This transcript has been edited for clarity.
Matthew F. Watto, MD: Welcome back to The Curbsiders. I'm Dr Matthew Watto, here with my great friend, Dr Paul Nelson Williams, America's primary care physician. It's fitting that we're going to be talking about knee pain, a very common complaint in your primary care clinic.
Paul N. Williams, MD: I think it's the number-two musculoskeletal complaint. Back pain will always be number one.
Watto: I've heard of this thing called patellofemoral pain syndrome, but I don't really know how to recognize it. When might you think of this diagnosis in your clinic?
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Williams: Otherwise known as anterior knee pain, it's typically caused by maltracking of the patella as the knee flexes and extends. When you ask patients, they will say that it's worse when squatting, descending stairs, or rising from a seated position. All of those actions put a lot of pressure on the joints, resulting in pain. Anterior knee pain tends not to be well characterized.
Another historical feature is the "theatergoer sign": When you've been sitting for a long period of time with your knees hyperflexed, you are in agony when you stand up.
Patellofemoral pain syndrome tends to happen more in women than men because of the configuration of their joints; they have a wider so-called Q angle.
Watto: It's wider because of how the hip and knee are connected in women. Wider hips pull the joint from a different angle.
I love the theatergoer sign. It also happens in stadiums where the seats don't provide much legroom. You have to curl your heels under your seat, and that pulls the patella sharply against the femur. It hurts when you stand up.
How do we treat anterior knee pain — surgery?
Williams: You know the saying: "A chance to cut is a chance to cure." Dr [Ted] Parks is a surgeon, but he says not to refer these patients for surgery if you can avoid it. The treatment is primarily stretching, trying to loosen things up. Tightness is a driver of this condition, so the patient should do hamstring stretches, bringing their heel to their butt and stretching that way. He also mentioned medial strengthening with an exercise bike. There are some fancy hinge braces and boots but he doesn't recommend any of them routinely. It's mostly stretching and exercise.
Watto: That was fascinating. Cycling strengthens your quadriceps muscles and seems to help with the alignment. To look for alignment problems, you can order an x-ray called the "sunrise view" or "merchant's view," which gives a top-down view of the kneecap. The patella should be sitting between the heads of the femur, and you can tell if it tracks off to one side, or you may see jagged osteophytes, which could also cause pain.
I usually get that view. It's nice to show a visual to the patient about what may be causing their pain.
Let's say a patient comes in to the office of America's primary care physician. They heard about you and saw the billboards all around Hershey, Pennsylvania. They are pointing to the middle of their knee, 2-3 inches below the joint line, saying, "It hurts right here." What might that be?
Williams: That medial inferior to the joint line point tenderness is consistent with pes anserine bursitis. There's a bursa there. Dr Parks described it as a "bony wasteland." You walk your fingers down and feel the bone. If you find the tender spot, then you have a pretty good idea of what's causing the pain.
Let's say you make the diagnosis based on palpation. It's a fairly straightforward diagnosis. What can you do to help this patient?
Watto: Three tendons insert there. Two of them are hamstring tendons, so hamstring stretches can help. This type of bursitis is so close to the surface that topical NSAIDs might help. In general, Dr Parks is not a fan of them; we've asked him every time he's on the podcast, but he tells us that we can try, but they don't work very well. In this case, being close to the surface, topical NSAIDs might work.
You can also inject cortisone. He has the patient indicate the point of maximal tenderness and gives the injection. Whether it's a tendonitis or pes anserine bursitis doesn't matter; the treatment should help.
The last thing that I want to talk about, because this is a bit more vexing and complicated, is the patient who has knee pain after knee replacement. It should be getting better; why are they still having pain?
Williams: Dr Parks differentiates between the patient who doesn't get better and has constant pain — they are never happy with the knee replacement; and the patient who has a great initial result and then the pain recurs. It's not arthritis, because the joint is gone. With the latter, you start thinking about potential late-stage surgical complications. And we went down a deep rabbit hole as to what those might look like. Let's focus on the patient whose pain recurs after a good result. What kinds of things should we think about?
Watto: Could the hardware be loosening? That can be aseptic or caused by an infection. You order an x-ray or a bone scan to look for lucency around the hardware. Several years after surgery, you should see activity around the implant. If you do, that would be a reason to go in and remove or revise the implant, because it's not going to get better.
The surgeon can also determine whether it's aseptic or infected by sending material for culture. If you don't see any loosening on imaging, then you can get a CRP and ESR, which are pretty sensitive for inflammation. If elevated, you can aspirate and look for infection, and then you get into antibiotics and spacers and things like that.
We shouldn't forget that the patient's knee wore out, so another joint could also be worn out. We should look at the hip. We can do the windshield-wiper test, in which the patient sits on the edge of the table with their hips flexed at 90 degrees. You move their heel back and forth to see if that action causes hip pain. You don't want to miss hip pain as a cause of knee pain.
Williams: Hopefully the surgeon is also doing that before they replace a knee. But it's true — a patient who has knee arthritis can also develop hip arthritis. You are allowed to have both, and many patients do.
Watto: This is just a little taste of what we talked about with Dr Parks on the podcast Kneedful Things: Knee Pain With Dr Ted Parks.
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Cite this: Three Types of Knee Pain in Primary Care - Medscape - Oct 24, 2023.
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