Background It is considered that postural changes that occur in patients with ankylosing spondylitis (AS) are biomechanically compensated for by contribution from movements of hip, knee and ankle joints . The effects of this phenomenon on the foot, the most distal segment of the kinetic chain, have not been fully elucidated.
Objectives In the present study, our aim was to investigate possible changes in plantar load distribution in AS patients.
Methods The study enrolled 30 AS patients diagnosed as per modified New York criteria and 30 healthy controls matched for age, gender and body mass index. Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI) scores were obtained for all patients. Using a foot pressure platform, the distance from the center of pressure (CoP) to the posterior heel line was measured in centimeters (cm) in both groups (DCoP) (figure 1). Percent total plantar load distribution over the proximal half and distal half of the foot was calculated.
Results Mean DCoP distance was significantly shorter in AS patients 9.65±0.96 cm) in comparison to that of control group (10.41±0.89 cm) (p=0.011). While the percent total plantar pressure applied on proximal half of the foot was 60.46±7.62% in AS patients, it was only 55.95±6.21% in the control group (p=0.031). However, AS patients had less percent pressure applied on the distal half of the foot (39.53±7.62%) versus control patients (44.04±6.21%) (p=0.031). The mean ratio of the percent pressure distribution over the proximal half of the foot to the percent pressure distribution over the distal half of the foot was significantly greater in AS patients (1.64±0.62) compared to control group (1.31±0.35) (p=0.037).
Conclusions Plantar pressure distribution seems to be displaced towards the heel in the sagittal plane due to biomechanical changes in patients with ankylosing spondylitis. This points out to the significance of the lower extremities in the compensation of postural changes in AS patients.
Murray HC, Elliott C, Barton SE, Murray A: Do patients with ankylosing spondylitis have poorer balance than normal subjects? Rheumatology 2000, 39:497–500.
Disclosure of Interest None declared