Fracture non-union: who is at risk?

Fracture healing is a complex physiological process. It is regulated by cells, mediators and growth factors, with different phases of activity occurring over time, till normal bone formation is established [1]. Cellular recruitment, proliferation and differentiation under the guidance of signalling molecules with the involvement of extracellular matrix play an important role in creating the foundation for a successful bone healing response [2]. If any stage during these events is disturbed, it could lead to an impaired healing response expressed as delayed healing or nonunion of the fractured bone fragments [2]. The development of this devastating complication is frequently associated with loss of limb function, muscle atrophy, stiffness of the adjacent joints, diffuse limb osteopenia and systemic deterioration especially in the presence of infection [2]. More over the social economic and family implications can be immense [3,4]. As such strategies to predict early which patient might go on to develop fracture non-union are desirable. Risk factors or predicting models of an impaired bone repair process would allow early identification and treatment initiation to ensure a timely based successful healing outcome. Clinicians managing patients with non-unions have made a number of observations related to potential risk factors that could be responsible for the failed internal physiological fracture healing response. In general terms, the identified parameters that have been implicated with a negative outcome have been divided into 4 categories: (a) Patient related factors, (b) Environmental factors, (c) Injury related factors and (d) Treatment modality related factors.