Pain referral and regional deep tissue hyperalgesia in experimental human hip pain models.
Hip disorder patients typically present with extensive pain referral and hyperalgesia. To better understand underlying mechanisms, an experimental hip pain model was established in which pain referrals and hyperalgesia could be studied under standardized conditions. In 16 healthy subjects, pain was induced by hypertonic saline injection into the gluteus medius tendon (GMT), adductor longus tendon (ALT), or gluteus medius muscle (GMM). Isotonic saline was injected contralaterally as control. Pain intensity was assessed on a visual analogue scale (VAS), and subjects mapped the pain distribution. Before, during, and after injections, passive hip joint pain provocation tests were completed, together with quantitative sensory testing as follows: pressure pain thresholds (PPTs), cuff algometry pain thresholds (cuff PPTs), cutaneous pin-prick sensitivity, and thermal pain thresholds. Hypertonic saline injected into the GMT resulted in higher VAS scores than hypertonic injections into the ALT and GMM (P<.05). Referred pain areas spread to larger parts of the leg after GMT and GMM injections compared with more regionalized pain pattern after ALT injections (P<.05). PPTs at the injection site were decreased after hypertonic saline injections into GMT and GMM compared with baseline, ALT injections, and isotonic saline. Cuff PPTs from the thigh were decreased after hypertonic saline injections into the ALT compared with baseline, GMT injections, and isotonic saline (P<.05). More subjects had positive joint pain provocation tests after hypertonic compared with isotonic saline injections (P<.05), indicating that this provocation test also assessed hyperalgesia in extra-articular soft tissues. The experimental models may open for better understanding of pain mechanisms associated with painful hip disorders.
Laboratory for Musculoskeletal Pain and Motor Control, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark Department of Orthopedic Surgery, Kochi University, Kochi, Japan.
Masashi
M
Izumi
Kristian Kjær
KK
Petersen
Lars
L
Arendt-Nielsen
Thomas
T
Graven-Nielsen
D000328:Adult; D005260:Female; D006615:Hip; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology*; D053591:Referred Pain / Q000139:chemically induced / Q000473:pathology; D011312:Pressure / Q000009:adverse effects; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D012677:Sensation; D016037:Single-Blind Method; D013710:Tendons / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology*; D055815:Young Adult
D012462:Saline Solution, Hypertonic
Deep tissue hyperalgesia; Hip pain; Hip pain provocation tests; Referred pain