Osteoarthritis in the knee

Osteo-(bone), arthro-(Joint) and itis(inflammation). Osteoarthritis is a condition that affects the whole joint including bone, cartilage, ligaments and muscles. This condition is considered as wear and tear in the joint. It is, however, thought to be the result of a joint working extra hard to repair itself *1 or multiple causes. *3

The knee is complex and the largest synovial joint. Synovial membrane lubricates sends nutrition to the articular cartilage where is often painful location due to excessive stress and loads.

Aetiology

• Trauma
• Mechanical force
• Biochemical reaction
• Occupation related (requires kneeling, climbing and bending)
• Previous knee injury *1, 2

There are 2 types of causes which are primary (no trauma or idiopathic) and secondary (trauma, mechanical misalignment such as abnormal articular cartilage) *2,8

Signs and symptoms

• Pain and stiffness in the knee
• Pain and stiffness get worse with activities *1
• Clicking noise*1
• Grating sensation *1
• Restricted ROM (Range Of Motion)
• Overweight *1, *4

Treatment *5

• Exercise (land and water-based)
• Weight control
• Topical NSAIDs
• Hands on treatment
• Intra-articular corticosteroids

All exercises such as with, without weight, and aerobic help reduce the pain. However, light or non-weight bearing has the most effective on patients with knee osteoarthritis. *6,7

Every condition and case is different. Thus, patients should be given prescribed exercises by qualified practitioners.

Differential diagnosis

When pain is medial side

• Medial collateral ligament (MCL) pathology
• Medial meniscus issue
• Vastus medialis oblique (VMO) related
• Pes anserine tendons and bursa inflammation
• Semimembranosus tendinopathy

When pain in lateral side

• Iliotibial band syndrome (ITB syndrome)
• Lateral collateral ligament (LCL) injury
• Lateral meniscus pathology
• Patellofemoral pain syndrome
• Biceps femoris tendinopathy

When pain is in anterior aspect

• Quadriceps tendon or muscle pathology
• Inflammation of tibial tuberosity
• Patella tendon injury
• Bursitis

Findings

• Multiple causative factors
• Pain originates from non-cartilaginous structures of the joint capsule, synovium, subchondral bone and ligament as cartilage does not have an ability to produce pain or inflammation due to lack of innervation and vasculature.
• Synovial effusion, synovitis, loose ligaments, weak muscles around joint, osteophyte formation and bone remodelling are often found in chronic osteoarthritis.  

Reference

1. Arthritis Australia Osteoarthritis What is osteoarthritis https://arthritisaustralia.com.au/types-of-arthritis/osteoarthritis/
2. Juan C Mora, Rene Przkora and Yenisel Cruz-Almeida Knee osteoarthritis: pathophysiology and current treatment modalities J pain Res 2018 11: 2189-2196
3. Ayhan E, Kesmezacar H, Akgun I. Intraarticular injections (corticosteroid, hyaluronic acid, platelet rich plasma) for the knee osteoarthritis. World J Orthop. 2014;5(3):351–361
4. Dulay GS, Cooper C, Dennison EM. Knee pain, knee injury, knee osteoarthritis & work. Best Pract Res Clin Rheumatol. 2015;29(3):454–461.
5. Mcalindon TE, Bannuru RR, Sullivan MC, et al. OARSI guidelines for the non-surgical management of knee osteoarthritis. Osteoarthritis Cartilage. 2014;22(3):363–388
6. Tanaka R, Ozawa J, Kito N, Moriyama H. Efficacy of strengthening or aerobic exercise on pain relief in people with knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials. Clin Rehabil. 2013;27(12):1059–1071
7. Esser S, Bailey A. Effects of exercise and physical activity on knee osteoarthritis. Curr Pain Headache Rep. 2011;15(6):423–430.
8. Hunter Hsu and Ryan M Knee Osteoarthritis 2019 StatPearls (Internet)