Novack et al [25] retrospectively reviewed 4,830 consecutive patients following cemented or uncemented TKAs and concluded routine recovery room radiographs after an uncomplicated primary TKA are not a reliable mechanism for preventing mechanical complications and did not alter patient care. Radiographic evaluation of wear is based on weightbearing AP and lateral radiographs and on axial radiographs. Liner wear is seen as joint space narrowing, varus or valgus deformity, or patellar tilt. An effusion may be present. Findings can be subtle and annual weightbearing radiographs are suggested for detecting subclinical wear [21]. Collier et al [36] found that 87% of measurements performed on standing frontal knee radiographs (on the basis of the minimum distance from the metallic femoral condyle to a line through the top surface of the baseplate at its widest dimension) were within 1 mm of the known implant thickness, but the accuracy decreased for evaluating polyethylene thickness in patients with wear requiring revision. Instability is evaluated on radiographs obtained in extension-flexion position, under varus-valgus stress, and during anterior and posterior drawer maneuvers. In contrast, malalignment refers to suboptimal alignment of the prosthesis components relative to each other (although it is occasionally used to describe alignment of the bones in relation to each other and to the joint) [37] and is evaluated on full-length standing radiographs of the lower extremity [21]. Radiographs including the entire prosthesis are the initial examination for assessment of suspected periprosthetic fractures. Radiographs are also usually satisfactory for assessment of patellar complications [20] and helpful in guiding treatment [38]. Axial radiographs demonstrate the degree of patellar tilt or subluxation [21]. Baldini et al [39] proposed a weightbearing axial radiograph to better assess patellofemoral kinematics.
Imaging After Total Knee Arthroplasty. Novack et al [25] retrospectively reviewed 4,830 consecutive patients following cemented or uncemented TKAs and concluded routine recovery room radiographs after an uncomplicated primary TKA are not a reliable mechanism for preventing mechanical complications and did not alter patient care. Radiographic evaluation of wear is based on weightbearing AP and lateral radiographs and on axial radiographs. Liner wear is seen as joint space narrowing, varus or valgus deformity, or patellar tilt. An effusion may be present. Findings can be subtle and annual weightbearing radiographs are suggested for detecting subclinical wear [21]. Collier et al [36] found that 87% of measurements performed on standing frontal knee radiographs (on the basis of the minimum distance from the metallic femoral condyle to a line through the top surface of the baseplate at its widest dimension) were within 1 mm of the known implant thickness, but the accuracy decreased for evaluating polyethylene thickness in patients with wear requiring revision. Instability is evaluated on radiographs obtained in extension-flexion position, under varus-valgus stress, and during anterior and posterior drawer maneuvers. In contrast, malalignment refers to suboptimal alignment of the prosthesis components relative to each other (although it is occasionally used to describe alignment of the bones in relation to each other and to the joint) [37] and is evaluated on full-length standing radiographs of the lower extremity [21]. Radiographs including the entire prosthesis are the initial examination for assessment of suspected periprosthetic fractures. Radiographs are also usually satisfactory for assessment of patellar complications [20] and helpful in guiding treatment [38]. Axial radiographs demonstrate the degree of patellar tilt or subluxation [21]. Baldini et al [39] proposed a weightbearing axial radiograph to better assess patellofemoral kinematics.