Diffuse narrowing of the joint space

1- If you find a diffuse narrowing of the joint space, look to the sub chondral surface.

2- If it shows sub chondral sclerosis without articular bone destruction, think for osteoarthritis.

3-If it shows sub chondral sclerosis with articular bone destruction, think for septic arthritis.

4-If it shows sub chondral sclerosis with uveitis, conjunctivitis and urethritis, think about Reiter's syndrome.

On the other hand

5-If it shows sub chondral osteoporosis, think for Rheumatoid arthritis.

Click diagram to enlarge