Quadriceps angle

The quadriceps angle is a measurement used to assess angular deformities of the femur and provide guidance for corrections. It is determined from a ventrodorsal radiograph of the hips or multiplanar reconstructed CT images of the femur.

For radiographic acquisition, the dog is positioned in dorsal recumbency, pelvic limbs extended caudally, femurs parallel to each other. Positioning is considered satisfactory if :

• the pelvis is symmetrical: the iliums and obturator foramina are symmetrical.

• the femur cortex pass through the middle of the sesamoid bones of the gastrocnemius muscle

• the patellas are centered on the trochlea of the femur.

To determine the quadriceps angle, a first line is drawn from the origin of the rectus femoris muscle at the lateral aera of recti femoris muscle, on the ventral aspect of the ilium to the middle of the trochlea of femur. A second line is drawn from the middle of the trochlea of femur to the tibial tuberosity.The middle of the trochlea of femur corresponded to the centre of the patella when it is in its anatomic position. The angle formed between these lines is the quadriceps angle.

The following values have been published for the quadriceps angle in healthy dogs:

• Small breed dogs: 14° (8-28) Garnoeva et al. 2018

• Small breed dogs: 18.3° (6.1-29.7) Pinna and Romagnoli 2017

• Large breed dogs: 8.7° (2.7 - 14.8) Pinna and Romagnoli 2017