# A Review of the Impacts of Implant Stiffness on Fracture Healing
## 3 Clinical Problems in Bridge Plating for Fracture Treatment  
The locking plate system was developed to enhance stability and minimize compression between the bone and the plate [16]. Furthermore, biological bridge plating aids in preserving the blood supply, facilitating a functional reduction in complex fractures [31]. Some types of locking plates offer a comparatively stable fixation for fractures while allowing adjustments to reduce the stiffness [32; 33]. Fracture treatment devices characterized by excessive stiffness have been reported to result in suboptimal outcomes, including delayed bone healing and failure of the healing process [17; 34]. Despite the recent focus on biologically favorable, indirect reduction techniques and the use of submuscular implants, clinical series published over the past decade have reported fracture non-union rates in the distal femur of up to 20% of patients [17; 18; 35]. The recent identification of several risk factors has been associated with an increased risk of non-union. A previous study examined 283 distal femoral fractures treated with locked plating [36]. Obesity, open fracture, infection occurrence, and the use of stainless steel plates were identified as prognostic risk factors for non-union. Another study reported that 64 of 335 patients with distal femoral fractures required reoperation to promote union [35]. Several studies comparing the effects of stainless steel versus titanium plates were identified. Two articles by [PERSON] et al., which analyzed data from the same group of patients, found a significant link between the use of stainless steel plates and the occurrence of non-union, with a highly significant \(p\)-value [36; 37]. Conversely, three other studies found no significant difference in outcomes between the two types of metal [38; 39; 40]. Specifically, [PERSON] et al. observed an increase in callus formation in patients who received titanium plates as opposed to steel plates at 6 and 12 weeks after surgery, with a statistically significant difference. However, this difference in callus formation was not considered statistically significant at the 24-week mark [39]. Although the results of these findings may vary when compared to plates made of metallic materials with greatly different Young's moduli, there are currently no clinically usable low Young's modulus fracture treatment plates. The most successful healing rates for unstable distal femoral fractures have been achieved through the application of titanium locking plates. While the theoretical biomechanical benefits of CP-Ti and its alloys appear to contribute to clinical enhancements, no high-quality study has conclusively validated this assertion. In a previous study involving 21 patients, mostly comprising young individuals with 22 high-energy distal femur fractures, treatment with titanium locking plates was utilized. Furthermore, the study noted that all 22 fractures healed promptly, obviating the necessity for secondary surgeries [41]. It was suggested that pure titanium and titanium alloys, which have a lower Young's modulus than high Young's modulus materials, such as stainless steel, may be useful for fracture treatment plates. Effectively managing fractures that are amenable to bridge plating involves understanding the concept of flexible fixation and techniques for regulating implant stiffness. The existing clinical and biomechanical data provide a foundation for the selection of suitable fixation methods. Additionally, when selecting an implant, it is important to consider titanium or titanium alloys because these metals have a lower Young's modulus than that of stainless steel. Nevertheless, it is essential to balance the biomechanical advantages with the limitations of titanium, such as difficulties in contouring and the risk of cold welding. Multiple studies have not found a statistically significant correlation between the length of the plate and the incidence of non-union [36; 37; 39].