Isokinetic evaluation of ankle muscle strength and fatigue in patients with ankylosing spondylitis.

AIM

The aim of the study was to compare the strength and fatigue of ankle plantarflexor/dorsiflexor muscles using isokinetic dynamometer in patients with ankylosing spondylitis (AS) versus healthy control subjects.

DESIGN

A controlled study.

SETTING

Outpatients clinic of our Department of Physical Medicine and Rehabilitation.

POPULATION

Twenty-six AS patients and 26 control subjects participated in this study.

METHODS

In both groups the isokinetic tests are conducted by isokinetic dynamometer.The evaluations were made in plantarflexion/dorsiflexion patterns;peak torque, agonist/antagonist ratio and work fatigue isokinetic parameters were evaluated for the ankle 30 º/s, 60º/s, 120º/s angular velocities. Pain severity, clinical findings, and functional status were also evaluated in the study group.

RESULTS

In the patient group, ankle plantarflexion muscle strength was significantly lower compared to the control group in all angular velocities (P<0.05). Agonist/antagonist ratio was significantly lower in the patient group compared to the control group in all angular velocities (P<0.01). The work fatigue was decreased for bilateral ankle plantarflexors at 120º/s angular velocities (P<0.05). There was no significant difference between the measurements of ankle dorsiflexors (P>0.05). There was no relation between the decreased muscle strength and pain severity, clinical findings, and functional status of AS patients.

CONCLUSION

We found ankle muscles fatigue and decreased ankle plantarflexor muscle strength in patients with AS compared to control subjects.