Darwin Chen, MD

Two Stage Exchange for Infected TKA with Metal Allergy

 

This is a healthy, active 57 year old male who underwent two knee procedures by another surgeon at an outside facility. Initially, he had a partial knee replacement, but this failed due to polyethylene bearing dislocation.

He was then revised to a total knee replacement but again did poorly. The knee had a wound healing delay. The patient reported the sensation of knee instability, and he developed a persistent skin rash over the front of his knee.

He saw Dr. Chen for a second opinion. An extensive workup revealed a low grade periprosthetic joint infection with Proprionibacter acnes bacteria. Additional testing revealed an allergy to nickel, explaining the persistent knee skin rash. X-rays demonstrated osteolytic defects in the medial tibia and the posterior femur, as well as femoral component loosening.

The patient underwent a two stage revision total knee replacement to treat the deep infection. Stage 1 consisted of removing the infected knee implants and debridement of extensive amounts of necrotic tissue. An articulated antibiotic spacer was placed, created with high dose antibiotic cement, absorbable antibiotic beads, Steinmann pins, a special titanium total knee femoral component, and a total knee polyethylene liner.

The patient was allowed to walk on the antibiotic spacer will full range of motion. He was treated with six weeks of IV antibiotics. Incredibly, he reported that the antibiotic spacer felt much better than any of the other surgeries he had gone through. At six months after Stage 1, his lab work and knee synovial fluid were clean and he went on to Stage 2. The knee was revised to a special allergy free knee implant made with ceramicized metal (Oxinium). Hybrid stem fixation was used on the femoral side, and a cemented stem was used on the tibia. Bone loss on both the femoral and tibial sides were addressed with porous tantalum cones.

At one year postoperatively, the patient is ambulating without a cane and has occasional discomfort. He is back to work and travels regularly with no issues.

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