Had surgery to straighten bowed legs, got a staph infection in 1974 in r upper thigh. again in same place in 2002 and 2011. why does it return?

Complicated: Would need to know what type of infection and what it involved. You might try a combination of nasal Mupirocin (bactroban) and total body washings for about a month solely with a Chlorhexidine containing soap. Getting rid of the nasal and skin carriage state would be desirable (50% success) if this was skin and soft-tissue infection.