Knee Osteoarthritis

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The lifetime risk of total knee replacement in New Zealand has grown rapidly from 2000 to 2015. The risk for females increased from 9.4% in 2000 to 16.8% in 2015, a relative increase of 78%. Males increased from 8.1% in 2000 to 16.0% in 2015, a relative increase of 97%.[1]



Exercise Therapy

  • Reduces pain and improves function
  • partially through anti-inflammatory effects in particular IL-6 even without weight loss
  • Maximal benefit at 2 months, thereafter slowly diminishes, being no better than usual care at 9 to 18 months โ€“ possibly due to poor adherence.
  • Better effects in those who are younger, with milder OA and who werenโ€™t awaiting knee replacement.
  • Doesnโ€™t harm the cartilage[2]

Physical therapy is more effect than a single glucocorticoid injection at one year[3]

Weight Loss

The pain associated with knee osteoarthritis is thought to be secondary to both local and systemic factors. Adipokines are directly involved in the inflammatory component of OA and cartilage damage. The best results are seen with combined diet plus exercise. The IDEA trial showed that exercise plus weight loss resulted in a 50% decrease in pain scores, and 38% of patients reported no or little pain at the end of the trial.[4] There is a dose response curve with weight loss, and best results are seen with at least 10% weight loss. In the elderly it is important to also add strengthening exercises. There appears to be a benefit from bariatric surgery, too.

Undertaking knee arthroplasty in order to allow for increased exercise and therefore weight loss is not evidence based. Most patients actually gain significant weight following knee arthroplasty despite physiotherapy. It is not known how to predict those that will gain weight following surgery. Obesity should be regarded as a separate condition that will not resolve with an improvement in function.[5]

Manual Therapy

Mobilisation with movement improves pain, range of motion, and functional[6]


  • Probably not effective
  • Medial knee OA โ€“ negative meta-analysis of 12 studies in 2013 for lateral wedge insoles when compared to a neutral insole. Publication bias was detected.[7] [LOE 1a-]
  • Lateral knee OA โ€“ one small study showing benefit with medial wedge insoles


Topical Therapies


  • Desensitisation of nociceptive fibres
  • Causative role of substance P depletion has come into question
  • Local burning, improves with continued application
  • Funded if NSAIDs contraindicated

Topical NSAIDs

  • Cochrane 60% achieved at least 50% improvement (better than placebo)
  • Comparable to oral formulations[8]


A systematic review concluded that the following supplements had the most evidence: L-carnitine, Pycnogenol, curcumin, Boswellia serrata extract, Curcuma longa extract, passion fruit peel extract, and collagen hydrolysate. [9]


Total Knee Joint Replacement

  • Resection of diseased surface, resurfacing with metal and polyethylene components
  • No sham studies
  • Reduced pain and improved quality of life (compared to non surgical treatment โ€“ exercise, diet, insoles, medication)
  • 20% experience chronic pain after surgery, causes not fully understood (but strong psychological risk factors)
  • Risks โ€“ DVT and stiffness requiring brisement force most common

On the topic of chronic pain post surgery, probably the best study is a non placebo controlled study by Skou et al who found a significant proportion still experienced chronic pain after surgery. [10]

Knee surgery Skou et al.png

Possible factors contributing to persistent pain following surgery are summarised by Wylde et al. M

Factor Examples
Biological Sensitizing impact of long-term pain from osteoarthritis
Complex Regional Pain Syndrome
Pain originating from the hip
Patellofemoral pain
Allergy-related problem
Inflammatory response
Surgical Infection
Localized nerve injury
Prosthetic loosening
Incorrect sizing

Arthroscopic Debridement

In one of the only placebo controlled trials in all of orthopaedic surgery, this procedure was proven to be no better than sham surgery and should no longer be performed. [11]

Unicompartmental arthroplasty

  • quicker recovery and improved ROM
  • Younger patients with low activity demands


  • High tibial osteotomy (for varus knee)
  • Distal femoral Osteotomy (for valgus knee)
  • Younger patients with high activity demands and poor alignment.

Again there are no sham studies[12]

Injection Treatments

Steroid Injections

No better than placebo with an increased risk of accelerated cartilage loss [13]


Initial evidence was "promising".[14] However a recent large RCT showed no benefit over placebo.[15]

Dextrose Prolotherapy

A systematic review found high risk of bias and that prolotherapy was no different from platelet-rich plasma on the pain subscale at the 6-month time point, and was inferior to platelet-rich plasma at 6 months.[16]


  1. โ†‘ Henzell et al.. Lifetime risk of primary total knee replacement surgery in New Zealand from 2000 to 2015. The New Zealand medical journal 2019. 132:48-56. PMID: 30703779.
  2. โ†‘ Goh, S.-L., Persson, M. S., Stocks, J., Hou, Y., Lin, J., Hall, M. C., โ€ฆ Zhang, W. (2019). Efficacy and potential determinants of exercise therapy in knee and hip osteoarthritis: a systematic review and meta-analysis. Annals of Physical and Rehabilitation Medicine.
  3. โ†‘ Deyle et al.. Physical Therapy versus Glucocorticoid Injection for Osteoarthritis of the Knee. The New England journal of medicine 2020. 382:1420-1429. PMID: 32268027. DOI.
  4. โ†‘ Messier SP, Mihalko SL, Legault C, Miller GD, Nicklas BJ, DeVita P, Beavers DP, Hunter DJ, Lyles MF, Eckstein F, Williamson JD, Carr JJ, Guermazi A, Loeser RF. Effects of intensive diet and exercise on knee joint loads, inflammation, and clinical outcomes among overweight and obese adults with knee osteoarthritis: the IDEA randomized clinical trial. JAMA. 2013 Sep 25;310(12):1263-73. doi: 10.1001/jama.2013.277669. PMID: 24065013; PMCID: PMC4450354.
  5. โ†‘ Zeni JA Jr, Snyder-Mackler L. Most patients gain weight in the 2 years after total knee arthroplasty: comparison to a healthy control group. Osteoarthritis Cartilage. 2010 Apr;18(4):510-4. doi: 10.1016/j.joca.2009.12.005. Epub 2009 Dec 21. PMID: 20060949; PMCID: PMC2846226.
  6. โ†‘ Gidey Gomera Weleslassie, Melaku Hailu Temesgen, Abayneh Alamer, Gebrerufael Solomon Tsegay, Teklehaimanot Tekle Hailemariam, Haimanot Melese, "Effectiveness of Mobilization with Movement on the Management of Knee Osteoarthritis: A Systematic Review of Randomized Controlled Trials", Pain Research and Management, vol. 2021, Article ID 8815682, 12 pages, 2021. DOI
  7. โ†‘ Parkes MJ, Nasimah M, Lunt M, et al. Lateral wedge insoles as conservative treatment for pain in patients with medial knee osteoarthritis. A meta-analysis. JAMA 2013;310(7):722-730.
  8. โ†‘ Derry  S, Conaghan  P, Da Silva  JAP, Wiffen  PJ, Moore  RA. Topical NSAIDs for chronic musculoskeletal pain in adults. Cochrane Database of Systematic Reviews 2016, Issue 4. Art. No.: CD007400. DOI: 10.1002/14651858.CD007400.pub3.
  9. โ†‘ Liu et al.. Dietary supplements for treating osteoarthritis: a systematic review and meta-analysis. British journal of sports medicine 2018. 52:167-175. PMID: 29018060. DOI.
  10. โ†‘ Skou, S. T., Roos, E. M., Laursen, M. B., Rathleff, M. S., Arendt-Nielsen, L., Simonsen, O., & Rasmussen, S. (2015). A Randomized, Controlled Trial of Total Knee Replacement. New England Journal of Medicine, 373(17), 1597โ€“1606. 
  11. โ†‘ Moseley, J. B., Oโ€™Malley, K., Petersen, N. J., Menke, T. J., Brody, B. A., Kuykendall, D. H., โ€ฆ Wray, N. P. (2002). A Controlled Trial of Arthroscopic Surgery for Osteoarthritis of the Knee. New England Journal of Medicine, 347(2), 81โ€“88. doi:10.1056/nejmoa013259 
  12. โ†‘ Dettoni F, Bonasia DE, Castoldi F, Bruzzone M, Blonna D, Rossi R. High tibial osteotomy versus unicompartmental knee arthroplasty for medial compartment arthrosis of the knee: a review of the literature. Iowa Orthop J. 2010;30:131โ€“140.
  13. โ†‘ McAlindon TE, LaValley MP, Harvey WF, et al. Effect of intra-articular triamcinolone vs saline on knee cartilage volume and pain in patients with knee osteoarthritis: a randomized clinical trial. JAMA 2017;317(19):1967-1975.
  14. โ†‘ Shahid & Kundra. Platelet-rich plasma (PRP) for knee disorders. EFORT open reviews 2017. 2:28-34. PMID: 28607768. DOI. Full Text.
  15. โ†‘ Bennell KL, Paterson KL, Metcalf BR, Duong V, Eyles J, Kasza J, Wang Y, Cicuttini F, Buchbinder R, Forbes A, Harris A, Yu SP, Connell D, Linklater J, Wang BH, Oo WM, Hunter DJ. Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial. JAMA. 2021 Nov 23;326(20):2021-2030. doi: 10.1001/jama.2021.19415. PMID: 34812863; PMCID: PMC8611484.
  16. โ†‘ Wee et al.. Dextrose prolotherapy in knee osteoarthritis: A systematic review and meta-analysis. Journal of clinical orthopaedics and trauma 2021. 19:108-117. PMID: 34046305. DOI. Full Text.

Literature Review