The term “anterior knee pain” is a generic description for various types of pain involving the patellofemoral joint. Similar to the use of the term chondromalacia patella, it is a relatively generic term which does not give any specifics about the anatomic structures involved with a particular joint pathology.
Many causes of anterior knee pain are due to a muscle imbalance between the quadriceps musculature, which is usually weak, and the hamstrings musculature, which is usually tight. The tight hamstrings can cause extra stress on the anterior knee structures as the knee strives to achieve full extension against these tight hamstrings. When this is combined with a less than ideally balanced quadriceps musculature, it can cause irritation with several of the anterior knee structures resulting in pain and dysfunction.
The most common cause of pain over the anterior aspect of the knee is irritation of the medial suprapatella plica. In addition, bursitis at the hamstring attachments areas (pes anserine bursitis, semimembranosus bursitis, or FCL-biceps bursitis), patellar tendon mechanism pain secondary to tight hamstrings or other causes (patellar tendinosus, Osgood-Schlatter’s irritation or deep infrapatellar bursitis, scaring of the retropatellar fat pad due to injury or surgery, other scaring in the patellofemoral joint or general pain and inflammation of the joint due to localized or generalized arthritis).
In addition, lateral patellar instability secondary to patellar subluxation or dislocation due to injury, malalignment, trochlear dysplasia, or muscle imbalance may contribute to irritation of the anterior knee structures. It is also important to assess for this when evaluating the patellofemoral joint. Medial patellar subluxation or dislocation can also occur, but is usually due to a lateral release, with the resulting medial patellar instability occurring in the initial 0°-30° flexion arc of the knee.
The usual treatment options for patellofemoral dysfunction involve a combination of low impact exercising, possible use of anti-inflammatory medications, bracing and the judicious use of injections. It has been well demonstrated that a knee and hip strengthening program is very beneficial to alleviating anterior knee pain. The types of exercises to include hamstring stretching can also be determined during the physical exam. McConnell taping may also be indicated to assist with the diagnosis of a problem especially if there is medial or lateral patellar instability.
The majority of patients who do have anterior knee pain structure irritation do respond well to a well guided rehabilitation program. However, it is important to define the exact source of the pain is to help guide this rehabilitation. In those patients who do not respond to this rehabilitation program, a re-evaluation may be necessary to determine if a change in rehabilitation or other treatment modalities may be needed.