Exploratory study to identify mechanical factors that may contribute to toe dactylitis in patients with psoriatic arthritis Richard J Wilkins, Dr Heidi J Siddle, Prof. Anthony C Redmond, Dr Philip S Helliwell Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds Background • Dactylitis (sausage digit) is one of the most commonly reported features of psoriatic arthritis (PsA) (Fig 1). • It has been hypothesised that dactylitis is a functional enthesitis at the proximal interphalangeal joints (hands and feet), resulting in synovitis, tenosynovitis, bone and soft tissue oedema to the digit. • Trauma and physical insult to the digit have been suggested as a possible cause. Results • PsA patients in both groups had a mean disease duration of 4.5years • Mean FIS-RAIFout of 21 - PsA Dactylitis 7.16 - PsA no history of dactylitis 6.83 - Controls 0.41 • Mean FIS-RAAPOut of 30 - PsA Dactylitis 8.75 - PsA no history of dactylitis 5.75 - Controls 0.16 Aim 1. To explore mechanical factors that may contribute to the occurrence of dactylitis in patients with PsA. • ANOVA analysis and subsequent post-hoc testing using Games-Howell test yielded significance in FIS-RA mean scores. 2. To explore the impact of dactylitis on impairment, function, activity and limitations. Figure 1. Dactylitis of the fourth toe Figure 2. Plantar pressure with masking 3. To provide insight into plantar pressure distributions in PsA. • No Significant difference in plantar pressures or gait variables between groups Results Methods • 12 participants with PsA and a history of dactylitis (group i), 12 participants with PsA and no history of dactylitis (group ii), 12 control participants (group iii) were recruited. Conclusions • This is the first exploratory study to investigate the mechanical factors that may cause dactylitis in PsA • Plantar pressure measurements were undertaken barefoot and in footwear. • FIS-RA scores indicate PsA patients have significant limitations compared to controls, but a history of dactylitis does not worsen outcomes. patient reported • Peak plantar pressure and pressure time integral were analysed at the most common and second most common sites of dactylitis reported in the foot; 2ndand 4thtoes, and 2ndand 4th metatarsophalangeal joints (MTP) of the left foot (fig 2). • Although reported in plantar pressure data or gait variables, the study was underpowered. no significant differences could be • Temporal and spatial parameters of gait were collected • Exploration of shear and friction in the forefoot may provide insight for a biomechanical trigger to dactylitis. Patient reported impairment and footwear (FISAP), and activity limitation and participant restriction (FISIF) were reported using the Foot Impact Scale for Rheumatoid Arthritis (FIS-RA). • Brockbank, J. E., et al. (2005)., Annals of the Rheumatic Diseases 64(2): 188-190. Chandran, V. (2009), J Rheumatol 36(2): 213-215. Firth, J. et al. (2007). Clinical Biomechanics 22(5): 603-606. Gladman, D. et al. (2005), Annals of the Rheumatic Diseases 64(suppl 2): ii14-ii17. Healy, P. J. et al. (2008), Rheumatology 47(1): 92-95. Healy, P. J. and P. S. Helliwell (2006). Current rheumatology reports 8(5): 338-341. Hyslop, E. et al. (2010). Annals of the Rheumatic Diseases 69(5): 928. Hyslop, E.,, et al. (2010). Gait & posture 32(4): 619-626. McGonagle, Det al. (2008) Annals of the rheumatic diseases 67(1): 1-4. Taylor, W, et al. (2006). Arthritis & Rheumatism 54(8): 2665-2673 Woodburn, J., et al. (2013). Scandinavian Journal of Rheumatology(00): 1-4.