A Protocol to Systematic Radiographic Assessment of Primary Total Knee Arthroplasty

Although total knee arthroplasty (TKA) is considered one of the most successful procedures, however, a subset of patients are unsatisfied with the results, even with the introduction of new technologies and implant designs. Radiological assessment of TKA is still considered the most prevalent imaging modality for evaluating the knee joint pre-and postoperatively. Assessment of various angles and indices which could be measured in different radiographic views of the knee provides valuable information about the alignment of the entire limb and the individual prosthetic components, more so in the light of recent nuanced concepts of technique, alignment, and balance. This review article aims to present a comprehensive yet systematic approach to the most useful radiographic parameters for assessing the knee preoperatively and post-TKA by explaining the tools and techniques used for measuring various angles, indices and ratios in the coronal, sagittal and axial planes for diagnosis, preoperative planning, postoperative assessment, and routine follow-up. The protocol we followed in this review entailed first reporting the possible applications and software which could help in measuring these variables, then we mentioned the required series of knee radiographs. For the desired variables, we divided the assessment according to each plane, and in each, we reported the optimum position of the desired radiographic view followed by determining the axis and lines which will later form the desired angles to be measured; finally, we collected all the measurements in a table with the native knee values and the most accepted values after TKA.