Advances in the Diagnosis of Joint Disease

Introduction

Early diagnosis of disease in the articular cartilage and subchondral bone is critical for prevention or retardation of the osteoarthritic process, as well as prevention of fracture or catastrophic injury. Detection of early or subtle disease on the past has been poor, but progress has been made.

The current status in horses is that clinical examination and radiographic imaging are still the most commonly used technique for diagnosis of osteochondral disease. There is usually good correlation between the severity of clinical signs (lameness and synovial effusion) and the amount of damage or disease found at arthroscopy. It is interesting that in human literature although the most common complaint of a patient with osteoarthritis (OA) is pain, only about 1⁄2 of the patients with radiographic OA have symptoms and it has been stated that there is “no diagnostic test” for OA in man. However, there has been a focus more recently on MRI and biomarkers in recent years and specific outcome parameters are being incorporated into longitudinal studies.

Diagnostic techniques used in the horse

Clinical examination is still critical. Imaging techniques include radiography, nuclear imaging, computer tomography (CT), magnetic resonance imaging (MRI) and ultrasonographic examination. Conventional synovial fluid analysis is still used to define infection, but more recent work with synovial fluids and serum biomarkers offers real potential for diagnosis early change in cartilage and bone. Arthroscopy still is the gold- standard for diagnosis for cartilage defects, as MRI is limited by resolution, particularly in the thin cartilage of the carpus and the fetlock. On the other hand, MRI has been useful for more extensive changes in the soft tissues, as well as the bone.

Clinical examination

This always includes lameness and synovial effusion, but swelling with fibrosis occurs in more chronic disease processes and there may be pain on flexion, as well as limited motion. For lameness examination the grading guidelines for AAEP is still used. Flexion tests are used, but are somewhat controversial. Motion analysis systems are being used on a research basis, but have not reached the practical clinical arena yet.

Modeling is a diagnostic technique for the future and is the computer-based mathematical based representation of the skeleton, ligaments and muscles used to calculate forces and geometry in muscles and joints. This is a non-invasive technique that requires inputs using gait analysis, as well as MRI and CT. An example of the use of modeling is a current project whereby finite element modeling is being used as potential screening for susceptibility for condylar fracture in the fetlock joint. [...]