We use bone cement to do this. The majority of total knees are affixed with cement, although un-cemented designs are also used. Outcomes from both are very good. For young and active patients, cement-less total knees are usually preferred because of excellent fixation and durability. Living bone next to the prosthesis keeps the implants secured over time, whether or not cement is used. The choice of cemented versus un-cemented knee depends on many factors, such as patient age, knee deformity, status of ligaments, and the quality of bone.
Although team members will assist, and resident physician or students may observe, rest assured that I will perform the entire operation.
In part, yes. On the underside your own kneecap (also called the patella) a thin layer of arthritic cartilage and bone is removed during surgery. In its place, we affix a plastic kneecap to your own remaining kneecap. This new part functions just like your own kneecap. The front surface of the kneecap is your own bone; it is the underside of the kneecap that is lined with plastic.
Internal knee ligaments (anterior cruciate ligament and posterior cruciate ligament) are usually so worn out in arthritic knees that what remains of them is removed. The knee prosthesis itself is engineered to substitute for internal knee ligaments and stabilize the joint.
New knee designs, such as the CONFORMIS custom-knee that is built for each patient offer the benefit of preserving knee ligaments. This is one reason we have switched to this brand and custom-design of knee replacement in our practice.
The supporting ligaments outside the knee joint are usually preserved during replacement surgery. These external ligaments are called the medial collateral ligament (located to the inside the knee) and the lateral collateral ligament (located to the outside of the knee). These ligaments continue to function after knee replacement surgery. For severe deformity, arthritic destruction, or unusual cases, we use prosthetic designs that can substitute for all knee ligaments, providing more stability when compared to routine total knee prosthesis.
Thus, even very unstable and deformed knee joints can be replaced successfully, allowing the patient to fully weight-bear immediately, without fear of the knee giving out, and without knee braces. The choice of implant is based on the individual case and amount of knee joint deformity, as well as surgical judgment.
No. A thigh tourniquet is a device like a blood pressure cuff. It is placed on your thigh and inflated to let the surgeon operate more easily by cutting off the blood supply to the leg while the knee joint is open. Tourniquets lead to increased tissue trauma to the thigh muscles, which are squeezed hard for the entire duration of surgery, and a lack of oxygen to the entire leg during the operation. The result is pain, tissue damage, and delayed recovery.
We do not use a tourniquet on any knee operation, no matter how complex the operation. Keep in mind that for convenience and out of habit, most surgeons in the United States do use a tourniquet for knee replacement surgery though, so our practice is very different in this regard.
Studies have shown no difference in blood loss during knee surgery done with or without a thigh tourniquet. Without a tourniquet, most blood loss occurs during the operation. If need be, this blood can be collected by a cell-saver device and given back to the patient. With a tourniquet squeezing the thigh, all the blood loss occurs after the tourniquet is let down and oxygen-deprived tissues get the blood flow restored. This blood is usually collected in a drain placed in the knee joint after surgery and discarded.
Given these considerations, our practice is to avoid damaging muscles and other soft tissues by not using a tourniquet to choke off the blood supply to the leg during knee replacement surgery. Our patients recover faster, in part because of this practice.
Precise alignment of the bones during knee replacement is critical to the long-term performance of the joint replacement. Computer programs can help in such alignment of bones, and reduce the possibility of error. Beyond computer-assisted technology, robotic arms help position bone preparation guides very precisely, and optimize the result for each patient.
With the advent of the custom-made knee replacement by CONFORMIS (Boston, MA), the need for gender-specific knees, left versus right knees, race-specific knees, high-flex knees, computer navigation, robotic-assisted surgery, and other supportive technologies is entirely obsolete and a thing of the past. With a custom-designed knee replacement, the fit, fill, sizing, orientation, rotation, depth, shape, contours, geometry, flexibility, and instrumentation are all optimized for one particular knee, unique to the individual patient. These parameters are optimized to their theoretical extreme, such that surgeon-to-surgeon variability is minimized, thereby maximizing patient outcomes, recovery, safety, reliability, and quality. This technology, in our opinion, is truly revolutionary, and we use it for all total knee replacement now in our practice. Added benefits are simplification of surgery, reduction in product inventory and complexity, and the reduced chance of error.
In the world of knee (and hip) replacement surgery of tomorrow, custom-built implants will increasingly become adopted as surgeons and hospitals see the efficiency and benefits of this technology, at no added cost, and little downside. That is why we prefer to build each knee implant on a custom basis, for each patient. No two people are alike, and that applies to the knee joints as well, providing the most compelling, logical, and reasonable rationale for a custom, patient-specific approach to knee replacement.
Note: Dr. Bal’s practice is to use the muscle-sparing approach to minimize the trauma of knee replacement surgery. Click here to more about this technique and watch animations.