The pes anserine (inner hamstrings) is made up of three muscles: the semitendinosus, the gracilis and the sartorius. Beginning in the pelvis, they all insert on the inner and upper region of the tibia (shinbone) and their primary role is to stabilize the knee. They are not particularly powerful muscles and therefore do not tend to initiate movement. Instead, their role is to ensure optimal alignment of the different bones that make up the knee (femur, tibia and patella or kneecap) in relation to the foot and the pelvis. They enable more powerful muscles, primarily the quadriceps, to play their key role.
Tendinitis is common among runners who place considerable strain on their bodies, for instance in activities such as hill running. The knee is placed in a difficult position on hills, particularly on descents: the muscles contract sharply to keep the knee from giving way.
As for any tendinitis, it is important to identify and remove the cause:
- Review the individual’s training regimen and verify his/her shoes
- Consider muscle insertions: look at the pelvis (and any other tension above the knee)
- Verify muscular flexibility: hamstrings (semitendinosus), adductors (gracilis)
- Normalize any potential injuries involving the sliding and/or rotation of the tibia with regard to the femur
- Verify the presence of any tension below the knee, e.g. a pronated foot that can create excessive tension on the inner side of the knee