Abstract: Nine randomised and two quasi-randomised clinical trials, involving a total of 2093 participants with 2123 fractures, were included. The evidence was dominated by one large multicentre trial of 1319 participants. Both quasi-randomised trials were at high risk of selection bias. Otherwise, the trials were generally at low or unclear risk of bias. There were very few data on functional outcomes; and often incomplete data on re-operations. The trials evaluated five different comparisons of interventions: reamed versus unreamed intramedullary nailing (six trials); Ender nail versus interlocking nail (two trials); expandable nail versus interlocking nail (one trial); interlocking nail with one distal screw versus with two distal screws (one trial); and closed nailing via the transtendinous approach versus the paratendinous approach (one trial). No statistically significant differences were found between the reamed and unreamed nailing groups in 'major' re-operations (66/789 versus 72/756; risk ratio (RR) 0.88, 95% confidence interval (CI) 0.64 to 1.21; 5 trials), or in the secondary outcomes of nonunion, pain, deep infection, malunion and compartment syndrome. While inconclusive, the evidence from a subgroup analysis suggests that reamed nailing is more likely to reduce the incidence of major re-operations related to non-union in closed fractures than in open fractures. Implant failure, such as broken screws, occurred less often in the reamed nailing group (35/789 versus 79/756; RR 0.42, 95% CI 0.28 to 0.61). There was insufficient evidence established to determine the effects of interlocking nail with one distal screw versus with two distal screws, interlocking nail versus expandable nail and paratendinous approach versus transtendinous approach for treating tibial shaft fractures in adults. Ender nails when compared with an interlocking nail in two trials resulted in a higher re-operation rate (12/110 versus 3/128; RR 4.43, 95% CI 1.37 to 14.32) and more malunions. There were no statistically significant differences between the two devices in the other reported secondary outcomes of nonunion, deep infection, and implant failure. One trial found a lower re-operation rate for an expandable nail when compared with an interlocking nail (1/27 versus 9/26; RR 0.11, 95% CI 0.01 to 0.79). The differences between the two nails in the incidence of deep infection or neurological defects were not statistically significant. The trial comparing one distal screw versus two distal screws found no statistically significant difference in nonunion between the two groups. However, it found significantly more implant failures in the one distal screw group (13/22 versus 1/20; RR 11.82, 95% CI 1.70 to 82.38). One trial found no statistically significant differences in functional outcomes or anterior knee pain at three year follow-up between the transtendinous approach and the paratendinous approach for nail insertion. Overall, there is insufficient evidence to draw definitive conclusions on the best type of, or technique for, intramedullary nailing for tibial shaft fractures in adults. 'Moderate' quality evidence suggests that there is no clear difference in the rate of major re-operations and complications between reamed and unreamed intramedullary nailing. Reamed intramedullary nailing has, however, a lower incidence of implant failure than unreamed nailing. 'Low' quality evidence suggests that reamed nailing may reduce the incidence of major re-operations related to non-union in closed fractures rather than in open fractures. 'Low' quality evidence suggests that the Ender nail has poorer results in terms of re-operation and malunion than an interlocking nail.

Plain-language summary: Eleven studies involving a total of 2093 participants were included. The evidence was dominated by one large multicentre trial of 1319 participants. The methods of two studies were flawed such that their results were likely to be biased. The remaining studies were at a lower risk of bias. The trials evaluated five different comparisons of interventions. Only the two comparisons tested by more than one trial are reported here. These were reamed versus unreamed intramedullary nailing (six trials) and Ender nail versus interlocking nail (two trials). The review found no evidence of a significant difference between reamed and unreamed intramedullary nailing in re-operations for complications, nor in various complications such as nonunion (where the bone fails to heal). However, reamed nailing was more associated with a lower implant failure, such as broken screws, than unreamed nailing. Moreover, there was some weak evidence that reamed nailing may be associated with fewer major re-operations for non-union when used for closed fractures (where the skin remains intact) compared with open (where the skin is broken) fractures. The review also found that the Ender nail resulted in more re-operations and deformity (malunion) than an interlocking nail. The review concluded that there is insufficient evidence to draw definitive conclusions on the best type of, or technique for, intramedullary nailing for tibial shaft fractures in adults.