If you're one of the 300,000 Americans going in for traditional hip replacement surgery this year, you can look forward to an incision 15 to 25 centimeters long, two to three months of waiting before you can take long walks again, and a 1 to 4 percent risk of dislocation. But new technology could make the surgery a lot less onerous. An emerging class of computer navigational systems will allow surgeons to conduct hip replacements through incisions as small as four centimeters and to align implants more accurately. That could mean less pain, faster recovery, and reduced risk of joint failure.

Spherical reflectors on hip surgery tools help doctors see an implant's location.