• Osteoarthritis (OA) is known as the most common chronic disease of the cartilage. As the cartilage breaks down due to wear-and-tear and/or mechanical stress, it causes swelling, pain and inflammation, leading to extracellular matrix (ECM) loss¹ .
  • Knee osteoarthritis (KOA) is a progressive joint disease that often involves intra- and per articular structures² and is considered pathology characterized by articular cartilage lesions, synovitis, subchondral sclerosis, and osteophytes³.
  • Knee osteoarthritis (OA) is most often a slowly progressive joint disorder characterized by cartilage degeneration and
     inflammation⁴. Knee OA commonly results in knee pain and decreases patients’ mobility (e.g. walking and stair climbing)⁵.
  • The pain of osteoarthritis is usually related to activity. For osteoarthritis of the knee (Fig. 1), activities such as climbing stairs, getting out of a chair, and walking long distances bring on pain. 
    Morning stiffness usually lasts less than 30 minutes.⁶ Patients often note that their knees “give way,” a so-called instability symptom.                                                            


  • Age is one of the most common risk factor⁷
  • Biological age-related changes in the joint structures⁷
  • Female sex (knee OA⁸
  • Obesity (knee OA)⁸
  • Previous knee injury (knee OA)⁸
  • Knee malalignment (knee OA)⁹,¹⁰ 
  • Knee extensor muscle weakness (knee OA)¹¹
  • Cam deformity and mild dysplasia (especially in the middle aged (55–65 years), but not in the older population (older than 65 years)) (hip OA)¹² Severe dysplasia (hip OA)¹²


OA Stages

Stage 0 (Pre-Osteoarthritis) –Asymptomatic
Stage 1 (Early o Doubtful)- Mild joint pain; No serious symptoms yet
Stage 2 (Mild or Minimal)- Pain with activity; Difficulty straightening and bending joints; Stiffness
Stage 3 (Moderate)- Frequent pain with movement; Stiffness in the morning or after sitting; visible swelling of joints possible
Stage 4 (Severe)- High pain with joint usage; Daily activities very difficult; Intense stiffness; Severe swelling and inflammation.                                                                      


The joint pain of OA typically described as being exacerbated by activity and relieved by rest. More advanced OA can cause pain at rest and during the night, leading to loss of sleep that further exacerbates pain. The cardinal symptoms that suggest a diagnosis of OA include Pain (typically described as activity related or mechanical; may occur with rest in advanced disease; often deep, aching, and not well localized; usually of insidious onset).

  • Reduced function
  • Stiffness (of short duration, also termed ‘‘gelling,’’ that is, short-lived stiffness after inactivity)
  • Joint instability, buckling, or giving way
  • Patients also may complain of reduced movement, deformity, swelling in the absence of systemic features such as fever, crepitus, discomfort associated with increased age (OA is unusual before age 40 years), and, when pain persists, pain-related psychologic distress.

Refferences (1-16)

R. Altman, E. Asch, D. Bloch, G. Bole, D. Borenstein, K. Brandt, W. Christy, T.D. Cooke, R. Greenwald, M. Hochberg, et al., Development of criteria for the classification and reporting of osteoarthritis. Classification of osteoarthritis of the knee, Diagn. Ther. Crit. Commit. Am. Rheum. Assoc. Arthritis Rheum. 29 (8) (1986) 1039–1049.

Lane NE, Brandt K, Hawker G, et al. OARSI-FDA initiative: Defining the disease state of osteoarthritis. Osteoarthritis Cartilage 2011;19(5):478–82.

Su K, Bai Y, Wang J, et al. Comparison of hyaluronic acid and PRP intra-articular injection with combined intra-articular and intraosseous PRP injections to treat patients with knee osteoarthritis. Clin Rheumatol 2018;37(5):1341–50.

Cheng OT, Souzdalnitski D, Vrooman B, Cheng J. Evidence-Based Knee Injections for theManagement of Arthritis. Pain Med (United States). 2012;13(6):740-753.

Guccione A, Felson D, Anderson J et al. The effects of specific medical conditions on the functional limitations of elders in the Framingham Study. American Journal of Public Health. 1994;84(3):351-358.

Altman R, Asch E, Bloch D, et al. Development of criteria for the classification and reporting of osteoarthritis. Arthritis Rheum 1986;29:1039-49.

Zhang Y, Jordan JM. Epidemiology of osteoarthritis. Rheum Dis Clin North Am 2008; 34: 515–29.

Silverwood V, Blagojevic-Bucknall M, Jinks C, Jordan JL, Protheroe J, Jordan KP. Current evidence on risk factors for knee osteoarthritis in older adults: a systematic review and meta-analysis. Osteoarthritis Cartilage 2015; 23: 507–15.

Brouwer GM, van Tol AW, Bergink AP, et al. Association between valgus and varus alignment and the development and progression of radiographic osteoarthritis of the knee. Arthritis Rheum 2007; 56: 1204–11.

Runhaar J, van Middelkoop M, Reijman M, Vroegindeweij D, Oei EH, Bierma-Zeinstra SM. Malalignment: a possible target for prevention of incident knee osteoarthritis in overweight and obese women. Rheumatology (Oxford) 2014; 53: 1618–24.

Oiestad BE, Juhl CB, Eitzen I, Thorlund JB. Knee extensor muscle weakness is a risk factor for development of knee osteoarthritis. A systematic review and meta-analysis. Osteoarthritis Cartilage 2015;23: 171–77.

Gala L, Clohisy JC, Beaulé PE. Hip dysplasia in the young adult Bone Joint Surg Am 2016; 98: 63–73.

Hunter, David J et al. “The symptoms of osteoarthritis and the genesis of pain.” Rheumatic diseases clinics of North America vol. 34,3 (2008): 623-43. doi:10.1016/j.rdc.2008.05.004

(M. Hemshekhar, R.M. Thushara, S. Chandranayaka, L.S. Sherman, K. Kemparaju, K.S. Girish, Emerging roles of hyaluronic acid bio scaffolds in tissue engineering and regenerative medicine, Int. J. Biol. Macromol. 86 (2016) 917928. doi:10.1016/j.ijbiomac.2016.02.032.)

Altman RD, Bedi A, Karlsson J, Sancheti P, Schemitsch E. Product Differences in Intraarticular Hyaluronic Acids for Osteoarthritis of the Knee. Am J Sports Med. 2015.

Pereira H, Sousa DA, Cunha A, Andrade R, Espregueira-Mendes J, Oliveira JM, Reis RL. Hyaluronic Acid. Adv Exp Med Biol. 2018;1059:137-153. doi: 10.1007/978-3-319-767352_6. PMID: 29736572.