Pain referral and regional deep tissue hyperalgesia in experimental human hip pain models

Pain. 2014 Apr;155(4):792-800. doi: 10.1016/j.pain.2014.01.008. Epub 2014 Jan 18.

Abstract

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.

Keywords: Deep tissue hyperalgesia; Hip pain; Hip pain provocation tests; Referred pain.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Female
  • Hip*
  • Humans
  • Hyperalgesia / etiology
  • Hyperalgesia / physiopathology*
  • Male
  • Pain / chemically induced
  • Pain / physiopathology*
  • Pain Measurement
  • Pain Threshold / drug effects
  • Pain Threshold / physiology*
  • Pain, Referred / chemically induced
  • Pain, Referred / pathology
  • Pressure / adverse effects
  • Saline Solution, Hypertonic / pharmacology
  • Sensation
  • Single-Blind Method
  • Tendons / drug effects
  • Tendons / innervation
  • Tendons / physiopathology*
  • Young Adult

Substances

  • Saline Solution, Hypertonic