To survey and analyze the relationship between the vastus medialis(VM) insertion on the patella and the body projection so as to provide an innovative path to the preoperative evaluation in selecting the subvastus approach in total knee arthroplasty(TKA).

Body-surface projection of the VM patellar insertion was surveyed and the anatomic shape was observed in 20 sides of lower limb specimens. The body-surface projection of the VM patellar insertion was also measured on 80 sides of lower limbs in healthy adults. The distribution results of the VM patellar insertion in the three conditions were compared.

The ratio of the vastus medialis body length to the patellar length was 40% to 60% in 55.0% specimens (11 cases). The ratios were (47.8±15.1)%, (48.7±15.4)% and (46.7±14.8)% in the cadaver-surface-observation group, autopsy group and in vivo surface group, respectively. There was no statistical difference (P>0.05).

There was no statistical difference in the ratios of the VM patellar insertion length to the patellar length calculated by the observed body-surface-projection values and by the measurements after anatomy. Preoperative evaluation of the body-surface-projection of the VM patellar insertion may play a referential role in the selection of the TKA approach.