Runner’s knee — also known as anterior knee pain or PatelloFemoral Pain Syndrome (PFPS) — is the most common running injury, with a prevalence of 19-30% in female runners and 13-25% in male runners, according to one recent review. The main symptom is pain below the kneecap that is generally mild at first and experienced only during running but becomes progressively more intense and increasingly present between runs if not properly addressed.
Pain Itself is the Problem
Many theories about the nature of the damage underlying the pain of PFPS have come and gone. The reason behind this revolving door of proposed etiologies is that, unlike other injuries such as knee meniscus damage, there is often no obvious structural abnormality associated with PFPS, whether the joint is examined by X-ray, MRI, or surgical arthroscope. Within the past 15 years, this reality has lead orthopedists to a revised view of PFPS in which pain itself is regarded as the essence of the injury. This, in turn, has led to a new approach to treatment that focuses on symptom management rather than healing.
In the past (or even today, if you consult the wrong doctor), if you were diagnosed with PFPS as a runner you would be advised to stop running. Today, however, experts like Greg Lehman, an Ontario-based physiotherapist, advise runners with overuse injuries including PFPS to do as much running as they can within an acceptable pain range.
“To get back to 100% of running you need to start with something less than 100%,” he writes on his website. As a runner, you don’t just want to be free of pain; you want to be able to do the training necessary to achieve your goals without pain. There’s a big difference. Sure, rest may fix your pain, but only through running can you develop the tissue durability required to handle intensive training.
As Lehman puts it, “Running got you into this mess and running can get you out.” The key is practice what’s known as graded exposure, which entails doing no more and no less running than your body can handle, as signaled by pain.
To begin the process, lace up your shoes, set out at an easy pace, and see how long you can run, and how frequently, with a pain level that doesn’t exceed 2 on a 1-10 scale. Train right up to that limit for a couple of weeks and then try a modest increase in duration and/or frequency. Continue in this fashion until you’re back to your pre-injury training level, taking a temporary step back in the process if the pain worsens at any point.
Strength for Relief and Prevention
In the new approach to beating runner’s knee, not only are you encouraged to keep running, but you’re also able to actively treat your pain with another type of movement. Research has shown that heavy isometric muscle contractions effectively reduce pain through an effect known as descending analgesia. Here’s an example: Lie on your back with a rolled towel positioned underneath the affected knee. Contract your quadriceps and try to press the towel into the floor with the back of your knee. Hold the contraction for 5-10 seconds and relax. Repeat 10 times.
When dealing with PFPS, it’s also important to address the factors that may have caused or contributed to your injury. Doing so will not only help you overcome an existing case of PFPS but also greatly reduce the likelihood of future recurrence. Research has shown that PFPS sufferers tend to be weak in certain important stabilizing muscles — in particular, the hip abductors and hip external rotators. Studies have also demonstrated a link between particular biomechanical patterns — including hip adduction (aka knock knees), internal rotation of the thigh, and lateral tilting of the pelvis — and PFPS. Fortunately, all of these issues are fixable.
The solution to weak stabilizing muscles is, of course, strength training. An example of an exercise that strengthens the hip abductors is the band walk. Loop a resistance band around your lower legs and stand with a slight bend in your ankles, knees, and hips. Take a step to the right with your right foot and then follow with your left foot, keeping your two feet far enough apart to maintain tension in the band. Repeat 10 times and then take 10 steps to the left.
An example of an exercise to strengthen the hip external rotators is the supine hip external rotation. Loop a resistance band around your legs just above the knees and lie on your back with your knees sharply bent and your feet flat on the floor about 10 inches apart. Now pull your knees apart and stretch the band as far as you can. Hold this position for one second, then relax. Repeat 10 times.
A few studies have found that simple ways of modifying the stride of runners with PFPS can be effective in correcting the patterns that lead to the condition and reduce pain. In one such study, conducted by researchers at the University of Salford, runners who were trained to increase their step rate by 10 percent exhibited reductions in hip adduction, lateral pelvic tilt, and pain. To make the same change on your own, purchase a swim tempo trainer and adjust its tempo to match your natural step rate while running. Note the number, increase it by 10 percent, and then practice running at this higher step rate (without speeding up).
In another study, researchers at the universities of Kentucky and Delaware used biofeedback to teach runners with PFPS to prevent lateral pelvic tilt over eight sessions. In a one-month follow-up, a majority of the subjects had lasting improvements in pain and function. You can try this one at home by concentrating on actively contracting your right buttock the instant before your right foot touches the ground when you run, and doing the same on the left side.
Other potential contributors to PFPS are improper footwear and tightness in the hip flexors, quadriceps, and tensor fasciae latae (top, outside of thigh) muscles. Stretching these areas regularly and choosing running shoes that maximize comfort (or minimize discomfort) may help you get back in the game and stay there. Scientific evidence linking specific footwear choices or stretching protocols with significant pain reduction in PFPS sufferers is lacking, however. At most, shoes and tightness are minor factors in the PFPS equation, and your efforts to overcome the condition should be focused on graded exposure running, strength training, and stride modifications if needed.
The good news about patellofemoral pain syndrome is that it’s a relatively minor condition. The bad news is that it can be just as debilitating and last just as long as more serious breakdowns. These tips can help to minimize the impact of knee pain on your running, if and when it strikes.