Clinical history A 17 year old Inlander gelding had an intermittent left forelimb lameness that has been evident for several months after being ridden. The horse has not been examined previously and has not received any treatment. Physical examination
- He is normal at the walk
- He is stiff on both front limbs when circled
- He shows minimal left forelimb lameness when trotted
- He shows only slight pain following flexion of the left fetlock joint
Left forelimb - lateral and dorsopalmar views EnlargementsRadiographic changes
- Loss of bone density within the subchondral bone in proximal P1 medially
- Minimal narrowing of the joint space medially
- Reactive new bone on proximal P1 medially
- Minimal soft tissue swelling
Diagnosis This form of bone injury could appear primary or secondary to bony change in proximal P1 - A primary bone lesion could be a developmental bone lesion in the subchondral bone - or the subchondral bone lesion could be associated with an old healed osteomyelitis at the site of physeal injury. The arthrosis, characterized by minimal joint space narrowing suggests injury to the articular cartilage - the cartilage injury could be primary with the bony changes secondary - or the injury to the articular cartilage could be secondary to an underlying bone lesion. The bone destruction does not appear active and no evidence of osteomyelitis is seen on these studies. Primary or metastatic bone tumors are not usually included on a list of differential diagnosis with a lesion in the bones of feet in the horse. The periosteal response is mature and may suggest a degree of chronic joint instability or traumatic injury. Comment on further studies
- The affected bone/joint can be followed radiographically, but probably will remain unchanged and only prove the chronic nature of the injury
- A bone biopsy will probably only show noninflammatory bone response
- Capsular distention is not evident radiographically/clinically and sampling of joint fluid may be difficult
- An US examination of the soft tissue injury may offer information relative to that part of the lesion
- A CT examination may produce information relative to the bone lesion and show it to include cavitary components that may suggest either developmental or infectious etiology and may or may not communicate with the joint space
- MR may detect bone contusion (bruising) by seeing the edema of the subchondral bone - however, this is usually present without radiographic changes and thus may not be considered in this horse
- Scintigraphy is probably not helpful in diagnosis of bone bruising
- A final comment is that this study is made of a fore limb in a horse that is 17 years old that is experiencing minimal lameness that has not demanded treatment before
- Why not send your comments on this patient
