[Minimally Invasive Osteosynthesis of Calcaneal Fractures Using the Anterolateral Locking Plate].

PURPOSE OF THE STUDY Extended lateral approach to calcaneus fractures is associated with a high risk of infection. Such risk can be reduced by using mini-invasive approaches. The sinus tarsi approach provides a good overview of the posterior joint facet of the calcaneus and can also be done as a mini-invasive procedure. The authors present their fi rst experience with osteosynthesis of joint depression calcaneal fractures using the anterolateral locking plate inserted through the sinus tarsi approach. MATERIAL AND METHODS During the period from 1 February 2020 to 31 January 2022, 18 patients were treated by the anterolateral locking plate in the authors' department (3 women, 15 men). Eleven fractures were classifi ed according to Sanders as IInd grade, fi ve as IIIrd grade and two fractures were classifi ed as tongue-type (as described by Essex-Lopresti). The fractures were treated by open reduction through the sinus tarsi approach and osteosynthesis by the anterolateral locking plate combined with headless screws. The following factors were examined: time from injury, duration of surgery, quality of reduction (post-op control with multiplanar CT scans), wound and technical complications, loss of reduction after treatment, substance abuse and comorbidities. The follow-up was 12-36 months (median 17). At one year after surgery, the functional outcomes were evaluated using the AOFAS Hindfoot score. RESULTS The most common negative predispositions for successful healing were smoking (9 cases), alcohol abuse, drug abuse, mild mental retardation, personality disorder, insulin-dependent diabetes and epilepsy (1 case each), hypothyreodism and bronchial asthma (2 cases each). The time from injury to surgery and duration of surgery surgery were measured. The quality of reduction was excellent in 12 patients (dislocation less than 1 mm), good in 6 patients (dislocation less than 2 mm), dislocation more than 2 mm was not present in the group. In one case, a revision surgery was performed because of screw malposition into the subtalar joint, delayed wound healing was observed in two cases. There was no case of deep surgical site infection or loss of reduction. The mean AOFAS score after one year was 85 points. The most common complaints were scar pain or discomfort. DISCUSSION The current studies on osteosynthesis of calcaneal fractures favor the sinus tarsi approach for its lower risk of wound-related complications compared to the extended lateral approach. The sinus tarsi approach requires the use of different osteosynthetic material than the conventional calcaneal plate. If a conventional locking plate is to be used, the surgical approach has to be modifi ed. In 2021, Wang et al. published an intermediate step leading to the reduction of early complications and the use of conventional locking calcaneal plate inserted through the sinus tarsi approach, with an additional incision. The sinus tarsi approach is used also when intramedullary nailing is performed, which is preferred by biomechanical studies evaluating the rigidity of osteosynthesis. However, when comparing nails and locking plates, the differences are insignifi cant. The use of anterolateral locking plates was presented by Xie et al., with results similar to those of our own group of patients. CONCLUSIONS The results of the followed-up group of patients confi rm low complication rate of the sinus tarsi approach as reported by current literature. At the same time, it provides good options for reduction even in complicated fractures. For successful osteosynthesis, the anterolateral locking plate with headless screws may be used. The incidence of post-operative complications is low even in high-risk patients. Adhesions of peroneal tendons can be treated with material removal and tissue release. They could be prevented by good physiotherapy. Key words: calcaneus, osteosynthesis, anterolateral plate, peroneal tendons, sinus tarsi approach.