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Metabolically hot kneecaps in almost half of patellofemoral pain patients

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Tags: diagnosis, etiology, running, patellar pain, biomechanics, pro, exercise, self-treatment, treatment, arthritis, aging, pain problems, knee, leg, limbs, overuse injury, injury

Four articles on PainSci cite Näslund 2006: (1) The Complete Guide to Patellofemoral Pain Syndrome(2) IT Band & Patellofemoral Pain Defy Common Sense(3) How PainScience.com Works(4) Patellofemoral Pain Diagnosis with Bone Scan

PainSci summary of Näslund 2006: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible.

Researchers bone scanned and x-rayed 80 patients diagnosed with PFPS and with many common similar diagnoses eliminated, a nice “pure” selection of unexplained knee pain patients. They divided them into three groups: 17 with pathology, 29 with “hot” kneecaps (metabolically active), and 29 without any findings (5 dropped out). All patients and 48 healthy subjects without any knee pain were then interviewed and examined by a surgeon and a physical therapist.

They could not diagnose the pathologies without the scans — all patients with pain tested about the same, and their symptoms were indistinguishable. Q-for-quadriceps angles were about 4˚ bigger in the afflicted, but the authors carefully explain that 4˚ too small to be reliably detected. The most interesting result of the study is that almost half the PFPS patients had kneecaps throbbing with metabolic activity — that’s a fairly strong pattern.

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

Patellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal disorders. However, no consensus on the definition, classification, assessment, diagnosis, or management has been reached. We evaluated symptoms and clinical findings in subgroups of individuals with PFPS, classified on the basis of the findings in radiological examinations and compared the findings with knee-healthy subjects. An orthopedic surgeon and a physical therapist consecutively examined 80 patients clinically diagnosed as having PFPS and referred for physical therapy. The examination consisted of taking a case history and clinical tests. Radiography revealed pathology in 15 patients, and scintigraphic examination revealed focal uptake in 2 patients indicating pathology (group C). Diffusely increased uptake was present in 29 patients (group B). In the remaining 29 patients radiographic and scintigraphic examinations were normal (group A). Knee-healthy controls (group D) reported no clinical symptoms. No symptom could be statistically demonstrated to differ between the three patient groups. Knee-healthy subjects differed significantly from the three patient groups in all clinical tests measuring pain in response to the provocations; compression test, medial and lateral tenderness, passive gliding of the patella, but they also differed in Q angle. Differences in clinical tests between the patient groups were nonsignificant. The main finding in our study on patients clinically diagnosed with PFPS is that possible pathologies cannot be detected from the patient's history or from commonly used clinical tests.

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