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 13 - Model of a total knee replacement. This implant may be inserted either using a traditional surgical approach, or through the minimally-invasive quadriceps-sparing technique, depending on factors unique to each patient.

Figure 14 - This patient had diffuse arthritis throughout his knee from an old fracture of the tibia (shinbone). It was treated with a traditional total knee replacement, rather than a minimally-invasive procedure, because of extensive scarring from prior

Figure 15 - This patient had rheumatoid arthritis and symptoms throughout her knee, resulting in the traditional total knee replacement pictured here.

Figure 16 - Model of a partial knee replacement. This smaller implant leaves undamaged cartilage in other parts of the knee intact.

Figure 17 - 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 qu

Figure 18 - This clinical photograph shows a typical incision used to insert a minimally-invasive partial knee replacement. The average length of the incision used in this procedure is 3 inches. Smaller incisions help permit faster recovery, and lead to less post-operative pain, compared to traditional knee replacement surgery.

Considering surgery

What kinds of surgery are recommended for knee arthritis?

Joint replacement surgery is the most effective method for restoring comfort and function to knees damaged by severe arthritis. When the normally smooth surfaces of the knee joint are severely damaged by arthritis, injury or surgery, total knee replacement may be the most effective method for restoring comfort and function to the joint. For a minority of patients with arthritis, a minimally-invasive partial knee replacement is an option instead of total knee replacement, but most patients with knee arthritis who undergo surgery are better served with total knee replacement.

Other surgical options, such as arthroscopy or “clean up” operations have not been shown to give lasting benefit.

Knee fusion can stabilize the joint and decrease pain, but does not allow motion at the knee joint.

For selected younger and more active patients, realigning the joint using a procedure called osteotomy may be appropriate; however, the durability and pain relief of this procedure does not seem to measure up to joint replacement, particularly in older patients.

Who should consider minimally-invasive (quadriceps-sparing) total knee replacement for knee arthritis and in what cases?

Joint replacement surgery is considered when:

• the arthritis is a major problem for the patient,
• the patient is sufficiently healthy to undergo the procedure,
• the patient understands and accepts the risks and alternatives,
• there is sufficient bone and tendon to permit the surgery, and
• the surgeon is experienced in knee replacement surgery.

What happens if nothing is done for knee arthritis (best case/worst case scenarios)?

What options exist for surgery for knee arthritis?

If a knee surgeon and a patient decide that non-operative treatments have failed to provide significant or lasting relief, there are sometimes different operations to choose from.

Total knee replacement

Long considered the “gold standard” operation for knee arthritis, total knee replacement is still by far the most commonly-performed joint replacement procedure (see figure 13). It is most suitable for middle-aged and older people who have arthritis in more than one compartment of the knee (see figures 14 and 15), and who do not intend to return to high-impact athletics or heavy labor. Results of this procedure generally are excellent, with 90-95% of total knee replacements continuing to function well more than 10 years after surgery.

There are now several ways to perform total knee arthroplasty:

Minimally-Invasive Quadriceps-Sparing Total Knee Replacement

This is a new technique that permits insertion of the joint replacement implants through a short incision – typically about 4” in length – and allows the surgeon to do so without disturbing the quadriceps muscle or tendon. The shorter incision, but more importantly the avoidance of the quadriceps muscle and tendon, may result in less pain, a quicker rehabilitation, and earlier restoration of function. However, this procedure may not be appropriate for all patients with knee arthritis who undergo knee replacement; patients who are heavier, have osteoporosis in addition to arthritis, and who have significant joint deformity or stiffness may be better served with traditional approaches to total knee replacement.

Traditional Total Knee Replacement 

The joint replacement in inserted using an incision that typically measures 8”-10” in length over the front of the knee. The quadriceps tendon and/or muscle is entered and the kneecap is moved out of the way to permit the surgeon to see the inside of the knee fully and clearly. Restoring range of motion and quadriceps strength is the biggest part of the patient’s rehabilitation after the surgery. This approach has been used for over three decades, with excellent results. It is adaptable, and permits surgeons to perform the procedure in patients who are heavy, who have joint deformity, or who have severe stiffness.

But not every patient with knee arthritis needs (or should have) total knee replacement. There are many other surgical options available for patients with certain patterns of knee arthritis. These include:

Minimally-invasive partial knee replacement (unicompartmental knee)

Patients who are of appropriate age--certainly older than age 40, and older is better--and who have osteoarthritis limited to one compartment of the knee may be candidates for an exciting new surgical technique, minimally-invasive partial knee replacement (mini knee) (see figures 16, 17, and 18). Partial knee replacements have been done for over 20 years, and the “track record” on the devices used for this operation is excellent. The new surgical approach, which uses a much smaller incision than traditional total knee replacement, significantly decreases the amount of post-operative pain, and shortens the rehabilitation period. The decision of whether this procedure is appropriate for a specific patient can only be made in consultation with a skillful orthopaedic surgeon who is experienced in all techniques of knee replacement.

Minimally-invasive partial knee replacement (mini knee) is not for everyone. Only certain patterns of knee arthritis are appropriately treated with this device through the smaller approach.

Generally speaking, patients with inflammatory arthritis (like Rheumatoid arthritis or lupus), and patients with diffuse arthritis all throughout the knee should not receive partial knee replacements.

Patients who are considering knee replacements should ask their surgeon whether minimally-invasive partial knee replacement (mini knee) is right for them.

Knee arthroscopy

If X-rays don’t show very much arthritis, and the surgeon suspects (or has identified by MRI) a torn meniscus, knee arthroscopy may be a good choice. This is a relatively minor procedure that is usually done as an outpatient, and the recovery is fairly quick in most patients.

However, if X-rays demonstrate a significant amount of arthritis, this may not be a good choice. Knee arthroscopy for arthritis fails to relieve pain in about half of the patients who try it.

Osteotomy

For younger patients (typically under age 40, but this age cutoff is flexible) who desire to return to a high level of athletic activity or physical work, a procedure called osteotomy (which means “cutting the bone”) might be worth considering. This option is suitable only if the arthritis is limited to one compartment of the knee (for more information about arthritis in one compartment of the knee, see the "Location" section on page 2 of this article).

Osteotomy involves cutting and repositioning one of the bones around the knee joint. This is done to re-orient the loads that occur with normal walking and running so that these loads pass through a non-arthritic portion of the knee. That’s why it doesn’t work well if more than one compartment of the knee is involved--in those patients, there is no “good” place through which the load can be redistributed.

Knee fusion

Knee fusion, also called “arthrodesis,” permanently links the femur (thigh bone) with the tibia (shin bone), creating one long bone from the hip to the ankle. It removes all motion from the knee, resulting in a stiff-legged gait.

Because there are so many operations that preserve motion, this older procedure is seldom performed as a first-line option for patients with knee arthritis. It is sometimes used for severe infections of the knee, certain tumors, and patients who are too young for joint replacement but are otherwise poor candidates for osteotomy.

Video: Minimally-Invasive Joint Replacement Video

When performed by an experienced surgeon, how effective is minimally-invasive (quadriceps-sparing) total knee replacement for knee arthritis likely to be and how long will the benefit last?

Current evidence suggests that when total knee replacements are done well, in properly selected patients, success is achieved in the large majority of patients, and the implant serves the patient well for many years.

Many studies show that 90-95 percent of total knee replacements are still functioning well 10 years after the surgery. Most patients walk without a cane, most can do stairs and arise from chairs normally, and most resume their desired level of recreational activity.

The goal of minimally-invasive quadriceps-sparing total knee replacement is to capitalize on the decades of experience surgeons have gained in total knee implant design and intra-operative ligament balancing, but provide patients with a faster recovery and less post-operative pain. The same knee replacement implants and materials are used, the point of attachment to the bones is the same (bone cement), and the same attention to surgical detail, limb alignment, and ligament balancing are given during the newer, less-invasive procedure as during the traditional approach. It is important to remember that this is a new procedure compared to traditional total knee replacement, and as a result, we do not have long-term follow-up on outcomes. However, short term studies on knee component and limb alignment and peri-operative complications have found results with those endpoints that are comparable to traditional approaches while providing patients with faster rehabilitation.

Regardless of the technique used to insert the knee replacement (traditional or minimally-invasive), in the event that a total knee replacement requires re-operation sometime in the future, it almost always can be revised (re-done) successfully. However, results of revision knee replacement are typically not as good as first-time knee replacements.

There is good evidence that the experience of the surgeon correlates with outcome in total knee replacement surgery; for this reason, it is best to have the initial surgery done by an individual who is experienced (fellowship-trained, and with a practice that focuses on knee replacement) in this kind of work.

Likewise, the new technique of minimally-invasive quadriceps sparing knee replacement should only be performed by surgeons who have taken special training on the instruments and surgical approaches, and who have experience using less-invasive surgical techniques around the knee.

Surgeons with this level of experience have been shown to have fewer complications and better results than surgeons who haven’t done as many knee replacements. It is therefore important that the surgeon performing the technique be not just a good orthopaedic surgeon, but a specialist in knee replacement surgery and in less-invasive joint replacement.

How urgent is minimally-invasive (quadriceps-sparing) total knee replacement for knee arthritis?

What are the most frequent and most serious risks of minimally-invasive (quadriceps-sparing) total knee replacement for knee arthritis? How common are they?

Like any major surgical procedure, total knee replacement is associated with certain medical and surgical risks. Although major complications are uncommon, they may occur; the possibilities include blood clots, bleeding, and anesthesia-related or medical risks such as cardiac risks, stroke, and in rare instances (large studies have calculated the risk to be less than 1 in 400), death.

Risks specific to knee replacement include infection (which may result in the need for more surgery), nerve injury, the possibility that the knee may become either too stiff or too unstable to enjoy it, a chance that pain might persist (or new pains might arise), and the chance that the joint replacement might not last the patient's lifetime or might require further surgery.

Minimally-invasive quadriceps-sparing total knee replacement is a new procedure. For this reason, it is fair to say that the specialty will need to pay close attention to results to make sure they are as good or better than the traditional techniques that have been in common use for quite some time now. However, preliminary studies on the technique have shown no increases in surgical or medical risk with this approach compared to traditional total knee arthroplasty, and these same studies have shown benefits in terms of post-operative pain and early recuperation and rehabilitation after surgery.

While the overall list of complications may seem long and intimidating, the overall frequency of major complications following total knee replacement is low, usually less than 5 percent (one in 20). Obviously, the overall risk of surgery is dependent both on the complexity of the knee problem but also on the patient's overall medical health.

The major apparent risks of the minimally-invasive quadriceps-sparing procedure compared to traditional total knee replacement include the following:

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.

If risks occur during or after minimally-invasive (quadriceps-sparing) total knee replacement for knee arthritis how are they managed?

Many of the major problems that can occur following traditional or minimally-invasive total knee replacement can be treated. The best treatment, though, is prevention. An orthopaedic surgeon will use antibiotics before, during and after surgery to minimize the likelihood of infection. (S)he will take steps to decrease the likelihood of blood clots, such as early patient mobilization and use of blood-thinning medications in some patients. Patients are evaluated by a good internist and/or anesthesia provider in advance of the surgery, in order to decrease the likelihood of a medical or anesthesia-related complication. Good surgical technique can help minimize the knee-specific risks--so choosing a fellowship-trained and experienced knee replacement surgeon is important.

Again, the overall likelihood of a severe complication is typically less than 5 percent when such steps are taken.

Surgery for knee arthritis at the University of Washington

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