Fracture non-union epidemiology and treatment
Mills, Leanora Anne
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Introduction Non-union (NU) is a fracture that will not unite. With over one million fractures per annum in the UK long bone non-union has serious social and economical implications. There is little epidemiological data available specifically looking at this NU patient cohort. Studies that are bone specific quote rates of non-union as a proportion of their study group but there is no data quantifying the incidence of NU in the population or per fracture. Studies have highlighted risk factors associated with atrophic non-union including age, diabetes, non-steroidals, and cigarette smoking. There is scientific interest regarding how best to classify non-unions and the role of biological agents in treating them. Aims • To quantify the incidence of non-union in a large population and calculate the risk of non-union per fracture according to age, sex and anatomical distribution. • To assess the causes contributing to non-union and outcomes of treatment in a non-union cohort and validate a new non-union scoring system. • To test the treatment potential of a novel molecule (monobutyrin) and a growth factor in a small animal model of non-union. Method • Using the ICD-10 data from the Scottish population as collected by NHS Scotland the incidence of non-union and fractures were calculated. • A cohort of 100 non-union patients were studied for risk factors associated with their non-union, treatment outcome and to assess a new NU classification system. • A rat model of tibial non-union was used to assess the potential of monobutyrin and BMP-2 in treating non-union in an animal model. Results • Fracture non-union is very rarely found in children (1 in 500 fractures) and occurs in up to 1 in 50 adult fractures. Non-union of a fracture has a significantly higher risk in young adults than the elderly by about 3 fold. Osteoporosis may not be a risk for non-union. The tibia and clavicle are the sites with the greatest potential for fracture non-union. • Non-union is multifactorial in two out of three patients. Biomechanical stability, patient host factors and infection must all be considered in every patient. Occult or unexpected recurrent infection is present in up to 10% of patients. When all factors are considered in treatment the outcome is 95% successful with 88% requiring 2 or less procedures to heal the non-union and only a minority requiring adjuvant graft or biological agents. The proposed new classification system is complex and did not clearly identify those patients who would require adjuvant treatment (eg bone grafting or BMP) or those likely to have unsuccessful non-union treatment. • Monobutyrin and BMP-2 when tested on the small animal non-union model did not improve the success rate of union. Conclusions Non-union affects approximately 1000 people per year in Scotland, this figure is not as high as 5-10% of all fractures. It is associated with fractures in young adults and of the clavicle and tibia, treatment can have a very high success rate without the need for adjuvant biological polytherapy when all contributing factors are considered and managed appropriately. A new non-union classification needs to incorporate the multifactorial aspects of non-union without being too complex to use in everyday clinical situations.