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Objectives: To determine the potential risk factors for intraoperative periprosthetic femoral fractures in patients with developmental dysplasia of the hip (DDH) undergoing total hip arthroplasty (THA). Methods: This was a retrospective study. Patients who were diagnosed with DDH and undergoing THA (by artificial joint replacement) at our hospital from January 1999 to December 2019 were included in this study. Clinical and radiological factors were obtained from their medical records, such as age, sex, Crowe classification, morphological features of proximal femur, and features of surgical procedure. The outcome of interest was the occurrence of intraoperative periprosthetic femoral fracture, which was recorded and classified according to the Vancouver classification system. According to the fracture status, the patients were divided into two groups: the fracture group and the non‐fracture group. Multivariate logistic regression model was built to identify the risk factors for these fractures. Results: A total of 1252 hips were finally included. Intraoperative periprosthetic femoral fractures were identified in 62 hips. The incidence of intraoperative periprosthetic femoral fractures in patients with DDH undergoing THA was 4.95%. There were 22 patients (proportion = 35.48%, incidence = 1.76%) with Type A fractures, 38 (proportion = 61.29%, incidence = 3.04%) with Type B fractures, and two (proportion = 3.23%, incidence = 0.16%) with Type C fractures. Six independent risk factors for intraoperative periprosthetic femoral fractures were identified: osteoporosis (OR = 3.434; 95% CI, 1.963–6.007), previous surgical history (OR = 4.797; 95% CI, 2.446–9.410), Dorr Type A canal (OR = 3.025; 95% CI, 1.594–5.738), retained femoral neck length (OR = 1.121; 95% CI, 1.043–1.204), implanted metaphyseal‐diaphyseal fixation stems (OR = 3.208; 95% CI, 1.562–6.591), and implanted stem with anteversion design (OR = 2.916; 95% CI, 1.473–5.770). Conclusions: The overall incidence of intraoperative periprosthetic femoral fractures in patients with DDH undergoing THA was 4.95%, which was at a moderate level compared to patients with other diseases undergoing THA. Six independent risk factors were identified: osteoporosis, previous surgical history, Dorr Type A canal, insufficient neck osteotomy level, implantation of metaphyseal‐diaphyseal fixation stem, and implantation of a stem with an anteversion design. Comprehending these risk factors might help surgeons prevent the occurrence of these intraoperative periprosthetic femoral fractures in patients with DDH. [ABSTRACT FROM AUTHOR]

In recent years, an increase in periprosthetic femur fractures has become apparent due to the increased number of hip replacements. In the case of Vancouver type B1 fractures, locking plate systems offer safe procedures. This study compared the distal lateral femur plate (LOQTEQ®, aap Implantate AG) with a standard L.I.S.S. LCP® (DePuy Synthes) regarding their biomechanical properties in fixation of periprosthetic femur fractures after hip arthroplasty. We hypothesized that the new LOQTEQ system has superior stability and durability in comparison. Eighteen artificial left femurs were randomized in two groups (Group A: LOQTEQ®; Group B: L.I.S.S. LCP®) and tested until failure. Failure was defined as 10° varus deformity and catastrophic implant failure (loosening, breakage, progressive bending). Axial stiffness, loads of failure, cycles of failure, modes of failure were recorded. The axial stiffness in Group A with 73.4 N/mm (SD +/− 3.0) was significantly higher (p = 0.001) than in Group B (40.7 N/mm (SD +/− 2.8)). Group A resists more cycles than Group B until 10° varus deformity. Catastrophic failure mode was plate breakage in Group A and bending in Group B. In conclusion, LOQTEQ® provides higher primary stability and tends to have higher durability. [ABSTRACT FROM AUTHOR]