buttocks cruciateligaments diagnosis dogdiseases dogs etiology gait injuries joints knee kneeinjuries ligaments measurement movement musculoskeletalpain musculoskeletalphysiologicalphenomena orthopedicprocedures orthopedics pathology physicaltherapymodalities physiology rangeofmotion rupture spontaneous surgery therapy treatment veterinary wb200g368p2002 we870m96052004 woundsandinjuries