Is Partial Knee Replacement For You?

For many years, total knee replacement surgery has been the usual treatment for people suffering from severe osteoarthritis of the knee.  After non-invasive approaches such as OTC pain medications, weight loss, physical therapy and injections have been exhausted; a surgeon’s next recommendation typically has been to replace the knee. 

Total knee replacement is a routine surgery with a solid history of good outcomes.  After a recuperation period, patients can expect to return to their daily activities and a life with little or no knee pain.  Surgical technique and implant technology has advanced substantially over the years as well, resulting in longer implant lifespans.  It is not uncommon for implants to last 20 years, which means many patients do not need another surgery to replace old or worn parts.

Total knee replacements remain a viable and effective solution for many patients.  However, medical technology and surgical technique advance on multiple fronts simultaneously.  As total knee replacement surgeries were improving, so were the science and techniques around a newer surgical approach: partial knee replacement.

Good Option for the Right Patient

For the right patient, partial knee replacement surgery is a good option and an acceptable alternative to full knee replacement as the surgical intervention to treat osteoarthritis of the knee.  The indications for patient qualification are strict, but for those who meet them, partial knee replacement offers some good benefits.

Generally speaking, partial knee replacements are performed on patients whose arthritis is restricted to one of the three compartments of the knee.  The procedure is most commonly performed on patients with arthritis on the medial -- or inside -- side of the knee.  There is some good published data showing positive outcomes for patients with arthritis in both the medial and patellofemoral -- or front -- compartments of the knee. 

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The majority of surgeries, though, are limited to replacements in the medial compartment.  Partial knee replacements are less frequently indicated for the lateral -- or outside -- compartment of the knee.

Patients generally need to demonstrate good range of motion and minimal stiffness in the affected knee to qualify for a partial knee replacement.  Other factors, including a patient’s age, weight, activity level, and knee structure are also considered during the qualification process. 

The orthopaedic surgeon’s philosophy is also important when considering a partial versus a full knee replacement.  Because it is a recently popular (but still standard) surgery, not all surgeons are comfortable with or believe in partial knee replacements.

Comparable Outcomes, Additional Benefits

According to the 10-year data, implant longevity outcomes are similar for partial and total knee replacements.  This means that the majority of patients who undergo either procedure -- in the 90% range -- do not require another surgery within 10 years after the initial surgery.  Partial knee replacements provide some additional benefits, though.

The orthopaedic surgeon makes a smaller incision during a partial knee replacement, reducing blood loss and surgical time and leaving a smaller scar.  Blood transfusions are generally not required after a partial knee replacement.  Generally, there is a better post-operative experience and a quicker short-term rehabilitation associated with a partial knee replacement, as well.  Studies have shown that patients who undergo a partial knee replacement also generally demonstrate a better post-operative range of motion and subjectively “feel” like their knee is more normal.

Making the Decision

Deciding to undergo any surgery requires serious consideration and the decision to have a knee replaced -- whether partial or total -- is no exception.  In most cases, patients are referred to me by their GP (general practitioner) or primary care physician, and we discuss their symptoms and their options.  We start with non-invasive measures, when appropriate.  Over time -- usually weeks to months-- we have an idea of how well the non-invasive measures are working and, if they aren’t, we begin discussing surgical intervention.

I encourage anyone who may be considering a partial knee replacement surgery to educate themselves about the procedure and be an active participant in the discussion process with their surgeon.  Ask questions.  I’m frequently asked, “how many of these surgeries have you performed?”  That’s a fine question, as there is a correlation between surgery volume and good outcomes.  

I think an equally important question is: “What is your Orthopaedic Surgery sub-specialty training?”  Essentially, you want to know whether the surgeon has been specially trained in how to perform partial knee replacements.  Surgical technique and implant positioning are key to successful partial knee replacements.  The most common reasons for revisions -- or corrective surgery -- are poorly positioned, loose or poorly fixed implants, and poorly indicated surgery. 

 So don’t be afraid to do your research and ask questions.  It’s a vital step in developing a trust-based relationship with your surgeon.  The process starts with first discussing your options with your surgeon and determining whether you are, in fact, a good candidate for a partial knee replacement.   

Ritesh Shah, M.D., is in Orthopaedic Surgery at Advocate Lutheran General Hospital.