Knee Osteoarthritis

Definition

Degenerative joint disease due to progressive loss of articular cartilage of knee joint

Epidemiology

Global prevalence is around 22.9% in those over 40

Mechanism

• Damage beyond repair
• Obesity, malalignment and prior injury raise the load
• Abnormal loading > Imbalance in joint force > Activate cellular components of OA pathophysiology
• Pain does not correlate well with radiographic severity

Risk factors

• Age
• Female > Male
• BMI (Overweight 2.5x, Obesity 5x)
• Previous knee injury (OA risk about 4x higher after ACL injury, 6x after meniscal injury)
• Malalignment and occupational loading
• Genetic (first-degree relatives)

Clinical Presentation

Diagnosis

Mostly clinical diagnosis.

Diagnostic criteria by American College of Rheumatology (ACR)

• Clinical + radiography: Knee pain PLUS osteophyte on x-ray AND at least 1 of 3:
  1. Crepitus
  2. Age >50
  3. Stiffness <30mins

EULAR recommendation

“In adults aged ≥45 years presenting with the above signs and symptoms, a firm diagnosis of knee OA can be made without radiographic assessment or even when the subject’s radiograph appears normal.”

Plain radiograph

• Must be weight-bearing / standing AP to analyze joint space narrowing
• Lateral
• Skyline view – analyze patellofemoral joint
• Findings: Joint space narrowing, osteophytes, subchondral cyst, subchondral sclerosis
• Kellgren-Lawrence Grading System

Ultrasound

• To be used as adjunct, provide additional value not for diagnosis but rather for monitoring of the progress & guided intervention
• Findings (mnemonic: ‘Ortho Sees Every Fluid Makes Pain Bad’)
  • Anterior – Effusion & synovitis at suprapatellar fossa, Trochlear cartilage thickness
  • Medial – Osteophytes, Medial meniscus extrusion (MME), Pes anserinus bursitis
  • Posterior – Baker cyst

Blood / synovial fluid

• Only if gout, inflammatory or septic arthritis is suspected

*Caution: radiographic severity does not predict pain or response to exercise, so do not withhold exercise because of a poor radiograph.

Management

• First-line: education, exercise and weight management (if overweight)
• Trial of SYSADOA (Symptomatic Slow Acting Drug for OA) such as Piascledine, Glucosamine Sulphate, Mobithron Advanced. Recommend for 1-2 cycles, if no improvement, can stop
• Non-surgical interventions include:
  • Steroid Injection
  • Hyaluronic Acid Injection
  • PRP Injection / HA-PRP Injection
  • Stem Cell / Non-Cellular Therapies
  • Ultrasound-Guided Nerve Blocks (e.g. Adductor Canal Block / Genicular Nerve Block)
  • Radiofrequency Ablation
• Surgical options
  • High tibial osteotomy (bone realignment)
  • Partial knee replacement
  • Total knee replacement

Recommended algorithm by the Malaysian consensus on the management of knee OA (2021)

Red flags and when to refer

This summary is for educational use by healthcare professionals and does not replace clinical judgement.

References

1. Kolasinski, S.L., Neogi, T., Hochberg, M.C., et al. (2020). 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis Care & Research, 72(2), 149-162. https://doi.org/10.1002/acr.24131
2. Bannuru, R.R., Osani, M.C., Vaysbrot, E.E., et al. (2019). OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis and Cartilage, 27(11), 1578-1589. https://doi.org/10.1016/j.joca.2019.06.011
3. Fransen, M., Harmer, A.R., van der Esch, M., et al. (2015). Exercise for osteoarthritis of the knee. Cochrane Database of Systematic Reviews, 2015(1). https://doi.org/10.1002/14651858.cd004376.pub3
4. Skou, S.T., Roos, E.M., Laursen, M.B., et al. (2015). A Randomized, Controlled Trial of Total Knee Replacement. New England Journal of Medicine, 373(17), 1597-1606. https://doi.org/10.1056/nejmoa1505467
5. Cui, A., Li, H., Wang, D., et al. (2020). Global, regional prevalence, incidence and risk factors of knee osteoarthritis in population-based studies. EClinicalMedicine, 29-30, 100587. https://doi.org/10.1016/j.eclinm.2020.100587
6. McAlindon, T.E., LaValley, M.P., Harvey, W.F., et al. (2017). Effect of Intra-articular Triamcinolone vs Saline on Knee Cartilage Volume and Pain in Patients With Knee Osteoarthritis. JAMA, 317(19), 1967. https://doi.org/10.1001/jama.2017.5283
7. Panunzi, S., Maltese, S., De Gaetano, A., et al. (2021). Comparative efficacy of different weight loss treatments on knee osteoarthritis: A network meta‐analysis. Obesity Reviews, 22(8). https://doi.org/10.1111/obr.13230
8. Poulsen, E., Gonçalves, G.H., Bricca, A., et al. (2019). Knee osteoarthritis risk is increased 4-6 fold after knee injury: a systematic review and meta-analysis. British Journal of Sports Medicine, 53(23), 1454-1463. https://doi.org/10.1136/bjsports-2018-100022
9. Yeap, S. S., Abu Amin, S. R., Baharuddin, H., Koh, K. C., Lee, J. K., Lee, V. K. M., Mohamad Yahaya, N. H., Tai, C. C., & Tan, M. P. (2021). A Malaysian Delphi consensus on managing knee osteoarthritis. BMC musculoskeletal disorders, 22(1), 514. https://doi.org/10.1186/s12891-021-04381-8

Related

• Meniscus Tear
• ACL Tear
• Osteoarthritis (patient info)
• Joint Gel Injection (Hyaluronic Acid) (patient info)
• Radiofrequency Ablation (RFA) (patient info)
• ISMEC Return to Play Protocol