When reconstructing an ACL one must decide what type of tissue to use to fabricate a new ligament. Biologic grafts can be either native tissue (autografts) or acquired cadaver tissue (allografts). Experience with prosthetic or artificial ligaments has led to failures.
Autografts: Patellar tendon, quadriceps tendon, and semitendinosus/gracilis bundled tendons are the primary autografts in use.
· Patellar tendons grafts are still the gold standard in high demand athletes and have the advantages of bone-to-bone fixation, at both ends, high ultimate tensile strength and high graft stiffness. When this graft heals to bone, the tendinous portion is essentially anchored at both ends. Multi-stranded grafts require healing of all strands to achieve their potential. Patellar tendon grafts may allow slightly earlier return to sport.
As I treat a large number of high level athletes at the professional and college level, I pattern my graft selection after the patterns used on NFL players.
NFL Team Orthopedic surgeons opinions on reconstructing the ACL on an NFL player:
-100% of those surgeons preferred patellar tendon auto grafts, in a recent survey
-0% preferred hamstring grafts
-0% preferred Achilles allograft (cadaver graft)
Patellar Tendon (BTB) (Autologous)
Pros: This graft has high tensile strength, high stiffness of the tissues and allows early bone-to-bone healing at both ends of the graft. Some studies have suggested a higher incidence of residual pain at the donor site however other studies have concluded this not to be the case.
This is the most common graft selected when treating high level, high contact athletes at professional, college and other levels.
Cons: I discourage the use of this graft if the patient spends a lot of time on his/her knees such as occurs in plumbers, tile setters, carpet layers etc. The scar at the donor site is right in the front of the knee may be annoying and uncomfortable in that situation.
Semitendinosus/gracilis bundled tendons (Hamstring)
Pros: This graft is made up by harvesting your semitendinosus and gracilis tendons (hamstring tendons), weaving them into a rope like structure and then implanting that "rope" into the knee in place of the ruptured ACL. It is a strong graft but since it is made up of multiple strands its ultimate strength is dependent on healing of all the strings with exactly the same tension on each strand. Cosmetically this graft is more pleasing as the scar is not directly in the center front of the knee.
Cons: Healing of the tendon strands to the bone occurs at a slightly slower rate than with a bone-to-bone graft. Since the tendons of two muscles are removed, atrophy of muscle in the back of the thigh will occur. This can lead to weakness and cosmetic deformity. This graft also tends to loosen a bit over time and may have a higher failure rate in high demand athletes.
Allograft (Cadaver graft):
Multiple allograft choices have become popular, particularly in the revision setting. These include bone-patellar tendon-bone, quadriceps tendon, hamstring tendon, Achilles tendon, and both anterior and posterior tibialis tendons.
Pros: The advantages of allograft use are less surgical time, less surgical morbidity, faster rehabilitation, and flexibility in graft preparation. The disadvantages include the risk of viral and/or bacterial infection, slower incorporation of allograft tissue, immunologic reactions, and a paucity of long-term outcome data. Cadaver grafts are also more expensive than using your own tissue.
Cons: Since cadaver material comes from a donor, the material must be carefully tested to avoid disease transmission. I have a very long track record with quality providers such that the risk of infection from donor material is actually less than the risk of infection normally associated with any type of surgery.
In reality, hundreds of thousands of various types of allografts are used safely in the U.S. each year. Although there is risk, the risk is very small.
After surgery you will receive pain medication and begin physical therapy. It is important to start moving your new knee as soon as possible after surgery to promote blood flow, to regain knee motion, and to facilitate the recovery process. You should be out of bed and walking with crutches or a walker within 24 hours of your surgery.
You will be shown how to safely climb and descend stairs, how to get into and out of a seated position, and how to care for your knee once you return home. It is a good idea to enlist the help of friends or family to help you once you do return home.
Before you leave the hospital, your therapist will show you a variety of exercises designed to help you regain mobility and strength in your knee. You should be able to perform these exercises on your own at home. When at home, it is very important to continue with your exercises as instructed.
The typical recovery from partial knee replacement is much faster than total knee replacement. Many patients go home after an overnight stay. Some may even go home on the day of surgery. Expect to aggressively attack your rehabilitation with the help of a physical therapist and, if possible, a supportive family member who can be with you during the physical therapy on the day of surgery and the next morning if you spend the night.
Timing of the surgery:
“When should I have my knee replaced?” This is a common question and the answer is patient- specific. It varies from patient to patient and is based on a number of variables.
Sometimes, even in the presence of minimal pain, it is appropriate to do a knee replacement because a deformity is rapidly progressing, or range of motion is deteriorating. This is something we can discuss together so that you can make the best-informed decision.
With few exceptions, I tell patients that they should have the surgery when they are ready. I generally will not tell patients to do it or when to do it, but rather wait for them to tell me that they want to proceed. I also like to emphasize that I “don’t take care of x-rays; but rather, I take care of ‘patients’”. Sometimes x-rays indicate the need for knee replacement but the patient’s symptoms are insufficient to warrant such intervention.
There are several companies that manufacture the hardware used in a Total Knee Replacement. There are a number of variables to consider:
Knees are available in two basic designs: fixed bearing or rotating platforms.
I have extensive experience with “fixed bearing” and “rotating platform” knees. In recent years I have stopped using “rotating platform” knees because, although they have excellent wear characteristics, they are often more difficult to obtain excellent range of motion.
In Europe and Asia, almost equal numbers of Fixed Bearing and Rotating Platform knees are implanted. In the US, fixed bearing has dominated the market because until recently, only J&J/Depuy had FDA approved components. Now most manufactures have FDA approved rotating platform devices.
I primarily use two systems of total knee components in my practice. I most often use a patient specific design manufactured by ConforMis. When a patient specific custom component is not appropriate, I use Medacta (a Swiss made component)
In the past few years I have enjoyed extensive experience with a custom made, patient specific total knee system. I have performed approximately 600 total knees with this technology. It has significant advantages when compared to “off-the-shelf” designs.
ConforMis is presently the only system in the US that manufactures patient specific total knees. All other systems can be classified as “off-the-shelf” designs. Examples of “OTS” knees include Zimmer, Biomet, Stryker, Depuy, Wright Medical, and ODC to name a few.
OTS (Off-the-shelf) knees are manufactured in bulk in a variety of sizes from which the surgeon chooses at the time of surgery. The ConforMis knee is designed from a CT scan of the patient’s knee. The CT scan is used by the manufacturer to create a component that exactly matches the patient’s knee both with respect to size and, more importantly, the actual shape of the knee. OTS knees have a “generic” shape. Individual knees vary tremendously with respect to size and shape. The ConforMis knee effectively “resurfaces” your existing knee as opposed to replacing it with a generic size and shape.
The ConforMis knee has been demonstrated to produce improved outcomes compared to OTS knees in the following areas:
Not all patients are candidates for a ConforMis knee. In those patients I use Medacta. This is an excellent OTS knee manufactured in Switzerland.
When is a patient NOT a candidate for a Patient Specific Knee?
Severe bone loss
Severe loss of motion
Severe ligamentous instability
The ConforMis knee is analogous to a “resurfacing procedure”. Some knees are so badly destroyed that resurfacing is inadequate in restoring function. In those situations I employ Medacta technology. In my practice approximately 90% of the knees I treat are good candidates for ConforMis technology.
Computer Navigation Technology:
I was one of the first surgeons in the US to routinely employ Computer Navigation in total knee replacement in the operating room. This enhanced my ability to properly align the total knee. The technology was expensive, added time to the operative procedure, but was an important improvement. With ConforMis knees, the CT scan is employed to correct alignment using Navigation technology however; it is done in the manufacturing process by creating patient specific cutting jigs along with the patient specific components. This enables the advantages of Navigation however that portion of the procedure is done prior to going to the Operating room thus reducing cost and time in the OR.
ConforMIS technology uses computer navigation technology in the manufacturing process rather in the Operating room. It uses the pre-operative CT scan of your leg.
Standard instrumentation does not use computer navigation; rather, it relies on external and internal alignment rods and jigs to help assure proper component positioning. Although it is a time proven technique it is not as accurate as Computer Navigation.
Fixation of implant:
Implants are fixed to the bone by using either cemented or non-cemented technique. Cemented technique is clearly the “gold standard” and according to most studies it produces the best long-term results. Sometimes non-cemented methods are appropriate. It requires ‘in’ growth of your bone into the implant to assure solid fixation. Although slightly less reliable than cemented technique, it can also produce good results.
Pain Control Protocol, Medications, and Hospital Stay
For several years I have been using what is referred to as a “multimodal” approach to pain management. It recognizes that there are various pain receptor sites in the brain and if we block those sites before we cause pain, the effect is much better than if we cause the pain and then try to ‘catch up’ with medication. Therefore, about an hour before the surgery we administer three different types of oral pain medications. We continue those for several days after the surgery to maintain the “blockade” of the receptor sites in the brain. Studies and experience has proven that this results in far superior pain relief.
If there are medications that you have already been taking from home (home medications), we will discuss them at your pre operative appointment. There may be some that you need to stop taking before surgery.
There are three basic types of receptor sites in the brain responsible for the transmission of pain. Each receptor type can be blocked with a specific medication. It is known that if we block the receptor site before the pain stimulus occurs, the result of reduced pain is far superior to that which occurs if the blockade is not started until after the pain stimulus happens. Again, approximately one hour prior to surgery, three separate oral medications are administered.
All three of these medications are continued in relatively low doses throughout the hospital stay and for the first week or two after hospital discharge in order to keep the receptor sites constantly blocked.
Anesthesia at time of Surgery:
I prefer, and almost require, regional anesthesia instead of general anesthesia, for total and partial knee replacement. Regional anesthesia means a spinal anesthetic combined with gentle sedation and a long acting local anesthetic injected in the tissues around the knee at the time of surgery.
This is superior in many ways—
What is a spinal anesthetic?
This is an injection of a long acting local anesthetic medication into the spinal fluid in your low back region. It causes numbness and weakness in the legs that can last for up to 24 hours. This is not to be confused with an epidural anesthetic where the numbing medication is placed adjacent to the spinal sack rather than in the spinal sack. In my experience, epidural anesthesia is less reliable.
The anesthesiologist primarily controls medications administered during the course of the surgery. They include the anesthetic agents that are part of the spinal anesthetic, as well as muscle relaxers and tranquilizing medications. Unlike general anesthetic, you are not completely asleep, however, drugs are often administered such that you do not remember any of the details of the experience since you are generally not completely asleep as occurs during a general anesthetic.
Additionally, antibiotic medication is provided to help reduce the risk of infection as well as any other medications that may be useful considering your general medication condition and anesthetic needs.
Immediately after surgery medications are given to help you wake up and recover. Intravenous antibiotics will be continued for 24 hours following surgery. Drugs are available to control nausea, provide pain relief and muscle relaxation. Most, if not all, of your “home medications” will probably be continued after surgery. If you take drugs that impact bleeding, they may be modified or temporarily halted. Anticoagulation therapy will be applied as described below in the “Blood Clot/Anticoagulation section on the following page. As part of the “multimodal” approach to pain control, I use a peri-articular long lasting local anesthetic, as well as a continued blockage of the receptor sites responsible for pain sensation as previously described (see Pre-Operative Medications- on previous page).
Medications at Time of Discharge:
When you are ready to go home you will most likely continue with any medications you were taking before you came to the hospital for this surgery. This will be discussed upon discharge.
You will also be given RX for the following:
Where do I go after hospital discharge?
Most of my total knee patients are discharged from the hospital on the 2nd or 3rd day following surgery. Most go directly home. This assumes that their home environment is sufficient to meet their needs. To go home, one must have sufficient help at home to help you through the first several days. If you think in-home nursing care might be needed then going to a local rehabilitation facility is probably a better choice than going directly home. An attentive spouse or family member is usually sufficient for discharge to home. If you are uncomfortable about your home situation, there are several local rehabilitation facilities that you might consider. My office can share with you our experience and recommendations.
If you go home, a home physical therapist will come to your home for 1-3 weeks and help continue the therapy program you started in the hospital. Not all home physical therapists are the same. We can advise you regarding those with whom we have good experience.
Once you are sufficiently mobile, it may be appropriate to continue your rehabilitation at a local outpatient physical therapy unit or a local gym. These decisions are dictated to a large degree based on your progress, your level of independence and your motivation.
Improved technology and improved outcomes now enable us, in some circumstances, to perform total knee replacement in an outpatient setting. In this situation you spend 23 hours in the outpatient facility and then go home or to a sub-acute skilled nursing facility for a few days. This may dramatically reduce the overall cost of total knee replacement.
Blood loss issues:
With current technology I rarely encounter the need for blood transfusion following total knee replacement. Thus it is NOT my practice to have you donate your own blood in advance, nor expect to have to receive a transfusion from someone else.
Exceptions to this are extremely rare in my experience.
Blood Clot (DVT- deep vein thrombosis) Prophylaxis/ Anticoagulation:
DVT describes the condition when blood clots within a vein, thus obstructing the vein. When the clotted or thrombosed vein is inflamed and painful, one may use the term thrombophlebitis. A DVT is a potentially dangerous condition. If the clot breaks loose from where it formed, it may move to the lungs and cause a pulmonary embolism. A pulmonary embolism can be fatal. A number of things are done both in the hospital and after hospital discharge to minimize the risk of this serious complication. Unfortunately there is no assurance that these treatments will work.
Treatments done both in and out of the hospital include mechanical measures as well as medicinal measures.
Some of the following measures MAY be used to attempt to reduce the risk of developing a blood clot:
Depending on your specific “risk” factors, some of the following measures may be used in attempting to reduce the risk of a blood clot during and following your procedure:
My Approach to DVT/Pulmonary Embolism Prophylaxis: I prefer to maximize mechanical and medical measures. This means:
A post-operative infection can be a significant and major complication. It may lead to complete failure of the surgery. A number of things are done to minimize this risk, although the risk can never be completely eliminated.
My Approach to preventing infection:
Physical therapy and exercise therapy when performed prior to surgery has some limited value. Unfortunately most patients anticipating surgery are in pain, and aggressive exercise often only makes the pain worse. Efforts to improve range of motion prior to surgery are not often effective. Resistive exercises to improve strength are encouraged. Recent studies demonstrate that efforts at physical therapy PRIOR to total knee replacement REDUCE the need for physical therapy after the surgery and improve outcomes.
Physical therapy and rehabilitation starts on the day of surgery. I prefer that you get out of bed and are at least standing, if not taking a few steps, on the afternoon following surgery. I start active and passive range of motion exercises on the day of surgery and continue through the hospital stay and at home following discharge. I employ CPM, which is a Continuous Passive Motion machine to help you gain range of motion after surgery.
After Discharge from the Hospital:
Home physical therapy is arranged to assist you for the first week or two following hospital discharge. It consists primarily of doing much of the same exercises that you started in the hospital. It will include use of the CPM as well as therapist directed exercises. Your specific need for these services will vary with your own difficulties and motivation. As soon as you are able to successfully continue on your own or in an outpatient facility home physical therapy can be discontinued.
Outpatient therapy is sometimes needed as an adjunct to home physical therapy. This involves going to a local facility and receiving instruction and assistance in gaining range of motion, strength and endurance. We can assist you in selecting a physical therapist with expertise in total knee rehabilitation.
Why do total knees fail?
What about infection?
It is known that patients with joint replacements who are having invasive procedures performed or who have other infections are at increased risk of the infection spreading to their prosthetic joint. Antibiotic prophylaxis may be considered for those patients who are at risk. Most recent recommendations are that antibiotics be employed on the day of the procedure for such things as dental work and other more invasive procedures. This should be done for at least the first two years following implantation of your new joint. Some believe that it should be done indefinitely. I will discuss with you the best approach for your particular situation.
Wear and implant Failure:
How long will a total knee last?
There are a number of factors that contribute to the answer.
The Most Common Reasons why total knees fail and require revision:
Minimally Invasive Total Knee Replacement:
Recently there have been attempts to do this operation through a smaller incision. Many surgeons use a 10-12 inch incision. My standard incision is approximately 6 inches; however the opening varies with the size of the patient. It is possible to do the surgery through a 3 ½ inch incision. Recent studies however, have shown there is a high complication rate, higher incidence of poor component alignment, and no significant advantage to the patient. Some sill advocate this approach. However, experience has taught that I can produce a more reliable result through a 6-inch incision. This is a decision I believe should be left to the surgeon. The fact that your incision is a couple of inches shorter will offer little pleasure if your knee fails prematurely, or does not work as anticipated.
Diagnostic Arthroscopy: top
Small incisions (approximately 4 mm) are made in the front of the knee joint. An arthroscope is introduced into the joint. The joint is infused with a physiologic solution. The joint and all structures are examined visually employing a video system. The arthroscope is a small tube with internal fiberoptic light and is attached to a video camera which directs the inside of your knee joint onto a video screen. Dr. Kimball routinely takes a series of still photographs of the findings in your knee such that he can demonstrate to you what he found and what he did. He can usually provide you with your own copy of photographs and will do so at your first post operative office visit.
Dr. Kimball looks the joint surfaces, the tracking of the patella, the medial and lateral meniscus and the anterior (ACL) and posterior (PCL) cruciate ligaments.
Upon completion of the diagnostic portion of the procedure, Dr.Kimball is prepared to proceed with repair and or reconstruction of the damaged structures.