Hello, This is very common in the patients with the cardiac surgery. Also, the medicine given is the right one as per my understanding. What I understand with the history is that you must be given good rest post the cardiac surgery and also your overall mobility is limited compared to before the surgery. So there might be changes in the normal biomechanics and physiology of the joints and muscles. You may have a weakness of muscles and also reduced joint space in the spine and lower limbs (hip, knee) which can give to nerve normal physiology a disturbed functionality. Kindly try doing simple spine strengthening exercises and isometric for gluteus and thigh muscles which can help you make muscles stronger and also improve the joint space. In my experience, with simple exercises mentioned above most of the patients recover and changes start by 2-3 weeks of time. Please let us know a detailed history if the symptoms don t improve and we can assist your further. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Jay Indravadan Patel, Physical Therapist or Physiotherapist