Pressure-induced referred pain areas are more expansive in individuals with a recovered fracture

Pain. 2018 Oct;159(10):1972-1979. doi: 10.1097/j.pain.0000000000001234.

Abstract

Musculoskeletal trauma and pain can sensitize central pain mechanisms, but whether these normalize on recovery is unknown. This study compared the extent of pain referral in individuals recovered from a musculoskeletal trauma and healthy controls. Twenty pain-free participants recovered from a shoulder fracture and 20 age-/sex-matched controls participated in 2 experimental sessions (day-0 and day-1) separated by 24 hours. On both days, pressure pain thresholds were measured bilaterally at infraspinatus, supraspinatus, trapezius, and gastrocnemius muscles. Referred pain towards the shoulder region was induced by a 60-second pressure stimulation (pressure pain threshold + 20%) at the infraspinatus muscle and recorded on an electronic body chart. After day-0 assessments, delayed onset muscle soreness (DOMS) was induced to challenge the pain systems by exercising the external rotators of the recovered/dominant shoulder. The size of pressure-induced pain referral on day-0 did not differ between groups, although there was a tendency for a smaller referred pain area in recovered group. Pressure pain thresholds at the infraspinatus muscle on the DOMS side were reduced on day-1 in both groups (P = 0.03). An expansion of pressure-induced pain referral was found in both groups following the DOMS protocol on day-1 (P = 0.05) with a relatively larger expansion (P = 0.05) and higher frequency of pain in the shoulder (P = 0.04) in the recovered pain group. After complete recovery and absence of pain symptoms after a fracture, central pain mechanisms seem to normalize in the region of the trauma after recovery but when sensitized a heightened response can emerge. Such mechanisms could be important for recurrence of pain conditions.

Publication types

  • Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Case-Control Studies
  • Cross-Sectional Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • Myalgia / physiopathology*
  • Pain Threshold / physiology*
  • Pain, Referred / etiology*
  • Pain, Referred / physiopathology
  • Pressure / adverse effects*
  • Recovery of Function / physiology*
  • Single-Blind Method
  • Statistics, Nonparametric
  • Time Factors
  • Young Adult