There are many possible causes for simultaneous soreness in both thighs, including: the first, a herniated disc in the upper lumbar spine that causes bilateral sciatic nerve pain after compression of the sphenopalatine nerve root, radiating to the lateral thighs. The second type, dermatomal neuritis occurring in the lateral femur, is usually unilateral and is less common with bilateral lateral femoral dermatomal nerve compression. The third, seen in severe inversion of the knee, causes the patient to have a lateral biologic line of force in the lower extremity, causing the iliotibial bundle to rub repeatedly against the femoral epicondyle, producing sterile inflammation and bursitis, which also often leads to soreness in the lateral thigh.