In recent years, minimally invasive surgery for hip or knee replacement has become generally regarded as a state-of-the art approach to these common orthopaedic procedures. Understandably, patients who read or hear about the advantages of smaller incisions and a speedier recovery are eager to opt for the technique. But according to Thomas P. Sculco, MD, Surgeon-in-Chief at HSS, it's important for potential patients to fully understand how this surgery differs from traditional joint replacement and to have realistic expectations about the procedure.
"The term minimally invasive surgery is somewhat misleading," Dr. Sculco explains. "Even though the technique allows us to reduce the size of the incision and to minimize trauma to the soft tissues, arthroplasty, or joint replacement, still involves cutting of bone, realigning the soft tissue mechanism that supports the joint and placing the implant. A more accurate term for what we're now doing would be 'modification of standard approaches.'"
That modification does indeed offer a number of advantages. In addition to reducing the size of the incision-in the case of hip replacement from 9 inches down to 3 or 4 inches, and with knee replacement from 12 to 4 or 5 inches-there is less damage to the soft tissues. Blood loss is reduced as a result of the smaller incision and also due to the availability of epidural hypotensive anesthesia, which is used in conjunction with light sedation. And the risks of complications associated with general anesthesia are avoided. "However, the most important consideration is that the end result of the operation is as good as it would be with a traditional incision." says Dr. Sculco.
Thus far the results are persuasive. In the more than 2000 hip replacement patients Dr. Sculco and his colleagues have followed from two years to six years following their surgery, there has been no greater incidence of problems with the modified incision compared to the traditional approach. Outcome measures examined in this study included position of components, dislocation rates, nerve injuries and wound problems.
As a pioneer in this field, Dr. Sculco not only developed the modified technique for hip arthroplasty, but has also worked with others at HSS to develop the customized instrumentation and implants needed for a successful result.
As good as all this sounds, Dr. Sculco says there are a number of factors to consider before electing to undergo this surgery. Minimally invasive joint replacement should be performed only by a well trained, highly experienced orthopaedic surgeon who does the procedure frequently. It's essential that he or she have the proper instrumentation and support team. The orthopaedic surgeon must also be experienced in appropriate patient selection. While many patients are candidates for the technique, it should not be used in overweight individuals, people with significant musculature, or in revision surgeries.
Patients should also be aware that all minimally invasive techniques are not the same. In contrast to the modified standard approach used at HSS, some orthopaedic surgeons are performing a hip replacement procedure in which two incisions are made, each approximately 2 to 3 inches in length. In this operation, the surgeon puts the socket piece of the prosthesis through an incision in the front of the leg, and, with the help of x-ray guidance, places the ball portion of the prosthesis through an incision in the back.
"The purported benefit to this approach is that the surgeon cuts less muscle and therefore that recovery is faster," says Dr. Sculco. "I'm skeptical that that's the case. The surgeon still has to traumatize soft tissues to replace the hip. Moreover, the complications with this approach are greater. Because you can't visualize the femur directly, the bone may be broken in some patients." In addition to these risks, patients undergoing this procedure are subject to continual x-ray exposure throughout the operation. The orthopaedic surgeon is also restricted in the type of prosthesis used because only those that are fixed without cement are suitable. Finally, Dr. Sculco points out, the learning curve for orthopaedic surgeons is significantly longer with the two-incision technique in contrast with the modified approach used at HSS.
The results achieved with the modified approach at HSS can be dramatic. Dr. Sculco described the progress of a young patient who recently underwent hip replacement. He was also enrolled in the HSS Fast-Track program, a system designed to allow discharge from the hospital within 48 hours of surgery. In this case, Dr. Sculco performed the operation on a Wednesday morning and the patient walked twice that afternoon. The following day he used a cane to walk through the hospital hallway. He was then permitted to walk without a cane before leaving the hospital 48 hours after surgery.
As Dr. Sculco points out, "Minimally invasive joint replacement for the hip or knee is not right for every surgeon, or for every patient. However, in the hands of a skilled surgeon performing the operation on a properly selected individual, the technique has much to offer."
In addition to these advances in minimally invasive hip and knee surgery, the orthopaedic surgeons at HSS have been involved in developing minimally invasive surgery in a number of different areas including trauma, sports and spine surgery.
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Summary prepared by Nancy Novick