Minimally-Invasive Surgery (MIS) Quadriceps-Sparing Total Knee Replacement: New Quad Sparing Technique May Provide Faster Recovery for Patients with Arthritis of the Knee.

Edited By: Seth S. Leopold, M.D.
Last updated Tuesday, April 15, 2008

Figure 1 - The incision used for minimally-invasive quadriceps-sparing total knee replacement is much smaller than the one used for traditional knee replacement, and in the less-invasive procedure, the important quadriceps muscle and tendon are not disrupted as in traditional knee replacement. LifeART image ©2004 Lippincott Williams & Wilkins. All rights reserved.

Figure 2 - The skin incision for minimally-invasive quadriceps-sparing total knee replacement is typically about 4" in length, compared to about 8" or more for traditional total knee replacements.

Figure 3 - X-ray of a traditional total knee replacement. This operation is done for patients who have arthritis throughout the knee. Excellent long-term results are obtained in most patients.

Figure 4 - Model of a traditional total knee replacement. The patella (knee cap) is not shown in this model.

Figure 5 - X-ray of a partial, or unicompartmental, knee replacement. This operation is done for patients whose arthritis is limited to one side of the knee. It may be done through a very small incision, and recovery from this procedure is usually much quicker than that seen with traditional total knee replacement.

Figure 6 - Model of a partial knee replacement. This smaller implant leaves undamaged cartilage in other parts of the knee intact.

Summary

Overview

Knee replacement is a surgical procedure that decreases pain and improves the quality of life in many patients with severe arthritis of the knees. Typically, patients undergo this surgery after non-operative treatments (such as activity modification, anti-inflammatory medications, or knee joint injections) have failed to provide relief of arthritic symptoms. Surgeons have performed knee replacements for over three decades, generally with excellent results; most reports have ten-year success rates in excess of 90 percent.

Broadly speaking, there are two types ways to insert a total knee replacement: the traditional approach, and the newer minimally-invasive (sometimes called quadriceps-sparing) approach.

Traditional total knee replacement involves a roughly 8” incision over the knee, a hospital stay of 3-5 days, and sometimes an additional stay in an inpatient rehabilitation setting before going home. The recovery period(during which the patient walks with a walker or cane) typically lasting from one to three months. The large majority of patients report substantial or complete relief of their arthritic symptoms once they have recovered from a total knee replacement.

Minimally-invasive quadriceps-sparing total knee replacement is a new surgical technique that allows surgeons to insert the same time-tested, reliable knee replacement implants through a shorter incision using surgical approach that avoids trauma to the quadriceps muscle (see figure 1), which is the most important muscle group around the knee. This new technique, which is sometimes called quadriceps-sparing knee replacement uses an incision that is typically only 3-4” in length (see figure 2), and the recovery time is much quicker – often permitting patients to walk with a cane within a couple of weeks of surgery or even earlier. The less-traumatic nature of the surgical approach also may decrease post-operative pain and diminish the need for rehab and therapy compared to more traditional approaches.

The main potential benefits of this new technique include:

1. More rapid return of knee function. Patients who undergo this procedure seem to get muscle strength and control back more quickly than patients who have had traditional total knee replacement. (See Video) This is because the quadriceps muscle and tendon are not divided in the course of the surgical exposure like in traditional knee replacement, and the kneecap is not everted (flipped out of the way) as it is in traditional total knee replacement.
2. Smaller incision. While this procedure would not be worth performing for cosmetic benefits, many patients do prefer the shorter incision. Traditional knee replacement incisions often measure 8” or longer; minimally-invasive quadriceps-sparing knee replacement incisions are about 4” in length for most patients.
3. Decreased post-operative pain. (See Video)This may be a function of the smaller incision and the fact that the incision stays out of the important quadriceps muscle/tendon group.
4. Same reliable surgical implants as Traditional Knee Replacement. Much has been learned about implant design in the nearly 40-year history of contemporary knee replacement. Minimally-invasive quadriceps-sparing total knee replacement is an evolution of surgical technique, which permits the use of time-tested implant designs (see figures 3 and 4). This gives some reassurance that while the surgical approach is new, the implants themselves have a good proven track record.

The major apparent risks of the procedure compared to traditional total knee replacement:

1. The procedure is new. Though surgeons have studied the approach, the studies are recent and have replicated (repeated and verified) by only a few groups of surgeon-scientists. These studies give some insight into which patients and patterns of arthritis are most suitable for this procedure, the relative novelty of the approach it is likely that as time passes we will discover more about the risks and shortcomings of this technique. Also, even an experienced knee replacement surgeon will have performed many more surgeries through the traditional approach than through the less-invasive method; we know that the more procedures one does, the more reliable the results are.
2. The procedure is more challenging. Operating through a smaller surgical window takes some getting used to, and this can increase operative time compared to procedures performed using the traditional technique. This may increase the likelihood that an intra-operative injury to tendon or ligament might occur, which could compromise the result. This may also increase the likelihood of component malalignments, which could affect function and durability. However, two preliminary studies on this technique in fact found that these adverse outcomes did not take place.

For some patients, an implant other than a total knee replacement may be a reasonable choice. Partial knee replacements, sometimes called unicompartmental (partial) knee replacements (see figures 5 and 6), also have a long track record in this country and in Europe. Partial knee replacements have been around for decades and offer excellent clinical results, just like total knee replacements. Less invasive techniques are available to insert these smaller implants as well, but only a minority of knee replacement patients (about 10%) are good candidates for this procedure. Minimally-invasive partial knee replacement (mini knee) is the topic of another article on this website.

By contrast, the minimally-invasive quadriceps-sparing total knee replacement is appropriate for most patterns of knee arthritis.

Downloads

• Video: In recovery 30 minutes after MIS total knee replacement. (3.76 MB)
• Video: Ten days after quad sparing total knee replacement, walking without a cane. (1.50 MB)

View a patient skiing deep powder at Bridger Bowl, Montana, about 8 months after a minimally-invasive total knee replacement; note that not all patients are able to ski, and we do not recommend this activity to patients with knee replacements.

Surgery for knee arthritis at the University of Washington

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