May 2014 Large animal case

May 2014

Alpaca

Male intact

12 Years of age

Severe lameness hind right, swelling centred on the stifle since weeks

Radiographs of the right stifle were taken

Lateromedial (on the left image) and caudocranial (on the right image) of the right stifle.

Radiographic findings and diagnosis

  • There is moderate soft tissue swelling centred on the stifle with loss of definition of the infrapatellar fat pad (empty arrow).
  • There is a moderate displacement of the patella, proximal and  lateral (arrow).
  • The patella is proximally elongated with a well defined smooth but peaked border (arrowhead).
  • The radiographic diagnosis was patella alta (high riding patella) right with suspicious of rupture of the patellar ligament and mild osteophyte formation. Moderate soft tissue swelling, likely articular, periarticular component also
  • A radiograph with flexion of the stifle was recommeded.

Radiographic examination

Close up of the LM view of the right stifle

Comments

 

LM view of the flexed right stifle.

  • The proximal dislocation of the patella is accentuated by the flexed position.

  • Camelids have a single patellar tendon and a single synovial compartement in the stifle joint.

  • Patellar luxation may occur as a congenital, developed or traumatic condition, unilateral or bilateral.

  • Congenitally affected cases are more commonly medially luxated and bilaterally affected. Luxation may be fixed or dynamic. Acquired luxation is more often unilateral and lateral, surgical approaches have been described.

  • In this case, the position of the patella was secondary to complete rupture of the patella ligament.

  • Because of poor prognosis, the animal was euthanised and sent to pathology.

  • The rupture of the patellar ligament was confirmed and multiple erosions in lateral femoral condyle and in the femoropatellar joints were seen.