Knee Electrotherapy

Original Editor - Michelle Lee Top Contributors - Michelle Lee, Kim Jackson and Jolien Rottie


This page will look at popular methods of electrotherapy and the evidence to support it in the use of knee conditons specifically. 

Pulsed Shortwave Therapy 

Pulsed shortwave therapy is an electrotherapy modality that is used in practice, and there are 2 types off effects suggested.

  1. Electric field – upon literature reviewing there is very little evidence to support this theory, and almost all of the literature supports the magnetic field effect.
  2. Magnetic field – the main effect of the pulsed magnetic field has been documented to work at a cellular level at the cell membrane. It has been suggested to assist in the transportation of ions across the membrane.

The effects are said to be in the acute and inflammatory process and documented effects are on:

  • Muscles
  • Nerves
  • Areas of oedema
  • Haematosis
  • Effusion [1]

Therefore this would suggest that the use of pulse short wave therapy in knee conditions that resulted in effusions and oedema is effective: i.e. ligamentous injuries, arthritis and meniscal lesions, as these can all produce inflammation and swelling. A study in 2010 by Al – Mandeel and Watson found that there were significant physiological changes (blood volume) through the use of low and high doses of pulsed shortwave therapy. Limitations of this study was that this was done in healthy subjects therefore there were no pathology within the joint and people with excess adipose tissue were excluded as this was identified to effect the effectiveness of the therapy. (Level of evidence: 2b) [2]

Whereas Callaghan et al in 2005 looked at the effects of PSWT on levels of inflammation in patients with OA knee. The primary outcome used was sophisticated radioleucoscintigraphy to identify levels of inflammations pre and post treatments. They found that there was little inflammation in those with OA knee to start with but that there was no significant change in their levels after PSWT. (Level of evidence: 1b) [3]

The National Institute for Clinical Excellence (NICE) has not recommended the used of PSWT for OA but the use of TENS as an adjunct only. (Level of evidence: 1a) [4]

There is limited evidence looking at the effect of PSWT on knee conditions specifically, therefore a search was conducted on the effectiveness of PSWT on oedema and effusions, a study was identified that looked that the use of cryotherapy versus PSWT on swelling post calcaneal fractures. There were no differences found in either group and swelling had significantly improve by day 5 anyway. Cryotherapy was recommended from this study as this was a cheaper alternative which could be transported anywhere. (Level of evidence: 4) [5]

The majority of the literature surrounding the used of PSWT in the knee looks at Knee OA, and due to the lack of evidence found it and guidance from NICE the use of PSWT cannot be recommended from the literature.

This Physiopedia page looks at the suggested effects of PSWT 

Transcutaneous Electrical Nerve Stimulation (TENS)

TENS is a method of electrical stimulation which primarily aims to provide a degree of symptomatic pain relief by exciting sensory nerves and thereby stimulating either the pain gate mechanism and/or the endogenous opioid system. 

Pain relief using a TENS machine with 'the pain gate' theory involves excitation of the 'A beta (Aβ) sensory fibres, and by doing so, reduces the transmission of the noxious stimulus from the ‘c’ fibres, through the spinal cord and hence on to the higher centres. The Aβ fibres appear to appreciate being stimulated at a relatively high rate (in the order of 90 - 130 Hz or pps). It is difficult to find support for the concept that there is a single frequency that works best for every patient, but this range appears to cover the majority of individuals.' [6] [7]

'An alternative approach is to stimulate the A delta (Aδ) fibres which respond preferentially to a much lower rate of stimulation (in the order of 2 - 5 Hz), which will activate the opioid mechanisms, and provide pain relief by causing the release of an endogenous opiate (encephalin) in the spinal cord which will reduce the activation of the noxious sensory pathways.'[8][9]

Although with all of the new research evolving about pain neuroscience the 'pain gate theory' is now being challenged. [10]It was initially developed in 1965 by Ronald Melzack and Patrick Wall, to which Wall had later said: “The least, and perhaps the best, that can be said for the 1965 paper is that it provoked discussion and experiment”[11]

A lot of the research for the use of TENS to manage pain has been focused on chronic pain, therefore a Cochrane review was done in 2000 which concluded that TENS could not be recommended for general chronic pain management at this stage due to the lack of consistent stimulation parameters or comments on long-term effectiveness.[12] Although a protocol has been published in 2015 for a more upto date review of the literature in the use of TENS as a pain management tool.[13] Although there is still the debate as to whether the use of TENS in chronic pain is effective, NICE and Arthritis UK have recommended this as an adjunct to other treatments.(Level of evidence: 1a)[14][15]

A more recent Cochrane review has looked at the use of TENS in the acute stages of pain and has evaluated that all studies reviews have found it beneficial there were lots of flaws to their studies such as high risk of bias, poor sample sizes, incomplete results reported and unsuccessful blinding,[16] therefore this needs to be taken into consideration when looking at the evidence but possibly something that can be used as an adjunct again with patients who have acute knee pain. 

Research is limited in the field of TENS and specific knee complaints therefore it is recommended that current research around the use of TENS for pain and clinical reasoning is used. 

Ultrasound (US)

Therapeutic US is divided into two effects: thermal and non-thermal, but each effect can occur at any one treatment. It has been suggested that US can help speed up and improve the quality of tissue healing. [17] To read more on how US can help at the different stages of healing read this Physiopedia page.

Around the knee the tissue that may be influenced by US are the patellar tendon and the ligaments. Looking at pathologies of the tendon (tendinopathy) and the effectiveness of therapeutic US there is little evidence which has specifically evaluated this, therefore a search was conducted looking further afield. There have in vivo and in vitro studies and studies on animal tissue which showed positive physiological changes in tendinopathy using US but there has yet to be any positive results using live human tissue [18]. This is confimed by a systematic review and meta analysis which was published in 2015 looking at the treatment of tendinopathy in the shoulder. They found that there were no good quality studies to base recommendation on this as a treatment modality therefore recommendation was made that US should not be used as a treatment. (Level of evidence: 1a) [19] It can only be concluded that evidence is lacking in proving the efficacy of US as a treatment modality for tendinopathy such as patella tendinopathy. 

Soft tissue injuries such as ligamentous injuries have historically been treated with therapeutic US, a study which looked at the MCL in rats and has shown that low-intensity pulsed ultrasound exposure is effective for enhancing the early healing of medial collateral ligament injuries. (Level of evidence: 3b).[20] Again when the research is then applied to the human population it has it's pitfalls as highlighted by Robertson and Baker in 2001 where they found that there was little evidence that therapeutic US is more effective than placebo ultrasound, for not only treating ligamentous pathologies but with patient who are in pain or a range of musculoskeletal injuries or for promoting soft tissue healing.(Level of evidence: 1a) [21] This was then clarified later in 2005 by Zammit and Herrington who specifically looked at the management of lateral ankle ligament sprains. They found no added benefit of using US at a set dose for lateral ligament ankle sprains.(Level of evidence: 1b)[22]

Overall from the literature reviewed including RTC's, Systematic reviews and meta analysis it cannot be concluded that therapeutic US is of benefit to soft tissue repair, patella tendinopathy or ligamentous sprains in humans. 

Extracorporeal Shock Wave Therapy (ESWT)

"Shockwave therapy is essentially a large-amplitude compression wave, as that produced by an explosion or by supersonic motion of a body in a medium. Just like an ultrasound wave, the shock wave consists of a high pressure phase followed by a low pressure (or relaxation) phase. When a shock wave reaches a 'boundary', some of the energy will be reflected and some transmitted." [23]

The research began with looking at calcific tendons and bone healing, where as today this has moved onto chronic tendon and ligament problems. [24] In 2009 NICE acknowledged that ESWT as a treatment modality for achillies tendinopathy (Level of evidence: 1a)[25]. Diehl et al, found that ESWT as a treatment for achillies tendinopathy demonstrated promising results but felt that long term studies were needed to fully evaluate their effectiveness. [26] Rees et al 2009, suggested from their review of the literature that ESWT had been shown to be more beneficial in international and calcific tendinopathies. (Level of evidence: 1a)[27] At this point all the literature was looking promising for the treatment of tendinopathy and calcific tendons, although the majority of the research had been done in the achilles tendon, it is possible to draw conclusion and apply elsewhere such as the patellar tendon. Then in 2014 van der Worp did a RCT to look at the different types of shockwave therapy in treating patellar tendinopathy. They found that there was no difference between the group who received focused or radial shockwave therapy, but that all of the participants had improved. (Level of evidence: 1b) [28]

Conflicting this; van der Worp was involved in research some previous years in 2011 where they found there was no effect of ESWT as a solitary treatment during the competitive season, and has no benefit over placebo treatment (Level of evidence: 1b) [29]. Thijset al 2016 was in agreement from their study that there was no added benefit of using ESWT in participants with patellar tentindopathy, although they did highlight that they only had a small sample size, therefore is not a true representation of the population.(Level of evidence: 1b) [30] Similarly was Park et al 2016, who looked at the use of ESWT in calcific and non calcific lateral epicondylopathy. (Level of evidence: 2b) [31]

In summary ESWT has conflicting evidence, there is some evidence to suggest that use in soft tissue complaints such as international or calcific tendinopathy may be beneficial, whereas other evidence conflicts that. ESWT is a painful / uncomfortable experience, that is expensive with confliting research therefore clinical reasoning and critiquing the literature is essential.


In summary the literature for supporting electrotherapy within knee pathologies is variable. The only guidelines that suggests the use of electrotherapy for a knee complaint is the use of TENS in knee OA. Pulsed shortwave therapy has limited evidence to support it's use in the management of tissue healing and the evidence that is available is of poor quality and conflicting, similarly to ultrasound and ESWT. The use of TENS is possibly the strongest evidence of all in pain management but the theory itself is under criticism, through the volume of literature surrounding pain neuroscience. 

There is a selection of evidence quoted and carried out by with references that are unobtainable; therefore they have not been taken into consideration in creation of this page. It would be beneficial to critique this literature, as this group of researchers highly promote the use and effectiveness of electrotherapy.

Ultimately the use of electrotherapy in the treatment of knee pathologies needs to be evaluated and clinically reasoned by the clinician prior to use, being  aware of all of the appropriate contraindications and precautions. 


  1. Electrotherapy. Pulsed Shortwave Therapy. (accessed 27 Nov 2016)
  2. Al‐Mandeel MM, Watson T. The thermal and non-thermal effects of high and low doses of pulsed short wave therapy (PSWT). Physiotherapy Research International. 2010 Dec 1;15(4):199-211 (Level of evidence: 2b)
  3. Callaghan MJ, Whittaker PE, Grimes S, Smith L. An evaluation of pulsed shortwave on knee osteoarthritis using radioleucoscintigraphy: a randomised, double blind, controlled trial. Joint Bone Spine. 2005 Mar 31;72(2):150-5.Ultrasound (Level of evidence: 1b)
  4. NICE. Osteoarthritis: Care and Management: Non-pharmacological management. (accessed 27 Nov 2016) (Level of evidence: 1a)
  5. Buzzard BM, Pratt RK, Briggs PJ, Siddique MS, Tasker A, Robinson S. Is pulsed shortwave diathermy better than ice therapy for the reduction of oedema following calcaneal fractures?: Preliminary trial. Physiotherapy. 2003 Dec 31;89(12):734-42. (Level of evidence: 4)
  6. Physiopedia. Transcutaneous Electrical Nerve Stimulation (TENS). (accessed 27 Nov 2016)
  7. Electrotherapy. Transcutaneous Electrical Nerve Stimulation. (accessed 27 Nov 2016)
  8. Physiopedia. Transcutaneous Electrical Nerve Stimulation (TENS). (accessed 27 Nov 2016)
  9. Electrotherapy. Transcutaneous Electrical Nerve Stimulation. (accessed 27 Nov 2016)
  10. Mendell LM. Constructing and deconstructing the gate theory of pain. PAIN®. 2014 Feb 28;155(2):210-6.
  11. Wall PD. Dorsal horn electrophysiology. InSomatosensory System 1973 (pp. 253-270). Springer Berlin Heidelberg.
  12. Carroll D, Moore RA, McQuay HJ, Fairman F, Tramer M, Leijon G. Transcutaneous electrical nerve stimulation (TENS) for chronic pain. The Cochrane Library. 2000.
  13. Catley MJ, Gibson W, Wand BM, Meads C, O'Connell NE. Transcutaneous Electrical Nerve Stimulation (TENS) for chronic pain‐an overview of Cochrane reviews. The Cochrane Library. 2015.
  14. NICE. Osteoarthritis: Care and Management: Non-pharmacological management. (accessed 27 Nov 2016) (Level of evidence: 1a)
  15. Arthritis Research UK. What treatments are there for osteoarthritis of the knee? (accessed 27 Nov 2016)
  16. Johnson MI, Paley CA, Howe TE, Sluka KA. Transcutaneous electrical nerve stimulation for acute pain. The Cochrane Library. 2015 Jan 1.
  17. Watson T. Tissue Repair: The Current State of the Art. SportEx Medicine. 2005;28
  18. Tsai WC, Tang ST, Liang FC. Effect of therapeutic ultrasound on tendons. American Journal of Physical Medicine & Rehabilitation. 2011 Dec 1;90(12):1068-73.
  19. Desmeules F, Boudreault J, Roy JS, Dionne C, Frémont P, MacDermid JC. The efficacy of therapeutic ultrasound for rotator cuff tendinopathy: A systematic review and meta-analysis. Physical Therapy in Sport. 2015 Aug 31;16(3):276-84. (Level of evidence: 1a)
  20. Takakura Y, Matsui N, Yoshiya S, Fujioka H, Muratsu H, Tsunoda M, Kurosaka M. Low-intensity pulsed ultrasound enhances early healing of medial collateral ligament injuries in rats. Journal of ultrasound in medicine. 2002 Mar 1;21(3):283-8. (Level of evidence: 3b)
  21. Robertson VJ, Baker KG. A review of therapeutic ultrasound: effectiveness studies. Physical Therapy. 2001 Jul 1;81(7):1339-50. (Level of evidence: 1a)
  22. Zammit E, Herrington L. Ultrasound therapy in the management of acute lateral ligament sprains of the ankle joint. Physical Therapy in sport. 2005 Aug 31;6(3):116-21. (Level of evidence: 1b)
  23. Electrotherapy. Shockwave therapy. (accessed 27 Nov 2016)
  24. Electrotherapy. Shockwave therapy. (accessed 27 Nov 2016)
  25. NICE. Extracorporeal shockwave therapy for refractory Achilles tendinopathy. (accessed 27 Nov 2016) (Level of evidence: 1a)
  26. Diehl PD, Gollwitzer H, Schauwecker J, Tischer T, Gerdesmeyer L. Konservative Therapie der chronischen Enthesiopathien. Der Orthopäde. 2014 Feb 1;43(2):183-93.
  27. Rees JD, Maffulli N, Cook J. Management of tendinopathy. The American journal of sports medicine. 2009 Sep 1;37(9):1855-67. (Level of evidence: 1a)
  28. van der Worp H, Zwerver J, Hamstra M, van den Akker-Scheek I, Diercks RL. No difference in effectiveness between focused and radial shockwave therapy for treating patellar tendinopathy: a randomized controlled trial. Knee Surgery, Sports Traumatology, Arthroscopy. 2014 Sep 1;22(9):2026-32. (Level of evidence: 1b)
  29. Zwerver J, Hartgens F, Verhagen E, van der Worp H, van den Akker-Scheek I, Diercks RL. No effect of extracorporeal shockwave therapy on patellar tendinopathy in jumping athletes during the competitive season A randomized clinical trial. The American journal of sports medicine. 2011 Jun 1;39(6):1191-9. (Level of evidence: 1b)
  30. Thijs KM, Zwerver J, Backx FJ, Steeneken V, Rayer S, Groenenboom P, Moen MH. Effectiveness of Shockwave Treatment Combined With Eccentric Training for Patellar Tendinopathy: A Double-Blinded Randomized Study. Clinical Journal of Sport Medicine. 2016 Jun 22. (Level of evidence: 1b)
  31. Park JW, Hwang JH, Choi YS, Kim SJ. Comparison of Therapeutic Effect of Extracorporeal Shock Wave in Calcific Versus Noncalcific Lateral Epicondylopathy. Annals of rehabilitation medicine. 2016 Apr 1;40(2):294-300. (Level of evidence: 2b)