The main reasons for the ineffectiveness of sodium hyaluronate injection alone are: ① fluid accumulation in the joint at the time of injection. ②No reduction in activity or insufficient reduction during the injection. ③Incorrect diagnosis, not only with chondromalacia patellae but also with patellar subluxation at the same time. ④Or there are other knee problems, such as meniscal injury of the knee. ⑤ No oral glucosamine sulfate was used in conjunction. The following tests are recommended for patients who do not respond to sodium hyaluronate injections alone: ① Axial patellar radiographs at 30°, 60° and 90° of knee flexion to identify patellar subluxation. It is important to take three axial views of the patella because if only one view is taken and the patella is not dislocated in that view, but the other two views or one view is subluxated, the diagnosis of patellar subluxation will be missed. ②If a meniscal injury is suspected by an experienced physician, MRI of the knee should be performed so that meniscal injury can be ruled out. After ruling out patellar subluxation by patellar axial film and ruling out meniscal injury by MRI, intra-articular water administration should be abated before injection of sodium hyaluronate, and activities should be minimized for five weeks during injection, preferably together with oral administration of glucosamine sulfate. After five weeks of treatment, if effective, muscle strength should be carefully practiced (see static exercises for quadriceps) to prevent future recurrence. Surgery should only be considered if significant patellar subluxation or meniscal damage is found and conservative treatment has been ineffective for a long time.