Many textbooks have been written regarding the basis of acupuncture and read like an organic chemistry textbook! To simplify, it appears that the local effect of putting a needle through the skin serves to improve local blood flow to an area that may have relative ischemia (a lack of blood flow), that then benefits greatly from a local improvement in circulation. This is particularly true for conditions that involve strain and swelling.
With the addition of electrical stimulation, which is frequently used in conjunction with acupuncture, there is proof of local production of beta endorphins, the body's natural pain killing and pain modulating substance. It appears that acupuncture provides pain relief by activating the pain modulation system of the body, and changes both the processing as well as the awareness of the painful information at various levels in the central nervous system. By modulating pain, decreasing the awareness of the incoming pain signals, improving blood flow, improving the production of pain relieving substances, and in general promoting healing in the area of trauma, acupuncture helps to generate improved blood flow resulting in improved healing to the area.
In my own clinical practice I have found that acupuncture serves as an excellent companion to conventional medical care for many knee conditions.
Medication management including anti-inflammatory agents, quality physical therapy with muscle lengthening, instructions for stretching and appropriate strengthening of the muscles that surround the knee, as well as appropriate orthopaedic intervention when medically necessary for such conditions as instability and meniscal pathology, can all be augmented with appropriate and timely use of acupuncture.