1. Ludwig Boltzmann Institute for Arthritis and Rehabilitation, 5760 Saalfelden, Austria
2. Rehabilitation Center of the Austrian Pension Insurance Company (PVA), 5760 Saalfelden, Austria
3. Rehabilitation Center of the Austrian Pension Insurance Company (PVA), 1021 Vienna, Austria
4. Ludwig Boltzmann Institute for Arthritis and Rehabilitation, 8962 Gröbming, Austria