See the drop-down lists on the right. If you are looking for a knee surgeon, scroll to the top of the first box and set it to Knee Surgeon. If you are just browsing through the list of Professionals, scroll up and set it to 'Any'.
The same with the Country. If you are not sure what country a named surgeon is in, just set that field to 'Any'.
You can search directly for a named surgeon by using the drop-down list to choose the Country and then Name, but try first with just the surname, as some surgeons use their nickname or may be listed with a middle name or initial. Note that a retired surgeon may be in the field Retired Knee Surgeon.
The results will appear below the search tool on the right. Click the name of the person you want in order to see more details.