SAN DIEGO, California—Minimally invasive surgery (MIS) for total hip replacement (THR) is in theory an attractive alternative to classic open THR but may offer few advantages in actual clinical practice, according to data presented at the 74th Annual Meeting of the American Academy of Orthopeadic Surgeons (AAOS) .

The attraction of the MIS approach is pain reduction because the incisions are smaller and leave smaller surgical scars. The downside includes longer operative time than conventional surgery, larger anesthesia requirements, risk of more muscle damage than traditional "open" surgery, and occasional poor positioning of the implants. According to the AAOS, there is little difference in recovery time with MIS versus open joint replacement procedures.

No peer-reviewed evidence of benefit

In an AAOS symposium presentation, Steven T. Woolson, MD, clinical professor of orthopaedics at Stanford University School of Medicine, in Palo Alto, California, reviewed published studies and AAOS presentations on complications associated with MIS for THR. He concluded, "There is no peer-review scientific evidence that there are any benefits to the patient from mini-incision THR after 5 years of study. The logical deduction is, wait to do small incision THR until there is evidence of benefits and safety. Make the smallest incision that allows you to do a good job. And measure the length of the incision at the end of the operation."

With regard to the one-incision MIS approach, Dr. Woolson said that a literature review turned up no study that reported any clinically significant advantages compared with open THR, and two studies showed higher complications rates and/or more component malpositions. Six controlled consecutive studies likewise showed no significant benefits to minimally invasive THR versus open THR.

"The cons of MIS THR outweigh the pros," Dr. Woolson said. "For prevention of complications, make incisions 2-to-3 inches longer."

Lab data cast doubt on whether procedure is really "less invasive"

Although there have been widespread claims that MIS is less invasive than open THR, Dr. Woolson reviewed  three randomized, prospective, blinded studies that found no benefits in terms of pain, multiple function parameters, blood loss, length of stay, or thigh swelling. He noted that postoperative C-reactive protein and interleukin-6 levels also showed that one-incision or mini-incision THR "is not less invasive" than open THR.

AAOS spokesman John J. Callaghan, MD, professor of orthopaedic surgery and biomedical engineering at the University of Iowa College of Medicine, in Iowa City, is concerned about the number of MIS procedures that have to be redone because of problems resulting from the first surgery.

"When doing MIS, the surgeon is working with inserting devices through a very small incision. It is critical that she or he makes sure the components are in the right position," Dr. Callaghan warned.

The increased numbers of obese patients requesting hip replacement also add to the problem and may be more likely to require revision after MIS procedures.

"It is very important that we have the good surgical candidates with correct fixation of the parts in hip replacement surgery," Dr. Callaghan said. "I do not want to see this procedure go 'backwards.'"

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Reference

1. Woolson ST. Complications associated with minimally invasive one incision THR surgery. Presented at: American Academy of Orthopaedic Surgeons 74th Annual Meeting; February 14-18, 2007; San Diego, CA. Proceedings book, p. 57.