Alteration in corticospinal excitability, talocrural joint range of motion, and lower extremity function following manipulation in non-disabled individuals

Background: Clinical outcomes of manual therapy procedures, including manipulation, have been studied. However, mechanisms underlying observed improvements remain unclear. Objective: To determine the effect of ankle joint manipulation on corticospinal excitability, ankle dorsiflexion range of motion (DF ROM), and lower extremity functional behavior in nondisabled individuals. Method: Six nondisabled individuals (age range: 31-50 years) received the main outcomes measurements of this study, before and after long axis distraction manipulation of the talocrural joint. Main outcomes measures were motor evoked potential (MEP) amplitude of gastrocnemius (GN) and tibialis anterior (TA) using transcranial magnetic stimulation, ankle DF ROM with the knee flexed and extended using standard goniometric techniques, and unilateral anterior squat reach (ASR) distance. All subjects received the main outcomes measures. Results: Significant increase in GN MEP amplitude (P \u3c .05), but not TA MEP amplitude, were documented following intervention. Significant improvements also were noted in ankle DF ROM with knee extended and flexed (P \u3c .001) and ASR distance (P \u3c .05) Significant correlations were found between standardized change in GN MEP amplitude and ankle dorsiflexion with knee flexed (ρ = .582, ρ 2 = .339, P \u3c .01), and standardized changes in GN MEP amplitude and ASR distance (ρ = .601, ρ 2 = .361, P \u3c .01). Conclusions: Increased corticospinal excitability appears to mediate improvements in ankle DF ROM and lower extremity function following long axis distraction manipulation 1 Assistant Professor, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, to the talocrural joint in nondisabled individuals. These results establish comparative values with which to compare the corticospinal responses to manual therapy intervention in individuals with pathology. INTRODUCTION Ankle sprains are the most common injury to the ankle joint, affecting up to 2 million people and approximately 53 per 10,000 individuals per year. 1,2 Ankle sprains are common in younger and active individuals. 3-8 Certain sports and work activities may result in an even higher incidence and risk for injury. 9-15 Ankle sprains are a clinically important problem because they result in a substantial number of missed work days 8 and participation in sports activity, 3,5 as well as lead to potential early arthritic changes in the talocrural joint. 16 The prognosis for functional recovery following ankle sprain typically includes a rapid clinical improvement within the first two weeks after injury. 17 However, a series of recent studies indicate a subgroup of individuals appears predisposed to continued pain, functional deficits, and prolonged risk for additional reinjury between 6 weeks and 3 years post injury. 17-25 The prolonged disability associated with ankle sprains represents the possibility of increased direct and indirect health care costs associated with ankle sprains, and may be reduced through identification of optimal approaches to clinical management. One reason for continued pain and elevated risk for reinjury may be limited ankle joint mobility, which may occur as either a cause or consequence of ankle sprain. Limited ankle dorsiflexion has been documented as a major short-term sequel to ankle sprain. 26,27 In addition, several studies have identified limited talocrural joint dorsiflexion range of motion (DF ROM) as an important predisposing factor to ankle sprains. 28-30 Limited ankle DF ROM will position the talocrural joint in plantar flexion during weight bearing activities. This position is notable because the most common mechanism of injury for ankle sprains involves plantar flex-ion and inversion of the ankle and foot. The injury mechanism places excessive load on the anterior talofibular ligament (ATFL). With failure of ATFL, secondary restraint to inversion occurs by way of the calcaneo-fibular and posterior talofibular ligaments, placing them at similar risk for injury. Thus, limited ankle DF ROM may result in injury and consequent structural and functional compromise of the ankle lateral collateral ligaments. Physical therapists use mobilization and manipulation to improve ankle DF ROM following ankle sprains. Despite the intuitive appeal of applying these procedures to promote parallel improvements in talocrural DF ROM and functioning in individuals following ankle sprains, this notion has been the focus of relatively few prospective studies. 31 Pellow and Brantingham 32 were among the first to report reduced pain and improved function in individuals with ankle sprains receiving an ankle mortise distraction technique. Whitman and colleagues 33 reported rapid functional improvement after talocrural manipulation in a competitive volleyball player with a mild unilateral