[Minimally Invasive Osteosynthesis with Intramedullary Nail: Evaluation of Outcomes]

Fractures of the calcaneus are always very serious injuries that, due to their nature or when inadequately treated, can have permanent consequences. Minimally invasive methods, such as the C-nail, help reduce both intraoperative and postoperative risks. The aim of the study is a retrospective evaluation of a group of 260 patients with 280 calcaneus fractures treated surgically with the C-nail in the period from 2011 to 2023. The hypotheses of a lower incidence of postoperative infection, a lower risk of sural nerve injury, and a higher AOFAS functional score need to be confirmed or disproved. Thanks to the higher biomechanical stability of the C-nail and the minimally invasive approach, a lower incidence of postoperative complications is expected.

In the period 2011-2023, 304 patients with 324 calcaneus fractures were operated on using the C-nail. A total of 260 patients were followed up at 12 months after surgery. The values ​​of Böhler's angle and incongruence of the posterior articular surface of the calcaneus were recorded from X-ray and CT documentation immediately after the injury, postoperatively, and 12 months after surgery. Furthermore, complications were monitored, namely the development of infection, neurological symptoms (sural nerve injury), presence of osteoarthritis, and the non-union formation. The functional outcome was assessed 12 months after surgery using the AOFAS (American Orthopaedic Foot and Ankle Society) scoring system. Data from the available medical literature were used as a control set.

The patients in the study group underwent surgery at the age between 17 and 75 years. Men represented 88.5% of cases, women 11.5% of cases. A total of 48.0% of patients were smokers and 8.2% were patients with diabetes. The patients were classified based on the CT scan as type I (n=19), type II (n=175), type III (n=62) and type IV (n=24) according to Sanders classification. Eight patients in the group sustained an open calcaneus fractures. The mean Böhler angle measured preoperatively was 7.9°, the Böhler angle measured immediately after surgery was 30.9° on average. A slight decrease to the mean value of 28.6°was observed one year after surgery. Based on the CT scan, the mean preoperative step-off was 6.0mm, while the mean postoperative step-off was 0.9mm. The mean AOFAS score at 12 months after surgery was 91.9 points.

When analyzing both surgical methods, the study confirmed that the calcaneal nailing method has comparable functional outcomes compared to the open lateral approach and the use of a locking plate. Comparative studies prove higher biomechanical resistance of the calcaneal nail and lower incidence of soft tissue damage than the use of calcaneal plates. Osteosynthesis with a C-nail can be indicated for all types of intra-articular calcaneal fractures. This method can also offer benefits to high-risk patients, for example, to patients with well-controlled diabetes, smokers or elderly patients. The group included cases where nailing was used in open fractures with satisfactory results. As for hypothesis No. 1, the incidence of infection in our study was 0.3% (ELA up to 2.69 %), as for hypothesis No. 2, the incidence of sural nerve injury was 0% (ELA up to 6.25%), and as for hypothesis No. 3, the AOFAS score was 91.9 points (ELA up to 72 points).

Osteosynthesis with a C-nail can be used for all types of intra-articular calcaneal fractures. The aim of the study was to evaluate the X-ray and functional outcome of intramedullary osteosynthesis at 12 months after surgery. A lower incidence of postoperative complications was recorded in the group. The established hypotheses were confirmed, namely a lower incidence of infection, zero percentage of sural nerve injury, and an increased AOFAS functional score. It is a surgical method that produces outcomes comparable to those of the open lateral approach and the use of a locking plate.