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We read with interest the article by Mohammed et al.  whereby the authors describe the single distal locking screw as a statistically significant cause for nonunion in the cases studied involving tibial intramedullary nailing. There are certain concerns we would like to raise. First, the sample size evaluated for making the conclusion of the single distal screw as a cause of nonunion (15 cases only) is relatively small for making a generalised statement. In fact, taking a closer look, there is no gross difference in the union rates in both the single screw group and the two screws group (single screw [34–12]/65%=33.84%; two screws [31–3]/65%=43%). Second, the authors have not detailed any randomisation criteria for including cases in the single or two screw groups. Were these two groups identical? If the decision for a single screw was based on more distal fracture characteristics, the reason for more nonunion cases in the single screw group becomes more obvious. The more distal the fracture is towards the articular margin, the greater are the fracture shearing forces. Third, the two groups are heterogeneous in terms of other variables (mode of injury, type of injury, fracture pattern, procedure), and there appears a likelihood of high degree of potential selection bias.
Concerning the article by Mohammed A, Saravanan R, Zammit J, King R (2008) Intramedullary tibial nailing in distal third tibial fractures: distal locking screws and fracture nonunion. Int Orthop. 10.1007/s00264–007–0356–3.