Background: Neovascularisation and microcirculatory changes have been reported in Achilles tendinopathy. Cryotherapy and compression as part of the RICE regimen are shown to decrease pain and improve function. However, the microcirculatory changes following a given dosage of cryotherapy on mid-portion Achilles tendon remain unclear.
Study design: Prospective clinical cohort study, Level of evidence 2.
Methods: Thirty subjects (12 males, 3312 years, BMI 25.65.3) were included with 3x10min KoldBlue™ ankle cooling bandage and continuous real-time assessment of parameters of Achilles tendon mid-portion microcirculation using a laser-Doppler-spectrophotometry-system (O2C, Germany).
Results: Superficial capillary blood flow was reduced from 42 relative units (rU) to 6rU in the 1st, 5rU in the 2nd and 3rU in the 3rd cryotherapy period (-65%, p=0.0003) with no significant capillary hyperaemia. Deep capillary tendon blood flow was reduced from 180rU to 82/53/52rU (-71%, p=0.0002) within 6-9 minutes of application without hyperaemia. Superficial tendon oxygen saturation dropped significantly from 43% to 26/18/11% (p=0.0004) after repetitive cryotherapy with persisting increase of tendon oxygenation during rewarming (51/49/54%, p=0.077) up to +27% of the baseline level. At 8mm tendon depth, cryotherapy preserved local oxygenation. Relative postcapillary venous tendon filling pressures were favourably reduced from 41±11rU to 31/28/26rU (-36%, p=0.0004) superficially and deep from 56±11rU to 45/46/48rU (-18%, p=0.0001) during cryotherapy facilitating capillary venous clearance.
Conclusion: Intermittent cryotherapy of 3x10min significantly decreases local Achilles tendon mid-portion capillary blood flow by 71%. Within 2min of rewarming tendon oxygen saturation is re-established following cryotherapy. Postcapillary venous filling pressures are reduced during cryotherapy favouring capillary venous outflow of the healthy Achilles tendon.