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Essentials of Diagnosis
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Pain experienced with bending activities (kneeling, squatting, climbing stairs)
Lateral deviation or tilting of the patella in relation to the femoral groove
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General Considerations
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Also known as anterior knee pain, chondromalacia, or "runner's knee," describes any pain involving the patellofemoral joint
Pain affects any or all of the anterior knee structures, including the medial and lateral aspects of the patella as well as the quadriceps and patellar tendon insertions
Patellofemoral pain is also associated with muscle strength and flexibility imbalances as well as altered hip and ankle biomechanics
Abnormal patellar tracking during flexion can lead to abnormal articular cartilage wear and pain
When the patient has ligamentous hyperlaxity, the patella can sublux out of the groove, usually laterally
There are two common presentations
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Pain
Usually occurs in the anterior knee with bending movements and less commonly in full extension
Localized under the patella
May sometimes be referred to the posterior knee or over the medial or lateral inferior patella
Symptoms may begin after a trauma or after repetitive physical activity, such as running and jumping
When maltracking, palpable and sometimes audible crepitus can occur
Intra-articular swelling usually does not occur unless there are articular cartilage defects or unless osteoarthritis develops
On physical examination, it is important to palpate the articular surfaces of the patella
Patellar mobility can be assessed by medially and laterally deviating the patella
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Radiographs may show lateral deviation or tilting of the patella in relation to the femoral groove
MRI may show thinning of the articular cartilage but is not clinically necessary, except prior to surgery or to exclude other pathology
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Apprehension sign
Patellar grind test
Performed by grasping the knee superior to the patella and pushing it downward with the patient supine and the knee extended, pushing the patella inferiorly
The patient is asked to contract the quadriceps muscle to oppose this downward translation, with reproduction of pain or grinding being considered a positive sign for chondromalacia of the patella
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