Learning issues What does medial buttressing mean and how does it affect our hypothesis? Is a medially luxating patella when the leg is in extension normal or abnormal? What does a pain on dorsal flexion of the tail indicate? Is it normal to have a pain response when testing for cranial drawer sign and when trying to luxate the patella? What does a grade 3/4 lameness mean? Hypothesis investigations: Investigate how degenerative changes could lead to pain in the stifle joint. Investigate how trauma could lead to lameness and pain in the stifle joint. Investigate how developmental abnormalities could lead to pain in the stifle joint.