Conversion Total Knee Arthroplasty: Prior Fracture or Osteotomy Around the Knee Leads to Increased Resource Utilization.

Background: Prior knee surgery before total knee arthroplasty (TKA) puts patients at higher risk of inferior outcomes and increased care cost. This study compares intraoperative and postoperative variables including procedure duration, components, length of stay, readmission, complications, and reoperations among patients undergoing conversion TKA.

Methods: Primary TKA from a single-surgeon database identified 130 patients with prior knee surgery to form a "conversion" cohort. One-to-one matching identified 130 patients of similar age, American Society of Anesthesiologists score, body mass index, and gender without prior knee surgery for comparison. Perioperative and 90-day postoperative variables were compared between patients with and without prior surgery, within the conversion group based on the type of prior surgery, and whether the prior surgery was bony or soft tissue.

Results: The conversion group had longer mean operative time (96.1 vs 90.0 minutes, P = .01), higher revision component utilization (8.5% vs 0.8%, P = .005), and higher calculated blood loss (1440 vs 1249 mL, P = .004). Thirty-eight patients with prior fracture or osteotomy were compared to the remaining 92 patients in the conversion group and showed longer operative time (107.1 vs 91.3 minutes, P < .001), higher 90-day readmissions (18.4% vs 3.3%, P = .003), more complications (23.7% vs 8.7%, P = .021), and greater utilization of revision components (26.3% vs 1.1%, P < .001).

Conclusion: Patients undergoing conversion TKA required increased resource utilization, particularly patients with a prior osteotomy or fracture. Policymakers should consider these variables, as they did in conversion THA, in adding a code to account for increased case complexity and resource utilization.