Objective: This study aimed to investigate which section of the quadriceps muscle has more evident muscle atrophy, in knees with gonarthrosis and genu varum.

Methods: In patients operated on because of gonarthrosis and varus alignment, intraoperative muscle biopsies are taken from the vastus lateralis (VL), vastus medialis (VM), and vastus intermedius (VI). The materials obtained were evaluated for connective tissue and fatty tissue and the ratio of atrophic muscle cells. The statistical evaluation is used to determine the relationship between atrophy and the varus angle.

Results: The mean varus angle is 11.7°. The results showed that the amounts of connective tissue in the VM muscle was significantly greater than in the VL and VI muscles (p=0.018). Additionally, no difference is determined between VM, VI, and VL with respect to the ratio of atrophic muscle cells to total muscle cells. The ratio of fatty tissue in the VL muscle was found to be statistically significantly greater in females than in males (p<0.05). The connective tissue was generally determined at a significantly higher rate in the VM muscle than in the VL and VI muscles.

Conclusion: With an increase in the varus angle of the knee, atrophy is seen to increase in the VM and VI muscles, and is more evident than atrophy in the VL muscle. Therefore, strengthening exercises directed at the VM for patients varus knees would be useful in the prevention of gonarthrosis.