Bilateral pain/lameness on the forefeetof an older dog These radiographs were made of an older member of a mixed breed with a history of having chronic intermittent pain in the forefeet - the clinical signs were short-lived and often presented after athletic activity - usually animals with these lesions eventually present for clinical examination which includes radiographic study of the feet often searching for an infectious or malignant lesion - dorsopalmar views of both front feet are included for your evaluation. DP radiographs of both forefeet Radiographic features Prominent periarticular new bone is seen on the distal metacarpal bones and the proximal first phalanges as well as around some of the proximal interphalangeal joints in a periarticular location the new bone is often shaped as a spur but some joints have a more poorly defined bony response the spur-like lesions appear an enthesophytes associated with collateral ligament attachments the new boney response on the first phalanx of the third digit on the right is larger - a different pattern of bony response is seen around the distal 5th metacarpal on the left appearing “lacy” like and extending further from the joint The joint spaces are rather well defined and the subchondral bone is well delineated Middle and distal interphalangeal joints are relatively normal or at least only minimally affected The proximal sesamoid bones seem to be normal except for the second bone on the left (arrows) in which the sesamoid bone is fragmented and displaced in appearance. Enlarged images Radiographic diagnosis The failure of identification of subchondral bone destruction tends to eliminate septic or rheumatoid-like arthritis as does the mature appearing periarticular new bone The pattern of new bone production is mature suggesting bone that is responsive to injury or trauma and not responsive to infection or tumor None of the new bone contains destructive portions that would support a diagnosis of infection or a malignant lesion The proximal sesamoid bones are in normal position with a normal appearance except for the 2nd bone on the left (arrows) - this finding tends to remove disease associated with the sesamoid bones as the etiology of the disease Involvement of multiple joints with some symmetry of change tends to suggest an etiology of repetitive injury to multiple joints within the foot The diagnosis is thought to be that of post-traumatic “arthrosis” Comments Lesions of this type are seen frequently with a degree of symmetry in the forefeet of older members of larger breeds that have a history of an active athletic life - the clinical histories include intermittent pain/lameness Biopsy of the new bone is of little value with an expected finding of mature reactive bone - joint taps are generally dry - biopsy of the “lacy-like” new bone on the 5th metacarpal bone on the left might be of value in this patient although even this pattern is often only suggestive of reactive new bone Treatment is usually symptomatic with a degree of relief of pain Radiographic follow-up shows a continual pattern of development of the periarticular new bone This pattern of presentation is often seen in Labrador Retrievers suggesting a familial trait of abnormal positioning of the feet rather than chronic trauma - the lesions are perhaps best understood by thinking of chronic hyperextension of the joints The pattern of disease is actually periarticular and thus the term of traumatic arthrosis is a misnomer
