Less cutting sounds like a good thing when it comes to hip replacement. But experts say knowing the right questions to ask is key to determining if this new technique is for you.
Research recently presented at a meeting of orthopaedic specialists shows that patients often fare no better with minimally invasive hip replacement than those having a standard hip replacement -- and may do worse.
Proponents of minimally invasive hip replacement say small-incision operations can lessen blood loss, ease post-operative pain, trim hospital stays, improve scar appearance, and speed healing. In the hands of properly trained surgeons, they say, patients can expect benefits that were once unimaginable.
Richard A. Berger, MD, who refined the technique, says most of his patients go home the same day as surgery and can walk without crutches within eight days. He says his technique steers clear of muscle and tendon damage during surgery. Berger is assistant professor at Rush-Presbyterian-St. Luke's Medical Center in Chicago.
But critics say minimally invasive hip replacement is overhyped and underproven. The scientific evidence supporting it has come from a small group of enthusiastic innovators, they point out. Poor positioning of hip implants during surgery can occur more frequently, in turn leading to hip dislocations and pain in the short run or failure in the longer term.
And the learning curve can be perilously steep. In one new study, the complication rate using a highly touted technique in an experienced surgeon's first 80 patients was nearly four times higher than normal. The complications were also disproportionately more serious. The study was presented during the recent annual meeting of the American Academy of Orthopaedic Surgery in Washington, D.C.
Experts advise patients who are considering minimally invasive hip replacement to educate themselves on the pros and cons of the operation and choose their surgeons carefully.
Wanted: Better Evidence
Experts say there is simply not enough scientific evidence about this new form of surgery to form firm conclusions.
More evidence and better evaluation of minimally invasive hip replacement will be necessary "before these techniques are recommended for more widespread clinical practice," concludes a recent advisory statement from the American Association of Hip and Knee Surgeons.
"The number of patients with dramatic benefits such as walking without [crutches or a cane] the day after surgery are very few, with surgery done by a very small subset of surgeons," Brian McGrory, MD, chairman of the expert panel that wrote the AAHKS advisory, tells WebMD.
What's more, the long-term outcomes remain unknown, says Daniel J. Berry, MD, professor and chairman of the department of orthopaedic surgery at the Mayo Clinic in Rochester, Minn.
The goal of joint replacement is to achieve "a long-lasting, well-functioning implant" that is free of complications, he points out.
"It's important for patients to understand that if there is an advantage to minimally invasive methods -- and I emphasize 'if' -- it will be for only a very short period of time, a few weeks or at most a few months," Berry tells WebMD.
"And after that, conventional methods are likely to be just as good or possibly better."
Hip Replacement Debate Heats Up
With release of the new research on complications from minimally invasive hip replacement, critics have turned up the heat.
"Is it justifiable to take patients through this learning curve?" asks Thomas S. Thornhill, MD, a professor at Harvard Medical School who uses the technique himself. "I'm troubled."
If only "miraculous" surgeons can get results, which "us lesser mortals can't," then the typical orthopaedic surgeon in the community "shouldn't be doing this operation," says Richard Rothman, MD, professor and chairman of orthopaedics at Thomas Jefferson University in Philadelphia.
For most people, the operation of choice right now is a standard hip replacement.
"We've been too polite to educate the public appropriately," says Rothman, who has taught and performed total hip replacements for decades.
"I'd go to a place that was convenient for me, where I could have good follow-up, and have a good rapport with the surgeon," says McGrory. "What I really want is a pain-free, stable hip that lasts a long time."
Hip Replacement Questions for Your Surgeon
If you're considering minimally invasive hip replacement, here are some questions to discuss with your surgeon.
What is minimally invasive hip replacement? Do you use one incision or two? How long is/are the incision(s)?
- "Minimally invasive" is a catchall phrase describing operations with incisions shorter than the standard 8 to 10 inches used by most surgeons today.
- The simpler of two techniques employs a single "mini-incision" of about 5 inches or less, a modification of time-tested techniques. The more demanding "two-incision" technique represents a radically new approach; in it, a surgeon performs the entire operation through two tiny portals, each incision often less than 2 inches long.
- Beneath these small incisions loom large operations. As in any total hip replacement, the surgeon cuts off the top of the thigh bone (femur) and replaces it with an artificial stem and ball. An artificial cup is inserted on the socket side of the hip.
Underneath the skin, is the operation the same as a standard hip replacement?
- Advocates of minimally invasive hip replacement say it reduces damage to muscles and tendons. Advocates of the two-incision technique say it completely eliminates muscle and tendon damage. But there is conflicting evidence for both claims.
- In a study presented at the AAOS meeting, researchers from the Mayo Clinic performed two-incision operations on 10 cadavers. The surgery "cut or damaged measurable amounts of muscle or tendon in every case," they concluded.
What are the potential limitations of a minimally invasive hip replacement?
- During minimally invasive hip replacement, surgeons sometimes can't see what they're doing. Potentially, this can result in improperly positioned implants -- which could dislocate, cause pain, or wear out faster.
The Reality of Complications
Are there complications unique to minimally invasive hip replacement? How serious? What is your own personal experience with complications?
- Two studies at the AAOS meeting provided unsettling clues about complications with two-incision operations. In one series of 80 patients from the Mayo Clinic, 14% of patients suffered complications -- nearly four times higher than normal. Problems included seven fractures of the femur and one deep infection.
- Patients at the University of Missouri at Columbia suffered a similar fate. Nine of 87 patients (10%) required a second hip operation within six months and 22 (25%) suffered nerve injury -- three to four times the normal rate of problems.
How many operations have you done with your current techniques?
- Each technique has its own learning curve. For the mini-incision technique, "it is short, probably about 10 cases," suggests Allan E. Gross, MD, professor and chairman of orthopaedic surgery at the University of Toronto.
- For the two-incision technique, however, surgeons should do a minimum of 50 two-incision operations per year, suggests Gross.
- "Patients should recognize that if they're going to use a minimally invasive method, they need to be skeptical about whether or not that procedure can be done at the present time by most surgeons with as low a complication rate and as high a durability as conventional methods," suggests the Mayo Clinic's Berry.
- "Is it hard? Of course it's hard. Should you go to someone with experience and training? Of course," says innovator Berger.
Are the short-term results of minimally invasive hip replacement any better than those for standard incisions?
- Two provocative clinical trials presented at the AAOS meeting suggest the mini-incision technique offers little more than a shorter scar. One trial from Belfast, Northern Ireland, compared more than 200 patients. The other trial, led by Jefferson's Rothman, involved 120 patients.
- Though the short- and long-incision operations were equally safe, none of the hoped-for advantages of the mini-incision technique materialized in either trial. "The size of the incision doesn't matter," Graham Bailie, MD, a co-researcher of the Irish trial, told WebMD.
- As for the two-incision technique, researchers haven't yet presented head-to-head trials comparing it with a mini-incision or standard technique.
Are some patients especially poor candidates for a minimally invasive hip replacement?
- Though there is disagreement, most experts say it is not the right operation for patients who have excessively fleshy or very muscular thighs and buttocks, severe hip deformities, or a previous hip replacement.
Can you provide me with the names of five or six of your patients I can talk to about this?
- Talking to others who have been through minimally invasive hip replacement may help you decide how to proceed.