The initial effects of a Mulligan's mobilization with movement technique on dorsiflexion and pain in subacute ankle sprains

Abstract

Physiotherapists frequently use manipulative therapy techniques to treat dysfunction and pain resulting from ankle sprain. This study investigated whether a Mulligan's mobilization with movement (MWM) technique improves talocrural dorsiflexion, a major impairment following ankle sprain, and relieves pain in subacute populations. Fourteen subjects with subacute grade II lateral ankle sprains served as their own control in a repeated measures, double-blind randomized controlled trial that measured the initial effects of the MWM treatment on weight bearing dorsiflexion and pressure and thermal pain threshold. The subacute ankle sprain group studied displayed deficits in dorsiflexion and local pressure pain threshold in the symptomatic ankle. Significant improvements in dorsiflexion occurred initially post-MWM (F_(2,26)=7.82, P=0.002), but no significant changes in pressure or thermal pain threshold were observed after the treatment condition. Results indicate that the MWM treatment for ankle dorsiflexion has a mechanical rather than hypoalgesic effect in subacute ankle sprains. The mechanism by which this occurs requires investigation if we are to better understand the role of manipulative therapy in ankle sprain management.

Introduction

The lateral ligament complex of the ankle, described as the body's “most frequently injured single structure” (Garrick, 1977), is mechanically vulnerable to sprain injury. At extremes of plantarflexion and inversion, influenced by the shorter medial aspect of the ankle mortise, the relatively weak anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) are prone to varying grades of rupture, often via minimal force (Hockenbury and Sammarco, 2001).

Immediate inflammatory processes produce acute anterolateral pain and oedema, with avoidance of movement and weight bearing (Wolfe et al., 2001). Subsequent losses of joint range, particularly dorsiflexion, and muscle strength results in significant gait dysfunction. Recent data from our laboratory highlights the presence of a dorsiflexion deficit not only in the acute stage, but also in the subacute stage (Yang and Vicenzino, 2002).

Early physiotherapy intervention consists of rest, ice, compression, elevation (RICE) and electrotherapy modalities to control inflammation, as well as manipulative therapy and therapeutic exercise techniques to address impairments of movement and strength (Wolfe et al., 2001; Hockenbury and Sammarco, 2001). Green et al. (2001) investigated the impact of combining non-weight-bearing talocrural anteroposterior (AP) passive mobilisations, believed to restore dorsiflexion range, with the RICE protocol in the treatment of acute ankle sprains. The experimental group (n=19) demonstrated a more rapid improvement in pain-free dorsiflexion and function than the control group (n=19) who were treated solely with RICE. This provides important evidence substantiating the role of passive joint mobilizations in an acutely injured population.

The mobilization with movement (MWM) treatment approach for improving dorsiflexion post-ankle sprain combines a relative posteroanterior glide of the tibia on talus (or a relative anteroposterior glide of the talus on the tibia) with active dorsiflexion movements, preferentially in weight bearing (Mulligan, 1999). Claims of rapid restoration of pain-free movement are associated with MWM techniques generally (Mulligan (1993), Mulligan (1993); Exelby, 1996). Through examination of the effects of MWM on ankle dorsiflexion in asymptomatic mildly restricted ankle joints, Vicenzino et al. (2001) found that both the weight bearing and non-weight-bearing variations of the dorsiflexion MWM technique produced significant gains in dorsiflexion range. However, weight-bearing treatment techniques are widely believed to be superior to non-weight-bearing techniques, as they replicate aspects of functional activities (Mulligan, 1999). Acute ankle sprains, whilst having marked reduction in dorsiflexion range of motion, are frequently painful in full weight bearing, and weight-bearing techniques are not clinically indicated. The subacute ankle sprain is characterized by significant residual deficits in dorsiflexion (Yang and Vicenzino, 2002) and the capacity to fully weight bear, making it a good model on which to study the initial effects of weight-bearing MWM on dorsiflexion.

The mechanism of action of manipulative therapy has been the focus of several reports in recent times, however spinal manipulative therapy appears to be the common subject of research. A synopsis of current evidence for the initial mechanism of action of manipulative therapy indicates in part a neurophysiological basis (Vicenzino et al (1996), Vicenzino et al (1998), Vicenzino et al. (2001)). Manipulative therapy treatment techniques studied have exhibited non-opioid hypoalgesia to mechanical but not thermal pain stimuli (Vicenzino et al. (1995), Vicenzino et al (1998)).

The primary objective of this study was to test the hypothesis that application of Mulligan's MWM technique for talocrural dorsiflexion to subacute lateral ankle sprains produces an initial dorsiflexion gain, and simultaneously produces a mechanical but not thermal hypoalgesia.