Major bone loss at elective aseptic revision of a primary total knee replacement is uncommon, but intraoperative defects are frequently underestimated pre-operatively.

Abstract

This study aimed to characterise the patterns and severity of bone loss at elective aseptic revision of a primary total knee arthroplasty (pTKA) and to identify factors associated with major bone loss. A national multi-centre prospective service evaluation was undertaken across NHS hospitals in England and Wales. Patients undergoing elective aseptic tibiofemoral revision of a pTKA were included. Baseline characteristics and the anticipated (pre-operative) and encountered (intraoperative) degree of bone loss were recorded, using the Anderson Orthopaedic Research Institute (AORI) classification. Reconstruction techniques were also captured. Logistic regression identified factors associated with intraoperative AORI type ≥2B bone loss. Analyses comprised 157 cases undertaken by 35 surgeons across 12 hospitals. The majority of cases were associated with intraoperative AORI type ≤2A bone loss (tibia = 73.2%; femur = 72.0%). Surgeons reported more bone loss than anticipated in 23.5% of cases, less frequently among patients with a pre-operative CT scan (17.0% vs 26.9%, p = 0.165). Metaphyseal fixation devices were used in 40.4% of tibial and 15.9% of femoral reconstructions. Tibial AORI ≥ 2B bone loss was associated with an indication of aseptic loosening/lysis (other indications OR 0.11-0.28), while femoral AORI ≥ 2B was associated with increased time from primary to revision (OR 1.07 (1.00, 1.14) per year, p = 0.037). Major bone loss at elective aseptic revision of a primary total knee replacement is uncommon, but intraoperative defects are frequently underestimated pre-operatively. Surgeons should ensure appropriate revision implants and bone-loss solutions are available. Future research should determine whether metaphyseal fixation devices improve patient-relevant outcomes in this setting.