Abstract & Commentary
Synopsis: Measurable deficits in kinesthesia and ankle position sense are present in subjects with chronic ankle instability.
Source: Konradsen L. Factors contributing to chronic ankle instability: Kinesthesia and joint position sense. Journal of Athletic Training. 2002;37(4):381-385.
Konradsen discusses the literature and his own work related to deficits in kinesthesia and joint position sense in chronic ankle instability and presents a pathogenic model that connects a deficit in position sense to an increased risk of stumbling with a resultant lateral ankle sprain. He first explains that kinesthesia (joint motion detection) and joint position sense are precise sensorimotor functions that require sophisticated instrumentation for measurement. Joint position sense requires the matching of a set of angles set by the researcher and can be assessed passively or actively. He suggests that passive assessment isolates the proprioceptive ability of the ankle receptors and that active assessment tests proprioceptors in the muscle-tendon unit. He supports this theory with his own work showing that an anesthetic ankle block increased ankle position error when the ankle was moved passively to the index angle by the researcher, yet did not increase error when subjects were allowed to actively move their own ankles.
Konradsen also discusses kinesthesia and position sense deficits in chronic ankle instability vs acute inversion injury. Most studies of chronic ankle instability report deficits in kinesthesia and position sense, and he attributes inconsistency in these findings to the definition of chronic instability and to differences in testing protocols. With acute inversion injury, he cites research that shows significant deficits in position sense from a single sprain. He questions whether the deficits in kinesthesia and position sense seen in chronic instability are the result of a predisposition, a single inversion injury, or a single event that was inadequately rehabilitated.
Konradsen’s pathogenic model attempts to make a link between deficits in position sense and the swing phase of stride. He explains that the swing phase requires very accurate sensorimotor control and that the lateral border of the foot passes just 5 mm above the surface of the ground during this phase. With this small margin for error, loading of the ankle complex with the body weight at unanticipated heel contact can lead to inversion torque, resulting in further forced inversion of the ankle and susceptibility to injury. Konradsen makes an experimental link between increased ankle position replication error following inversion injury and increases in rotational error that drop the lateral border of the foot and engage the ground during the late swing phase. He postulates that small differences in replication error can have substantial clinical impact in the form of chronic ankle instability.
Comment by David H. Perrin, PhD, ATC
Konradsen correctly points out that measurement of kinesthesia and position sense requires sophisticated instrumentation. He proposes that clinical tests of postural stability and agility may be superior, yet these tests fail to isolate the components of the sensorimotor system that might be involved in chronic ankle instability. Additional research is needed to establish the efficacy of these and other tests to clinicians who do not have access to sophisticated laboratory instrumentation.
Konradsen’s pathogenic model of unprovoked ankle sprain and the importance of adequate sensorimotor control during the swing phase of stride seems consistent with Tropp’s suggestion that inappropriate positioning of the lower limb before heel strike likely increases the potential for injury.1 If the lateral border of the foot passes just 5 mm above the ground during level-surface walking, one can imagine the challenges uneven ground and externally induced forces and perturbations present to the athlete with chronic ankle instability. Tropp recommends rehabilitation that includes coordination training activities that provoke ankle inversion and eversion. Konradsen points out that the effect of these activities on kinesthesia and joint position sense is not exactly known. However, rehabilitation programs concerned with balance, coordination, and strength are known to reduce postural sway and increase peroneal muscle strength. These programs continue to be recommended for patients with chronic ankle instability while research seeks to find the best protocols for restoration of kinesthesia and ankle joint position sense.
Dr. Perrin, Dean, School of Health and Human Performance, University of North Carolina—Greensboro, is Associate Editor of Sports Medicine Reports.
Reference
1. Tropp H. Functional ankle instability revisited: Special communications/commentary. Journal of Athletic Training. 2002;37(4):512-515.
Measurable deficits in kinesthesia and ankle position sense are present in subjects with chronic ankle instability.
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