Have to thank Erik Meira and J.W. Matheson for recommending this study. PT Inquest is the best.
Take note of the fat pad, synovium, and capsule:
"We concluded that a simple method to directly document possible conscious neurosensory perception of the intraarticular components of the human knee would be to arthroscopically palpate the components without intraarticular anesthesia and record the subjetive experience.
Penetration of the unanesthetized anterior synovium and fat pad region during the initial examination of the right knee produced severe pain that elicited involuntary verbal exclamations from the subject and nearly resulted in cessation of the study. Further documentation of this sensory finding in the left knee was thought to be unnecessary.”
Take note of cartilage and chondromalacia patella NOT causing pain:
"Palpation of the patellar articular cartilage in the central ridge and medial and lateral facets resulted in no sensation, or a 0 score, even at 500 g of force.
**Asymptomatic*** grade II or III chondromalacia of the central ridge was identified on both patellas.
The anterior synovial tissues, fat pad, and capsule were exquisitely sensitive to the mechanical loading stimulus of the probe, whereas the sensation experienced with similar probing of the cruciate ligaments and menisci did not result in accurate spatial localization. This observation may provide an explanation for the often poor localization of structural damage that many patients experience with a cruciate ligament or meniscal injury. The painful synovitis and capsular inflammation frequently associated with a meniscal injury may be a more important factor in the subjective localization of the site of possible cartilage damage than sensation arising solely from the damaged meniscus.
The general absence of articular cartilage sensation noted in the current study provides an explanation for the presence of asymptomatic chondromalacia that is often found at surgery. This observation may provide support for those who question the causal relationship between the presence of patellar chondromalacia and the occurrence of anterior knee pain. Our present study also confirms the association of asymptomatic chondromalacia and normal technetium scintiscans documented in prior work, which revealed that homeostasis of the patellar osseous components is possible despite normal age-related structural failure of the articular cartilage."