Some surgeons now use a technique called minimally invasive surgery, which might limit damage to muscle and tissue. The potential advantages are faster recovery and reduced pain—but at the cost of longer operative time and a higher risk of surgical errors, including incorrect implant positioning, nerve injury, and bone fracture. The benefits of the procedure are still being debated, but marketing claims have fueled patient demand. "Many surgeons feel they need to offer it or they'll lose patients to someone else," says Mark Pagnano, M.D., an associate professor of orthopaedic surgery at the Mayo Clinic. "But the scientific evidence that this technique makes a substantial difference is lacking."

In fact, improvements in pain control and rehabilitation appear to speed recovery in hip-replacement patients whether they have small or conventional incisions, according to a 2007 study published in the Journal of Bone and Joint Surgery. Physicians note the same effect in knee patients.

Many surgeons now use "mini" cuts that are significantly smaller than traditional incisions but large enough for them to view the operating field. Our consultants support that approach because it provides most of the benefits of minimally invasive surgery without compromising safety. But they note that large-boned patients still require larger incisions, as do those who are overweight, have a joint deformity, or have had prior surgery on the joint.