Conversion total hip arthroplasty for early failure following unstable intertrochanteric hip fracture: what can patients expect?

Purpose To report surgical outcomes in patients treated with conversion total hip arthroplasty (CTHA) for early failure of cephalomedullary nails (CMNs). Methods A retrospective review was conducted of CTHA for treatment of failed CMN within 1 year of initial surgery for intertrochanteric (IT) hip fractures. The cohort was matched 1:5 to patients who underwent elective primary THA (PTHA). Patient demographics, mechanism of CMN failure, surgical outcomes, and complication rates were assessed. Results 22 patients met criteria with a mean time to failure of 145 days. Modes of failure included: lag screw cut-out with superior migration (9, 40.9%), or medialization (8, 36.4%), and aseptic nonunion with implant failure (2, 9.0%) and without implant failure (3, 13.6%). Fourteen of the patients (63.6%) had acetabular-sided damage secondary to lag screw penetration, all in the screw cut-out groups. Patient demographics were similar between cohorts. Compared to PTHA, CTHA patients had increased operative time, blood loss, LOS, and readmission rates. After IMN failure, the operative leg was shorter than the contralateral leg in all cases. CTHA restored leg lengths to < = 10 mm in 15 (68.1%) of patients, with an average leg length discrepancy after CTHA of 6.7 mm. CTHA patients had increased rates of overall surgical complications and medical complications, specifically anemia (all p < 0.01). Tranexamic acid was used less often in the CTHA group (p < 0.01). Rate of periprosthetic joint infection (PJI), dislocation, and revision were all higher in the CTHA, though did not reach statistical significance. Conclusion The majority (77.3%) of CMN implant failure for nonunion within 1 year was due to screw cut-out. CTHA is a salvage option for early failed IT hip fracture repair, but expected surgical outcomes are more similar to revision THA than primary THA, with increased risk of readmission, longer surgery and LOS, increased blood loss, and higher complication rates.