Treating Tibia Fractures With Far Cortical Locking Implants

For statistical analysis, we used Welch 2-sample t test to compare categorical data, including rates of fracture union, infection, and revision surgery. We chose this test because it was unclear whether variance in the groups would be similar. FCL and control data were compared for significant differences by calculating P values. Similarly, for continuous data, Fisher exact test was used to calculate P values for mean time to union and mean time to full weight-bearing in order to compare FCL and control outcomes.

Results

Twelve patients treated at 2 level I and 1 level II trauma centers between November 2010 and May 2012 met the inclusion and exclusion criteria for this study. Another 10 patients were treated with standard plating techniques (control group). Mean age was 52 years (range, 25-72 years) for the FCL group and 46 years (range, 28-67 years) for the control group. The FCL group included 2 open fractures (control, 0) and 2 patients with diabetes (control, 1) (Table 1).

Eleven of the 12 FCL patients and all 10 control patients achieved fracture union by most recent follow-up (Table 2). The difference was not statistically significant (P = .363). The FCL-treated fracture that did not heal received an interfragmentary screw in addition to the standard FCL technology construct. The interfragmentary screw inhibited motion at the fracture site and could potentially have led to nonunion. For this patient, revision surgery to an intramedullary nail was required. Removal of the interfragmentary screw was uneventful. Each of the 2 open fractures in the FCL group required bone grafting because of large segmental bone loss. One of these fractures, a type 3B, became infected after bone grafting, and complete healing required plate removal. The patient was eventually treated with a brace. An infection that occurred after union in a closed tibia fracture in the FCL group required hardware removal. No patient in either group experienced loss or failure of fixation.

Discussion

Far cortical locking is a relatively new technology designed to increase fracture fixation flexibility by functionally lengthening the distance between the locking plate and the screw cortical purchase, which occurs at the far cortex rather than the near cortex. This construct thereby functions as an internal fixator and is functionally similar to an external fixator. Rather than there being bars external to the skin, a plate is placed internally, adjacent to but without compressing fracture fragments or the plate to the bone. This theoretically leads to a desirable amount of interfragmentary motion, promoting callus formation and secondary healing. However, too much motion at the fracture site disrupts healing by shearing proliferating cells attempting to bridge the fracture gap. Therefore, there is a narrow target zone of desirable motion between fracture fragments required to promote secondary bone healing—defined as 2% to 10% gap strain.2 FCL constructs are thought to fall in this range of gap strain and thus better promote secondary healing over standard locked plates. Although biomechanical studies have been used as proof of concept, there are no published clinical data on the effectiveness of FCL implants. The present article describes early data on clinical outcomes of this new type of implant.

The main limitation of this study is its small cohort size, which is largely a result of the short time these implants have been available and our attempt to compare only similar fractures in this analysis. In addition, follow-up was on average less than 1 year. We consider such follow-up acceptable, though, as all fractures essentially reached final healing status within that period. Another limitation is that we combined compression plating and locked plating in the control group. Considering the mechanism of the theoretical advantage of FCL implants, with larger cohorts it would be useful to perform a subanalysis in which compression and standard locking plates are separately compared with FCL implants.

This study found no statistically significant difference between FCL and standard plating, suggesting FCL likely is not inferior to standard plating. Although the FCL group included a nonunion, it is important to note that, in this case, there was a technical discrepancy in the ideal technique whereby another interfragmentary screw was placed, eliminating the interfragmentary motion that establishes the premise of FCL technology. This case thereby demonstrated that a breach in the FCL technique, as with standard locking techniques, may lead to fracture-healing complications. In the FCL group, 2 open fractures with significant segmental bone loss requiring bone graft subsequently healed. In addition, compared with the control group, the FCL group included more patients with diabetes and more tobacco users (both diabetes and tobacco use are associated with poor bone and wound healing). The FCL group was also, on average, 6 years older than the control group. None of these group differences, however, reached statistical significance. Indeed, part of the impetus to use FCL implants in this population was that these patients likely were at higher risk for poor healing and nonunion. This factor therefore represents a selection bias—the FCL group was more predisposed to nonunion—and a study limitation.