Abstract：Objective This study aimed to explore the reliability and accuracy of lower limb alignment as measured by non-weight-bearing short knee radiographs after total knee arthroplasty.Methods A total of 84 patients (31 males, 53 females; 46-82 years old, 66.96±7.54 years old on average)in picture archiving and communication systems(PACS) of Affiliated Hospital of Xuzhou Medical University who underwent total knee arthroplasty(TKA) from January 2019 to December 2019 were recruited. All patients' whole leg radiographs (1 month postoperatively) and non-weight-bearing short knee radiographs (1 month postoperatively) were collected. Two experienced orthopedists independently measured mechanical alignments by using postoperative whole leg radiographs and non-weight-bearing short knee radiographs. Two weeks later, the radiographs were measured again. According to the mechanical alignment as measured by postoperative whole leg radiographs, the patients were divided into a neutral group (deviation in mechanical alignment was less than 3°) and a deviated group (deviation in mechanical alignment≥3°). The mechanical alignments as measured by the two radiographs between the two groups were compared.Results The reliability of mechanical alignments as measured by the two postoperative radiographs was excellent. With regard to the mechanical alignments as measured by whole leg radiographs, the intraclass correlation coefficient(ICC)of intraobserver and interobserver reliability was 0.992 and 0.973, respectively. With regard to the mechanical alignments as measured by non-weight-bearing short knee radiographs, the ICC of intraobserver and interobserver reliability was 0.975 and 0.987, respectively. No significant differences were observed between the values of the mechanical alignments measured by the two radiographs in the postoperative neutral group (179.44°±1.68° vs. 179.80°±1.99°, t=1.308, P>0.05). By contrast, the mechanical alignment as measured by non-weight-bearing short knee radiographs was significantly larger than that measured by whole leg radiographs in the deviated group (178.66°±2.91° vs. 178.66°±2.91°, t=4.252, P＜0.01).Conclusions When postoperative mechanical alignments are in the neutral position, non-weight-bearing short knee radiographs can be used to postoperatively determine recently followed up lower limb alignment. In dealing with malalignment, the use of whole leg radiograph in prospective follow up is recommended.
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2021, Vol. 26 
