Conversion Total Knee Arthroplasty: A Distinct Surgical Procedure With Increased Resource Utilization.

Background: Current Procedural Terminology coding currently makes no distinction between primary total knee arthroplasty (TKA) and conversion TKA, in which periarticular hardware components must be removed prior to or during TKA. We hypothesize that conversion TKA will carry increased operative time, blood loss, postoperative complications, and 90-day emergency department/readmission rate compared to primary TKA.

Methods: Patients undergoing conversion TKA from 2005 to 2017 were identified from an institutional database and matched to primary TKA patients by age, gender, American Society of Anesthesiologists score, body mass index, and procedure date (±1 year). Intraoperative data and 90-day postoperative complications were compared between groups.

Results: One hundred nine conversion TKA patients with periarticular hardware were removed prior to (n = 51) or during (n = 58) TKA and 109 primary TKA control patients were included. Conversion TKA was associated with increased tourniquet time (91 vs 71 minutes, P < .001), operative time (147 vs 113 minutes, P < .001), blood loss (225 vs 176 mL, P = .010), 90-day readmissions (14.6% vs 4.2%, P = .020), wound complication (5.6% vs 0.0%, P = .025), periprosthetic joint infection (7.9% vs 0.0%, P = .005), irrigation/debridement (9.0% vs 1.1%, P = .016), and a trend toward increased mechanical complication (6.7% vs 1.1%, P = .058). Timing of hardware removal did not affect intraoperative or postoperative outcomes.

Conclusion: Conversion TKA is associated with higher operative time, blood loss, readmission rate, and postoperative complications compared to primary TKA. Without a proper billing code and appropriate reimbursement level to match the expected operative and postacute resource utilization by these cases, physicians may be disincentivized to perform these operations.