Graduated in 1981 from the University of Applied Sciences Leiden as a physiotherapist. She has worked in hospitals in the Netherlands and abroad and has worked in private practices. Since 2000 Gertie has been working at Physiotherapy Health Centre Wassenaar as a physiotherapist with a specialization in Bugnet therapy (postural resistance therapy).
She is an advising physiotherapist of the Bugnet Foundation in the Netherlands and also provides workshops and courses. Beside this she is a member of the Paramedic Advisory Panel of the contact group Marfan in the Netherlands. Her specialties are patients with hypermobility (HDS, Ehlers-Danlos, Marfan), instability and postural deviations including scoliosis, kyphosis and kyphoscoliosis.