Treatment of periprosthetic fracture Vancouver B2-B3 in cementless total hip arthroplasty: are we able to predict stem mobilization?

BACKGROUND: In common clinical practice a definitive statement on stem mobilization in periprosthetic fracture (PPF) Vancouver B2-B3 is only possible during surgery. The aim of this work was to identify preoperative Radiological Index of stem mobilization and report outcome at mid-term follow-up of patients with PPF. METHODS: Inclusion criteria were: patients with a femoral PPF classified as Vancouver B2 or B3, age >18 years, previous implant of cementless total hip arthroplasty or hemiarthroplasty, capability of giving informed consent, complete clinical and radiological follow-up of minimum 1 year, surgical treatment with osteosynthesis (ORIF) or stem revision (SR). All the preoperative X-rays were analyzed using the Gruen system in antero-posterior (AP) and latero-lateral (LL) views and the proximal femur was divided into 3 zones in both projections. The preoperative blinded measurement of interested Gruen zones was investigated to search if it can predict intraoperative verified stem mobilization. RESULTS: A total of 104 patients were included in the study. A total of 61 patients underwent ORIF and 43 patients underwent SR. All the 43 patients who showed a stem mobilization showed a minimum of three zones interested by fracture. This preoperative quantification of fractured femoral zone showed a 100% sensibility and 64% specificity if we considered a threshold of minimum three involved zones, and 67% sensibility and 98% specificity if we considered a threshold of minimum four involved zones. CONCLUSIONS: A preoperative evaluation and stadiation of Gruen zones involved in PPF could help in planning the correct surgical procedure for these fractures.