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Purpose To verify the accuracy of supine nonweight‐bearing radiography versus standing radiography in preoperative planning and to determine the predictors of unintended limb alignment correction in medial open‐wedge high tibial osteotomy (OWHTO). Methods Consecutive patients who underwent medial OWHTO for medial osteoarthritis of the knee with varus alignment were retrospectively reviewed. The analyzed pre‐ and postoperative radiologic measurements included postoperative mechanical axis deviation (MAD) on standing whole‐leg radiographs (WLRs), the predicted value of the postoperative MAD on the preoperative supine (predicted MAD supine ) radiograph, and standing WLRs (predicted MAD stand) . Multiple linear regression analysis was used to identify variables predicting the postoperative MAD and unintended MAD stand correction, defined as the difference between predicted MAD stand and postoperative MAD. Results Predicted MAD supine showed statistically greater reliability in predicting postoperative MAD than predicted MAD stand (intraclass correlation coefficient, 0.82 vs 0.45). Postoperative MAD was correlated with the predicted MAD supine and the difference in hip–knee–ankle angle between preoperative standing and supine WLRs (ΔHKA angle stand‐supine ) (R =763, R 2 = 0.582, adjusted R 2 = 0.569, P < .001) and did not differ significantly from the predicted MAD supine , with a mean difference of 0.28% ± 5.11% ( P = .656). The mean unintended MAD stand correction was 6.52% ± 8.66%. The difference in preoperative MAD between standing and supine WLRs was a significant predictor for unintended MAD stand correction (β = –0.350, P = .004). Conclusions Preoperative planning with supine WLRs can predict postoperative limb alignment in medial OWHTO more accurately than standing radiographs. The clinical significance of the ΔHKA angle stand‐supine for the risk of overestimation of postoperative limb alignment might be low because of the low power in the prediction model and small value of the ΔHKA angle stand‐supine . Preoperative soft‐tissue laxity was significantly correlated with unintended correction of postoperative limb alignment resulting from preoperative planning with standing radiographs. Level of evidence Level IV, retrospective comparative study
Shin et al. (Thu,) studied this question.