Snapping Popliteus Tendon

Krause D.A., Stuart M.J. Snapping Popliteus Tendon in a 21-Year-Old Female J Orthop Sports Phys Ther 2008:38(4):191-195

This case study describes a woman who presented with a 7-year history of pain and audible clicking at her lateral left knee when moving the knee through 20 to 30 degrees knee flexion. This occurred both actively and passively, and was present whether moving into knee flexion or extension. The patient reported that she had been very active previously, but now had to limit her activites due to pain. She had undergone several rounds of previous physical therapy, when she was diagnosed with snapping iliotibial band and treated with passive modalities, stretching, strengthening, and NSAIDs. She denied any improvement with those treatments.

On evaluation, all clinical and radiographic findings were normal with the exception of pain with palpation of the lateral epicondyle of her femur, as well as pain and an audible click with the knee at 20 to 30 degrees of flexion. Initial treatment consisted of posterior mobilization of the distal fibula, which eliminated the pain and clicking with knee movement. A trial of taping was performed, but the patient couldn’t tolerate it, which led to use of an exension brace for two weeks, with the goal of avoiding knee flexion and decreasing irritation to the painful site. This was effective while the brace was on, but had no lasting benefit after returning to activities without the brace. The patient was then referred to the surgeon, and open surgical exploration revealed that the popliteal tendon was snapping over the tubercle of the popliteal sulcus. There is a terrific video of the snapping tendon at the JOSPT website. At 6 weeks after surgery she was performing all activities without complaint.

I thought this was a great case study, and a few things jumped out at me:

Before reading this article, if this patient had come to me, I might very well have diagnosed it similarly to her previous therapists (snapping iliotibial band), and while the treatment might have been a bit different, it’s unlikely that it would have been any more effective.

It’s interesting that they tried a posterior distal fibula mobilization as the initial treatment, versus just going right to an anterior proximal mobilization, if that was the goal. I wonder if this mobilization technique was the first thing the author tried, or just the one that had such a dramatic effect. Either way, it’s a great idea and a good way to isolate the lower leg and help to further rule out the iliotibial band.

The author references a few case series that highlight clinical tests to provoke the snapping popliteus, neither of which I had ever heard of. One description is of increased snapping when a varus force is applied to the knee, and the other describes the Cabot sign, in which the knee is extended against resistance with the leg in a figure four position. I doubt that these have been studied extensively for reliability and validity, but they may be helpful to keep in mind the next time someone comes in with snapping at the lateral knee.

The authors note that although this patient required surgery, there are some reports of treating this conservatively; all of those reports were of patients with relatively acute symptoms, who may very well have improved without treatment. If someone comes in with a chronic case, and the above signs are noted, it’s probably a good idea to start thinking about more aggressive measures fairly early, rather than go through multiple visits of ineffective treatment.