Superior Achilles tendon microcirculation in tendinopathy among symptomatic female versus male patients

Background: Higher estrogen levels in women seem to play a role regarding an increased ligament and tendon injury rate among women. However, gender differences of tendon microcirculation have not yet been reported. Hypothesis: Female patients suffering Achilles tendinopathy have worse tendon and paratendon microcirculation than symptomatic male patients. Study Design: Cross-sectional study; Level of evidence, 2. Methods: A total of 139 Achilles tendinopathy patients (58 women, 81 men) were analyzed according to their gender for tendon and paratendon microcirculation by mapping at 12 positions (4 tendons, 8 paratendons) in each limb. Tendon and paratendon capillary blood flow, oxygen saturation, and postcapillary venous filling pressures were measured at 2-mm and 8-mm tissue depths. Results: Symptomatic women had similarly elevated tendon capillary blood flow as men at 4 Achilles tendon positions. However, distal medial (83 +/- 40 vs 105 +/- 74, P < .05) and lateral (98 +/- 49 vs 121 +/- 74) paratendon capillary blood flow were significantly lower among men. Symptomatic female patients had superior tendon and paratendon oxygen saturation at 11 of 12 positions (P < .05) as well as reduced postcapillary venous filling pressures at the proximal midportion tendon (55 +/- 17 vs 63 +/- 20, P < .05) and paratendon (69 +/- 19 vs 77 +/- 26) location. Pain level was not different between female (5.3 +/- 2.2) and male patients (5.4 +/- 2, P = .864). Female patients had significantly higher Foot and Ankle Outcome Sports Scores (71 +/- 22 vs 64 +/- 23 in the men, P = .041), while 4 out of 5 other Foot and Ankle Outcome Score items were not different. Conclusion: Symptomatic female patients have similarly elevated tendon capillary blood flow compared with symptomatic male patients suffering Achilles tendinopathy, but superior tendon and paratendon oxygen saturations and reduced postcapillary venous filling pressures indicate better tendon and paratendon Achilles tendon microcirculation in women.