Ankle sprain : subjective and objective measures of functional impairment and treatment

Abstract

This thesis is based upon a series of studies were performed in order to provide more information about the etiology of late symptoms after ankle sprain, most often referred to as functional instability of the ankle joint. In a retrospective study of basketball players, the incidence of ankle sprains and the prevalence of late symptoms after such an injury were investigated. The injury incidence was calculated to 5.5 ankle injuries /1000 activity hours, which is three to four times higher than in Swedish elite basketball, soccer and orienteering. 52% reported late symptoms after ankle sprain.

Impaired proprioception is a suggested cause of chronic symptoms after ankle sprain. We registered increased postural sway in basketball players with previous ankle sprain by stabilometric recordings as a sign of a proprioceptional deficit. The active dorsiflexion angle was smaller in the basketball players than in the controls and may contribute to the high incidence of ankle sprains in basketball players.

Postural sway was registered in classical ballet dancers. During the study six dancers sustained an ankle sprain and for this group recordings before and after the injury were obtained. Following ankle sprain, postural sway was increased for several weeks. During rehabilitation postural stability gradually improved, also after professional dancing had been resumed.

In a prospective study of 73 patients we studied the influence of an ankle sprain on objective modalities of ankle joint function. We also studied if treatment with an Air-Stirrup® ankle brace could enhance the restoration of function compared to a traditionally used compression bandage. Ankle sprain resulted in a decreased active range of motion in eversion-inversion during the ten week follow-up period. We registered increased postural sway standing on the injured foot up to four weeks after the injury, a deficit in evertor muscle peak torque and a evertor-invertor muscle imbalance at ten weeks. A longer curve running time with the injured ankle in outside of the curve was noted during the follow-up.

The group treated with Air-Stirrup® ankle brace was more mobile as measured with Sickness Impact Profile self-rating questionnaire, showed a larger range of motion in the initial phase of the rehabilitation and a shorter sick leave. Ankle brace treatment resulted in socioeconomic savings.

A late follow-up two years after the ankle sprain was performed. 33% reported late symptoms, 30% in the ankle brace group and 38% in the control group. In the group with no symptoms, arestoration of evertor muscle torque was registered, which had not occurred in the subjects with late symptoms of instability, leading to a manifest evertor-invertor muscle imbalance.

The effect of taping of the ankle on postural sway at perturbation was studied in subjects with chronic ankle instability, using a specially designed pelturbation device. Taping of the ankle resulted in a decreased postural sway at perturbation before but not after a training session, indicating that the prophylactic effect of laping is most important during the first part of a practice session or a game. With untaped ankle, the postural sway decreased after the training session. The results could beexplained by a faster neuromuscular response to dysequilibrium with the tape applied and also awarm-up effect from exercise.

In summary, subjective and objective measures of ankle joint function are used in subjects with acute and chronic instability. The presented results and methods could be used when designing and evaluating a rehabilitation program in patients with ankle sprain or symptoms of chronic instability in order to prevent reinjuries.