Temporary pain in the front of the knee is very common following ACL reconstruction. This can occur in up to 20 out of 100 patients and is usually related to the type of graft used. However, over time with physical therapy and activity modification, this pain normally improves. Permanent pain is very rare and usually associated with lack of full extension of the knee. It may also be due to pre-existing damage to cartilage which occurred at the time of the injury or arthritis.