Thermal effect for optical imaging of knee osteoarthritis

Knee is the most important hinge joint with complex geometry in our musculoskeletal system, which allows stability, flexion, extension and slight internal and external rotation in our entire day to day activities. Knee mainly consists bone (femur, patella, tibia and fibula), cruciate ligaments (anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL)), collateral ligaments (lateral collateral ligament (LCL) and medial collateral ligament (MCL)) and cartilages (meniscus and articular cartilages). Meniscus and articular cartilages used as shock absorbers, which help to move bones smoothly over one another throughout their range of motion. Cruciate and collateral ligament prevent backward-forward movement and side to side movements of the bones respectively. However, knee is highly vulnerable to injuries that might happen due to vehicle accidents, during physical exercise, and other sudden events in our day to day activities. In addition, knee joint is highly affected by diseases like; osteoarthritis, rheumatoid arthritis, osteonecrosis and other syndromes which are afflicting millions of people every day throughout the globe. Osteoarthritis only affects around 250 million people worldwide.1 According classic rehabilitation statistical up to date report, one-third of all Americans experiencing knee pain at some time or another and around 100 million people suffer from chronic pain annually. According to Genome-wide association study, half of people aged above 50 suffer knee pain.6 Ligament, cartilage injuries and OA are the most common chronic knee pain and cause of disabilities.2–5 In USA, there are about 60 acute meniscal tears per 100000 people7 and around 200000 ALC injuries per year.8 According to national health survey around 3 persons have OA per 10 people with disabilities.9