BLOG: Patellofemoral joint is no longer a ‘black box’
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Before 2000, some referred to the patellofemoral joint as a “black box.” However, that probably sounds odd to most readers in 2024.
Many practicing orthopedic surgeons saw a close connection between emotional difficulties and complaints of anterior knee pain in teenagers. But which causes which? Today we understand that this is complicated.
Kinesiophobia and low pain thresholds play roles in the experience of pain, but also consider that intractable, undiagnosed knee pain may cause depression in young people. Anterior knee pain has many sources, including articular, synovial, referred, retinacular and, to some extent, emotional.
The patellofemoral joint is no longer a “black box.” We now have a great opportunity to help patients with patellofemoral pain by zeroing in on the exact source from which pain originates using better diagnostic tools, better understanding of 3D anatomy and detailed physical examination. I hope no one thinks of the patellofemoral joint as a “black box” in 2024.
Tertiary referral care of patients with patellofemoral pain requires a relentless search to find the cause. I have found that allowing patients to define a source of pain with one finger can be helpful. This is particularly true of retinacular and tendon pain sources that are sometimes missed when a patient has had a prior diagnosis of “patellofemoral syndrome,” a conclusion that often ends the search for a specific pain source.
Articular pain related to soft cartilage and vulnerable subchondral bone – where the nerves are – can often be isolated by loading the patellofemoral joint while progressively increasing knee flexion. This can pinpoint a very specific pain locus. Swelling and infrapatellar pain also may signal the presence of a highly innervated synovial pain source.
Referred pain from the hip or back becomes clearer upon specific examination with this in mind and should be part of any examination related to anterior knee pain. Patients are usually happy to understand where the pain comes from, and they appreciate a thorough search as this directs optimal management and provides hope of relief.
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