Muscle-tendon tissue properties in the hypermobility type of Ehlers-Danlos syndrome.
OBJECTIVE
To investigate the passive properties of the plantar flexors muscle-tendon tissue in patients with the hypermobility type of Ehlers-Danlos syndrome (EDS-HT).


METHODS
Twenty-five women with EDS-HT and 25 sex- and age-matched healthy control subjects participated in the study. Passive resistive torque (PRT) of the plantar flexors was measured with an isokinetic dynamometer during 2 standardized stretch protocols to obtain the passive muscle tension. Protocol 1 consisted of 4 continuous cycles to a predetermined angle of 10° dorsiflexion. Protocol 2 consisted of a slow stretch to the onset of pain. Torque, angle, and electromyography were simultaneously recorded during the tests. To take muscle thickness into account, muscle cross-sectional area (MCSA) was obtained with peripheral quantitative computed tomography. Stiffness of the Achilles tendon was assessed using a dynamometer in combination with ultrasonography.


RESULTS
The results demonstrate a significantly larger maximal joint angle in the EDS-HT patients accompanied by a similar PRT compared to the control subjects (protocol 2), indicating a lower passive muscle tension in the patient group. PRT for the predetermined angle (protocol 1) was the same for both groups and there was no difference in MSCA. Furthermore, a significantly lower Achilles tendon stiffness was seen in the patient group than in the control group.


CONCLUSIONS
This study is the first to provide evidence for altered passive properties of the muscle-tendon unit in EDS-HT patients. These changes are thought to be associated with structural modifications in connective tissue.
Department of Rehabilitation Sciences andPhysiotherapy, Ghent University and Artevelde University College, De Pintelaan 185, Ghent, Belgium. Lies.Rombaut@ugent.be
Lies
L
Rombaut
Fransiska
F
Malfait
Inge
I
De Wandele
Nele
N
Mahieu
Youri
Y
Thijs
Patrick
P
Segers
Anne
A
De Paepe
Patrick
P
Calders
D000125:Achilles Tendon / Q000503:physiopathology*; D000328:Adult; D004535:Ehlers-Danlos Syndrome / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D008875:Middle Aged; D009129:Muscle Tonus / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011795:Surveys and Questionnaires