Regional load bearing of the canine acetabulum

Objective To determine the load bearing areas of the canine acetabulum. Materials and methods A kinematic study of four healthy dogs was used to determine the orientation of the femur to the pelvis at mid-stance. Femora and pelves from 10 canine cadavers were loaded with the physiological canine hip reaction force and angle being replicated. Impression material placed within the acetabulum was extruded from areas of load bearing. Digital images before and after loading were used to assess if six different regions of the acetabulum were fully, partially or non-load bearing. Results All areas of the acetabulum were partially or fully load bearing. The cranial and caudal thirds of the acetabulum were 7.9 and 13.1 times more likely to be fully load bearing than the central third, respectively. There was a significant difference in load bearing between the axial, middle and abaxial thirds of the acetabulum in all tests, with the middle and abaxial thirds 72.4 and 351 times more likely to be fully load bearing than the axial third, respectively. Conclusion The cranial and caudal thirds and the middle and abaxial thirds of the canine acetabulum are fully load bearing. Clinical relevance The caudal third of the canine acetabulum is loaded and therefore recommendations that fractures in this area be managed conservatively need to be reconsidered.