L sided medial knee pain in a TKR patient

So, why does this gals L knee hurt, posterior and medial on the left?

  • L total knee replacement 6 years ago; she thinks they used too large a size, we would have to agree.
  • occassional peripatellar discomfort
  • current pain descending hills and stairs, posterior and medial on the left

Physical findings

  • tenderness at posterior, medial aspect of knee at the top of the tibial plateau
  • positive anterior and posterior drawer +2
  • McMurrays for clicking with valgus and varus stresses
  • negative valgus/varus stress
  • all muscles test strong except for one, which one is it?

Read on…

Here is our theory:

This particular muscle fires at heel strike and again from loading response until toe off (you can look at the diagram above if needed). It also acts as an acessory posterior cruciate ligament (PCL).

Think about the forces on the knee while descending hills or stairs. The momentum will carry the femur forward (or anteriorly). There needs to be something to reststrain this; enter the PCL.

Because of the laxity (and instability), the poplitues needs to fire to take up the slack. Palpation confirmed it being tender throughout its course, with most at the tibial attachment. The attachment is largest here, so that makes sense. The muscle also tested weak.

We gave her popliteus and 1 leg balancing exercises in addition to doing acupuncture (origin/insertion work) as pictured. 5 days later she was 60% improved. She may need to return to her ortho, depending on her response to additional care.

Think about the popliteus the next time someone has posterior medial knee pain, especially when descending.