Total hip arthroplasty (THA) is commonly performed for conditions like osteoarthritis, avascular necrosis, hip fractures, and hip dysplasia. Complications following THA can result in major proximal femoral defects (MPFD), which are challenging to manage. Megaprostheses provide a solution, offering stability and early weight-bearing, though they present their own challenges. However, maintaining hip symmetry with megaprostheses is challenging in accurately restoring femoral offset, acetabular orientation, and soft tissue tension. These factors can contribute to instability, altered biomechanics, and functional impairment. Therefore, achieving hip symmetry through femoral and acetabular offset, limb length discrepancy (LLD), and center of rotation (COR) is an important consideration. Achieving proper symmetry may improve gait, quality of life, and overall outcomes. This case series includes 10 patients with non-tumoral pathology treated with megaprostheses for complications after THA between 2014 and 2024. Megaprosthesis conversion was performed for sepsis (n = 2), aseptic loosening (n = 4), and periprosthetic fracture (n = 4). Dislocation occurred in 20%, with one case showing restored hip symmetry but dislocating due to trauma and noncompliance. Another case had an LLD of 3 cm, contributing to dislocation. Periprosthetic infection was observed in 20%, managed with a two-stage approach. Although hip symmetry was not fully restored in all patients, strict follow-up and rehabilitation were essential for improving functionality and quality of life. Megaprosthesis is an effective solution for MPFD in non-oncological patients when performed correctly. Restoring hip symmetry is challenging and depends on patient care and compliance, though it is an important factor influencing outcomes.

Objectives: Periprosthetic joint infections represent a serious complication following joint arthroplasty, often leading to significant morbidity, with an economic and social impact on the health system. Timely diagnosis of periprosthetic joint infections remains a major challenge. Our study aimed to investigate the diagnostic value and accuracy of several markers, including the neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, and C-reactive protein-to-serum-hemoglobin ratio in revision surgery for periprosthetic joint infections. Methods: A total of 251 revision arthroplasty cases, including 137 cases of periprosthetic joint infections and 114 cases of aseptic revision arthroplasty, were included from the time span January 2016 to May 2025. The diagnostic value and accuracy of the C-reactive protein-to-hemoglobin ratio, neutrophil-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio were evaluated using sensitivity, specificity, and receiver operating characteristic (ROC) analysis with area under the curve analysis. Results: The highest diagnostic performance was obtained by the C-reactive protein-to-hemoglobin ratio, yielding an AUC of 0.859 (SE = 0.0263, 95% CI: 0.809–0.899). This ratio also demonstrated a strong discriminative capacity, with a threshold of >0.0667, sensitivity of 80.45%, and specificity of 85.96%. For the neutrophil-to-lymphocyte count ratio and monocyte-to-lymphocyte count ratio, we obtained an AUC of 0.615 (95% CI: 0.551–0.676) and 0.620 (95% CI: 0.556–0.680), respectively, demonstrating lower sensitivity and specificity than the C-reactive protein-to-hemoglobin ratio. Conclusions: The C-reactive protein-to-hemoglobin ratio demonstrated better diagnostic strength in detecting periprosthetic joint infections, with superior sensitivity and specificity compared to the neutrophil-to-lymphocyte count ratio and monocyte-to-lymphocyte count ratio. Our findings offer new insights into the accurate and early diagnosis of periprosthetic joint infections in cases requiring revision surgery and suggest incorporating these new biomarkers and ratios into the diagnostic algorithm. Future large-scale studies are further needed to validate these results and facilitate their clinical use.