The characteristic of isometric contraction (static contraction) is that it does not cause joint motion and does not cause joint damage. In the early postoperative period when the joint cannot be moved, the exercise is mainly based on isometric contraction, which does not cause local instability of the fracture. Quadriceps static contraction exercise: sitting or supine position, lower limbs straight (mainly keep the knee joint straight state), ankle joint as far as possible in the direction of their own arms hook foot, feel the muscle contraction above the thigh tense, maintain 5-10 seconds, relax for 1 second. Each group of 10-15 times. Medial femoral muscle exercise method: standing position, sitting position or supine position, lower limbs straight (mainly to keep the knee straight state), a pillow between the knees, both knees as hard as possible to the inner pillow, can feel the inner thigh muscle contraction, maintain 5-10 seconds, relax 1 second. Each group of 10-15 times. Lateral femoral muscle exercise method: standing position, keep the body standing upright (shoulders, hips, ankles in a line), hand on the back of a chair or table to support, to the healthy side of the leg for support, the affected limb to the side to lift the leg, can feel the contraction of the lateral thigh muscles, maintain 5-10 seconds, relax for 1 second. Each group of 10-15 times. Be sure to pay attention to the upper body to maintain the original posture, do not tilt, the knee joint has been kept straight state. Patients who cannot stand can take the lateral recumbent position to exercise. The affected side in the upper side of the lying position, keep the body in a straight line, the affected limb to the ceiling leg lift, can feel the contraction of the outer thigh muscles, maintain 5-10 seconds, relax for 1 second. Each group of 10-15 times. Biceps femoris and gluteus maximus exercise method: standing position, keep the body standing upright (shoulders, hips, ankles in a line), hand on the back of a chair or table for support, to the healthy side of the leg for support, the affected limb to the back of the leg lift, can feel the contraction of the back of the thigh and hip muscles, maintain 5-10 seconds, relax for 1 second. Each group of 10-15 times. Note the same as the lateral muscle exercise. Patients who cannot stand can take the supine position to exercise. Lower limb extension (mainly to keep the knee joint straight), a pillow under the affected knee, knee as hard as possible to press down the pillow, can feel the posterior thigh muscle contraction, maintain 5-10 seconds, relax for 1 second. Each group of 10-15 times.