The future is here!
We are thrilled to announce that we are establishing a robotically assisted total joint replacement program here in Hudson, New York. We will be using the Stryker Mako system for partial knee replacements, total knee replacements, and total hip replacements.
What is the big deal?
Patients and surgeons are very fortunate in that total joint replacement is reproducible, predictable and forgiving. That does not mean it is perfect.
While patients routinely report dramatic pain relief once rehabilitated, we as surgeons are thrilled when they report that their new joint feels "normal." This occurs less often than anyone would like.
During surgery, we use alignment guides designed to produce certain angles, or remove a particular amount of bone. These guides have been the same for decades. Good surgeons will achieve consistent results, but even the very best surgeons will admit that there is more variability than anyone would like. This can occur for a variety of reasons, but it is impossible to completely avoid.
Using a robotic arm during surgery, we can implant joint prostheses within a millimeter and a degree of the intended plan. Every time. No surgeon, anywhere, can do this using manual tools.
Before you begin imagining a robotic arm like those seen in vehicle assembly, let me explain how the Styker Mako robotic arm works. Preoperatively, the patient undergoes a CT scan. The surgeon then plans the surgery virtually on the computer, determining the intended alignment and position of the prosthesis. In the operating room, the surgeon makes the surgical approach and then uses a probe to orient the robotic software to the position of the patients bones. During preparation of the bone, the robotic arm prevents anything but the exact plan from being executed. It does this passively. At no point can the robot move itself. The surgeon positions the tools and prostheses and once perfectly aligned, the robot locks the tool into this perfect position. The handpiece, which is operated by the surgeon, will not be activated until it is perfectly aligned and in a safe position. The surgeon then activates the tool, or manually impacts the prosthesis depending on the step in the procedure. The surgeon gets real-time information regarding implant position as it is happening.
From the surgeon's perspective, this information is invaluable! We can adjust our plan intraoperatively if needed. We can execute our plan perfectly, every time. During knee replacement, we can balance ligaments degree by degree. During hip replacement, we can optimize acetabular (socket) placement, leg length, and offset.
When dealing with complex biological systems, there will always be factors beyond our control. Robotic total joint replacement is an amazing tool, which gives us tighter control over prosthetic implantation and soft tissue balance. This will improve the function and longevity of implants for patients.
Much of this website is directed toward proper rehabilitation after joint replacement. While prosthetic alignment and soft tissue balance will be improved using the Mako robot, appropriate rehabilitation will always be crucial to maximizing outcomes.
Total knee replacement has become a very common elective surgery, and patients are often amazed at how quickly they can get back to "normal" life after surgery. Within hours of their surgery, my patients are often able to begin walking with the assistance of a physical therapist and a walker. While most of my total joint replacement patients can be discharged to home within 48 hours, many are stable for discharge within 24 hours of surgery.
In spite of the anticipated rapid early recovery following total knee replacement, there is still a significant healing process that must occur. This healing process progresses through an inflammatory cascade and continues for over a year from surgery. It is this inflammatory cascade that requires a dedicated stretching regimen to ensure optimal knee range of motion following surgery.
Many patients are concerned that their knee feels warm, and may appear swollen and/or pink in the early post-operative period following knee replacement. In the vast majority of cases, this is normal and an anticipated part of the recovery period. Of course, if there is ever a concern, you should always discuss this with your orthopedic surgeon. Why does this happen? Basically, the body increases blood flow to the knee region to support the healing process. This increased blood flow results in the warmth, swelling and redness often experienced by the patient.
As the healing process progresses, the warmth, swelling and redness dissipate. The warmth can take 6 months or longer to resolve. Swelling and redness generally resolve within a few weeks of surgery.
A bone scan is a nuclear medicine radiological study that reveals bone metabolic activity. It will light up in areas that are irritated such as fractures, stress reactions, tumors and arthritic joints. If a bone scan is performed within 2 years of a total joint replacement, it will show increased bone metabolic activity adjacent to the relatively new prosthesis (even when the prosthesis is functioning properly). This is further indication that the healing process following joint replacement progresses over a very long period of time. Thankfully, the replaced joint usually feels great, long before the body has fully recovered.
So, after total knee replacement you can monitor the healing process by feeling the skin overlying your knee. As your skin gradually cools off, month-by-month, you know the healing process is winding down.
Please note: Severe swelling/redness, drainage from the wound, increasing pain, and/or loss of range-of-motion should not be assumed to be normal. If there is any concern, you need to be evaluated by your orthopedic surgeon immediately.
When can I drive?
This is a very common question patients ask following surgery. Some studies have suggested that reaction time and/or braking force is reduced for weeks or even months following total knee replacement surgery. This could lead us to recommend that patients do not drive for a prolonged period of time following total knee replacement surgery. Logistically, this can be challenging.
A recent study showed that patients with osteoarthritis of the knee (without having undergone knee replacement surgery) had reduced driving ability based on diminished reaction time, movement time, and they ultimately had reduced braking performance. In spite of these findings, is not reasonable to tell patients with osteoarthritis of the knee that they can never drive.
A brand new article in the Journal of Arthroplasty shows that 80% of patients have regained their pre-surgery braking performance by 2 weeks following total knee replacement. All patients in this study were back to baseline by 4 weeks.
This reinforces my standard recommendation, but still leaves out one key issue. Pain medication. Narcotic pain medication is commonly used for several weeks following total knee replacement. This can impair driving skill and reaction time independent of knee surgery.
My recommendation to patients after total knee replacement surgery is that they should not drive while they are using narcotic medications. Furthermore, they should not drive until they feel comfortable doing so. This time period is patient specific, and there is a wide range. Common sense should prevail. I believe patients generally know themselves, and certainly do not want to place anyone at risk by driving prematurely.
I recommend patients focus as much as possible on rehabilitating their new total knee replacement for the first few weeks, limiting their driving to the essentials: food shopping, physical therapy, and follow-up with their orthopedic surgeon. Soon, their pain level will be down, and their confidence to drive will return.
We can then add driving to the list of lifestyle improvements made possible by total knee replacement.
As always...please discuss specific recommendations with your surgeon.
How much motion should you have at any given point after surgery? Of course, you should speak to your surgeon about the specifics of your case. However I'd like to provide some general guidance on this subject.
During knee replacement surgery, the knee will be reconstructed using a metal and plastic prosthesis, and the ligaments balanced. At the conclusion of the operation, the knee will be able to fully extend (straighten) and fully flex (bend back). After surgery, although initially pain will prevent full range of motion, scar tissue has not had a chance to form. Most patients are able to move from full extension (0 degrees) to 90 degrees (foot flat on floor while sitting in normal chair) within 24-48 hours.
It is not uncommon for patients to lose a bit of motion around 7-10 days from surgery. This is a result of increased pain and swelling due to the inflammatory cascade. This inflammation peaks around 10 days from surgery. It is ok to go a bit easy on yourself during this time. Use plenty of ice and anti-inflammatory medication if it is allowed by your surgeon. But keep stretching. Do not allow yourself to lose full extension. This is crucial.
By the first postoperative visit around 2 weeks from surgery I would like to see a minimum of 0-90 degrees of motion.
By 6 weeks from surgery I would like to see 0-120 degrees minimum.
Patients may gain an additional 5-10 degrees of deep flexion over the course of the first year following surgery if they've gotten to 120 degrees by 6 weeks.
If these parameters are not met, other options are available. I begin asking patients to follow-up with me every other week or more to track their progress, to answer questions, and provide motivation and support. I understand that this process isn't always easy and is never fun. If inadequate range of motion isn't achieved by 6 weeks, I then recommend manipulation under anesthesia to break up scar tissue that has been allowed to form. This buys us some time and generally gets things back on track.
Total knee replacement surgery is an effective way to relieve arthritis pain when non-operative measures have failed. A substantial portion of the outcome, however, is based on adequately rehabilitating after surgery. The most important part of the rehabilitation program is regaining normal range of motion.
This is easier said than done.
At the time of a properly performed knee replacement surgery, the soft tissues are balanced and the range of motion should be full. That is: all the way straight, to all the way bent. This is something we test during surgery. Then the incision is closed and the healing process begins. Initially, there could be some swelling and acute surgical pain from the incision/surgical approach. Soon this acute pain subsides and stiffness begins. The stiffness is experienced by many patients as pain, especially when moving against the endpoint.
In a prior posting I discussed the tissue planes that need to glide to allow proper motion. Each day that passes after knee replacement surgery, more healing occurs. This process can create connections, or adhesions, between these tissues. After about 6 weeks, enough scar tissue has formed, that most patients are unable to obtain more range of motion by stretching. In other words, at around 6 weeks from surgery no more progress with regard to range of motion is possible.
The trouble is, in order to regain excellent function, adequate knee range of motion is necessary. Most patients are anxious to walk, ride a stationary bike, and are often quite focused on regaining strength. While these are fine things to do, and I certainly understand this desire, redirecting the focus to stretching appropriately remains my priority during the first 6 weeks postoperatively. Once range of motion is reestablished, all of these activities will be possible. Because we have a limited time to regain this range of motion this needs to be the priority early on.
Thankfully these stretches are simple. Gently and progressively force the knee straight. And then gently and progressively force the knee bent. Simple! Except when it's not.
Sometimes, and fortunately it is rare, a patient really struggles to regain range of motion after their total knee replacement. This can be a very frustrating situation for the patient and surgeon alike.
I recommend stretching early, often, gently, but progressively. It is better to regain motion early than to attempt to catch up when stiffness is setting in.
The simplest stretches are shown below:
This is one of the easiest stretches for extension. Place your ankle on a pillow. Relax your muscles to allow your knee to sag down. Then attempt to push the back of your knee down. This is a side view of my knee. It is important to note that my kneecap and toes are pointing straight up. This stretch can be held for minutes, gradually relax your muscles more and more, allow gravity to do the work. The longer the stretch the more the viscoelastic tissues will elongate.
This is the wrong way to stretch. This is a view of my knee from above. There is a natural tendency to externally rotate as your hips relax. Our goals are not being accomplished if this is allowed to happen. If you find this happening, simply place additional pillows or folded blankets along the outside of your foot and thigh to hold your toes and kneecap pointing up.
Now we are working on regaining flexion. In this example we are working on gaining flexion in my right knee (in the back ground of this photo). Here I have placed my left leg in front of my right ankle. I am using my left leg to help bend my stiff right knee more. This works best when done progressively over a period of minutes as opposed to seconds. Use your hamstrings in both legs to try to flex both knees further.
For deeper flexion than the previous stretch, this position utilizes a step-stool to provide deeper knee flexion. As shown, leaning forward and applying pressure with your hands can increase the stretch.
This is a stretch that can achieve extreme flexion. This time I am lying on my back. My knee is pointing up toward the ceiling. Flexing the hip relaxes the quadriceps. The hands are used to to pull the leg toward your body. The effect is increased hip and knee flexion.
Please note: if you have a total hip replacement, be very careful with this position as it can produce significant hip flexion.
These stretching positions should take care of 90% of total knee replacement patients. These stretches should be done everyday, ideally multiple times per day, with no days off. The longer the stretches can be held, the better. Remember to relax as much as possible while stretching and remember that a little pain is normal an expected. If no pain is encountered, I would recommend pushing a little bit harder. As always, if you have any specific questions about your particular case, discuss with your surgeon.
Occasionally we encounter a patient that has a very difficult time regaining motion. I have a few additional recommendations in these cases and will address that situation in an upcoming posting.
Biologic tissues are viscoelastic. That means their stretchiness changes depending on how hard they are stretched. We can take advantage of this characteristic when we are rehabilitating a stiff joint. This becomes very important with certain medical problems. Specifically: total knee replacement and frozen shoulder. This concept is generally helpful in orthopedic rehabilitation and I take advantage of it whenever applicable.
Think of silly putty. When slowly stretched it can be drawn out into a long strand, but when pulled aggressively it will snap and break in two. This is an extreme example of viscoelasticity.
Your tissues are similar. While extreme force stretching can cause tissue to tear, this is generally far beyond any amount of stretching a patient can do, even with a physical therapist. A manipulation under anesthesia is a maneuver performed by a surgeon to rapidly regain motion in a particular joint that has become stiff. Tissues tear, and inflammation results. This is the most extreme example of a high force, low duration stretch. It is best to avoid this type of intervention if possible. It is preferable for a patient to spend the time necessary to recover joint range of motion using a long duration, low force stretch. It will result in less inflammation and less pain.
Shoulders and knees commonly become stiff. Total knee rehabilitation requires stretching to regain range of motion after surgery. Stretching is required to speed up the recovery of a frozen shoulder. When attempting to regain range of motion patients are often told to stretch for 10-15 seconds and then relax. Over and over. Sometimes this is effective. Sometimes it is not. There is significant genetic variation with regard to tissue strength and inflammatory response, and significant psychological variation with regard to pain tolerance, and ability to relax while stretching. When a patient has trouble regaining range of motion I try to focus them on long duration, low force stretching. This tends to create less inflammation and is more likely to allow a patient to relax the muscles while stretching. Relaxing is very important because any muscle resistance will prevent gains in range of motion.
This sketch depicts how I think about stretching. A high force, brief stretch is more likely to cause inflammation. A gentle prolonged stretch is less likely to create an inflammatory response. The "amount of stretch" or the total area under the curve depicted by the hash marks could be identical, but my experience suggests the long duration, low force stretching will give a superior result.
How do I know this?
When I was a resident, I developed a frozen shoulder and used long duration, low force stretching to cure myself. I have subsequently recommended this technique to countless patients who presented with frozen shoulders that had failed to improve after many weeks of standard physical therapy. Although occasionally surgical intervention was necessary, the vast majority progressed using this technique and never needed surgery. This technique has become my standard recommendation following total knee replacement and to rehabilitate a frozen shoulder, and has minimized the need for manipulation.
So you finally decided to have your arthritic knee replaced. You got through the surgery just fine. As expected, you had some surgical pain, but almost immediately you realized that your arthritic pain was gone. Awesome! Things seemed to be going very nicely, and now you are home...
Your knee may begin feeling tight and warm. This is normal and expected. Healing occurs in part through an inflammatory process. Inflammation shows up as swelling, warmth, and pain. You have been told to stretch, but may be questioning this recommendation now. You may be concerned that because it hurts you could be damaging yourself or your new knee. This is a very common concern. Please resist the urge to stop stretching.
The knee is a complex joint. There several moving parts and potential spaces (otherwise known as tissue planes). During total knee replacement these parts are moved around , the tissue planes are opened. I think it makes sense to patients when they have some pain after surgery. But as the wound is healing on the outside, why does it feel like things are getting worse on the inside?
As the healing process proceeds, the tissue planes that have been opened begin sticking together. Gradually adhesions, or scar tissue, may form between these planes preventing them from gliding properly. Initially this scar tissue is weak, but it will get stronger every day. For this reason, there is some urgency to regain range of motion as soon as possible. This is because after about 6 weeks or so from surgery this scar tissue becomes strong enough that a patient is unlikely to be able to stretch it out any more. The range of motion you have achieved at this point will be how far your knee will move permanently...without additional intervention.
To better understand knee range of motion lets begin with a couple of definitions. Flexion of the knee means bending. When you sit in a chair and your feet are flat on the floor, your knee is bent, or flexed. Extension of the knee means straightened. When you stand up and your knee is straight it is extended.
Now lets discuss these tissue planes a bit.
The skin must be able to slide over the kneecap (patella). The body achieves this by only loosely attaching the skin to the patella. This loose connective tissue allows motion to occur. Under abnormal conditions, fluid can collect here and create swelling. A potential space such as this is referred to as a bursa. The loose connective tissue found here is called bursal tissue. The specific space, or tissue plane, between the skin and the kneecap is called the pre-patellar bursa. It is shown in purple in my sketch.
The kneecap (patella) is embedded within the tendon that attaches your thigh muscles (quadriceps) to your shin bone (tibia). A tendon is the tissue that attaches muscle to bone. The quadriceps tendon must be able to slide relative to the thigh bone (femur). The area above the patella shown in my sketch as orange is called the supra-patellar pouch.
If either of these tissue planes sticks together, the knee will not be able to bend completely.
In the back of the knee there is a sheet of tissue called the posterior capsule. This is green in my sketch. This tissue is irritated during surgery and will gradually tighten as it heals. If this is allowed to happen, the knee will not fully extend.
So, how do you prevent a stiff total knee? It is not by walking around a lot. It is not by cycling the knee back and forth a lot. It is by gently and progressively stretching. Even though it hurts. The longer you are from surgery, the longer these stretching sessions must be because the scar tissue becomes stronger each day. Gentle progressive stretching works by taking advantage of the viscoelastic nature of biologic tissues.
My basic recommendations:
Future posts will further develop these concepts.
Orthopedic Surgeon focused on the entire patient, not just a single joint.