The popliteus is a muscle which is located at the back of the knee. It originates from the outer part of the lower aspect of the femur and inserts on the inner tibia. The action of popliteus is to ‘unlock’ the extended knee by rotating the femur outwards (laterally) on the fixed tibia when the knee starts to bend. This muscle also rotates the leg inwardly when the knee is fixed in a straightening position.
Injury to this muscle can occur after:
1) An acute injury, such as a fall or car accident, when the knee is in a straightened position.
2) Chronic overuse of the popliteus muscle can also occur as a result of faulty biomechanics, such as excessive hyperpronation of the feet.
3) Reactive muscle tone secondary to:
a) Postsurgical knee joint effusion from interventions, such as ACL reconstruction.
b) Compensation for poor quadriceps function, whereby the popliteus becomes hyperactive in an effort to maintain stability to the back of the knee.
c) Compensation for poor rotary control by the hamstrings, leading to overuse of the popliteus.
ASSESSMENT FINDINGS AND SYMPTOMS
This injury is often underdiagnosed, as it is difficult to diagnose through routine clinic assessment. The main symptoms are of posterior knee pain and a feeling that the knee does not fully extend or alternatively a “blocked up” feeling on flexion of the knee. The main findings on orthopaedic assessment are palpatory tenderness when the knee is bent to 20 degrees or alternatively a reduction in passive external rotation of the knee in the sitting position.
(The list of conditions given above and subsequent explanations are intended as a general guide and should not be considered a replacement for a full medical examination. Furthermore, we do not purport to treat all the conditions listed. Should you wish to discuss any of these conditions with our chiropractors, please do not hesitate to phone the clinic on 020 7374 2272 or email firstname.lastname@example.org).