ObjectivesSystematic review and meta-analysis of published observational cohort studies. To quantify the increased risk smokers have of experiencing a delayed and/or non-union in fractures, spinal fusion, osteotomy, arthrodesis or established non-unions.SettingMedical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica database (EMBASE), Allied and Complementary Medicine Database (AMED) and Web of Science Core Collection from 1966 to 2015.Study eligibility criteria, participants and interventionsObservational cohort studies that reported adult smokers and non-smokers with delayed and/or non-union or time to union of the fracture, spinal fusion, osteotomy, arthrodesis or established non-union were eligible.Data extraction and outcome measures2 authors screen titles, abstracts and full papers. Data were extracted by 1 author and checked independently by a second. The relative risk ratios of smoking versus non-smoking and the mean difference in time to union patients developing a delayed and/or non-union were calculated.ResultsThe search identified 3013 articles; of which, 40 studies were included. The meta-analysis of 7516 procedures revealed that smoking is linked to an increased risk of delayed and/or non-union. When considered collectively, smokers have 2.2 (1.9 to 2.6) times the risk of experiencing delayed and/or non-union. In all the subgroups, the increased risk was always ≥1.6 times that of non-smokers. In the patients where union did occur, it was a longer process in the smokers. The data from 923 procedures were included and revealed an increase in time to union of 27.7 days (14.2 to 41.3).ConclusionsSmokers have twice the risk of experiencing a non-union after fracture, spinal fusion, osteotomy, arthrodesis or treatment of non-union. Time to union following fracture, osteotomy, arthrodesis or treatment of an established non-union is longer in smokers. Smokers should be encouraged to abstain from smoking to improve the outcome of these orthopaedic treatments.

Propionibacterium acnes is found increasingly as a cause of delayed infection, usually involving implanted biomaterials. Despite susceptibility to common antibiotics, such infections are very difficult to treat and usually require surgical removal of the device. Three clinical isolates of P. acnes were assessed for ability to adhere to titanium, surgical steel and silicone, with and without a plasma conditioning film. After adherence, the biomaterials were then incubated for a further 6 days and examined for biofilm development. All three isolates adhered to all three biomaterials similarly. Importantly, we were able to demonstrate biofilm formation, including production of exopolymer similar in appearance to the polysaccharide intercellular adhesin of Staphylococcus epidermidis. A case summary also demonstrated failure to eradicate P. acnes infection in a hydrocephalus shunt after prolonged treatment. The removed shunt showed obvious biofilm formation, initially obscured by exopolymer when viewed by environmental scanning electron microscopy. Biofilm development by P. acnes explains the difficulties encountered in clinical management of such infections.

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