...because living with pain isn't really living!

Total Knee Replacement

Surgical Techniques - Total Knee Replacement

You need help for the knee pain from arthritis that has gotten so bad you can no longer function well or tolerate the pain with even simple daily activities. The evaluation of your knee by physical exam and X-ray review; and the failure to respond to more conservative measures has left you wondering about your next step. What can be done now? …..

The answer may well be a total knee replacement or a unicompartmental knee replacement done with the most advanced minimally invasive surgical techniques and rehabilitation program available anywhere in the world. As a recognized leader, teacher and innovator in minimally invasive surgical techniques for total knee replacement surgery, Dr. Robert Zehr of the Zehr Center for Orthopaedics has had the opportunity to refine the various aspects of the surgical experience for his patients both in the operating room and in the care postoperatively.

Knee replacement surgery is really quite common. In fact, last year it is estimated that some 550,000 Americans underwent this highly successful operation to relieve the pain of an arthritic knee joint. In this procedure the worn articular cartilage is removed from the ends of the femur and tibia and replaced with a metal cap with a hard plastic bearing between them.

Since the original knee replacements were done in the 1970’s great improvements in the surgical technique, the implants and the recovery rehabilitation have been made. Yet the question for surgeons always remains — can it be done better? The answer is unequivocally — YES!

Personalized Knee Replacement with Custom Alignment

Another great advancement in the field of knee replacement surgery is the customizing of the knee specifically to the individual patient. This will be particularly important to younger patients who need a knee replacement. To understand why alignment of a knee replacement is important, you must first know how the knee is designed. The knee is a “hinge joint” formed by the joining of the tibia (shinbone), femur (thighbone) and patella (kneecap). In addition, there are four key ligaments and several tendinous muscle attachments that control the mechanical motion of this joint. The normal knee joint not only flexes and extends, but also rotates slightly as you run, walk, sit, squat or climb stairs, etc.

Over the years the sliding articular cartilage that covers the ends of these bones wears away exposing the underlying bone. Constant weight bearing and motion across this raw bone is very painful and not well tolerated by most of us. A “replacement knee” implant simply caps these worn out surfaces with metal and plastic attempting to re-establish a painless and functional knee joint with natural motion.

To best reproduce this natural motion in a replacement knee, implant designers must often compromise on some of these elements and substitute for others to create an implant that not only moves well but will also stand the test of time and hopefully last your entire remaining life. In general, most knee implant systems allow enough variability in size and shape to match up with most of our knees, but the natural movement of each person’s knee can be quite unique. With these limitations in mind several new technologies are now available and others will soon be available to the average patient who will need their knee replaced.

No surprise to you — You are unique! Your knee is unique only to you. Wouldn’t it be just great if somehow a knee replacement could be designed specifically for YOUR knee? — An implant that aligns to the exact angle that YOUR knee was born to follow from your hip to your ankle. — An implant that matches the rotation that YOUR knee tracks along naturally,rather than one that is "slightly off". Guess what — we are there!

Custom Aligned Total Knee

A very specific three-dimensional image of YOUR knee can now be created by computer assimilated MRI images of your hip, knee and ankle from which preoperative planning of your knee replacement can be performed long before coming to the operating room. Additionally, a proprietary system that utilizes these MRI images to construct personalized femoral and tibial positioning guides which are then used in the actual surgery. These personalized guides fit over your femur and your tibia and direct the surgeon to make properly aligned bone resections which provide for exact positioning of the implants onto your bone. This precise attention to the positioning of your implants gives you the best match up of the natural flexion and extension as well as the natural rotation of your original knee – thus personalized and customized just for YOU!

You may ask -- “How is this different from systems already being used by surgeons?” Typically, surgeons use routine X-rays images (2-dimensional) to help choose the size of joint replacement components before surgery from a series of templates. Then, during the knee replacement procedure, the surgeon uses an assortment of instruments to verify component sizing and to establish proper positioning and alignment. Traditional total knee replacement uses instruments or long rods temporarily placed inside or adjacent to the outside of the femur and/or tibia to assist with implant alignment. Not only is this system potentially not as accurate, but can lead to complicating medical issues after surgery.

Signature™ Personalized Patient Care using Vanguard® Complete Knee System

With the MRI guided design of your "personalized positioning guides", a greater level of detail and precision for implant position and alignment is prepared long before the procedure is even started. More importantly this personalized implant positioning helps enhance surgical efficiency and lessens the chance of certain medical complications.

Additionally, you may ask –“Why do we really care about being this precise about the positioning of the components?” As it turns out, the longevity of your implant (how long it will last?) is in large part determined not just by the design of the implant, but also by how it is 3-dimensionally positioned relative to your hip and ankle. When used in conjunction with a standard array of implants, this computer aided design system allows for a more of a custom fit specifically for you, regardless of race, size or especially gender. The scientific data indicates unequivocally that better aligned knee replacements will last longer than those which are implanted with less precise alignment.

As an aside, you may have heard that knees can also be implanted more precisely with the use of computer alignment system used during surgery. This is quite true, but what you probably don’t know is that most of the computer alignment systems require the surgeon to bury large pins screwed into your thigh bone and shin bone that have reflective surfaces on them. These reflective arrays are sensed by a computer as the surgeon moves your leg around. Upon removal the pins leave holes in the bone which can lead to post operative pain, persistent drainage, infection and even fracture of the bone through this hole. Also, in virtually all cases with the intraoperative computer guided systems, there is a significantly longer operative time for you and the surgeon.

Finally, and even more exciting is that just around the corner lies the technology to take these same MRI derived images of your knee and design a knee implant that is wholly and uniquely just for YOUR OWN KNEE! It will be a great breakthrough that will bring customization to a new level of excellence. Imagine—an implant that is designed from scratch only for you. It really can’t get much better than that – other than a cure for arthritis in the first place!