Hypothesis 3: Traumatic Luxation of Left Coxofemoral Joint

Coxofemoral joint luxations are most often the result of external trauma, i.e. hit by car. Young large breed dogs such as Ramon are more susceptible because of their inherent instability of the hip joint.  Strong forces acting against the trunk when the leg is weightbearing (hit by car) will cause the limb to move into the adducted position and the femoral head into increased anteversion.  Because the femur is so long, it acts like a lever.  Due to traction of gluteal muscles, the femoral head slips into the cranial dorsal position.  Luxations can occur in four directions, caudocranial, caudoventral, plain ventral or just caudal.  86-90% of luxations are in the caudocranial direction.  Two main groups are fracture dislocation and a simple luxation.  In both cases the capsule is torn.

In this case there will be a lot of soft tissue damage that will lead to swelling.  A portion of the joint capsule of the round ligament may be torn.  One or more of the gluteal muscles may be partially or completely torn.  The dorsal rim of the acetabulum or part of the femoral head may be fractured.  Clinical signs would include a history of trauma, sudden onset of pain and crepitice.  Abnormal movement of the limb, nonweightbearing lameness is present.