Analysis of third body particles generated during total knee arthroplasty: is metal debris an issue?

There is a concern amongst knee surgeons that during total knee arthroplasty (TKA) certain particles could be generated which might become left inside the knee, and which could become a possible cause of third body wear. Especially during the sawing process, when an oscillating saw is used through slots in a cutting block, there is a potential cause for metal debris generation. So far however, no data exist to substantiate and quantify the amount of metal debris left in situ after TKA, and it was the purpose of this study to evaluate this.

In seven consecutive patients undergoing primary cemented TKA, we measured the amount of debris that was present at the end of the operation immediately before closure. The debris was retrieved using pulsed irrigation with 1 l of normal saline, which was then collected and centrifuged. Obtained pellets were subsequently washed and chemically treated to quantify the different components present in the debris.

Overall an average amount of 134.9 mg (range 73.6-198.0 mg) debris was retrieved. The debris contained on average 75.8 mg of bone particles (range 41.2-109.3 mg), 57.2 mg (range 31.2-83.9 mg) of cement particles, and 1.96 mg (range 0-7.2 mg) of metal particles. On average the total amount of debris consisted for 56.5% of bony fragments, 42% cement fragments and 1.5% metal particles.

Even despite precise surgical technique including pressurized irrigation, a significant amount of debris is still present after TKA. The debris consists predominantly of bone and cement particles. The presence of metal debris is limited, and contributes only 1.5% to the total amount.