Plate osteosynthesis of a fracture is a common procedure with well-established efficacy for achieving union, reducing pain, and improving function in appropriately selected patients [11–13]. However, the occurrence of plate-screw construct breakage is hard to avoid. The rate of nonunion for mid-shaft clavicle fractures is 1.4% [14], whereas that of femoral fractures is 6% to 17% [15–18]. In recent years, there has been an increase in the frequency of implant breakage along with the increasing use of plate fixation; yet, there are few studies describing the factors that contribute to this complication. The present study used a long-term follow-up of a large patient population to identify the independent risk factors associated with plate fixation breakage among patients with traumatic fractures.
Our single-factor analysis showed that the risk of fracture was associated with the weight or not weight limbs, the type of broken plate, breakage site within/outside the fracture line, the number of plate holes, the number of plate screws, and inserting screws closely adjacent to the fracture line. A multivariate Cox regression analysis confirmed that inserting screws adjacent to the fracture line was related to an increased risk of implant breakage for patients who had a fracture of the limbs, clavicle, hands, or feet. Previous studies have reported various risk factors for implant breakage, including being female, higher comorbidity scores, surgeons with fewer years’ experience, the use of longer plates, among other factors [19, 20]; we did not identify any of these factors as risk factors in our study.
In the current study, most implant breakages occurred within the first year, just as showed in Table 1. Most patients were aged between 20 and 50 years (62.5%), were male (72.0%), overweight (66.0%), and from a rural area (78.6%). Patients at risk were more likely to have experienced a high-energy trauma (73.8%) or complex fracture (88.1%) to a lower limb (79.2%), with failure occurring as a result of plate breakage (67.9%).
Plate osteosynthesis can provide relative stability, keep the fracture in a better biological position, and promote callus formation and fracture healing [21]. For complex fractures, recommendations are to use longer plates but without placing screws into the holes adjacent to the fracture line. In addition, increasing the bridging plate-work length to help distribute the stress over a larger area of the plate and thereby minimize the risk of breakage is advised. Similar rules exist for the treatment of simple and comminuted fractures, with surgeons advised against placing screws into the holes adjacent to the fracture line [22, 23]. For comminuted fractures, leaving these holes empty allows for slight movement among the fracture fragments, which is beneficial for callus formation within a reasonable scope of strain [24].
Many previous studies have shown that following biological and bridge plate techniques can obtain good radiological and functional results [25–28]. In the current study, most of the surgeons (86.9%) did not place the screws close to the fracture line; however, 13.1% of surgeons did not adhere to the principle for screw placement, and this caused an increase in the rate of plate breakage.
The presence of holes positioned adjacent to the fracture line provides an opportunity for their use, which is against recommendations. Thus, we suggest that it is unnecessary for these plates to be manufactured with these additional holes. We therefore designed a plate without holes at a part of the plate (patent number: ZL201520890025.3), and we suggest this part can be placed adjacent to the fracture line (Fig. 5). For example, surgeons can position the portion without holes in the middle for a ulnar shaft fracture, at the distal part as used in the fixation of supercondylar femoral fracture, or at the proximal part as used in the fixation of surgical neck fractrue of the humerus (Fig. 6). Another feature is that the part of the plate without holes is thickest, becoming thinner gradually to both ends (Fig. 5). This kind of plate will improve the mechanical strength of the whole plate-screw construct and subsequently reduce the risk of implant breakage.
Limitations
Our study has a few limitations. First, this was a retrospective study, and inevitable recall bias exists. Second, we did not distinguish between bridge plating fixation and compression fixation because both principles were used in many of the cases and they are difficult (and somewhat unnecessary) to distinguish. Third, it is not certain precisely when the construct breakage occurred, with breakage time determined as the time of the latest radiographic evidence.