PROSPECTIVE VALIDATION OF AORI AND UPENN SYSTEMS IN PREDICTING ACTUAL BONE LOSS IN TKA REVISION.

Abstract

Introduction: A critical technical and economic challenge in total knee arthroplasty revision (TKAR) is bone loss management. Easily applied, valid pre-operative measurements of bone loss are essential to allow accurate planning and meaningful comparisons between series. We compared 2 radiographic measurement ment systems with actual intra-operative bone loss in order to determine their validity.

Methods: A prospective IRB approved cohort study of 290 consecutive TKAR patients was utilized to assess the Anderson Orthopaedic Research Institute (AORI) system and the University of Pennsylvania (UPenn) assessment system. These preoperative measures were performed on standardized antero-posterior and lateral knee radiographs by 31 orthopaedic surgeons trained in their use. The validity and reproducibility of both systems was determined versus the gold standard measure of actual intra-operative bone loss.

Results: 215 patients (74.1 percent) were assessed to have bone loss pre-operatively versus 222 (76.4 percent) intra-operatively. Using the AORI classification system agreement between preoperative and intraoperative classification was moderate for the femur (K = 0.50) and good for the tibia (K = 0.63). The UPenn system gave resultant mean scores of 0.137 for femur and tibia versus intraoperative findings of resultant mean scores of 0.14 and 0.143 for the femur and tibia, respectively. These differences were not statistically significant (p < 0.02).

Discussion: This study demonstrates a high incidence of bone loss among TKAR patients, emphasizing the importance of effective measurement tools. Both the AORI and UPenn systems are valid tools for pre-operative estimation of actual bone loss facilitating planning and clinically successful, cost effective management of bone loss in TKAR.