Signature Knee Replacement – The Custom Total Knee Replacement
If you require a total replacement of the knee because more than one part of your knee is worn out, you should take advantage of NEW medical breakthrough technology. The breakthrough is a Signature knee replacement, a custom designed, via MRI, total knee replacement that aligns the knee properly.
Up until now, a small but significant percentage of total knee replacement patients have been unhappy with their surgery because the new knee “hurts”, is “too tight”, is ”too loose”, or just “doesn’t feel right”. Signature total knee replacement technology is now being shown to improve on these problems and provide a better chance for a patient to have a perfect result. But, what is a “perfect result”? To Dr. Likover it is a knee that works great and feels great. This means that the knee obtains a full range of motion (bends and straightens all the way) and feels good with no pain or instability. In short, a perfect result feels like a natural, normal knee; this is our goal for our patients.
Patients call and email all the time about which brand of implant we use or which is the best implant for them. In Dr. Likover's opinion this is due to the direct advertising of knee implants to the public by the various manufacturers. In the United States there are five major companies that compete and several smaller ones. The major five companies are Biomet, Depuy, Smith and Nephew, Stryker, and Zimmer in alphabetical order. The truth is that all of the top of the line implants of these companies are about the same. The differences between the design and materials used in these competitor's implants are minimal. What makes the difference in how well a total knee replacement surgery performs, is how well the implant is placed into the knee, not which brand of implant is used. The patient should be shopping for the best surgical technique, and not try to pick a brand of implant for his or her case. The patient needs to understand that the motion of the knee is very complex. As the knee bends, the lower leg rotates internally. The knee is not a simple hinge joint. Signature knee replacement technology is aimed at implanting the new knee into the correct position in the body so that the complex motion of the human knee is retained. The technique of surgery (How good is the surgeon and what technique of implantation does he or she use?), and the position of the implanted knee in the patient is what counts, NOT which brand of knee is used.
Up until Signature and Otis technology, the surgeon used standard external knee guides (click here to see them). With a standard, non-MRI designed knee replacement, the surgeon designs the implantation at surgery as he is going a long during the procedure. Many surgeons always cut the posterior cruciate ligament and then perform soft tissue balancing. Soft tissue balancing requires cutting or lengthening the collateral ligaments on the side of the knee. These additional procedures can cause more post -operative swelling and pain, and a longer recovery. **Dr. Likover performs a posterior cruciate retaining procedure, which is known in orthopedics as a cruciate retaining knee (CR). He sacrifices the posterior cruciate ligament only rarely, as he believes in saving as much of the natural structure of the knee.
Signature Total Knee Replacement - The Custom Design Advantage
The breakthrough of Signature knee replacement technology is that a computer designs the procedure so that the implant size and placement is custom designed to the patients unique anatomy. Ligament releases (or cuts) are rarely required, and the knee should obtain a more natural range of motion, both bending and straightening as a result of the knee replacement being specifically designed for the patient's own knee anatomy.
applied to the diseased knee
This design advantage is accomplished by obtaining an MRI of the knee bone shape four weeks before surgery to obtain precise digital data down to 1mm as to the exact size, dimensions and alignment of the patient's arthritic knee. The data is then sent to Biomet corporation and a virtual digital model of the diseased knee is made by computer. Special computer software is used to align the knee to what it was before any disease occurred, correcting either the bow leg or knock knee deformity that usually occurs with advanced arthritis. Next, the correct size of knee implant is selected and designed into the proper position in the knee. Single use custom made cutting guides are then made (click here to see them). When the new knee is placed, the knee should be aligned properly. This is what makes this breakthrough in surgery amazing. (see illustration below)
View samples of remainder of Signature total knee replacement technology
- Signature planning software showing the correct amount of diseased bone to removed for proper implant fit
- Signature software showing a model of the cut ends of the bone before implant applied
- Signature software showing the total knee implant applied to the bone in ideal position
This patient-specific Signature knee replacement design technology procedure is now a technical advance beyond "Gender Specific" implant design. Gender specific implant design only offers smaller and more tapered sizes of "off the shelf" implants, or "Computer Navigation" which only helps align the knee, but does not size and place the implant to the bones. Computer navigation has now been shown to not improve the implantation or final result.
Signature Can Shorten Total Knee Replacement Recovery Time
Signature knee replacement technology shortens the operating time, which reduces the chance of infection and other systemic complications. The patient's recovery to normal function is enhanced because the knee is placed in the correct position for the patient to easily recover range of motion without struggling. Instead of taking three to four months to recover from a total replacement, it now appears possible for some patients to return to normal daily activity in as little as six weeks with much greater satisfaction about the surgery.
Two of the more common questions asked are: 1. How long will a total knee replacement last? And, 2. How young is too young for the procedure? The answers now being given are fifteen to twenty years for a cemented total knee to last. If the cement fails or the polyethylene in the implant wears out, it can be revised with a second surgery. It is not a big problem for this to be done. In younger patients, less than age 60, Dr. Likover is now doing a porous bone in-growth Regenerex tibial plate. This implant does not use cement has the potential to last a lifetime because it is a living fixation construct and should not come loose due to fatigue of cement. Dr. Likover is now doing osteoarthritis patients down to age 45 and younger patients with rheumatoid arthritis or other arthritis diseases.
See below the cemented implant and the porous Regenerex implant utilized in younger patients.
Take Advantage of Dr. Likover’s MRI Designed Knee Replacement Experience
Dr. Likover has performed over 1200 MRI computer designed knee replacement procedures either with the old Otis knee or the new Signature technology. You should take advantage of his vast experience.
In summary, Signature and Otis knee patients have reported:
- Greater range of motion, immediately after surgery and throughout recovery
- Better flexion to allow for more natural kneeling
- Quicker return to every day activity (driving, shopping, golfing)
- Shorter operative time, which reduces time under anesthesia
- Less post-operative pain
For further information go to www.biomet.com/patients/signature.cfm
Case Study 1
Before: A photograph of a gentleman with severe bowleg due to advanced osteoarthritis of the knee.
After: This is the correction obtained with a CustomFit knee. This man has a perfect result and is super happy.
These are this man's xrays with severe arthritis causing a bowed leg. The arthritis involves two compartments, the medial compartment (inside) and the patellofemoral joint (kneecap joint). In this case a Custom total replacement, not an Oxford is required.
Custom Total Knee Replacement in place, with complete correction of the bow leg and with resurfacing of the kneecap joint.
This is the computer-generated image of the patient's knee bones for this case, with the disease taken out, the deformity corrected, and the implant positioned for an ideal result. The patient-specific cutting guides are then made from this design.
Case Study 2
Before: The worst pair of bowlegs I have ever seen, the left was especially bad.
After: Both knees are now replaced. The left is 9 weeks and the right is three weeks after surgery. The patient is now very happy with full motion of both knees and he is actually slightly taller!
Pre-op xrays with severe bow. There is bone on bone on the inside of the knee, and screw in place from previous surgery.
Post-op xrays with bio-ingrowth tibial component (screws not cement initially holding it in place) and complete correction of the deformity.
Click here to see actual surgical photographs of what arthritis looks like and what an installed total knee looks like. DON’T CLICK IF YOU DON’T WANT TO SEE INSIDE THE HUMAN BODY.
People ask all the time what are the restrictions after a Signature knee replacement. The answer is that it is not made for any high impact activity such running every day, basketball and volleyball. You can play tennis, golf, fish, hunt, exercise in the gym on any machine, lift weights, hike, ski, bowl and dance. If you have any further questions, please email Dr. Likover by submitting your information in the “Contact Dr. Likover” form at the top right.
The new concept in knee joint replacement is to replace only the worn out part of the knee and perform a total replacement only when absolutely necessary. If only the kneecap joint (patellofemoral joint) is worn out, only the kneecap joint needs to be replaced. If only the inside of the knee is worn out, then only that portion of the knee needs to be replaced with an Oxford knee replacement. If more than one part is worn out, that is the only time to replace the whole knee with an Otis or Signature total knee replacement.