The patient was supine position, one knee angle was 90°, the foot was flatted on the ground. The ankle was flexed to contract the quadriceps on the other side. Then straighten the knee joint and the hip was 30° and lift the thigh, the heel was about 20cm away from the ground, and put down the lower limb after 2 seconds. Ten times are in a group, each practice has 5 groups, rest between the groups is 1 minute. Practice 5 times a week, practice on both sides, take uniform respiration without holding breath.

The subjects' upper body was upright, the distance between feet was same as width of shoulder, and hands were placed on each side of the body or above the thighs. Tiptoes were towards the front, and perpendicular to the wall. The distance between the wall and heel was about a foot long, and the back was close to the wall, squatted slowly.

The subjects stood on the flat ground, the upper body was upright, the distance between feet was same as width of shoulder, and tiptoes were towards the front. The trunk was adjusted forward according to the Angle of static squat. The specific method is to adjust the trunk position to the line of the shoulder joint and knee joint perpendicular to the ground. Knee joint can bend at a large angle.The center of gravity was between the feet, put hands in front of body.The angle was set at 30° for the first two weeks, increased to 45° after two weeks, and set at 60° for the last two weeks.

The patient was supine position, one knee angle was 90°, the foot was flatted on the ground. The ankle was flexed to contract the quadriceps on the other side. Then straighten the knee joint and the hip was 30° and lift the thigh, the heel was about 20cm away from the ground, and put down the lower limb after 2 seconds. Ten times are in a group, each practice has 5 groups, rest between the groups is 1 minute. Practice 5 times a week, practice on both sides, take uniform respiration without holding breath.

Investigators assessed the efficacy of wall squat, direct squat and wall squat assisted by elastic bands by measure Kujala score, Lysholm score, VAS-W score, VAS-U score, thigh circumference score, results of peak knee torque in isokinetic muscle strength test and peak knee moment results for isokinetic muscle strength test by using USA Biodex isokinetic muscle strength tester at 3rd week and 6th week. Before statistics, the measurement data are tested for normality and homogeneity of variance. The data meet the conditions of normal distribution and homogeneity of variance, and the statistical results are expressed in the form of mean ± standard deviation (x ± s).Count data were analyzed by the chi-square test. P <0.05 represents a statistically significant difference.

Higher values for all scores proved better intervention treatment.