No Evidence That Modalities Alone Help With Patellofemoral Pain Syndrome
Patellofemoral pain syndrome (PFPS) affects one of every four young athletes. Pain along the front of the knee with activities like squatting, running, sitting for long periods of time, and going up and down stairs is common. The condition is so common in runners that it is often called runner's knee.
physiotherapists and sports physicians are actively seeking ways to help treat this problem. The goals of treatment are to reduce pain, decrease swelling, and restore function by improving strength and joint motion.
These goals are accomplished in one of two ways: conservative (nonoperative) care and surgery. Of course, the conservative approach is recommended first. The physiotherapist uses a variety of techniques to assist the patient with patellofemoral pain syndrome (PFPS).
Tools (also referred to as modalities) are used such as cold or heat therapy, electrical therapy, and biofeedback. Each of these modalities provides several options to choose from.
For example, therapeutic heat to increase blood circulation and stimulate healing can be applied using ultrasound, moist hot packs, and whirlpool. Electrical stimulation (e.g., transcutaneous electrical nerve stimulation, neuromuscular electrical stimulation) helps control swelling and encourages muscle contraction. Other modalities used to reduce pain and inflammation can include laser, ultrasound, and phonophoresis/iontophoresis.
But how well do these modalities work? Which one is best for each patient? Should they be used alone or is there some combination of two or more that yield the most optimal outcomes? To be honest, we don't really know.
That's why the authors of this study carried out a review of all the studies published on the use of modalities for patellofemoral pain syndrome. They searched all computer databases available from 1970 to 2010 looking for full articles in peer-reviewed journals on the use of therapeutic modalities in the treatment of this condition.
They found 12 studies that fit the required standards but most of these were low-to-moderate quality. None of them were able to show a positive benefit in the treatment of patellofemoral pain syndrome when used without other treatment as well (such as taping, exercises, surgery, bracing).
The authors provided a detailed four-page table comparing each study based on the intervention (modality or combination of modalities used), outcomes measured, and statistical results. The studies did not all evaluate and measure results in the same way so there wasn't a direct item-by-item comparison possible.
For example, some (but not all) studies measured isometric muscle strength. Even when isometric muscle strength was the outcome measure used by more than one study, different muscles were evaluated (i.e., they didn't all measure the same muscles).
Some researchers used specific tests such as a step test or squat knee test to look for muscle fatigue and endurance. Others used reliable and validated tests (e.g., Lysholm Knee Scoring, Kujala patellofemoral score, Functional Index, Patellofemoral Pain syndrome Severity Scale) to assess pain, edema, and/or daily activities.
The number of treatments per week and number of weeks treatment was administered also varied from study to study. This could be an important variable accounting for differences in results from one group to another.
Taking a look at several specific modalities, laser compared with a sham (pretend) laser had no difference in results. But there are dozens of considerations when studying laser: wavelength used, power density, length of time laser is used (duration of treatment), how long between injury and treatment, and so on.
EMG biofeedback seemed to work best when combined with exercise in the short-term. But long-term results didn't show a difference. And biofeedback was combined with taping of the patella so there is a combination of two treatments that couldn't be separated out.
In the end, there simply wasn't enough scientific evidence to support the solo or combination use of modalities mentioned. This may be the first study to make such comparisons and bring this information to our attention.
There's no doubt that sorting out which modalities might be useful and in combination with what other treatment options (in terms of modality use) is a challenge. If there is no added benefit of using such modalities, then they should be discontinued. With so many variables yet to study, it's clear that future research in this area is needed.
Reference: David A. Lake, PT, PhD, and Nancy H. Wofford, PT, DPT, OCS, Cert MDT. Effect of Therapeutic Modalities on Patients with Patellofemoral pain Syndrome: A Systematic Review. In Sports Health. April/May 2011. Vol. 3. No. 2. Pp. 182-189.