Muscle pain around the femur may be caused by several reasons. First, it may be caused by overexertion, such as when the patient performs heavy weight-bearing or does excessive exercises for the lower limbs, which may cause a large amount of lactic acid deposition inside the muscles around the femur. Patients may noticeably feel soreness in the muscles around the femur and have symptoms of weakness. Second, it may be caused by muscle damage here. Although the muscle cover around the femur is very thick, it is very easy to cause muscle-related damage and pain if it suffers a direct violent blow. In this case, it is common for the patient to do excessive and vigorous activities, resulting in strain of the muscles and tendons, and then produce very obvious pain. Third, it may be caused by peripheral nerve-related lesions, such as when the patient has a lumbar disc herniation, the peripheral nerves are stimulated by compression, which may produce radioactive pain here and cause the patient to mistake it for muscle pain. Fourth, it may also be caused by the body’s autoimmune reaction, such as when patients develop rheumatism, rheumatoid arthritis, or influenza and other diseases, which may cause pain in the muscles due to the autoimmune reaction.