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 (17 month old Doberman Pinscher) 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.  In this case , Ramon was hit on the left side due to the findings of abrasions on the right lateral side.  This makes us believe that he was hit on the left side and then pushed over to the right side.  The direction of the hit correlated to the finding of a subluxated left coxofemoral joint.  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 massive soft tissue damage that will lead to the diffuse swelling of the entire limb.  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 in this case include a history of trauma, sudden onset of pain and crepitice.  Abnormal movement of the limbs, nonweightbearing lameness in both hindlimbs is present.  The reflex response is inconsistent and nonrepetitive due to abnormal nerve conduction in a traumatically luxated joint.  All of these clinical signs are consistent with a luxated coxofemoral joint.

We would like to do a V/D/ and Left Lateral view of the coxofemoral joint under anesthesia to distinguish between the two types of dislocations.  This distinguishment between fracture dislocation and simple location will guide our treatment.  The findings that we would expect on radiographics would be the femoral head not in the acetabulum.  We would also evaluate on lateral view, the femoral head and acetabular rim for the presence of small fractures.  We want to look for fracture separation of capital femoral physis.  We also want to look for the presence of hip dysplasia, which will give us a good estimate of the prognosis after treatment.  We would also like to palpate the joint again under anesthesia.  We would like to evaluate the direction under which it has dislocated.