Research Review by Dr. Shawn Thistle©


Aug. 2006

Study Title:

Patellofemoral arthritis (Current Concepts Review)


Grelsamer RP & Stein DA

Publication Information:

Journal of Bone & Joint Surgery 2006; 88-A(8): 1849-1860


The Journal of Bone and Joint Surgery always contains a current concepts review - which essentially reviews the state of knowledge about a certain condition from epidemiology and pathology to the focus of the journal - surgical intervention.

Many in the manual medicine field may miss these useful articles because of the surgical focus of the journal, but I often find at least parts of these articles very useful. They often provide concise, contemporary information about conditions commonly seen in musculoskeletal practice.

This review discusses patellofemoral arthritis, or degenerative changes behind and around the kneecap. Isolated arthritis of this joint was once thought to be quite rare; however recent studies have suggested that its prevalence may have been underestimated in the past.

Pertinent Results:

  • the prevalence of isolated patellofemoral arthritis in painful knees is now thought to be 8-9%
  • this condition is most common in those older than forty, but can occur in younger patients
  • predisposing factors are thought to be: repetitive deep knee flexion, obesity, malalignment, dysplasia, or blunt trauma
  • during knee flexion, the contact point of the patella migrates from distal to proximal up to 90°, after which the contact area migrates back toward the centre of the kneecap
  • thus, the central portion of the patella is most important for load bearing (and hence has the thickest cartilage - up to 5mm)
  • clinical presentation includes: anterior knee pain upon rising from a seated position and/or ascending stairs; pain diminished while walking on level ground
  • physical examination findings may include: over-pronation of the feet or other biomechanical findings, tenderness of the lateral (or occasionally medial) facet of the patella, and isolated joint swelling
  • differential diagnosis must include any condition that can refer pain to the anterior aspect of the knee including: plicae, abnormal patellar tilt, neuromas, tendinopathy, synovitis, or focal patella lesions
  • pain at rest should raise suspicion of a nerve-related cause such as a neuroma, complex regional pain syndrome, or radiculopathy
  • potential imaging options include: Merchant view plain films (or Rosenberg/Schuss views), nuclear bone scan, MRI, or arthroscopy
  • non-operative treatment should be the first option, and can include: activity modification (ex. avoiding squats and large steps), oral pain medications, weight loss, bracing/taping, nutritional supplements (ex. glucosamine), viscosupplementation
  • there are a variety of surgical techniques for this condition - a lack of uniform reporting and high quality research makes it difficult to recommend one procedure over others at this time

Conclusions & Practical Application:

In addition to the treatment options listed above, I feel future research should investigate the merit of specific soft tissue therapies (such as ART®), traditional or medical acupuncture (which already has a growing body of evidence to support its use for knee osteoarthritis), and specific rehabilitation exercise for the treatment of this condition.

I know many of us are already using these techniques with some degree of success in our practices. I feel it is also important to stress the importance of general aerobic exercise and proper weight management for anyone with knee arthritis.

We all have clients, friends, or parents that have knee pain. Patellofemoral arthritis should be a diagnostic consideration in these patients. Hopefully this review will remind us to look specifically at the patella as a potential cause of pain in some cases.