Dear Ammar, 

First, I found this link: 

https://www.hopkinsarthritis.org/physician-corner/education/arthritis-education-diagnostic-guidelines/#class_knee

As an article, I recommend the publication attached. 

Hope this was helpful :)

Article Clinical classification criteria for knee osteoarthritis: Pe...

Dear Ammar,

this is the reference for ACR for the classification and reporting Knee OA:

R. Altman, E. Asch, D. Bloch, G. Bole, D. Borenstein, K. Brandt, et al. The American College of Rheumatology criteria for the classification and reporting of osteoarthritis of the knee. Arthritis Rheum 1986;29:1039--1049.

and Recommendations for treatment:

Arthritis Care & Research

Vol. 64, No. 4, April 2012, pp 465–474 DOI 10.1002/acr.21596

© 2012, American College of Rheumatology

SPECIAL ARTICLE

American College of Rheumatology 2012 Recommendations for the Use of Nonpharmacologic and Pharmacologic Therapies in Osteoarthritis of the Hand, Hip, and Knee

MARC C. HOCHBERG,1 ROY D. ALTMAN,2 KARINE TOUPIN APRIL,3 MARIA BENKHALTI,3 GORDON GUYATT,4 JESSIE MCGOWAN,3 TANVEER TOWHEED,5 VIVIAN WELCH,3 GEORGE WELLS,3 AND PETER TUGWELL

hope is useful

Carlos Pineda

To start with, the ACR no longer endorses diagnostic criteria.

You may find the attached review article from ACR  (Published in 2015) useful. You can also download it from this link

http://www.rheumatology.org/Portals/0/Files/Distinctions%20Between%20Diagnostic%20and%20Classification%20Criteria%20Aggarwal%20et%20al.pdf

You can readily get it with American studies of Rheumatology