Structural characteristics and functional consequences of lateral ankle sprains

Abdeen, R

Abstract

Ankles injuries account for 8% of health care consultations and ankle sprains
constitute about 85% of all ankle injuries. Lateral ankle sprain is a type of injury that affects
both the general and the sporting population. Lateral ankle sprain has a high rate of
recurrence which can often lead to individual developing chronic ankle instability. This
chronicity contributes to continue deficits of sensorimotor and constrained functioning)
which could have a decrease effect on the health-related quality of life, the level of physical
activity, and absence from training or competition for athletes, thus create a substantial global
healthcare burden. With such negative consequences and related financial burden associated
with LAS and CAI enhanced effort to understand structure and function differences between
those that develop CAI and those that do not following an initial acute LAS is needed.

Understanding the relationships between the integrity of the ankle structures pre and
post sprain, and functional ability of the ankle is important to inform our understanding of the
long-term effects of sprains and consider better targeting of interventions. This thesis aims to
study the structural characterisation and functional consequences of lateral ankle sprain.
Three studies were undertaken.

The first study used ultrasound to characterise and compare selected ankle structures
between healthy (n=48), coper (n=22) and chronic ankle instability (n=32) groups.
Participants with prior injury had significantly longer anterior talofibular ligament when the
ligament was under tension (by 6% when compared CAI to healthy participants), and thicker
anterior talofibular ligament and calcaneofibular ligament compared to healthy participants
(by 54.21% and 8.3% respectively when compared CAI to healthy participants). These gross
structural differences are evidence of residual structural damage. However, they do not
indicate whether the quality and nature of the ligament tissue is similarly affected.

In study 2 image analysis techniques were used to provide a quantitative measure of
the echogenicity of the anterior talofibular ligament by computer-aided greyscale analysis.
Echogenicity was used as an indicator of ligament quality. The result showed that the echo
intensity of anterior taloibular ligament was lowest intensity in chronic ankle instability (40
% and 18.8% lower than the intensity of healthy and coper respectively) followed by copers
and healthy respectively. The echogenicity of the anterior talofibular ligament in copers was
significantly different from chronic ankle instability and from healthy participants.
Characterisation of these further structural changes reveals the extent of residual tissue
damage. However, it does not provide any insight into any functional consequences of these
changes.

In a third study, the dynamic balance was evaluated in healthy (n=28), coper (n=18)
and chronic ankle instability (n=22) ankles during the star excursion balance tests, using
force plate and ankle kinematic analysis. This sought to investigate the functional
consequences of the structural changes identified in studies 1 and 2. Participants with chronic
ankle instability demonstrated poorer dynamic balance and altered ankle kinematics
compared to healthy and coper participants, and copers also had altered kinematics. There
was a significant negative relationship between the thickness of the ligament and the distance
achieved when reaching in the anterolateral direction of the balance test (r = -0.53,
p<0.001and r = -0.40, p<0.001 respectively). Characterisation of normal and injured
ligaments appears to differentiate post sprain functionally. Balance tests reveal functional
balance deficits and altered kinematic strategies that relate to the lateral ankle structures
previously injured.

Lateral ankle sprain causes damage to lateral ankle ligaments and impaired sensory
pathway to the CNS. Then the initial consequences lead to structural alteration (increased the
laxity of ATFL and increased the thickness of ATFL and CFL). Joint loading could be altered
and changes in normal movement patters occur as demonstrated in decrease reach distance
and alter the kinematics of the ankle joint in injured participants compared to healthy
participants. This is the first study that combined both structural changes and functional
consequences of lateral ankle sprain and investigate any relationship between them to provide
an overall understanding of how these two factors are related..

Citation

Abdeen, R. (in press). Structural characteristics and functional consequences of lateral ankle sprains. (Thesis). University of Salford

• Thesis Type: Thesis
• Acceptance Date: Apr 30, 2019
• Deposit Date: May 7, 2019
• Publicly Available Date: May 7, 2019