In trauma surgery and hand surgery treatment strategies of none healing bone fractures aim at replacing pseudarthrosis by well vascularized bone and improving microcirculation. Although previous studies indicate that remote ischemic preconditioning (RIPC) can accelerate bone healing in case of non-union, only a few studies focused on the elucidation of its mechanisms of action. Therefore, the aim of this study is to evaluate the microcirculatory effects of remote ischemic preconditioning (RIPC) on scaphoid bones and metacarpal bones and metatarsal bones in a human in-vivo setting for the first time.

Inclusion Criteria:

• Group A (n=20): Consent-capable male and female patients ≥18 years of age who have an intact scaphoid bone.
• Group B (n=20): Consent-capable male and female patients ≥18 years of age who have an intact metacarpal bone.
• Group C (n=20): Consent-capable male and female patients ≥18 years of age who have a fractured scaphoid bone.
• Group D (n=20): Consent-capable male and female patients ≥18 years of age who have a fractured metacarpal bone.

Exclusion Criteria:

• below 18 years of age
• scar tissue above measuring focus
• osteoporosis or comparable bone disease
• medication that influences bones