MIS Knee Replacement May be Linked to Early Failure?

A high incidence of failures performed using a Minimal Incision Surgery (MIS) technique was noted in a paper presented at the 2009 annual meeting of the American Academy of Orthopaedic Surgeons (AAOS). 1

In total knee replacement, the worn ends of the bones that make up the knee joint are resurfaced with metal and plastic implants. The surgeon must carefully align the implants relative to the bones and must restore the proper alignment of the bones to one another. If proper alignment is not achieved, excessive wear and premature loosening of the implants may result.

In “Minimal Incision” or “Minimally Invasive” Surgery, exposure of the surgical site is limited. Often the landmarks used in standard total knee replacement surgery may be obscured. The surgeon must rely on experience and sophisticated instruments to properly align the components. Although MIS knee replacement has grown in popularity in recent years, the possibility of issues arising due to the limited exposure has remained a primary concern.

In their paper, Dr. Derek Miller et. al. examined a series of revision cases performed by five surgeons at three different centers between 2004 and 2006. Excluding revisions due to infection and re-revisions, 236 first time revisions were recorded. Of those, 43 were originally performed via MIS, and 193 were revisions of implants first implanted using a “standard” knee replacement technique. In comparing the two groups of revisions, the findings were dramatic. On average, the time to revision was 14.8 months in the MIS group compared to 80 months for the standard group. Thirty-seven percent of the MIS group were failures less than 12 months after surgery compared to only 5% in the standard group. More than eight out of ten of the MIS revisions were in total knee replacement patients that had their implant in for less than two years.

Although MIS knee replacement may lead to quicker recovery and less scarring, this study suggests that the long-term performance of these procedures may be compromised. It remains to be seen whether continued advances in the technique and surgeon experience can counteract this trend.

1 Miller DW, Barrack RL, Barnes CL, Clohisy, JC, Maloney WJ, “Minimal Incision Surgery As A Risk Factor For Early Failure Of Total Knee Arthroplasty?” 2009 AAOS Annual Meeting, Podium No. 272

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