Dr. Todd Dietrick is an orthopedic surgeon who went to Dartmouth and then studied medicine at University of Southern California. He specializes in adult reconstructive surgery, which includes hip and knee replacement. Dr. Dietrick performs about 400 to 500 joint replacements a year—60% of them being knees and 40% hips. Joints, according to Dr. Dietrick, most commonly wear down since they were not designed to last as long as we live these days. People, in general, are more active than they used to be and are active for longer throughout their lives. There can also be congenital factors, which contribute to joint issues. Dr. Dietrick commonly sees patients who mildly injured themselves when they were younger so they didn’t seek treatment but now seek help. Dr. Dietrick says it’s also very common for a patient to complain of pain in one joint witch is actually radiating from another joint. To make a diagnosis, Dr. Dietrick, says getting an x-ray of the joint in pain is the first thing to do and if he needs further information, he will then order an MRI. The main thing Dr. Dietrick looks for is the condition of the cartilage in the joint.
TODD: My name’s Dr. Todd Deitrick I’m a practicing Orthopedic Surgeon, I went to Dartmouth Cartilage undergraduate and I studied medicine at USC medical school. I did my training for orthopedic surgery at USC and then did a fellowship at UC San Diego specializing in adult reconstructive surgery which included hip and knee replacement. Over the course of a normal year I will perform between 400 and 500 total joint replacements. Typically it's 60 percent knees and 40 percent hip replacements. People often ask why did this joint break down? Way back when people didn't live so long as joints weren't really necessarily designed to live and work for seventy or eighty years. So general wear and tear over time is one of the main reasons and people are more active nowadays as well. People are active in sports as they get older and older and that will tend to wear joints out. Historically we thought that this was something that was not a genetic problem but we found out more recently that genetics do play a large role in evolution of arthritis and it does tend to run and families.
TODD: The hip and the knee will tend to break down they have different mechanisms. The knee is a little bit more complex there's a lot more motion that occurs in the knee and so there's a lot of different reasons why the knee can break down. Some of it has to do with the alignment of the legs some people are born what we call knock kneed or some people are bow-legged and so if all the stress isn't going immediately through the center of the knee that can lead to overload on one side and uh, that can lead to the wearing down of cartilage on one side or the other.
TODD: Patients will come in and complain of knee pain and as clinicians it's our job we examine the whole patient to make sure that that pain is not being referred down from the hip joint because that's a very common complaint that happens at least once a week that someone comes in saying that they injured their knee it didn't go away and it's actually pain that’s radiating down from the hip joint.
TODD: We always start out with an x-ray because an x-ray gives us a lot of information about overall alignment which will tell us how much cartilage is present between the bones. If the patient has narrowing of the cartilage and if they have bone spurs typically there's no other testing needed. If a patient has bone on bone in they’re painful and there's no need for an additional study. The only time that we would need to order an MRI is if the diagnosis is unclear and that can give us a lot more information about the soft tissue and the bone itself actually.
TODD: Patients often ask “What is really happening with my knee?” And in the case of degenerative osteoarthritis it typically is a breakdown of the actual surface of the end of the bone. There's two types of cartilage one is the articular cartilage which caps the end of the bone, okay and then there's the other type which is a meniscus which is a shock absorber between the bones. When people talk about arthritis they say, “Oh I've got arthritis.” And so you say, “Well what kind of arthritis?” Well it's degenerative osteoarthritis which means that that articular surface is breaking down and it's a degenerative disease which means that it gradually occurs over time. That can be due to uh, over stressing the particular joint it can be due to a loose body or an injury if you had a fracture at some point and it altered the alignment of the leg, caught it caused added stress on that knee or if he had a simple impact injury at some point in your life then that will add to the breakdown of the cartilage.
TODD: It doesn’t take very much injury to that articular cartilage to damage the cells and one of the unique things about cartilage which makes it so great for everyone is that there are no nerve endings in cartilage. So if you have healthy cartilage on the end of your bones you're not going to feel pain whenever they rub against each other and that allows us to move around. What happens when you develop arthritis is that that cartilage breaks down and then you have bone which is exposed, that has nerve endings that's what hurts, that's what causes the pain. So those cartilage cells which are so great because they don't have any nerve endings allow us to move are also delicate. So if we injure them that it doesn't take very much for those cartilage cells to die and the problem is they don't regenerate. We've only got really very few good cartilage cells and when they die they get replaced was sort of a poor man's articular cartilage called fibrocartilage that does have some nerve endings it doesn't work nearly as well and eventually the added stress causes the breakdown of the joint.
TODD: You need to keep the muscles around your joints very strong and that will decrease the load on the joints especially around the knee joint. If you're heavier you're going to tend to put more stress on the joints themselves and that will lead to further and quicker break down of the cartilage and lead to more arthritis. You want to have a certain amount of activity level but you don't want to overdo it you want to try to avoid injury as much as possible uh, because that can lead to the breakdown of the joints. Any type of injury to the Joint will overload it and uh, potentially improve the chance of developing arthritis.
TODD: Patients always ask when should I have this done and when is the best time to replace your joint if it's appropriate at that time. From our standpoint we always want you to wait until you need to have the joint replaced but I think a lot of people do put it off longer than they should. I think it comes down to a quality of life issue with each individual patient. I tell patients they need to make that decision it's not something that the doctor can say you need to have this now it's our job to help guide them and give them the information about what is going to happen down the road and in the case of arthritis you know, it's a pretty simple picture it's going to worsen over time. And eventually it gets to the point where the joint itself is interfering with quality of life and I think that's the main issue. From a medical standpoint it's really critical to have everything under control. If you are a diabetic you need to make sure that your blood sugars are stable we want to make sure that you're on a good diet make sure your immune system is boosted before the operation when you replace a knee.
TODD: There's a little bit of a misconception people think
That we cut the whole thing out and put a whole new knee in and I think it's more like capping the ends of the bone or capping a tooth is uh, is sort of an analogy I like to use. When we go in to replace a knee uh, we're not replacing the tendons and the ligaments or the soft tissue around the knee but what we're doing is we're taking, we’re replacing the end of the articular surface.
TODD: And so this is a model of a knee. It will help illustrate that when we do the operation the part that is worn out is your articular surface which is the end of the bone and so what we want to do is take that part off and replace it with metal which has no nerve endings and plastic which has no nerve endings. So when they rub against each other you won't have any pain just like a healthy knee with articular surface. We make an incision over the knee we cut down into the knee joint itself um, and we expose the knee joint and uh, basically what happens is if this is the end of the bone here, we make very small cuts, we only take about 9 millimeters of composite of bone and cartilage and we replace it capping it with metal, okay, on one side. On the other side on the tibia we do the same thing. We take a very small sliver of bone on the very top so that we can replace it with a tibial tray which is titanium and we put a plastic liner in okay, which is the padding. We can reduce that, we can balance our ligaments which we need and this particular model does not have the knee cap on it but the knee cap is the same thing. The underside of the kneecap we do resurface the majority of the time the top part that you touched when you touching your knee that is maintained.
TODD: So people want to know how it is aligned. Often times reasons why we operate is because the knee is either bow-legged or knock kneed uh, we call that a veris or vovis [PH] and to line everything up the way I like to do it is by using a computer uh, and what we do is we have a computer in the room which we line the knee up and it allows us to get the alignment over all the knee starting and then allows us to place our trackers on here and our cutting guides so that we can make the perfect cut every time. That's extremely accurate and now allows to restore the natural mechanical axis of the knee and that will lead to greater longevity, better range of motion and we hope less pain and a little revision rate. One of the reasons why it doesn't work so well is if the knee is not aligned properly and so the computer really allows us to get very accurate as far as our alignment goes.
TODD: The computer is helping to align the guys where exactly this replacements going to go and that, those cuts dictate and result in a straight knee or a crooked knee and so the computer will help us define what those cuts are it also allows us to ensure that the range of motion of the knee is going to be accurate. Some people go into the operation they can't fully extend their knee and we can make note of that on the computer it will tell us if the knee doesn't fully stand and how much it bends before we start the operation and then during the operation uh, it will allow us to fine-tune the alignment of the knee so that by the end of surgery the knee is perfect every time.
TODD: The-the knee replacement typically takes about 85 to 90 minutes to perform at that point patients are in the recovery room. The total time the operating room is about 2 hours. The recovery from a knee replacement is a little bit different from a hip replacement and if you talk to anyone who's had both they'll tell you that the knee does take longer to recover from. It's a little bit more painful certainly in the first couple of weeks after surgery that is the main challenge and I think one of the big advances that we've made uh, in orthopedic surgery is that we now partner with an anesthesiologist to have excellent pain management after surgery. Over the past decade we incorporate different types of regional blocks and techniques which really limit the pain that you have in the first 48 to 72 hours after the operation. When patients wake up from surgery they’re able to get up and walk the first couple of days after surgery it's critical in the first couple of weeks to keep your leg up above your heart to limit the amount of swelling. We like to have patients do quad sets to really work on getting that quadriceps muscle active and functioning again we like to have patients raise their legs so that they can get used to doing that. And have them get comfortable getting out of bed and moving around, working on the range of motion that's really a critical component of the first two weeks after a knee replacement. We have patience that drop their leg over the side of the bed there’s some very simple exercises that you can do which help getting that motion before it gets too painful.
TODD: After surgery there is going to be some swelling in the knee that's normal. I think that ice is critical, ice is excellent for pain management as well as for controlling of the swelling. Other things that we do we have patients move their calves back and forth we call those calf pumps and that will limit the amount of swelling in the knees after surgery. If the leg gets too swollen after surgery it swells up like a balloon and it won't want to bend and so I tell patients that we don't want you sitting in a chair all day long because the blood will go down. If you're sitting down keep the leg up an elevated above your heart. So after surgery there is typically no brace you will have a bandage that we place on the knee we use a waterproof bandage so it allows you to shower immediately. The bandage I like has a silver impregnated in it which is actually a bactericidal which means it helps prevent infection which is critical and that bandage can stay on for 4 or 5 days after you leave the hospital and by that time the incision is healed enough that you can shower on your own.
TODD: Typical knee incision is going to go from about here to about here because I like using the computer to help guide the alignment I put the computer inside of my incision instead of making extra incisions and so my incision may be just uh, slightly longer. The incision is closed with sutures that go underneath the skin and then on top of the skin we put metal clips in which stay in for 2 weeks. It typically feels really well that way you know when you have a scar over a joint and the joint is moving sometimes the scar opens up a little bit if we're lucky it won't open up too much. It will take about a year and the scar will fade and if you're lucky and you’re a male and you have a little bit of hair you're not even going to see it, often times women don't even see it either. I'll tell patients who are active enjoy playing golf and tennis I think it's realistic to go back to those types of activities probably after about the three or four month period. Most patients uh, won’t really feel like going out and walking 18 holes of golf after a knee replacement for three or four months. If patients want to go back and become triathletes we have a different conversation.
TODD: After a knee replacement on a rare occasion the knee will be stiff for painful at certain periods of time if you haven't gained a certain amount of motion then we will either order a more aggressive Physical Therapy, uh, we will change the pain management to make sure that you are making appropriate gains. On occasion if you haven't reached those particular goals and a certain amount of period for me it's usually six weeks after surgery if you haven't bent to about a right-angled then I will recommend that we take you back and put you to sleep and what, perform what I call a very aggressive physical therapy session, manipulation under anesthesia, where we can break through some of that scar tissue which is formed we don't know who is going to form scar tissue quicker than other people. And it's uh, it’s really tough to predict and so sometimes on occasion about five percent of the time a patient will develop stiffness and we’ll have to go back to the operating room, not perform an operation but just a manipulation to improve the range of motion and take a patient back on track to recover.
TODD: Uh, when you go home uh, there will be therapists that come to the house and it's critical that you communicate with them and they communicate with the physician so that we know every step of the way, you’re making the appropriate progress so that you have the greatest chance for a successful outcome. After the home therapists are finished you will go to outpatient Physical Therapy and communication between the physical therapist is critical to make sure that you're reaching the milestones appropriate for your particular case.
TODD: One of the most gratifying parts of my job is I get to see patients who come into my office limping and in pain and I know that a certain time line whether it be 2 3 or 6 months down the road that I will see them back in my office walking and happy and grateful for the operation. It takes time, it takes effort on the part of the patient it is not always pain-free. It’s a great operation for patients to have and that's what I like to tell them. The bad news is that you need an operation and I say, “But the good news is that it's one of the best operations ever invented.” And hip replacement surgery or knee replacement surgery is so great at improving function and quality of life and that's what makes my job so gratifying is that I see patients I can tell when they come back in at 6 weeks or at 3 months at 1 year after the surgery and they've forgotten about their joint, they forgot they even had the surgery. And they're just so happy and they're able to do things that they weren't able to do before it's really rewarding.