Mid-Term Migration Pattern of a Cemented Collared Anatomical Stem-A Retrospective Study Using EBRA-FCA.

It was already known that aseptic loosening represents a primary driver for femoral stem revision in orthopedic patients. Radiographic monitoring serves as a vital diagnostic strategy to evaluate the stability of prosthetic components over time. Specifically, Einzel Bild Röntgen Analyse-Femoral Component Analysis (EBRA-FCA) provides a non-invasive method to detect subtle shifts in implant positioning. These early measurements of distal stem migration often function as reliable predictors for the eventual longevity of the hip replacement. Clinicians rely on these longitudinal data sets to identify patients at risk of premature mechanical failure. The ability to distinguish between normal settling and pathological migration is essential for improving surgical outcomes. This absence of evidence motivated the current retrospective evaluation of a specific cemented collared anatomical design.

This investigation quantifies the migration patterns of a cemented Lubinus SP II femoral component over a mid-term follow-up period. Researchers sought to establish a clear profile of how these anatomical stems settle within the femoral canal during the first few years post-surgery. The analysis focuses on determining whether specific patient-related factors influence the rate of implant subsidence. Investigators specifically targeted the potential impact of femoral morphology and body mass index on the mechanical stability of the prosthesis. By defining these parameters, the study provides a benchmark for expected movement in successful cemented fixations. The work clarifies the relationship between early post-operative shifts and long-term implant retention. Understanding these dynamics helps surgeons predict which patients might require closer radiographic surveillance.

The research team conducted a retrospective analysis of patients who received the Lubinus SP II stem between 2003 and 2019. Utilizing the EBRA-FCA software from the University of Innsbruck, the authors measured precise changes in the vertical position of the femoral component. Medical histories provided essential data regarding patient demographics and physical characteristics. The study categorized femoral shapes using the Dorr classification system to compare outcomes between type A and type B morphologies. Statistical models assessed the correlation between Body Mass Index (BMI) and the observed distal stem migration values. Every radiographic measurement underwent rigorous validation through the specialized femoral component analysis framework. The inclusion criteria ensured that only patients with complete radiographic records and consistent follow-up intervals were evaluated.

Analysis of 61 stems revealed a median subsidence of 0.7 mm at both the 24-month mark and the final follow-up of 78 months. The cohort, consisting of 48 females and 13 males, met the strict inclusion criteria for the retrospective analysis. The mean age of the participants at the time of surgery was 76 years, with a broad range spanning from 30 to 93 years. According to the EBRA-FCA migration analysis, a median subsidence of 0.7 mm was observed at the 24-month interval. This same median value of 0.7 mm persisted through the final follow-up, which occurred at a median of 78 months post-operation. Distal stem migration was significantly higher at the 6-month time point in patients with Dorr type A femurs compared to those with Dorr type B femurs (p = 0.016). Body Mass Index (BMI) demonstrated no significant effect on the migration behavior of the anatomical stem throughout the study period.

The measured subsidence for the Lubinus SP II stem remains well below established clinical thresholds for mechanical failure. These results suggest that the cemented collared anatomical design offers excellent mid-term stability and long-term durability. While Dorr type A femurs show increased initial movement, their migration rates eventually stabilize to match other femoral configurations. Surgeons can expect predictable performance from this specific stem regardless of the patient's body mass index. The study reinforces the utility of EBRA-FCA as a robust tool for monitoring prosthetic health in clinical practice. Future research may build upon these findings to refine the selection criteria for anatomical femoral components. This evidence supports the continued use of cemented anatomical stems in elderly populations with varying femoral bone qualities.