This is the best I can find. For the record, my Mom was a Very early knuckle replacement recipient, done in her late 60's and still functional when she died at almost 85. She was very careful not to abuse it.
My hand surgeon just told me she considers them the last resort, because even now the success rate is only 40 - 50%. The issue is that RA damaged bone often fails to accept the implant and grow in solidly.

Sue