Dear kudisbetta:
One of the most overlooked muscles group in the knee is the muscles that lock and unlock the knee. Have a practitioner palpate the popiletus and the planterius. These can and do make the knee feel like it cannot move or moves with difficulty.
The other muscle often overlooked is the adductor longus. It acts in harmony with the hamstrings. Have a practitioner assess the adductor longus. You can do a self test on the adductor longus and pelvic bones positions. Stand in front of a mirror. Find the ASIS of the innominate bones ( the prominent feature of the pelvic bones on the anterior) both right and left. Stand in a closed foot stance and widen the foot stance directly lateral to 30 cm, 60 cm, 90 cm, 120 cm. If the left ASIS moves superior to the right or the right moves inferior to the left then you possibly have a left adductor magnus problem. There could be much more that is needed than this. Have your practitioner contact me. The superior movement of the left ASIS is a flag that the adductor magnus is in a guarding response, but other factors could also be indicated.
Please let me know what you find out.
Best regards,
Neuromuscular.