Acute Low-G Stress Fracture
Earth designation: Acute Stress Fracture
Acute presentation of Stress Fracture in lunar residents. Bone fatigue fractures paradoxically occurring despite reduced gravitational loading — caused by the combination of osteopenic bones and the unique biomechanical stresses of low-gravity locomotion (bounding, hopping gait) that concentrates force differently than normal walking.
Lunar Risk Factors
Osteopenia from chronic low-g exposure. Novel locomotion patterns (bounding gait). Mining and construction vibration. Suit-induced altered biomechanics. Return-to-exercise after periods of illness-related rest.
Symptoms
Localized bone pain that worsens with activity and improves with rest. Swelling, point tenderness.
Lunar Presentation
Pain during bounding locomotion or EVA. Common sites differ from Earth: metatarsal and tibial stress fractures remain common; lumbar spine stress fractures more frequent due to altered loading.
Diagnosis
Clinical suspicion high in affected resident. X-ray (portable unit) often negative initially. MRI if available. Ultrasound can detect periosteal reaction.
Treatment
Activity modification, protected weight-bearing, possible immobilization, gradual return to activity.
Lunar Medical Bay Protocol
Remove from EVA duty. Activity modification. Low-gravity orthopedic principles: gravity-assist walking using handrails. Moonboot/controlled ankle walking device from medical supplies. Bisphosphonate if underlying osteopenia. 6-week healing protocol with gradual return. Nutritional support.
Evacuation Criteria
Complete fracture (displaced). Stress fracture at fracture-prone site (femoral neck) with ongoing osteopenia. Unable to perform mandatory emergency duties.
Prevention
Gradual introduction to lunar locomotion. Proper footwear. Osteoporosis prevention. Avoid repetitive bounding gait patterns.