Can We Predict Fracture When Using a Short Cementless Femoral Stem in the Anterior Approach?

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Short cementless femoral stems offer surgical advantages like easier insertion.
• The anterior approach (AA) for hip arthroplasty with short stems carries a notable perioperative fracture risk.
• Understanding patient-specific morphology is crucial for mitigating this risk.

Purpose of the Study:

• To evaluate the influence of patient-specific femoral and pelvic morphology on perioperative fracture risk with short cementless stems.
• To identify anatomical thresholds that alert surgeons to increased fracture risk.
• To assess the role of surgical technique, specifically canal fill, in fracture occurrence.

Main Methods:

• A retrospective, case-control matched study of 1,145 primary anterior approach total hip arthroplasties (THA) using short cementless stems.
• Radiographic analysis of femoral (canal flare index [CFI], morphological cortical index [MCI], calcar-calcar ratio [CCR]) and pelvic (Ilium-ischial ratio [IIR]) morphologies.
• Multivariate and Receiver-Operator Curve (ROC) analysis to identify fracture predictors and thresholds.

Main Results:

• Significant differences in CFI, CCR, and Ilium-ischial ratio (IIR) were observed between fracture and non-fracture cases.
• Reduced percent canal fill was noted in fracture cases.
• A canal flare index (CFI) threshold of 3.17 was highly predictive of fracture (84.6% sensitivity, 75.6% specificity).
• Patients with CFI > 3.17 and IIR > 3 had a 29-fold increased fracture risk.

Conclusions:

• Patient-specific anatomical parameters are significant predictors of fracture risk when using short cementless femoral stems.
• Preoperative radiographic assessment of morphology, especially CFI, can identify high-risk patients.
• Consideration of alternative stem options is recommended for patients identified as high-risk.