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Short knee X-rays may be inaccurate for assessment of coronal alignment after TKA
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A recently published study showed use of the femorotibial angle on short films led to the misclassification of a significant proportion of patients as having varus, valgus or neutral coronal alignment after total knee arthroplasty compared with the hip-knee-ankle angle.
Femorotibial angle, hip-knee-ankle angle, medial proximal tibial angle and the lateral distal femoral angle were measured in 262 patients with short and full-length standing radiographs before and after primary total knee arthroplasty (TKA). A femorotibial angle between 2.4° and 7.2° on short knee X-rays or a hip-knee-ankle angle between -3° and 3° on full-length films were considered neutral coronal alignment, according to researchers.
Although results showed 13.9% of knees had a neutral femorotibial angle on short films preoperatively, full-length films showed 50% of those were in varus or valgus. Similarly, researchers found short films had 51.4% of knees listed as having a neutral femorotibial angle while full-length films showed 27.4% of those knees were in varus or valgus. According to results, discordant alignment classifications were identified in 13.9% of patients on preoperative imaging and in 33% of patients on postoperative imaging when comparisons were based on the short vs. full-length images. – by Casey Tingle
Disclosures: Park reports no relevant financial disclosures. Please see the full study for a complete list of all other authors’ relevant financial disclosures.
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