Femoral component sizing in total knee arthroplasty: size matched resection versus flexion space balancing.

Generally, 2 different methods are used to select femoral size. These can be termed "size-matched resection" and "flexion-space balancing." The purpose of this paper is to compare these 2 methods during 50 sequential total knee arthroplasty surgeries. The flexion-space-balancing method led to a smaller size selection than the size-matched-resection method in 28 (56%) knees. In the remaining 22 knees, the measurement methods led to the selection of the same size femoral component. The difference in measurement methods was significant (P<.05). The preoperative varus knees were more sensitive to the differences in measurement methods than the valgus knees (P<.05). A flexion space that is too small may adversely affect the clinical outcome of knee arthroplasty.