Table 1.

AS-Balance studies with devices

Studies	Sawacha et al. [12]	Murray et al. [27]	Batur et al. [28]	Aydog et al. [11]	Vergara et al. [2]	Durmus et al. [13]
Subjects	12 healthy, 12 AS	30 AS(mild, moderate, severe)	34 healthy, 34 AS	35 healthy, 70 AS	17 healthy, 16 AS	50 healthy, 64 AS (tragus to wall distance<15 cm Group I and≥15 cm Group II)
Clinical assessment	BASMI, BASDAI, BASFI, manual muscle strength test, ROM	Schober test, tragus to wall, chest expansion	Schober test, hand to ground distance, tragus to wall distance, occiput to wall distance, BASMI, Berg Balance Scale, Functional Reach Test, Lateral Reach Test.	BASMI	BASDAI, BASMI, BASFI, Ankylosing Spondylitis Quality of Life Index (ASQoL), patient global assessment, total and nocturnal back pain scores	BASMI, BASDAI, BASFI, Chest expansion, fingertip-to-floor distance, occiput to wall distance
Instrumental assessment	Six cameras stereophotogrammetric system (60–120 Hz, BTS S.r.l., Padova, Italy) synchronized with a Bertec force plate (FP4060-10, 960 Hz)	Sway magnetometry	Kinesthetic Ability Trainer 3000 (KAT-3000, Med-Fit Systems Inc., Fallbrook, CA, USA). Postural sway was calculated by using the Emed®-X (Novel GmbH, Munich, Germany) system	Biodex Stability System (Biodex Medical Systems, Shirley, NY, USA).	Two AMTI force platforms (Model OR6-7; Advanced Mechanical Technologies, Inc, Watertown, MA, USA) for ground reaction forces. VICON motion analysis system (VICON Motion Systems, Oxford, UK,128 Hz) for force plate data	Biodex Stability System (Biodex, Inc., Shirley, NY)
Summary result	-AS subjects had poor posture with reduced pelvic anteversion and excessive trunk and knee flexion -AS subjects displayed balance impairment also during Romberg test both in eyes closed and open condition. -AS people who are characterized by a stoop posture when asked to watch a target at a higher or lower level than eyes height, they increased their knee flexion with a dorsiflexed ankle.	-Balance was worse in AS patients in both eyes were open and closed conditions -No significant differences between AS severity and balance	-Eyes closed anteroposterior sway significantly higher in the subject group - Occiput to wall distance was found to be correlated with anteroposterior center of pressure sway.	- The anteroposterior, mediolateral, overall stability indices were not significantly higher than controls.	- Frontal and sagittal plane net center of pressure displacement was greater at patient group.	-Anteroposterior, Mediolatera and Overall Stability Index were significantly different between healthy and AS groups. - Anteroposterior, Mediolateral and Overall Stability Index were significantly different between group 1 and group 2.

AS: ankylosing spondylitis; BASMI: bath ankylosing spondylitis metrology index; BASDAI: bath ankylosing spondylitis disease activity index; BASFI: bath ankylosing spondylitis functional index; ROM: range of motion