Here, try this site, maybe something here:
Poultry Podiatry
https://sites.google.com/a/poultrypedia.com/poultrypedia/poultry-podiatry
or maybe here:
https://thegardensmallholder.wordpress.com/2012/02/11/how-to-deal-with-a-damaged-chicken-claw/
or here, read the comments and perhaps email...