The sesamoid index in psoriatic arthropathy.
OBJECTIVE
The sesamoid index was originally described as an aid to the diagnosis of acromegaly. We performed this study to assess the value of the thumb sesamoid index in the diagnosis of psoriatic arthropathy.


METHODS
Retrospective measurement of the sesamoid index (length x width of the medial thumb sesamoid), along with the age and sex were recorded for patients as described below. Patients with psoriasis were subdivided into those with or without radiographic evidence of hand arthropathy.


METHODS
Fifty-nine consecutive patients attending rheumatology clinics with arthralgia and psoriasis were studied. Comparison groups with radiographic evidence of rheumatoid arthritis (52 patients), osteoarthritis (44) or normal hands (55) were also recorded.


RESULTS
Twenty-one of 59 patients with psoriasis and arthropathy had a sesamoid index>40, compared with two of 52 with rheumatoid arthritis, none of 44 with osteoarthritis and none of 55 normals.


CONCLUSIONS
Psoriatic arthropathy is a recognised cause of bone enlargement, usually in the phalanges due to periostitis and proliferative enthesopathy. We have confirmed that psoriatic hand arthropathy can cause significant enlargement of the thumb sesamoids, a feature which is easily quantified and may assist diagnosis.
Whitehouse
Richard W
RW
Department of Clinical Radiology, Manchester Royal Infirmary, Oxford Road, Manchester, M13 9WL, UK. Richard.Whitehouse@cmmc.nhs.uk
Aslam
Rizwan
R
Bukhari
Marwan
M
Groves
Clare
C
Cassar-Pullicino
Victor
V
D000328:Adult; D000367:Age Factors; D000368:Aged; D015535:Arthritis, Psoriatic / Q000150:complications / Q000175:diagnosis*; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000150:complications / Q000175:diagnosis; D011565:Psoriasis / Q000150:complications*; D011859:Radiography; D012189:Retrospective Studies; D012716:Sesamoid Bones / Q000000981:diagnostic imaging*; D012737:Sex Factors; D013933:Thumb / Q000000981:diagnostic imaging*