Diagnosis of osteoarthritis Flashcards
What does the loss of GAGs lead to?
The cartilage consists of collagen, and hyaluronic acid with GAG chains attached, which holds water. With disease we see loss of GAGS and a loss of the ability to hold water and release it under loading.
Why isn’t there pain involved in the early stages of OA?
Cartilage is avascular and aneural. The aneural part means there isn’t pain in the early stages, until other joint structures become involved, and the avascular part means its very poor at healing itself.
What clinical signs are associated to OA?
Varying levels of severity / tissue involvement:
* Synovitis
* Partial thickness cartilage erosions
* Full thickness erosions
* Subchondral bone lesions
* Peri-articular new bone
* Peri-articular soft tissue damage (including collateral ligaments)
* Peri-articular fibrosis
* Joint ankylosis
What aspects of the horse are different in OA compared to other species?
- High motion joints such as the distal interphalangeal joint, fetlock, tarsocrural and stifle joints can be significantly affected by mild disease and can have a poor prognosis for return to function
- Small changes, e.g. small osteophyte formation can be clinically significant in high motion joints
- Low motion joints such as proximal interphalangeal joint, and distal tarsal joints can sometimes tolerate quite significant changes, but unpredictable – severity of radiographic signs does not always relate to severity of clinical signs
- Radiographic signs in low motion joints can include lysis, new bone formation and ankylosis – can look quite ‘aggressive’
Describe these LM radiographs
Right fore –
* Slight rotation of foot, which obscures some aspects of distal interphalangeal joint, osteophyte formation on extensor process of third phalangeal bone, new bone formation on proximal and distal aspects of dorsal surface of second phalangeal bone, ossification of collateral cartilage of third phalanx.
* Changes in shape of navicular bone, but may be due to rotation / position – need to redo radiograph to confirm
Left fore –
* Osteophyte formation on articular surface of dorsal and palmar aspect of second phalanx (distal interphalangeal joint).
* Periosteal new bone on dorsal aspect of second phalanx, mid body, non articular
What bones are shown by arrows?
What can you see on the LM and DP views of the hock?
LM view: Bone remodelling on dorsal aspect of third and central tarsal bones. Lysis and sclerosis on dorsal aspect of the distal intertarsal joint. Loss of joint space (fusion) of joint space on plantar aspect
DP view: Lysis and sclerosis on medial aspect of the distal intertarsal joint. Loss of joint space (fusion) of joint space on lateral aspect
