It must be reiterated that pain referral is the cardinal feature of the myofascial trigger point (MTrP). As such simply trying to identify a MTrP by the presence of a taut band and tender point is insufficient. The referred pain patterns generated by the MTrP usually, but not always, occur within a predictable distribution as described by Travell and Simon’s. If the referred pain is familiar to the patient, i.e reminds them of the symptoms for which the patient may have sought treatment, the MTrP may be considered active. If the referred pain is unfamiliar is may be considered latent, but arguably the MTrP may still be worth treating.

Is the referred pain phenomenon a peripheral or central effect?

Evidence has concluded that referred pain is most certainly a central effect. My understanding of this has mostly centred at the dorsal horn where a ‘wind up’ may occur in response the afferent nociceptive barrage arising from the MTrP. This results in a progressive pain referral mostly within the associated segment. This effect has been supported by studies which have shown MTrP’s in rats capable of sensitising the dorsal horn with the development of new neurons.

A recent network meta-analysis was performed which considered acupuncture versus other physical therapies in the treatment of Osteoarthritis (OA) of the knee.

This complex research method is a first in acupuncture studies and was used to show how acupuncture compares with other physical interventions in the treatment of this condition. In a nutshell this research approach has the advantage of being able to pull large amounts of data together. In this study physical interventions were compared with standard care, and then acupuncture was compared with standard care. Interventions compared 18 physical therapies with 4 comparators - standard care, sham, placebo or no treatment.

The results showed that acupuncture is more effective that all other forms of physical therapy and significantly outperforms sham acupuncture. The conclusion was that acupuncture can be considered as one of the more effective physical treatments.

Given the fact the there is still significant deniability within the wider medical community regarding the existence of myofascial trigger points (MTrP), I am always interested to learn of further physical evidence to back up our clinical assessment findings.

Although the ability to image MTrP and taut band on ultrasound is not new, recently I was fortunate to view not only a still frame but a video clip of a needle penetrating a taut band an eliciting the local twitch response. The vigorous response from the muscle when the MTrP was targeted directly would suggest a level of reactive dysfunction within that particular portion of muscle which would be difficult to dispute, especially if the patients familiar pain was reproduced at the same time. Further ultrasound findings have included hypoechogenicity, alterations on local muscle tension and muscle entropy (Shah et al, 2008).

Introduction

Patellofemoral pain syndrome (PFPS) is the single most common condition seen by sports medicine practitioners.1 There is extensive literature investigating the efficacy of physical interventions for this condition,2 however there is relatively little considering the role of Acupuncture. This would be in contrast to knee osteoarthrosis which has been well investigated over recent years.3 In this case study an Acupuncture based approach was used to treat PFPS. What has been highlighted are the limitations of Acupuncture treatment if perpetuating factors are not adequately considered and addressed.

Presenting complaint

M complained of regular intermittent knee pain which was localised to the right supero-lateral aspect of the patella. He reported a VAS of 5 on the day of assessment. He also reported the same area as being tender to local pressure. Aggravating factors would be walking for 10 minutes or longer, climbing stairs, sitting with the knee flexed greater than approximately 80 degrees and any attempt to run. Rest and maintaining the knee in extension would ease the knee. Occasionally at night, if he were to roll onto the right knee, pain would wake him. Morning stiffness would be common. He noticed mild swelling around the lateral patella which would worsen towards the end of the day depending on how active he had been.

When using Medical Acupuncture in the treatment of musculoskeletal pain, I find myself in the main selecting either segmental points or trigger points if present, sometimes both.

Segmental points are basically those where tissue, preferably muscle, which shares the same segmental innervation as the structure likely to be responsible for nociceptive input, is stimulated. Trigger points must meet with the relevant diagnostic criteria and when using Medical Acupuncture to deactivate may be referred to as dry needling. These terms are often used interchangeably however, at least in Europe.

One of the conditions for which I find segmental Acupuncture particularly useful is that of knee osteoarthrosis and associated pain symptoms. The evidence would generally support using more local to the knee joint (White, 2007) and I would select points within muscles which act on the knee joint as well as sharing the same segental innervation. That said, so called sham Acupuncture can also be beneficial in providing pain relief and often extra-segmental points, those outside the segment, are used to augment the effects of segmental points.