The Concept of Treatment for Surgical Infection in the Hindfoot.

Background: Chronic osteomyelitis of the calcaneus (OC) and open infected calcaneal fractures, especially when complicated by infected soft tissue defects, present significant surgical challenges. Accepted recommendations for the surgical treatment of this pathology are yet to be established. Methods: Drawing from our experience and the consensus among experts, we have developed a concept for selecting optimal, well-known surgical approaches based on the specific pathologic presentation. This concept distinguishes 4 main forms of hindfoot infection: infected wounds, open infected fractures, OC, and their mixed forms. Patients with conditions that could confound the treatment outcomes, such as diabetes mellitus and neurotrophic diseases, were excluded from this analysis. We present a retrospective analysis of the treatment outcomes for 44 patients (4 women and 40 men) treated between 2009 and 2022 using some refined surgical techniques. Treatment success was evaluated based on the absence of disease recurrence within a 2-year follow-up, the avoidance of below-knee amputations, and the restoration of weightbearing function. Results: The treatment results were considered through the prism of our proposed concept and according to the Cierny-Mader classification. There were 4 instances of disease recurrence, necessitating 6 additional surgeries, 2 of which (4.5% of the patient cohort) resulted in amputations. In the remaining cases, we were able to restore weightbearing function and eliminate the infection through reconstructive surgeries, employing skin grafts when necessary. Conclusion: Surgical infections of the hindfoot area remain a significant challenge. The strategic concept we propose for surgical decision making, tailored to the specific pathology, represents a potential advancement in addressing this challenge. This framework could provide valuable guidance for orthopaedic surgeons in their clinical decision-making process. Level of Evidence: Level IV, case series.

Investigation of the process intergrowth of bone tissue into the hole in titanium implants (Experimental research).

INTRODUCTION: Despite the use of modern implants, complications such as nonunion and avascular necrosis of the femoral head are observed in femoral neck fractures (FNF). We have created a new perforated I-beam implant for FNF osteosynthesis and developed a new osteosynthesis philosophy based not only on the mechanical and biomechanical interaction of the bone-implant system, but also on the interaction of the biological properties of the bone and the implant. The purpose of the work is to study the interaction of the biological process of the bone - its regeneration (germination) of bone tissue into the holes of the implant. MATERIALS AND METHODS: The experiment was carried out on fourteen Chinchilla rabbits in accordance with all international standards. A perforated implant specially made of titanium (ChM, Poland) was surgically implanted into the proximal femur. The implant measurements were as follows: length - 6 mm, width - 3 mm, thickness - 2 mm, 2 holes with a diameter of 2 mm. The 14 rabbits were divided into 7 groups. After 1, 2, 3, 4, 5, 10 and 12 weeks the animals were withdrawn from the experiment according to the standard rules in sequential order. The preparations were placed in a formalin solution and sent to the pathomorphology laboratory (CITO, Russia) for histological studies. RESULTS: Weekly histopathological studies revealed a gradual transition from the organization of a hematoma to the formation of mature bone tissue in the holes of the implants. The titanium implant is bioinert and did not cause any visible reactions from the bone tissue. Simultaneous integration of vascular proliferation and newly formed bone tissue into the implant holes were revealed. On 10-12-week preparations, the formation of trabecular structures of mature bone tissue was revealed in the holes of the implants and elements of adipose and bone marrow tissue were observed. Macroscopic examination of 4-5-week preparations showed almost complete filling of the holes with bone tissue. On 10-12-week preparations, the bone tissue in the holes of the implants did not differ from the bone tissue surrounding the implant. The processes of formation of mature bone tissue in the holes of the implants were similar to the processes of physiological bone healing (regeneration) at the fracture site. CONCLUSIONS: The obtained results show the following: 1.The titanium implant is bioinert and does not cause any visible reactions from the bone tissue; 2. There is a gradual process of formation of new vessels, and then the formation of new bone tissue in the holes of the implant instead of the one damaged during implantation. Thus, the results of this experiment indirectly confirm our assumption that a perforated implant for FNF osteosynthesis will participate not only in the mechanical and biomechanical interaction of the bone-implant system, but will also include the 3rd element in this system - the biological properties of the bone itself. We assume that these properties of the new implant will increase blood flow in the femoral neck and partially replenish the volume of bone tissue destroyed during osteosynthesis which does not occur with FNF osteosynthesis by any of the known implants.

Efficiency of an implant: new criterion of objective assessment of implants for osteosynthesis of femoral neck fracture.

PURPOSE: In line with several designs for osteosynthesis of femoral neck fracture (FNF), their effectiveness is still estimated by the results of biomechanical and clinical trials, finite element method (FE). But surgeons require the criteria which would define their properties in advance and allow improve the results of treatment. METHODS: When new implant (NI) is being designed, we developed such criterion - index efficiency of an implant (IEI) - and performed mathematical comparative researches of properties of NI with the known designs. We analyzed the results of comparative clinical trials on treatment of FNF with various implants considering their IEI. RESULTS: Analysis showed that results of comparative clinical trials with the use of various implants for osteosynthesis FNF completely correlated to their IEI; IEI of the NI two to three times exceeds IEI of all known designs, and the destruction percentage of a bone tissue is two to three times less when it is applied. CONCLUSION: The offered IEI can be used for designing new implants and allows improving the results of treatment of patients with FNF by optimizing the choice of implant for osteosynthesis.