of multiple blades may have resulted , in part , from heavy lifting the patient partook in during the two years preceding arthroplasty . metallosis involving the knee joint most often results from metal - on- metal contact late in the life of a failing implant following polyethylene wear ( 1 - 3 ) . the metallic components may come into contact at the tibio - femoral or patella - femoral interface with metal - backed patellar components ( 2 ) . we report a case of metallosis following knee arthroplasty in which synovitis developed acutely after joint replacement , most likely as a result of deposition of metallic debris from oscillating bone saw blades . on march 18 , 2011 , a healthy 59-year - old male was diagnosed with left knee osteoarthritis by arthroscopy ; no abnormalities of the synovium were detected at this time . on june 27 , 2011 , the patient underwent left knee arthroplasty for severe osteoarthritis with necrosis and bone edema in the medial femoral condyle and tibial plateau . a hemipatellectomy was undertaken along with transection of the femur and tibia which , because of density of bone , required the use of three saw blades ( brasseler usa , blade number km71 - 563 ) using a conmed linvatec motor . total knee replacement was undertaken using an 83 mm tibial tray with a 75 mm femur ( biomet ) , a large patella and a 12 mm spacer . a pre - operative varus deformity of the knee was corrected with an absolute neutral position after insertion of the implant . because of persistent swelling , decreased range of motion , and joint pain following months of intensive physical therapy with icing and treatment with non - steroidal anti- inflammatory agents , on march 22 , 2012 the patient underwent revision arthroplasty with partial synovectomy ( discolored , brown - tan portion removed ) and exchange of the spacer from 12 mm to 14 mm . a radiograph of the knee prior to the procedure did not reveal the metal - line sign . inspection revealed pristine prosthetic implants and the absence of loose fragments of bone or glue . the joint exhibited full range of motion without tendency toward subluxation , and the patella tracked down the midline with good stability in extension and without lift off in flexion . after irrigation of the joint with nine liters of saline with antibiotic solution , the wound was closed . on pathologic examination , the synovium exhibited marked chronic inflammation and hyperplasia with extensive finely granular foreign material resembling metallic debris ( figs 1 and 2 ) . laboratory analysis of synovial tissue for iron , chromium , and cobalt demonstrated the presence of each metal at the following levels : iron ( 150 micrograms / gram ) , chromium ( 17 micrograms / gram ) , and cobalt ( 14 micrograms / gram ) . although reference ranges for these metals in synovium are not established , normal tissue levels of chromium and cobalt should be undetectable ; iron would be detectable in tissue with hemorrhage , but the synovium did not show evidence of significant hemorrhage . lymphoid infiltrate and synovial lining cells in 59 year old male with acute - onset metallosis following total knee replacement ( hematoxylin - eosin x 100 ) . intracellular metallic debris in synovial lining cells ( thin arrow ) and giant cells ( thick arrow ) in 59 year old male with acute - onset metallosis following total knee replacement ( hematoxylin - eosin x 1000 ) . in june of 2013 , the patient was found to have the following blood metal results : serum iron , 141 micrograms / deciliter ( reference range , 40  155 ) ; plasma chromium , 2.6 micrograms / deciliter ( reference range , 0.1  2.1 ) ; and plasma cobalt , 1.7 micrograms / deciliter ( reference range , 0  0.9 ) . to determine the likely origin of the synovial metals , we investigated the composition of the prostheses , cutting block , and saw blades ( table ) . chemical composition ( expressed in percents ) of saw blades , prostheses , and cutting block used during total knee replacement in a 59- year - old male1 . patellar component , 100% polyethelene ; spacer , 100% polyethylene with titanium pin brasseler blade number km71 - 563 ( large bone oscillating blade ) biomet item numbers : tibial plate - # 141236 ; femur - # 183184 biomet 4-in-1cutting block ( 2 ) , 14 patients developed metallosis within two years of receiving a dual - coated uncemented femoral component from which alumina ceramic particles may have dislodged from an overlying layer of hydroxyapatite . revision surgery was undertaken between seven and 32 months after the initial operation in all 14 patients , and the retrieved implants showed deep scratching to the naked eye . the novelty of the present case is the early onset of synovitis in a patient who exhibited pristine implants nine months after initial surgery . we believe metallosis developed acutely following deposition of iron from the three saw blades used during surgery , and that these fragments were not dislodged entirely by four liters of saline irrigation . a diagnosis of metallosis was supported by findings on pathology of finely granular foreign material resembling metallic debris in the synovium , and on laboratory analysis , the principal metal detected was iron . first , in over twenty years of performing knee replacement surgery , this was the first arthroplasty in which the surgeon required the use of three blades . although we can not exclude the cutting block as an additional source of iron , the fact that the same model had been used for years without evidence of debris deposition argues against this possibility . finally , the tibial and femoral implants were unlikely to be the source of iron given iron comprised < 1% of the implants . the minute amounts of synovial chromium and cobalt may have derived from the prostheses as a result of metallosis - induced inflammation . cobalt - chromium particles have a high specific surface area that promotes dissolution of these metal ions into surrounding tissues ( 4 ) . after phagocytosis by macrophages , the ions are transported to lysosomes , which , in turn , release the metal ions into peri - prosthetic tissues following apoptosis and necrosis of the phagocytosing cells ( 4 ) . although subchondral bone density is known to increase during the course of osteoarthritis of the knee ( 5 ) , we hypothesize that a unique activity undertaken by the patient during the two years prior to arthroplasty may have significantly increased bone density . specifically , after purchasing a wood stove , the patient began lifting heavy logs prior to splitting them into firewood . it is possible that repeated lifting over two years contributed to cartilage loss and subchondral bone compression . indeed , the patient reported an accelerated worsening of symptoms of osteoarthritis following purchase of the wood stove and the attendant wood - lifting activities that followed . recognizing that bone cutting blades may differ in hardness , we believe it is important that surgeons have ready access to comparative ratings of blades in terms of hardness . such information may inform surgeons in their choice of blades prior to , or even during , surgery should they encounter patients with unusually dense bone , mitigating , thereby , the need for multiple blades with the consequent risk of irretrievable debris deposition . we believe the clinical features described herein represent a case of acute metallosis following knee arthroplasty , a condition that has not been reported heretofore .
introduction : metallosis involving the knee joint most often results from metal - on - metal contact late in the life of a failing implant following polyethylene wear . 
 we report a case of acute metallosis following knee arthroplasty in a previously healthy 59-year old male.case report : in june 2011 , the patient underwent left knee arthroplasty for severe osteoarthritis with necrosis and bone edema in the medial femoral condyle and tibial plateau . 
 nine months later , because of persistent pain and swelling in the joint , revision arthroplasty was undertaken along with partial synovectomy . 
 examination revealed pristine prosthetic implants in the absence of loose fragments of bone or glue . 
 synovial pathology exhibited marked chronic inflammation and hyperplasia with extensive finely granular foreign material resembling metallic debris . 
 laboratory analysis of synovium revealed a predominance of iron , the principal component of the saw blades.conclusion:we hypothesize the patient experienced acute metallosis resulting from deposition of metallic fragments from three saw blades used during arthroplasty . 
 we believe the increased density of the patient s bone that required use of multiple blades may have resulted , in part , from heavy lifting the patient partook in during the two years preceding arthroplasty .