Member Case Study: Pes Anserine Tendonitis

author : AMSSM

comments : 0

I think I have pes ansurine tendonitis. I have had tender to-the-touch pain on the medial aspect of both knees after riding. The pain is more acute the couple of days after a ride.

Member Question from aquagirl

Among other knee issues I am facing now (probable torn medial meniscus, but that's another story) I think I have pes ansurinus tendonitis. I have had tender to-the-touch pain on the medial aspect of both knees after riding that I ALWAYS assumed was from hugging the frame with my knees when I descended, but I have not rode any hills since August and lo and behold the pain is still there.

So my question is: is this likely to be aggravated by a poor cleat position?  I have hardly been running at all because of the OTHER knee issue, so I am assuming it's the riding. The pain is more acute the couple of days after a ride, then subsides if I have not biked for a few days. 

Apart from RICE is there any other way to deal with it? I am going to try Speedplays...

Answer from Matt Schaeffer, MD
Member AMSSM

Anatomy

The pes anserinus is the cojoined tendon of the sartorius, gracilis, and semitendinosis muscles. These muscles and their cojoined tendon insert on the medial aspect of the tibia (lower leg) approximately 6 cm below the medial joint line of the knee. There is a fluid filled sac (pes anserine bursa) that sits deep to this tendon and serves to reduce friction and protect the tendon.

Symptoms and Diagnosis

Acute trauma or chronic overuse can cause the pes anserine bursa and/or tendon to become inflamed, conditions known as pes anserine bursitis or pes anserine tendonitis. The usual presentation is that of pain and tenderness at this site, such as you describe, and possibly some associated swelling, warmth, and redness to the skin depending on the degree of inflammation present. These conditions can result from direct trauma, such as hugging the frame with your knees as you mentioned, but are more commonly caused by abnormal biomechanics. Due to the repetitive nature of cycling (at an average of 80 RPM, 5400 revolutions per hour, up to 30,000 revolutions over a 100 mile course, and 81,000 revolutions over the span of 1 week) even a slight abnormality in bike fit can easily translate into an overuse injury.

A Good Bike Fit

Proper bike fit is a very individual process that involves both static and dynamic measurements. Both the “science” and “art” of bike fitting have evolved significantly, and now riders have the option of very individual and complex fitting processes such as those offered by bike shops and specialty services; some examples can be found at Masterbikefitters.com.

Biomechanical Causes and Fixes

That being said, the common biomechanical errors causing medial knee pain in cycling are toes that are pointed out, feet that are too close together, pedals that have too much float, and exiting clipless pedals that are too tight.

Therefore, adjustment recommendations to reduce medial knee pain caused by cycling would be to point the toes further in, use cranks with less offset and/or shorten the bottom bracket axle (to move the feet closer together), limit the pedal float to 5 degrees, and lower the tension on clipless pedals. As with any bike fit modifications, these changes should be made one at a time and in small increments.

Matt Schaeffer, MD
Primary Care Sports Medicine
Ohio Medical Group

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date: December 28, 2009