Patellar Tendon Straps Decrease Patellar Tendonitis and Patellar Tendon Strain
Patellar tendon straps, or infrapatellar straps, have been long used to decrease pain and patellar tendon strain in individuals with patellar tendonitis. However, the exact mechanism behind why patellar tendon straps work has been unclear, despite much anecdotal reports of their effectiveness. We have talked in the past about the effectiveness of lateral epicondyle straps, or tennis elbow straps, in reducing symptoms of tennis elbow and it is commonly reported that they reduce the strain on the extensor carpi radial brevis tendon by applying counter-force pressure. But for some reason, there have been few studies looking patellar tendon straps.
One proposed mechanism of reducing strain on the patellar tendon using patellar tendon straps was recently assessed in a study published in Sports Health. The authors report that past modeling of the knee suggest that patellar tendon strain at the site of patellar tendonitis increased as the angle of insertion of the patellar tendon to the inferior pole of the patella decreased. Here is an example of the patella-patellar tendon angle (PPTA):
Basically, what this means is that a patellar tendon strap may reduce strain on the patellar tendon by changing the angle that the patellar tendon inserts into the patella and the length of the patellar tendon (if you really want to read the whole computational modeling study from AJSM, here it is).
Patellar Tendon Straps Reduce Strain on the Patellar Tendon
The current study’s authors sought to calculate the change in PPTA, patellar tendon length, and patellar tendon strain using two common patellar tendon straps in 20 subjects. The two straps that were used were the Cho-Pat Knee Strap and the DonJoy Cross Strap. Here is the Cho-Pat on the left and the Donjoy on the right:
The methodology of the study was pretty sound and fairly complicated, enough so that I won’t go into the details here but feel free to read the entire study here. One thing of note was that all subjects were asymptomatic males, however past studies have shown no anatomical differences in PPTA or inferior patellar pole anatomy between symptomatic and asymptomatic subjects.
Results of the study demonstrated the following findings:
- Patella straps do alter the PPTA as well as the patellar tendon length, the authors believe that these two factors contributed to the reduction in patellar tendon strain.
- The DonJoy strap reduced patellar tendon strain in 15/20 subjects, the Cho-Pat strap reduced strain in 16/20 subjects. 3 subjects did reduce patellar tendon strain with either strap.
- The DonJoy strap reduced strain by an average of 34% while the Cho-Pat strap reduced strain by an average of 20%.
- The patellar tendon straps did not significantly alter patellar tilt or congruence, so this is likely not the cause of effectiveness of Patella straps.
My Recommendations on Patellar Tendon Straps
We know that there are studies that show anywhere between 70-80% of people wearing patella straps reported improvement in both acute and chronic cases of patellar tendonitis. It also now appears that patellar tendon straps are effective in reducing patellar tendon strain in the majority of subjects, which may be the mechanism behind the pain reduction.
One thing I did note about the study was that all participants were instructed on how to apply the straps but there was no standardized application. For those that have used these straps, you know that you can really vary the amount of tightness of the straps significantly. Past research on lateral epicondylitis straps have shown that both the location and tension of the strap has a significant impact in the reduction of strain.
This may explain why the DonJoy strap had a much larger decrease in strain on the patellar tendon than the Cho-Pat strap. With the DonJoy strap, you can tighten the strap as much as you would like. You can see this well in the photo, the two straps intercross and the tightness can be adjusted. (I should also note that “Procare” is a DonJoy company, it is the same strap). This is the main reason why I recommend the DonJoy strap, as you can pull it really tight if you would like, but more importantly, you can adjust the tension very easily while you are wearing it. This is helpful for everyone but especially in athletics as the strap can loosen a little with activities. For the fitness enthusiasts, this is a cheap and simple option to at least try if you are experiencing some patellar tendon discomfort. Check them out on Amazon for under $20.
To summarize my recommendations on patellar tendon straps:
- Patellar tendon straps are worth trying and may reduce pain and patellar tendon strain
- The location of application is likely important, try to aim for right in the middle of the patellar tendon
- The tightness of the strap is likely important, try to use an adjustable strap like the DonJoy Cross Strap used in this study to make sure that you can tighten it well.
- The DonJoy/Procare Cross Strap is pretty affordable too, here is a link to it on Amazon, try it and let me know what you think.
What has been your experience with patellar tendon straps?