Severe metallosis following total knee arthroplasty: a case report and review of radiographic signs

Abstract

Metallosis is an uncommon complication following total knee arthroplasty that leads to osteolysis and implant loosening due to chronic inflammatory reaction. Abrasion between the metallic surfaces of the implant releases metallic debris that interacts with the periprosthetic soft tissues and causes chronic synovitis. Here we present a case of a 65-year-old man who had undergone total knee arthroplasty 10 years ago and developed implant loosening associated with severe metallosis and varus instability. Radiographs show the three typical signs of metallosis: metal-line sign, bubble sign, and cloud sign. This patient was subjected to revision surgery consisting of debridement and primary implant replacement by a hinged endoprosthesis. Knowledge of the typical radiographic and clinical findings of metallosis is important to rapidly diagnose this complication and avoid progressive joint destruction.

Elusive Differential of a Painful Unstable Total Knee Arthroplasty – Metal on Cement Disease

“…The de-bonding between the metal component and underlying cement could be triggered by a variety of reasons, including weak quality cement, poor cement mixing techniques, inadequate immobilization of the knee joint while the cement is curing, or inadequate cementing non-low viscosity cement use [1-2]. This interface failure can cause gradual loosening and dissociation of components with neighboring ALTR that could mimic PJI, inflammatory synovitis, or tumor formation occasionally, along with systemic signs of metallosis, but they rarely coexist [3]. In our observation, the clinical presentation, laboratory studies, radiological impressions, histopathological findings, and intraoperative findings in both patients were markedly similar.…”

“…Although metallosis and polyethylene wear disease in the hip have been adequately reported in the literature, there is not much information on a similar phenomenon in the knee and the literature lacks evidence on the typical clinical presentations, investigations, and approaches to the diagnosis or management options [3]. Also, there is limited information on outcomes of particle disease involving cement, ceramic disease, or even their combination that could be causing a myriad of pathological changes in the adjacent bone and soft tissues [4].…”

“…Also, there is limited information on outcomes of particle disease involving cement, ceramic disease, or even their combination that could be causing a myriad of pathological changes in the adjacent bone and soft tissues [4]. Literature evidence suggests that metallosis in a knee is possible from breakage of polyethylene, metal fracture, insert displacement, failed metal-backed patella implant, cementless total knee arthroplasty designs with manufacturing issues, modular hinged knee designs, and saw blade debris-related foreign body reaction [3-5]. Ongoing abrasion, corrosion, and wear at the metal-cement junction can cause shedding of metal or cement particles into the joint from abrasive wear, leading to adhesive third-body wear of the polyethylene insert and subsequent signs of joint failure [2, 5].…”

“…On gross examination of the inside of the knee, there is visible dark pigmentation and hypertrophy of the synovium with a shiny, smooth, intact cement mantle on the rear side of the loose implant and strong cement adherence to most of the underlying bone [6]. These metal, cement, and polyethylene particles are cytotoxic and, when phagocytized, lead to soft tissue and occasional bone necrosis [3]. The sequelae of this phenomenon are defined as an aseptic, lymphocyte-dominant, vasculitis-associated lesion (ALVAL) or adverse local tissue reaction (ALTR), also known as a pseudotumor, in isolated metal particle disease.…”

The Sequelae of Metallosis Resulting in Skin Pigmentation and Tattooing: A Case Presentation and Literature Review

“…An often nonspecific radiographic sign observed is periprosthetic osteolysis; more specific signs that have been reported are the "bubble," "cloud," and "metal-line" signs. 7,8 Serologic testing for metallic ions reveals elevated levels. A normal serum cobalt level is around 0.19 μg/L, with levels greater than 5 μg/L posing risk of neurologic and cardiac abnormalities.…”