Tibiofemoral joint space width in semiflexed standing position: no difference by weightbearing on one or two knees by manual and computerized measurements

BackgroundSingle knee weightbearing (SKW) radiographs are considered more accurate for detecting minimal joint space width (mJSW) than double knee weightbearing (DKW) but have not been compared using a standardized method.PurposeTo compare medial and lateral tibiofemoral mJSW between SKW and DKW radiographs using manual and computerized measurements.Material and MethodsStandardized posteroanterior radiographs of both knees were obtained from 98 patients with knee pain (55 women; mean age = 64.5 years; age range = 41-81 years) using the DKW technique in semiflexion, followed by SKW. Medial and lateral mJSW, coronal translation, and tibial plateau alignment (intermargin distance) were measured manually. Intra- and inter-rater agreement was assessed using 100 knee radiographs. In addition, mJSW was measured using a fully automated computerized technique. Manual measurements were adjusted for magnification, while computerized measurements were not.ResultsInter- and intra-rater reliability of manual measurements was excellent. Both manual and computerized mJSW measurements showed a non-significant trend toward larger medial mJSW with DKW compared to SKW. Coronal translation did not differ between SKW and DKW. The intermargin distances were small, with no significant differences between SKW and DKW, indicating reproducible knee positioning. Computerized measurements consistently showed larger mJSW than manual measurements.ConclusionMedial and lateral mJSW did not differ significantly between SKW and DKW techniques using either manual or computerized measurements. However, a systematic difference was observed between manual and computerized mJSW measurements. The SKW technique did not offer any advantages over the DKW technique for assessing knee osteoarthritis.