Keel bone fractures in laying hens represent one of the most significant unresolved welfare problems in commercial egg production, affecting 50-80% of hens in aviary systems and 30-50% in enriched colony cages. The keel bone - a prominent sternum extension - is frequently fractured during collision with aviary structures, perch edges, and during falls. Research demonstrates that fractures cause pain based on changes in gait, posture, and production parameters. Hens with keel fractures show altered perch use, reduced activity, and behavioural indicators consistent with chronic pain. Despite high prevalence, keel fractures have received less industry attention than leg disorders or footpad dermatitis. Risk factors include aviary design (perch diameter, inclination angle, positioning), genetics (bone density), nutrition (calcium, vitamin D), and management. Mitigation strategies include softer perch materials, optimised aviary design, and selection for bone density. Welfare certification bodies are beginning to incorporate keel bone scoring into audit protocols, driving industry attention.