The most severe complication of joint arthroplasty is periprosthetic infection, which can lead to complications such as sepsis, renal amyloidosis, dystrophic changes in parenchymatous organs, and the appearance of septicopyemic foci [9,17,18]. Two-stage revision remains the gold standard for the treatment of deep periprosthetic hip infection . Performing revision surgery on the hip joint in patients with severe defects in the acetabulum, especially those with pelvic discontinuity, remains a challenge for surgeons . It is worth noting that the purpose of the spacer is not only to treat infection but also to improve the function of the joint. Previous studies have shown that functional outcomes in patients who have undergone articulated spacer implantation are significantly better than those in patients who have undergone non-articulating spacer implantation [21; 22].
However, when placing articulating spacers, there is a risk of mechanical complications. Some authors have demonstrated a 19.5% to 50% rate of mechanical complications, which included dislocation, breakage of the spacer, and peri-implant femur fracture due to acetabular protrusion and component migration into the pelvic cavity . In a previous study, J. Jung et al. observed mechanical complications in 40.8% of cases (17% for dislocations, 10.2% for spacer breakages, and 13.6% for hip fractures) . Faschingbauer et al analysed 138 patients who received spacers and found mechanical complications in 19.6%, including spacer breakage in 8.7%, dislocation in 8.7%, hip fractures in 0.7%, pelvic protrusions in 0.7%, breakdown in and dislocation of the spacer in 0.7% . In our study, we evaluated groups of patients with massive bone defects of the acetabular region, namely, IIIA and III B defects according to the classification system described by W.G. Paprosky with dissociation of the pelvic bones. We observed mechanical complications in only 8.3% of cases. It should be emphasized that among the patients for whom we used 3D technologies to manufacture a spacer, we did not observe a single mechanical complication.
When the number of indications for primary hip arthroplasty increases, the number of operations performed increases, which subsequently increases the number of complications. Younger patients, despite their low rate of pre-existing comorbidities, are not exempt from a risk of deep periprosthetic infection. Naturally, young and active patients will place large demands on the implant, including the spacer.
In the study, the patients in whom we implanted spacers made using 3D technology showed significantly better functional outcomes than did the patients who received spacers not made with 3D technology. In our study, after the first stage of surgical treatment, 8 (33.3%) patients among the entire study population were able to return to their previous job.
The use of 3D tactile models helps plan the extent of surgery. The tactile models that are produced on a 3D printer enable us to analyse the already established hip pathological anatomy, classify the bone defects of each patient individually, and pick the most correct implant that can be used not only for the second stage but also for the first stage for the treatment of periprosthetic infections. Therefore, severe cases can be properly evaluated, which makes it possible to plan and personalize further treatment for each patient individually, which significantly reduces the execution time of each operating session and therefore reduces the number of complications .
With intraoperative 3D model fittings and evidence of the functional outcomes, doctors can be trained to think in 3D and help young surgeons overcome difficulties while performing primary surgery on a scale of 1:1. In addition, the results can serve as training material for future training of surgeons . Some authors have highlighted the importance of tactile 3D basin models. In one study, the authors described 50 surgical interventions carried out with 3D models of the pelvis and demonstrated that printed models help reduce surgery time and improve the accuracy of positioning of the component .
The application of the 3D method allows good results to be achieved in hip revision surgery. At present, we should strive to improve the quality of life of patients after the first stage of revision surgery and to remember that the goal of the spacer is not only to stop progression of the infection but also to restore normal articulation of the joint. We also noted that the custom, individualized 3D models for the first phase of treatment can serve as a basis for the creation of the component for the second stage. 3D modelling is a promising direction in hip revision surgery, but because of its high cost, we cannot use it routinely when performing both the first and second stages.