Risk of Malalignment with Mini-Incision Knee Replacement

There's a lot of interest in the new mini-incision for knee joint replacement. In this study surgeons compared two groups of patients. One group had the mini-incision done. The second group had the standard length incision. There were 30 patients in each group. They each got the same type of joint implant.

Pain, function, and blood hematocrit (to measure blood loss) were reported for each patient. Other factors related to the surgery were also compared. For example, they looked at surgical time, use of drugs for pain, and problems after surgery.

The authors report the mini-incision group used 15 percent less pain medication. Their range of motion was slightly greater than the standard group. This was only true for the first three days after the operation.

The biggest problem reported was malalignment in the mini-incision group. With this method the surgeon has more trouble seeing inside the joint and finding the landmarks needed.

The authors conclude improvements are still needed. Special surgical tools are needed for the mini-incision method. Better implant designs and the use of computers to guide the surgeon may help reduce problems of alignment.



References: David F. Dalury, MD, and Douglas A. Dennis, MD. Mini-Incision Total Knee Arthroplasty Can Increase Risk of Component Malalignment. In Clinical Orthopaedics and Related Research. November 2005. No. 440. Pp. 77-81.