Impact of Spaceflight on Upper Extremity Orthopedic Health.

Introduction: With increased access to commercial spaceflight and space tourism, plus a push for longer duration spaceflights, it is especially important to understand the impact of spaceflight on musculoskeletal health. Upper extremity injuries are the most common musculoskeletal injuries in spaceflight. It is, therefore, vital to determine the changes to the upper extremities during spaceflight. The purpose of this study was to examine the state of knowledge on the impact of spaceflight on upper extremity orthopedic health, and to identify knowledge gaps and future areas of research.

Methods: A literature review was performed and studies and reports that amassed data on shoulder, elbow, wrist, and hand health were included.

Results: Spaceflight decreases bone mineral density in the upper extremities and increases risk of fracture, especially upon return to gravitational environments. Spaceflight does not uniformly affect all muscles; in the shoulder, the various muscles crossing the joint appear to be variably affected: the deltoid experiences a greater degree of atrophy than the rotator cuff muscles. Spaceflight additionally affects the peripheral nervous system, with astronauts experiencing hand numbness and loss of manual dexterity but cause of these symptoms is undetermined. Spacesuits have also been implicated in causing upper extremity injury, especially while training for or performing extravehicular activities.

Discussion: While upper extremity orthopedic health in spaceflight is incompletely understood, known adaptations increase risk for weakening and injury. Existing research provides valuable information for best practices, but there is still much to be discovered to optimize upper extremity health in spaceflight. Fiedler B, Jami M, Rakauskas T, Ahmed AS. Impact of spaceflight on upper extremity orthopedic health. Aerosp Med Hum Perform. 2024; 95(10):777-783.