Table 2.

Characteristics of arthritis in BS.

Localization*	Knee	33%
	Ankle joint	24
	Wrist	14
	Hand	11
	Foot	8
	Elbow	5
	Sacroiliac joint	<5
	Hip	<5
	Shoulder	<5
Number of joints†	Monoarticular	66
	Oligoarticular	29
	Polyarticular	4
Duration†	Acute (<6–8 weeks)	89
	Chronic (>8 weeks)	11
Synovial fluid examination§	Cell count	11,000/ul (1,600–36,000/ul)
	Cell type	Predominantly polymorphonuclear
Radiography	Typically non-erosive

^*Calculated with a total of 609 arthritis episodes extracted from the publications of Yurdakul et al. (79), Gur et al. (37), and Fatemi et al. (36).

^†Calculated with a total of 493 (duration) and 369 (number of Joints) arthritis episodes extracted from publications of Yurdakul et al. (79) and Fatemi et al. (36).

^§Calculated with extraction 38 synovial fluid analyses from Yurdakul et al. (79) and Gibson et al. (81).