These reference links should help you find credible resources about hip and knee replacement surgery and orthopaedic issues.
An excellent resource for hip and knee surgery patients is www.bonesmart.org
OrthoInfo is an extensive resource center from the AAOS (American Academy of Orthopaedic Surgeons).
Here are articles related to Hip & Thigh problems:
Here are articles related to Knee & Lower Leg problems:
Use this tool to find an orthopaedic surgeon in your area.
Article, How to Find the Best Orthopedic Surgeon:
Excellent article from May 2018, published in U.S. News & World Report magazine. Covers what an orthopedic surgeon does, how they are trained, specialties they might have (say, hand surgery or sports medicine), and how to evaluate if that surgeon is right for you.