Dr. Kevin Stone: Why 80% of Knee Replacements Are Not Needed

Full transcript of the Tom Rowland Podcast, Episode 543, featuring Dr. Kevin Stone...

Dr. Stone, an orthopedic surgeon at the Stone Clinic in San Francisco, explains why so many people are told they need a knee replacement when they don't, and what it really takes to keep playing the sports you love for the rest of your life.

From a Torn Meniscus to a Career in Orthopedics

Dr. Kevin Stone: I'm Dr. Kevin Stone, and this is the Tom Rowland Podcast.

Tom Rowland: Alright, Dr. Stone, thank you for being here.

Dr. Kevin Stone: Pleasure.

Tom Rowland: You've done some really innovative stuff. I've been watching your TED Talks, I've been watching some other videos. I'm very interested in what you have to offer today, because just like me, an aging athlete and an aging outdoorsman, these are things we're faced with. As you get to your forties and fifties and you want to continue to do what you want to do, sometimes your body can be limiting. I love the title of your new book, Play Forever, and I want to get into your story, what you do, and understand that there's hope for playing forever.

Dr. Kevin Stone: Well, let's start from the beginning, because you said you're an aging athlete, but you're really not very old.

Tom Rowland: I'm 53.

Dr. Kevin Stone: So, as we like to say, if I'm managing you as your doc, I've got another fifty years of you playing to think through. What do I do for you? How do I counsel you? How do I inspire you to look at the fact that you're only halfway there? Everything we're going to talk about today, everything I want to encourage you to be thinking, is: how do I drop dead at age 100 playing the sport I love? If you can adopt that attitude, and if the doctors and therapists and people caring for you can look at you that way, then everything we do has that perspective.

Tom Rowland: I love that. What you go directly to is attitude, the way you think about this. Because a lot of people think, man, when you're 40 it's all downhill after that and then it's over. And I think with that attitude, it probably is. But for the people who really take care of their body, you've got a lot of road left.

Dr. Kevin Stone: You do.

Tom Rowland: So what's your story? How did you get into this field and into these particular innovations?

Dr. Kevin Stone: It started out pretty young, as a college athlete who tore my meniscus cartilage playing soccer at Harvard. I remember the Brown defender going by, and I reached out at just that last moment—a mental error, and I shouldn't have done it. I tore my meniscus, the shock absorber inside your knee. Inside the knee there are two major types of cartilage: the meniscus, and the articular cartilage, that white shiny surface. When you get arthritis, it's that surface wearing down to the bone. In any case, I tore my meniscus, and that started off the history that millions of Americans have gone through. They tear that shock absorber, the well-meaning doctor goes in and takes it out, and that starts the downhill course for their knee, because without that shock absorber the knee just wears out over time.

Eventually I came to admire the doctor who took out my meniscus. He was walking around the training room taking care of athletes, giving a few encouraging words to the injured athlete, and I remember thinking, I could do that, and I'd be inspired if I could. So I went to medical school, and I was out for a run with my eventual mentor, a guy named Dick Steadman, who many listeners may remember. He looked at me running with my bow legs and said that if I could figure out how to replace the meniscus, I'd make a real contribution to orthopedics. And in my arrogant, typical Harvard attitude I said sure, I'd do it—as long as he paid for it. That started us off in the late 1980s, and I designed the first collagen template for regrowing the meniscus. That became a product in the marketplace, tested worldwide, acting as a regeneration template. It's one of the first examples of us thinking through that the body has the ability to regrow its tissues—it's just lost that skill over time. Look at a little child: when they lose a fingertip, they regrow it. Look at a salamander: it loses its tail, it regrows it. The genes within your body are there. They're programmed to regrow injured parts, but they're suppressed as you get older. Our challenge, and the fun of what I've done in orthopedics over the last thirty years, has been figuring out how to give the body a regeneration template—how to put a little trellis there, like a rose trellis, and stimulate the body to regrow through it.

Tom Rowland: And this is in all joints? I know you specialize in the knee, and shoulders too, but does this apply all over the body?

Dr. Kevin Stone: Fundamentally the biology is similar, though with differences. At the Stone Clinic in San Francisco we specialize in shoulder, knee, and ankle, and even among those three joints there are tremendous differences. When you walk around on your ankle, that tiny joint carrying your whole body, why doesn't it develop arthritis naturally the way your knee and hip do unless you have an injury? There's something unique about the cartilage in the ankle that we study. I see tremendously destroyed ankles that people have been told need a fusion or replacement, and when we do our biologic stimulation techniques we can regrow good enough cartilage that the ankle works well for a long time. Each joint is a little different, but fundamentally the biology wants to regrow tissue, it's just suppressed, and our job is to figure out how to turn it back on.

Stimulating the Body's Own Stem Cells

Tom Rowland: So how do we do that? That's the million-dollar question.

Dr. Kevin Stone: There are lots of ways today, and the science is evolving. We have a public nonprofit research foundation called the Stone Research Foundation in San Francisco, and we do studies on exactly that. Many listeners have heard of PRP and stem cell injections. Within your own blood you can take the platelets out and get them to release their growth factors into a joint or an injured tissue—that's the PRP injection. We're getting better at identifying which factors are important for which tissues. An injured ACL should probably get a different therapy than an arthritic knee, and much of our research is around that personalized medicine, studying an individual patient's tissue and figuring out which factors it responds to. Right now injection therapies are a potent tool for regrowing tissue, along with scaffolds such as a meniscus allograft, a donor ligament, or a collagen scaffold—providing a replacement tissue and then stimulating it.

Athletes always ask why it takes a year to recover from an ACL injury. There are two parts to that. First, the tissue we put back in to act as a new ACL takes a long time to remodel, so we're adding growth factors to make it heal faster. Second—and this is the worse part for most athletes—it's not usually the pain, it's the atrophy, and they spend a year building back their muscle. We have a study going on right now looking at how we can block that atrophy from occurring.

Tom Rowland: How do you block atrophy from happening? That's super interesting.

Dr. Kevin Stone: We're right in the middle of the study, but here's the thinking. Surgery is a huge stress reaction, and that stress releases cortisol, the stress hormone. Cortisol binds to muscle receptors and stimulates the atrophy we see from surgery within eight hours. In this study we're preloading the patient before surgery with a long-acting blocking agent—testosterone—which binds those same muscle receptors, so the cortisol can't. We want to know if we can block those receptors and stop the atrophy, or at least a percentage of it.

Tom Rowland: I remember when a kid would break an arm or leg and be in a cast, and when the cast came off one leg looked like a pencil next to the other. Give it six months and the legs are equal again. But why didn't the uninjured leg get even bigger in the meantime? That is so weird.

Dr. Kevin Stone: Great observation, and the honest answer is we don't fully know. But the body clearly can direct the healing response to the site of injury. That's exactly how we're using growth factors and stimulants—to recruit your body's own stem cells to the site of injury. You have billions of stem cells in your body no matter your age; as you get older you have fewer, but still billions. The body knows when you have an injury or arthritis, and it stimulates those stem cells to release from their resting site, usually on the walls of vessels. They divide in two: one reproduces the stem cell, and one becomes a progenitor cell that rushes to the site of injury and directs the healing. That's exactly what happened in the kid's cast analogy. When you have an injury or arthritis, we want to stimulate your body to release those progenitor cells so they migrate to the injury and direct the healing, and we're getting better and better at targeting that.

Tom Rowland: Does that research have potential to help people with whole-body atrophy, like someone in a coma or on long bed rest?

Dr. Kevin Stone: That brings up how much your mind and attitude direct your healing response. We don't yet know how to stimulate a whole-body healing response for somebody in a coma. We do know exercise induces bone and muscle formation, and without exercise it's very difficult to build either. But also, without your head in the right space, it's very difficult to produce muscle and bone, and when you have pain it's extremely hard to rebuild a joint. Patients often ask whether they should work out and get stronger before surgery. Almost nobody can build muscle if they're in pain—it's a huge inhibitor. So the brain, the mind, and the attitude control all of this. We can give as many stimulants as we want, and it won't work without all those things working together.

Why the Mind Determines Recovery

Tom Rowland: That's fascinating to me. An underlying theme of this whole podcast is what effect the mind plays in success, injury, athletic performance—whatever it is. It's not measurable, but it's very observable. People with the same tools available to them end up with different outcomes because their mindset is different. To see that brought into conventional, mechanical medicine like orthopedics is fascinating. Do you think doctors in general give the mind its due?

Dr. Kevin Stone: Not enough, which is why we wrote the book Play Forever and why I lecture around the world. Here are two examples. The patient who goes into surgery with a big smile on their face does better—they make the recovery room team happy, the OR team happy, the surgeon happy, and it colors the entire experience. The patient who goes in angry or skeptical just doesn't do as well. It's bizarre, but true. The other thing I think about is that every athlete gets hurt somewhere in their career, and if you can use the injury as an opportunity—asking how you can become fitter, faster, and stronger during that window of time—you do great, even through a complication or a bump in the road. The ones who tell themselves they're injured and can't do anything for a year never do as well. The mind really controls what happens.

Tom Rowland: Are you personally talking to your patients about that, or do you let their sports psychologists take the lead?

Dr. Kevin Stone: It's absolutely part of our care. The moment we see a patient, our rehab team, physical therapists, fitness trainers, and nursing team are all involved, and every patient sees all of them. Part of the deal between me and the patient is: I'll give you my best surgery, but you give me your best effort in the recovery program. We see it as creating an athlete for life. Once you enter our world, we never want to lose you. We do something called the Stone Fit Test at intervals—a lot in the first weeks and months, when patients spend two hours a day with our rehab team starting day one after surgery, and then once or twice a year after that. No athlete, not even an Olympian, should ever be able to pass it completely.

Tom Rowland: It's designed that way on purpose?

Dr. Kevin Stone: Exactly—it's designed to find out where you're weak, what you've been favoring, what part of you you've been ignoring, so we can help you cross-train and think about total-body fitness. It's individualized to the sport. You might be a great skater with phenomenal side-to-side ability but weak core strength or weak glutes. You'd be shocked how many phenomenal athletes don't pay attention to the rest of their body—our cyclists, for instance, tend to have very weak cores and arched backs. We look at strength, mobility, flexibility, power, accuracy, coordination, and balance—the big principles of fitness—and figure out where you're good and where you're weak. If we can help you there, you won't come back for injuries nearly as often. That's our goal: do as many things for you, and as few things to you, as possible.

What Arthritis Actually Is

Tom Rowland: I'd love to talk specifics about joint replacements, but let's start with arthritis, since it's so common. Can you give us a base level of what arthritis is, why we get it, and why so many people have it?

Dr. Kevin Stone: Let's think of it in two or three major groups. There's inflammatory arthritis—rheumatoid, psoriatic, Lyme disease—where some other agent is involved, and that's about three percent of all arthritis. The remaining ninety-seven percent is either osteoarthritis, which can have a genetic component, or—what we see the most—post-traumatic osteoarthritis, where you've had an injury: a surgeon took out your meniscus, you tore your ACL, dislocated your shoulder, tore your rotator cuff, or twisted an unstable ankle. Over time that white, shiny bearing surface, the articular cartilage, wears down to the bone from that irregularity, and that's what arthritis is. It's like a car that's out of alignment wearing out its tires faster: a joint left out of line, without the meniscus, without the ACL, unstable, wears down that white shiny surface and you get bone deformity, inflammation, and pain.

Traditionally doctors would tell you to take an anti-inflammatory or shoot cortisone into the joint, which we try never to do anymore if we can avoid it. Those approaches shut down inflammation but don't treat the disease. To treat the disease we need to either regrow the cartilage, replace the meniscus and rebuild the ligaments, or—if it's already bone-on-bone with no joint space left—resurface the joint. Eighty percent of people who've been told they need a total knee replacement don't.

Tom Rowland: Wow.

Dr. Kevin Stone: They could have a biologic replacement—a meniscus put back in, or regrown cartilage—or, if they're bone-on-bone, a partial replacement that just resurfaces the one worn-out part of the joint. That's a huge advantage because, usually done with a robot as an outpatient procedure, we don't touch the ACL or any other tissue—we just resurface the part that's worn out. The knee feels much more normal, they get a full range of motion, and they can weight-bear right away. It's really changed how we look at arthritic joints.

The Haptic Robot and Precision Joint Resurfacing

Tom Rowland: What's recovery like from something like that? And is it done robotically, remotely, the way I've heard about with some surgeries?

Dr. Kevin Stone: No, we're not there yet with remote robotic surgery. In the knee you can do a partial replacement, resurfacing just the one worn-out part, or a full replacement, resurfacing the femur, tibia, and sometimes the kneecap. Placement of those implants is critically important—off by even a few millimeters and the wear pattern goes abnormal, just like a car out of alignment. About nine years ago a haptic robot came into our practice. We do a CT scan of the patient's knee, build a model, place the implants on the model before ever touching the patient, and optimize the positioning. Then in surgery we hold a haptic robotic arm that, like paint-by-numbers, won't let us take away any bone except where we've planned it. It increases the surgeon's precision dramatically. In my first fifteen or twenty years doing partial replacements I used saws and guides and thought I was pretty good, but once the robot came along I realized how much better I could be.

This is an outpatient procedure taking about an hour and a half. The next day, patients are with our rehab team for an hour with a physical therapist and an hour with a fitness trainer. Even with a knee just operated on, you can sit on a bike and spin, do upper-body weightlifting, and core work. Doing that right away flushes out the anesthesia drugs, gets good blood flow to the injured site, and I want people thinking of themselves as an athlete in training, not a patient in rehab.

The most common question is whether patients can run again, and yes is the answer—we have people doing triathlons, marathons, and centuries on these partial and total knee replacements. There's been a huge sea change in that advice. For decades, patients were told to go home and rest the knee, which just caused atrophy and muscle loss. About thirty years ago at the Stone Clinic we started telling patients to go home and exercise even more, and we looked to see if that raised the failure rate—it didn't. I used to ask surgeons in lecture audiences around the world to raise their hand if they'd ever seen a patient knock a total joint loose from sports, and no one ever raised their hand. On top of that, because of the robot's precision, we can now use cementless implants that press-fit, and the bone actually grows into the implant—it becomes part of you, so you're not going to knock it loose. Go run, go exercise, do the things you love. Most likely you'll have a much better outcome.

Biologic and Bionic Materials, and Donor Tissue

Tom Rowland: Let's go back to the implant itself—what's it made of? Is it cadaver bone, or something else?

Dr. Kevin Stone: Keep in mind we're doing either biologic or bionic replacements. On the bionic side, that's artificial material—cobalt chrome on the femur, titanium on the tibia, with a high-molecular-weight polyethylene in between. These are supposed to be thirty-year implants, and we still never see people wear them out even with running. On the biologic side, those are donor tissues—a donated meniscus or donated ligament. We no longer take tissue from another part of your own knee to rebuild one part; we take donor tissue out of the freezer from the donation bank.

Tom Rowland: That's such hope. So why, when people go to their own doctor, do they often not hear about these options? A lot of doctors are telling people it's a total knee replacement or nothing, or cortisone injections, and I'd love your opinion on hyaluronic acid too, since I've had it in my knee before.

Dr. Kevin Stone: It's a complicated question with lots of answers. Health care systems have different motivations and restrictions on what they can offer, and physicians have their own experience and biases. You should always know the bias of your surgeon. I'm very biased toward keeping people extremely active, toward a biologic solution to avoid or delay a bionic one, and toward only doing a partial replacement if that's all that's needed. Other surgeons, in their own experience, do a full knee replacement quickly and consider that good enough—and often, for their patients, it is good enough. But patients seeking out my care are looking to get back hunting, back climbing, back in cold streams, and my job is to figure out how to get them back in the mountains or back in the stream. If you're a fisherman who loves being on unstable rocks and surfaces, I need to train you on unstable surfaces immediately after surgery—standing on a trampoline, balancing, doing pad exercises—so when you're back in the stream you feel mentally prepared, and I love the cold water for cooling down the knee anyway. Our whole attitude is built around identifying what you love to do and helping you get back there. Treat yourself the way a pro athlete would treat an off-season injury—great strength training, physical therapy, massage therapy, nutrition counseling, mindset training. You deserve that same treatment even if your sport is walking through the mall.

Avoiding Surgery When Possible

Tom Rowland: When someone comes to you with knee pain—say, patellar tendonitis, which I've dealt with myself—are you looking to avoid surgery as much as possible with imaging and other tools first?

Dr. Kevin Stone: As much as possible, when appropriate. We want to identify whether avoiding surgery is good or bad for you. If you've got a torn meniscus acting like a windshield wiper inside the knee, you're hurting it more by doing the sport you love, and it's better to repair, regenerate, or replace it and get you back to sport. But if it's something we can address with injections and growth factors—hyaluronic acid, for example—that's a great way to avoid surgery. The natural lubricant in your joint is called hyaluronic acid (another is lubricin), historically sourced from chicken comb, now produced by recombinant techniques. We've injected it into joints for decades, but unfortunately it only lasted a little while. In a prospective, double-blind, randomized trial, we found that adding a bit of growth factor to the hyaluronic acid injection causes the joint lining to produce more of its own hyaluronic acid, and we got up to a one-year response from a single injection. It doesn't work for everyone, but the response rate is about eighty percent or better, and when it works, it's awesome. It's useful for tendons too, like lateral epicondylitis, and we now have a spine injection specialist in our clinic working on getting cortisone out of the spine, since we know cortisone degrades tissue, inhibits protein metabolism, and shuts down cell behavior.

Tom Rowland: It's funny, because you're so certain about that, but my friend just went to his doctor with knee pain and the first thing they did was shoot him up with cortisone, even after he asked about hyaluronic acid. That's just how that doctor practices. I ran into something similar with my son's eyes—he had a condition called keratoconus, where the eye wants to take a football shape instead of round, because the fibers in the eye weaken. The common solution we were told was a cornea transplant. I did some research and found a doctor, Dr. Brian Boxer Wachler, who used a vitamin B treatment and blue light to stop the keratoconus, and it worked. My son can see better than 20/20 now with special contact lenses and never had to have that surgery. But some doctors insisted a transplant was the only way.

Dr. Kevin Stone: That's a great story, and here's a good rule of thumb. As I mentioned, all doctors have biases, and it's good to know your physician's bias. But I also just listen to my patients—I always ask them what they think is wrong, what they think the diagnosis is, what they think they need. It's stunningly common and accurate. Patients often intuitively know what's wrong, and if you listen well enough the diagnosis is often made before we ever put hands on. Within the first minute or two I usually know exactly what's wrong just from the patient telling me—a patient describing something catching in the knee usually means a torn meniscus; what we call the two-fisted sign, where a patient makes a fist and says their knee feels like that, usually means a torn ACL. In your son's case, you intuitively knew there had to be another way to work with the biology, and it's okay to Google your doctors and search around. There are doctors trying to push the science forward, and doctors more comfortable doing what they've always done—that's not a criticism, but it takes a team, an attitude, and a willingness to take some risk. I have an entire research team and a public nonprofit research foundation, information available at stoneresearch.org. If we're doing the same thing next year that we're doing this year, we haven't learned anything, and we need to figure out how to make it better.

Tom Rowland: There's so much hope in this. I do CrossFit, and most doctors roll their eyes at that. But if I told you I swim, row, walk, lift weights, and watch my diet closely, you'd say those are all great things—call it CrossFit and suddenly it's the worst thing ever. I get that there are injuries when people jump in too fast, but when it's what you love and want to keep doing, this conversation is full of hope.

Animal Tissue and the Future of Donor Grafts

Tom Rowland: I wanted to ask about something from your TED Talk—the idea that we don't have enough human cadaver tissue for knee replacements globally, and that animal tissue could be used instead.

Dr. Kevin Stone: Traditionally in orthopedics, when someone injured their ACL or meniscus, surgeons would take another part of the patient's own body to rebuild it—the patellar tendon or hamstring tendons. We knew that second-site surgery caused damage in another part of the knee, which wasn't a good idea. So we started studying donor tissue many years ago, and it's become popular now; every tissue source has pros and cons, but in our practice we almost always use donor tissue rather than the patient's own, even in young athletes. The problem is there's never enough young, healthy donor tissue, because in America you have to opt in to become a donor—it should be the other way around, opt-out, and we'd have far more donors and tissue. So the opportunity is to use animal tissue that's already being harvested for food or other purposes and would otherwise be thrown away, if we can remove the antigens that cause rejection.

There's one key carbohydrate responsible for about ninety-five percent of the rejection when animal tissue is placed in a person. In orthopedics, unlike a heart transplant, we have the ability to sterilize the tissue and strip those antigens. We designed techniques for doing that with bone-patellar-tendon-bone from pigs, the most common ACL replacement tissue, and took it through a wide clinical trial in Europe and got it approved for sale there. Unfortunately, the company that carried it through isn't functioning right now, so it's not currently on the market, but it will come back, and eventually there will be a good supply of animal tissue to replace human tissue. Right now animal tissue treated with cross-linking or glutaraldehyde is used in the shoulder and for patch grafts—durable, though it doesn't remodel as well, so it's not ideal for a knee ligament but works for a shoulder patch or wound graft. The whole world of tissue donation will keep evolving, and we're very sensitive to animal rights issues and to making sure any tissue used is sourced responsibly.

Tom Rowland: So the rejection carbohydrate is what makes the body reject foreign tissue, and if you strip that out, it can actually grow into human tissue?

Dr. Kevin Stone: Exactly—it acts like a regeneration template, the same way we talked about with collagen scaffolds. Put in a bone-patellar-tendon-bone graft from a pig, and the human body grows into it and humanizes the tissue over the course of a year.

Tom Rowland: So conceivably you could choose source tissue that's stronger than human tissue?

Dr. Kevin Stone: That's exactly right—that's what I touched on in the TED Talk. Elephants grow to huge weights, run sixty miles an hour, live forty to sixty years, weigh fifteen thousand pounds, and never seem to develop natural arthritis. I'm not proposing elephant tissue, but we can learn from the biology of their tissue, the same way we can learn from your ankle joint why it doesn't develop natural arthritis. There's much to learn from the animal kingdom, and I think we'll eventually be transplanting tissues that are better than the ones people injured, using better recruitment factors to bring in the body's own stem cells and accelerate healing. That whole field of biologic replacement is exciting, and it's where I love spending my time.

Regrowing Cartilage with Paste Grafts

Tom Rowland: When I watched your TED Talk, you talked about grinding tissue up and making a different material that fits exactly what a knee needs. What's that process called?

Dr. Kevin Stone: Today, for an arthritic or a sudden traumatic injury that's knocked off cartilage inside the joint, we do something called an articular cartilage paste graft. We take a little bone and cartilage from the intercondylar notch, where the ACL passes through, because that notch always regrows beautifully. We take it out of the knee, smash it into a paste, and pack that paste back into the prepared defect. People have heard of microfracture, which makes holes and releases marrow cells into the bone, but unfortunately that typically only forms scar tissue that lasts a few years. If we add a paste of articular cartilage, it carries stimulating factors that tell the bone marrow cells and stem cells coming out of those holes to see that paste and form new, better cartilage. We've demonstrated that in patients over many years and are expanding the technique to make it heal faster and better. That's why I say eighty percent of people told they need a knee replacement don't—there are other options, and it's worth taking advantage of them to stay active.

Staying Active for Life: Dr. Stone's Rules

Tom Rowland: That's a nice segue—what should people do to stay active and not need to come see someone like you, or at least push that timeline out?

Dr. Kevin Stone: The first answer is: do what you love, because it's hard to keep doing something you don't love. CrossFit made such a great contribution to fitness because it turned working out into a competition, a team sport you could quantify and measure. We trained Kelly Starrett here in San Francisco early in his career as a physical therapist, so we had a lot of experience with CrossFit as it was first getting popular, and we're still huge fans—injuries can occur in anything, and CrossFit's intensity drives more patients to my office than I'd like, but the idea is to find what turns you on and optimize it. Rule two: get a great trainer—it's hard to train at the level that improves your fitness without guidance, even if it's only for a while. Rule three: find a new sport every six months, just add to your repertoire; that variety works different muscles, builds different flexibility, and makes you a smarter, better athlete. Rule four: optimize your weight. Use water as your primary beverage, always reach for a glass of water before you pick up the fork, and hydrate well—athletes' minds and bodies both work better hydrated. Ten pounds overweight matters: you take two to three million steps a year at up to five times your body weight, so a ten-pound loss across that many steps is an enormous reduction in force. We encourage the usual sports—cycling, swimming, hiking, climbing—but it's more important to find what you genuinely love, because you'll actually do it.

How to Avoid Injury in the First Place

Tom Rowland: Your bio mentions several things you teach clients, starting with how to avoid injury.

Dr. Kevin Stone: The first thing is the mind game—make sure your head is in the game, whatever you're doing, whether it's CrossFit or anything else. Don't be distracted by your phone or by whatever else is on your mind. So many injuries are mental errors: you're going a little too fast, you knew you shouldn't be, and you just weren't paying attention. Second, flexibility and mobility matter—exercising within limited ranges overuses that part of the joint, and increasing your range of motion in every joint will decrease your injury rate. Most good trainers have learned that by now. Third, technique matters—if you're training with squats, which we think is one of the best exercises you can do, using good technique will help you avoid injury and build power and flexibility.

Tom Rowland: And the second thing on your list was how to repair and replace what does get injured.

Dr. Kevin Stone: Simply put: don't live with your injuries. It's not worth telling yourself you'll just live with it—there's no need to anymore. So many of these tissues are repairable, and they do so much better if you repair or replace them right away. If a surgeon takes out your meniscus, put it back in or repair it right away if you can. Don't live with an unstable knee or shoulder. Use it as an excuse to get better—grab new information and new training rather than telling yourself you'll just live with it.

Tom Rowland: A lot of athletes just live with it because they're tough, and they'd rather not sit in the doctor's office over every little thing. But that means they're maintaining rather than making progress.

Dr. Kevin Stone: Exactly—you can continue to make progress for a long, long time instead of just avoiding decline.

Balance, Bone Strength, and Community

Tom Rowland: The next item on your list was how to train for balance and strength, build bone, and join a team—I found that interesting.

Dr. Kevin Stone: Balance is key right off the bat. Personally I stand-up paddle a lot, so I'm on unstable water, and I just started efoiling as a new sport—I'm crashing all the time, but I'm learning. Adding things that are fun but require balance really helps. If you're not near water, standing on a pillow while lifting weights, or other simple unstable exercises, or just standing on a trampoline for balance—those little things matter a ton. Second, build bone: bone responds to force, so weightlifting, resistance exercise, or hiking up and down hills are the two easiest ways. Every person after about age twenty-five is losing bone mass, women more rapidly than men, and it's crucial to counteract that with resistance exercise—which comes back to why, after a knee replacement, we want you exercising more than before, not less, to build bone around the implant and muscle to protect the joint.

Tom Rowland: Rucking—putting on a heavy backpack and walking up hills—is one of the things we do a lot, and it does great things.

Dr. Kevin Stone: And the last one on that list is join a team. There's nothing better than a team sport—it's part of why CrossFit grew so fast; you felt like you were part of a team, your name was on the wall, you were competing. Team sports increase the fun, and everything we've talked about today, even going into surgery, goes better with a smile on your face, and nothing puts a bigger smile on your face than teammates. As we get older we tend to lose our teams and do things individually. Change that dynamic—look around for where the teams are, do stuff together, push each other, laugh about it, and that laughter will keep you going.

Mental Toughness and Reframing What You Can Do

Tom Rowland: The next item was being mentally tough, which is interesting, because a lot of people think toughness means pushing through an injury rather than dealing with it.

Dr. Kevin Stone: Toughness isn't just resisting or bearing pain—we actually don't want our patients to have pain. We do a hundred tricks to get rid of it: we preemptively numb the knee before we ever operate, and we have great post-op pain resolution techniques with icing and soft-tissue massage. We want you to shift into a positive mindset. There's an old, semi-fake expression, illegitimate carborundum—don't let the bastards get you down—and it applies here: don't let the injury get you down. Your toughness isn't in enduring pain, it's in resetting your agenda, and the better you are at that, the better you'll do in everything you do in life.

Tom Rowland: That resonates with something I did when I tore my soleus muscle—I decided to get really great at pull-ups since I didn't need my soleus for those, and to focus on what I could do instead of what I couldn't.

Dr. Kevin Stone: You did it perfectly—that's about seeing the opportunities and being creative. Don't forget how much imagination and creativity affect your ability to recover from an injury, avoid one, or set a new goal. We talk about fantasy versus visualization: visualization is memorizing the exact steps to do something, like the precise motion of a cast; fantasy is dreaming big, like imagining catching the enormous fish. You'll enjoy it more, and do better, with a little more fantasy mixed in with the visualization.

Tom Rowland: And positioning yourself for continual improvement.

Dr. Kevin Stone: As we said, you're fifty, but that means you've got fifty more years to get better, and you've got the experience in your head to apply to the things you're going to play with now. I don't love the phrase work on nearly as much as play with. Bring maturity, playfulness, experience, and wisdom to it, dream big, and be creative about what you do.

Coaching, Partnership, and Finding the Right Fit

Tom Rowland: What strikes me is that you remain imaginative, creative, and playful in the way you speak. Do you pay attention to the words you choose and how language affects mindset?

Dr. Kevin Stone: Sure. Essentially a surgeon is a coach. Much of what I do all day is coach people. I can fix a knee or a meniscus, but the only way I'll have success, and the only way the patient will have success, is if I can coach them into a mindset that says not only can I do this, I can do it better than I've ever done it before. If I can get inside that head space and convince them to become athletes for life with us—to keep training, keep evolving as we evolve—then we're going to have a great experience together. If I can't connect that way with a patient, then maybe I shouldn't be the one to operate; I should guide them to someone they can really listen to and bond with, who speaks their language. Just like with your son's care—you found someone who was thinking creatively, and it felt right to you. My guidance to your listeners is: use that. Think about what feels right to you, and generally it will be on track.

Getting a Second Opinion at the Stone Clinic

Tom Rowland: A lot of people listening right now, myself included, are probably thinking they want you to take a look at their knee. How does someone get a second opinion if they can't travel to see you?

Dr. Kevin Stone: There are two ways. The best way is to come see us at the Stone Clinic in San Francisco, because then I can bond with you, get my hands on your knee or shoulder, and watch how you move and train with our fitness team. But I treat patients from all over the world, and we've set up an outside consult system at stoneclinic.com where you can upload your X-rays, MRI, and history, work with our patient coordinator, and get on the phone with me. I'll look at your images and give you my best guidance on what's likely to help, with a final decision made when you do come see me. Generally I can give pretty good direction from X-rays and an MRI of the injured part, and we don't charge for that—it's free. The only real challenge is getting enough time and gathering the information, since X-rays and MRIs are often tied up in different health systems, but there's a simple uploader on the site and we try to make it as easy as possible. To the best of my ability, I'm happy to help people get on the right path.

In part, that's also what the Play Forever book is—a way to reach more people than one-on-one conversations allow, hopefully inspiring them around these same ideas. I've optimized the book around that, and I hope people will read it and send me feedback, or tell me what I missed or where I should go next. I learn the most from my patients, and honestly, I learn the most from the ones who don't follow my advice to the letter—the ones who come back having pushed past a limit I set, having given up a crutch early and done even better. Over the years I've studied why that worked for them, and it's taught us that you can push a lot harder than people thought, and the limits aren't always what we assumed. That came from listening to patients and learning from them.

Tom Rowland: We're going to get along just fine—I've been told by orthopedists that I should be in a padded room because I wanted to exercise through a torn soleus. But exercise increases blood flow throughout your entire body, and that's got to be good for something. That's been my experience of healing faster: a good, positive attitude, plenty of exercise, and paying attention to nutrition, fueling your body like an athlete preparing for competition rather than sitting around recovering.

Dr. Kevin Stone: And to be sure we speak to listeners who aren't naturally athletes—there are great ways to exercise gently. If you have access to a pool but aren't a swimmer, just walking laps in chest-deep water, side to side, twenty times, and trying to go a little faster each day is a very gentle way to get your heart rate up and move your muscles. If you just like to walk, set a small goal of walking a little farther each day, find a hill, or use a fitness app to quantify it and add a bit more each time. And never watch TV or read a book while on a spin bike—you lose half the benefit of the exercise, because you have to learn to listen to your body, to your heart rate and your breathing, and then push a little farther. Music is different, and an audiobook is fine too—we want you listening to yourself, getting in tune with your own body, learning where your limits really are and how to push beyond them a little. That's true whether you're a CrossFit athlete or just going for a longer walk, and especially for hunters: get exercise in around the times you're sitting still in a blind. Look at every opportunity you're already living within and ask how you can be creative with it to change your dynamic a little bit.

The Future of Orthopedics

Tom Rowland: With all this hope, what does the future look like for orthopedics, or at least for your corner of it? Where do you see the frontier?

Dr. Kevin Stone: We want to repair tissues so people come back better than they were before. So much of what we talked about today was the mind and body coming back better, but I also want to put in tissues that are actually stronger, and stimulate healing that makes a stronger tissue. Why should you tear your soleus once and then be at risk of tearing it again? If you come to me with a torn soleus, I want to add growth factors to that repair and a rehab program so it doesn't tear again. The whole field of orthobiologics and sports medicine is about helping people become fitter, faster, and stronger—better than they were before. That's the fun of what we're doing, that's where the research is, that's where the science is, and that's the challenge. We can't succeed everywhere we thought we might, but maybe we can if we look at it a little differently.

Tom Rowland: That's awesome. Thank you so much for coming on. You've given us so much to think about, and for a lot of people, real hope that it's not over—you're only thirty or forty percent there, with a lot more to go.

Dr. Kevin Stone: I hope the book Play Forever communicates what we talked about today. I'd love to hear from readers whether we did a good job of that, and whether there are other subjects they'd love to hear about, because communicating this information is something I love to do.

Tom Rowland: The book comes out December 14th, is that right, and it'll be available on Amazon?

Dr. Kevin Stone: Yes. It'll be ebook and print first, at a discount that first week, with an audiobook to follow. And for more on getting your knee helped, stoneclinic.com has all the information, and stoneresearch.org has all the research.

Tom Rowland: Dr. Stone, thank you very much. That was awesome.

Dr. Kevin Stone: Thank you.