TY - JOUR
T1 - Acid-induced experimental knee pain and hyperalgesia in healthy humans
AU - Asaki, Toshiyuki
AU - Wang, Kelun
AU - Luo, Yi
AU - Arendt-Nielsen, Thomas
AU - Graven-Nielsen, Thomas
AU - Arendt-Nielsen, Lars
PY - 2018/2
Y1 - 2018/2
N2 - Inflammation and the related acidity in peri-articular structures may be involved in pain generation and hyperalgesia in knee osteoarthritis. This study investigated pain and associated hyperalgesia provoked by infusion of acidic saline into the infrapatellar fat pad. Twenty-eight subjects participated in two sessions in which acidic saline (AS, pH 5) or neutral saline (NS, pH 7.4) were infused into the infrapatellar fat pad for 15 min. Pain intensity, pain area, mechanical and thermal sensitivity, and maximal voluntary knee extension force were recorded. Repeated infusions were performed in 14 subjects. Infusion of AS caused significantly higher pain intensity, larger pain areas, induced hyperalgesia around the infused knee, and reduced extension force. No significant pain facilitation or spreading of hyperalgesia was found after repeated infusions as compared with single infusions. Acidic saline infused into the infrapatellar fat pad provoked pain and localized mechanical hyperalgesia. Thus, this acid-induced pain model may mimic the early-stage responses to tissue injury of knee osteoarthritis.
AB - Inflammation and the related acidity in peri-articular structures may be involved in pain generation and hyperalgesia in knee osteoarthritis. This study investigated pain and associated hyperalgesia provoked by infusion of acidic saline into the infrapatellar fat pad. Twenty-eight subjects participated in two sessions in which acidic saline (AS, pH 5) or neutral saline (NS, pH 7.4) were infused into the infrapatellar fat pad for 15 min. Pain intensity, pain area, mechanical and thermal sensitivity, and maximal voluntary knee extension force were recorded. Repeated infusions were performed in 14 subjects. Infusion of AS caused significantly higher pain intensity, larger pain areas, induced hyperalgesia around the infused knee, and reduced extension force. No significant pain facilitation or spreading of hyperalgesia was found after repeated infusions as compared with single infusions. Acidic saline infused into the infrapatellar fat pad provoked pain and localized mechanical hyperalgesia. Thus, this acid-induced pain model may mimic the early-stage responses to tissue injury of knee osteoarthritis.
KW - Journal Article
KW - Gender difference
KW - Experimental pain
KW - Acid-induced pain
KW - Osteoarthritis
KW - Hyperalgesia
KW - Humans
KW - Skin/innervation
KW - Male
KW - Dose-Response Relationship, Drug
KW - Young Adult
KW - Pain Threshold/drug effects
KW - Knee Joint/innervation
KW - Time Factors
KW - Adult
KW - Female
KW - Muscle Contraction/drug effects
KW - Physical Stimulation
KW - Double-Blind Method
KW - Pain/chemically induced
KW - Functional Laterality/physiology
KW - Sex Characteristics
KW - Cross-Over Studies
KW - Analysis of Variance
KW - Acids/adverse effects
KW - Hyperalgesia/chemically induced
KW - Pain Measurement
KW - Hydrogen-Ion Concentration
UR - http://www.scopus.com/inward/record.url?scp=85038217471&partnerID=8YFLogxK
U2 - 10.1007/s00221-017-5155-5
DO - 10.1007/s00221-017-5155-5
M3 - Journal article
C2 - 29250706
SN - 0014-4819
VL - 236
SP - 587
EP - 598
JO - Experimental Brain Research
JF - Experimental Brain Research
IS - 2
ER -