The use of open reduction through a minimally invasive sinus tarsi approach and stabilization with a locking plate is now a widely accepted treatment for calcaneal fractures [5–7, 15, 16]. However, all the currently used locking plates are in one piece, which requires a large working space for placement, leading to the necessity of sufficient exposure of the lateral wall of the calcaneus and even establishment of assisted incision [7]. This may increase the injuries to the soft tissues and the risk of wound complications. In addition, simultaneous fixation of multiple fracture blocks also induces difficulty in operation, easily causing poor anatomic reduction [5, 17]. To minimize the above problems, we newly designed and patented a combined plate in 2014. Our plate can be inserted through the sinus tarsi incision by using only appropriate dissection of subcutaneous tissues and the periosteum, without the need for the creation of a complete subcutaneous tunnel [7]. The streamlined shape of the head end can reduce the injuries to the surrounding soft tissues, whereas the chimeric structure of the tail end with a coupling screw can form a triangle support with the anterior and posterior calcaneus, which are respectively fixed with three locking screws, thus providing a rigid fixation and avoiding reduction loss. Furthermore, the angle between the forearm and the rear arm was set to 130°, with reference to the normal ranges of the Böhler angle (20–40°) and Gissane angle (110–140°), as well as the biomechanical characteristics of the calcaneus, by which the maximum area can be fixed under sufficient axial stress resistance and the risk of plate breakage can be decreased. We hypothesized that our combined plate may be effective and safe for the management of calcaneal fractures.
The present study aimed to preliminarily confirm the treatment outcomes of the plate for calcaneal fractures, by retrospectively collecting our clinical data, which, to our knowledge, have not been reported. As expected, our results demonstrated that the Böhler angle, Gissane angle, calcaneal height, width, and length were all significantly corrected postoperatively, without any accompanying postoperative wound complications and implant loosening during the follow-up. Our results seemed to be superior to those of the study by Kikuchi et al. [10], in which the sinus tarsi approach was also used: three of their cases (13.6%) had superficial wound infections, and no statistical differences were present in the Gissane angle, calcaneal height, and calcaneal length between preoperatively and postoperatively. Moreover, in the study of Basile et al., three patients (7.9%) who underwent the sinus tarsi approach failed to achieve anatomic reduction [5]. These findings indicated the effectiveness and safety of our plate for calcaneal fractures.
Better reduction of the calcaneus may result in better recovery of foot function. As anticipated, our findings indicated that the mean MFS reached 88.1?±?8.8, with an excellent and good rate of 83.3% (15 of 18). This result seemed to be comparable with, but not higher than, that of previous studies [6, 7]. We believe that this may be attributed to the small sample size (18 vs 33) and shorter follow-up (9.3?±?3.7 vs 21?±?8.9 months) [2].
In line with the simple and convenient procedure for placing our plate, the operative time was obviously reduced in our study when compared with previous studies (64.4?±?8.0 vs 69?±?14.6 min [2]; 64.4?±?8.0 vs 122.15?±?8.32 [5]), which may possibly further decrease the infection rate and promote fracture healing, resulting in a shorter hospital stay. Furthermore, it had also been demonstrated that the radiation exposure time in our study was dramatically shorter than that in the study by Cao et al. [2] (13.0?±?3.5 s vs 3.6?±?0.5 min). Thus, the use of our plate may prevent radiation-associated toxicity in surgeons and patients, further indirectly demonstrating the safety of our procedure.
The severity of closed calcaneal fractures is known to be negatively correlated to the subsequent foot function reduction and the quality of life after open reduction and internal plate fixation [18]. Thus, we also compared the MFS between Sanders types II and III calcaneal fractures. However, the results indicated a similar outcome, demonstrating that our self-designed plate may be equally suitable for these two types of fractures. However, further studies are still needed to prove our conclusion because of the small number of included patients with Sanders type III calcaneal fractures.
By summarizing our clinical experience, we consider that the indications for our plate treatment are as follows: (1) Sanders type II or simple type III fracture; (2) uneven articular surface, with displacement ?1 mm; (3) loss of calcaneal height 1.5 cm and increase of calcaneal width 1 cm; (4) Böhler angle ?20°, Gissane angle ?100° or ?130°; or (5) calcaneal varus angle ?50° and eversion ?10°. However, there are still some limitations in our technique. For example, percutaneous cannulated screw fixation is still needed as an assisted reduction for the treatment of Sanders type III calcaneal fractures with involvement of the sustentaculum tali or extra-articular calcaneal fractures (e.g. beak/avulsion fracture of the calcaneal tuberosity). Further optimization of our combined plate is still necessary.
Our study has some limitations. First, this was a retrospective review and the patients were not randomized to receive our surgery. Thus, the choice of surgery might be biased by surgeon preference and patient factors. Second, we did not have a control group, which made our comparison inconclusive. Third, our sample size of 18 was relatively small and the follow-up was short, which may have led to the underestimation of the complication rate and long-term reduction effect. Fourth, we preliminarily assessed the biomechanical properties of our combined plate but did not conduct a confirmation with a cadaver study or with bone models. Therefore, further investigation is still essential to obtain a more precise efficacy evaluation, by conducting a biomechanical study in human cadavers or bone models, or by means of a clinical study with a large sample size, longer follow-up time, and a randomized control (with other plates).