Thanks for your question on HCM. Possibility of Deep vein thrombosis (DVT) is high after major orthopedic surgery like knee surgery. But the risk is highest in first six months post operatively. And after than risks are reduced gradually. So your calf and thigh pain can be due to DVT. And chest pain and breathlessness can be due to Pulmonary Embolism (PE) due to detachment of thrombus from leg veins. Though the possibility of both is very low, it is better to rule out both of these So get done lower limb venous Doppler, D dimer and CT pulmonary angiography to rule out DVT and PE. Better to consult pulmonologist and discuss all these.