The immediate effect of soleus trigger point pressure release on restricted ankle joint dorsiflexion: A pilot randomised controlled trial

Summary

Objectives

The primary aim of this study was to investigate the immediate effect on restricted active ankle joint dorsiflexion range of motion (ROM), after a single intervention of trigger point (TrP) pressure release on latent soleus myofascial trigger points (MTrPs). The secondary aim was to assess aspects of the methodological design quality, identify limitations and propose areas for improvement in future research.

Design

A pilot randomised control trial.

Participants

Twenty healthy volunteers (5 men and 15 women; mean age 21.7 ± 2.1 years) with a restricted active ankle joint dorsiflexion.

Intervention

Participants underwent a screening process to establish both a restriction in active ankle dorsiflexion and the presence of active and latent MTrPs in the soleus muscle. Participants were then randomly allocated to an intervention group (TrP pressure release) or control group (no therapy).

Results

The results showed a statistically significant (p = 0.03) increase of ankle ROM in the intervention compared to the control group.

Conclusion

This study identified an immediate significant improvement in ankle ROM after a single intervention of TrP pressure release on latent soleus MTrPS. These findings are clinically relevant, although the treatment effect on ankle ROM is smaller than a clinical significant ROM (5°). Suggestions for methodological improvements may inform future MTrP research and ultimately benefit clinical practice in this under investigated area.

Introduction

An adequate ankle range of motion (ROM) is considered a necessary component for functional activities such as running, ascending and descending stairs and normal gait (Cavanagh, 1990, Donatelli, 1996, Brukner and Khan, 2006). A disturbance of ankle ROM, resulting from muscle tightness during gait, may affect not only the ankle-foot complex, but also the remaining joints of the lower extremities (You et al., 2009). Chronic myofascial pain in the calf muscles has been documented to cause a biomechanical abnormality of gait, resulting in an excessive knee flexion angle during the stance phase of gait (Wu et al., 2005). Adequate ankle dorsiflexion (>10°) is required in midistance for the tibia to advance over the foot and allow forward body movement (Norkin and White, 2003). If this ankle ROM is restricted by tight musculature, compensation may occur in the form of genu recurvatum, early knee flexion, early heel lift or excessive pronation at the subtalar joint (Prior, 1999). These compensatory mechanisms put undue stresses on structures and may lead to foot pathologies such as plantar fasciitis, achilles tendonitis and metatarsalgia (Hill, 1995). Increased subtalar joint pronation has also been identified as a “remote” contributing factor in patellofemoral pain (Crossley et al., 2006).

A commonly used description of myofascial trigger points is that by Travell and Simons (1992) and Simons et al. (1999), who define MTrPs as hyperirritable areas within taut bands of skeletal muscle or fascia. Within the literature, MTrPs have been classified as active or latent. Active MTrPs refer pain at rest or with muscular activity, whereas latent MTrPs are normally pain free unless direct pressure is applied to them (Travell and Simons, 1992, Simons et al., 1999). Latent MTrPs often cause stiffness and restricted ROM without pain and are far more common that active MTrPs (Simons et al., 1999).

MTrPs refer pain along a limb or body part and are found regionally, for example the neck, back, shoulder and lower limb. This muscular pain disorder is termed a myofascial pain syndrome (MPS) (Simons et al., 1999). MTrPs are considered a hallmark finding of MPS and within clinical practice are claimed to be a common source of musculoskeletal pain and dysfunction, in people presenting for manual therapy (Friction, 1990, Blanco et al., 2006).

Travell and Simons (1983) originally termed compression of a MTrP as “ischaemic compression”. Clinical evidence and the nature of MTrPs indicate that when applying digital pressure to inactivate a MTrP there is no need to exert sufficient pressure to produce ischaemia, as the core of the MTrP is already suffering from severe hypoxia (Travell and Simons, 1999). Therefore “ischaemic compression” has been replaced by “trigger point pressure release” which, according to Simons et al. (1999) is less vigorous, equally or more clinically effective and employs the barrier release concept advocated by Lewit (1999). TrP pressure release applied downward on a MTrP tends to lengthen sarcomeres and can be effective in increasing ROM and reducing muscle tension (Simons, 2004).

The need to include ROM measurements in future studies on the efficacy of manual therapy in MTrPs has been recommended as myofascial pain is characterised by restricted ROM (Fernández de las Peñas et al., 2005). Physiotherapists, particularly in orthopaedic practice, have traditionally focused on the measurements of impairments such as pain, range of motion and muscle strength (Abrams et al., 2006).

There is limited clinical evidence on the efficacy of manual therapy on MTrPs/MPS in the lower limb. A systematic review of the literature on the effectiveness of non invasive treatments for active MTrP pain, found twenty of the twenty-three included trials assessed the treatment of MTrPs in the neck and/or upper trapezius region (Rickards, 2006).

Although the available literature suggests that MTrPs may cause restricted joint ROM (Travell and Simons, 1983, Travell and Simons, 1992, Simons et al., 1999, Lucas et al., 2004, Fernández de las Peñas et al., 2005; Blanco et al., 2006), there is a scarcity of research suggesting that TrP pressure release may be an effective intervention for restriction in ankle ROM. It has been proposed that soleus MTrPs specifically relate to a restriction of dorsiflexion of the ankle (Travell and Simons, 1992).

The primary aim of this pilot study was to investigate the immediate effect of a single treatment of TrP pressure release of soleus on restricted active ankle dorsiflexion ROM. The secondary aim is to assess the methodological design quality of the pilot study and identify areas for improvement in future research.