title: A relationship between spinal new bone formation in ankylosing spondylitis and the sonographically determined Achilles tendon enthesophytes.
abstract: Spinal new bone formation is a major but incompletely understood manifestation of ankylosing spondylitis (AS). We explored the relationship between spinal new bone formation and ultrasound (US)-determined Achilles enthesophytes to test the hypothesis that spinal new bone formation is part of a generalized enthesis bone-forming phenotype. A multicenter, case control study of 225 consecutive AS patients and 95 age/body mass index (BMI) matched healthy controls (HC) was performed. US scans of Achilles tendons and cervical and lumbar spine radiographs were obtained. All images were centrally scored by one investigator for US and one for radiographs, blinded to medical data. The relation between syndesmophytes (by modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and the number of syndesmophytes) and enthesophytes (with a semi-quantitative scoring of the US findings) was investigated. AS patients had significantly higher US enthesophyte scores than HCs (2.1(1.6) vs. 1.6(1.6); p = 0.004). The difference was significant in males (p = 0.001) but not in females (p = 0.5). The enthesophyte scores significantly correlated with mSASSS scores (ρ = 0.274, p < 0.0001) with the association even stronger in males (enthesophyte scores vs. mSASSS ρ = 0.337, p < 0.0001). In multiple regression analysis, age, BMI, enthesophyte scores and disease duration were significantly associated with syndesmophytes in males, and keeping all other variables constant, increasing US enthesophyte scores increased the odds of having syndesmophytes by 67%. Male AS patients that have more severe US-determined Achilles enthesophyte also associated spinal syndesmophytes suggesting a bone-forming gender-specific phenotype that could be a useful marker predicting of new bone formation.
authors.affiliation: Department of Rheumatology, School of Medicine, Koc University, Guzelbahce sok, No: 20, Nisantasi, 34365, Istanbul, Marmara, Turkey. drsibelaydin@gmail.com.
authors.forename: Sibel Zehra
authors.initials: SZ
authors.lastname: Aydin
authors.affiliation: Rheumatology, Marmara University, Istanbul, Marmara, Turkey.
authors.forename: Meryem
authors.initials: M
authors.lastname: Can
authors.affiliation: Rheumatology, Marmara University, Istanbul, Marmara, Turkey.
authors.forename: Fatma
authors.initials: F
authors.lastname: Alibaz-Oner
authors.affiliation: Internal Medicine-Rheumatology Department Izmir, Ege University Medical School, Izmir, Turkey.
authors.forename: Gokhan
authors.initials: G
authors.lastname: Keser
authors.affiliation: Statistics, Istanbul Medeniyet University, Istanbul, Marmara, Turkey.
authors.forename: Esra
authors.initials: E
authors.lastname: Kurum
authors.affiliation: Internal Medicine-Rheumatology Department Izmir, Ege University Medical School, Izmir, Turkey.
authors.forename: Vedat
authors.initials: V
authors.lastname: Inal
authors.affiliation: Department of Internal medicine, Division of Rheumatology, Akdeniz University Hospital, Antalya, Turkey.
authors.forename: Veli
authors.initials: V
authors.lastname: Yazisiz
authors.affiliation: Division of Rheumatology Izmir, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Merih
authors.initials: M
authors.lastname: Birlik
authors.affiliation: Department of Rheumatology, School of Medicine, Koc University, Guzelbahce sok, No: 20, Nisantasi, 34365, Istanbul, Marmara, Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Emmungil
authors.affiliation: Rheumatology, Marmara University, Istanbul, Marmara, Turkey.
authors.forename: Pamir
authors.initials: P
authors.lastname: Atagunduz
authors.affiliation: Rheumatology, Marmara University, Istanbul, Marmara, Turkey.
authors.forename: Haner
authors.initials: H
authors.lastname: Direskeneli
authors.affiliation: Rheumatology LEEDS, Leeds, Yorkshire, UK.
authors.forename: Dennis
authors.initials: D
authors.lastname: McGonagle
authors.affiliation: Division of Rheumatology, Gulhane School of Medicine, Ankara, Turkey.
authors.forename: Salih
authors.initials: S
authors.lastname: Pay
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D016015:Logistic Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010012:Osteogenesis; D010641:Phenotype; D011237:Predictive Value of Tests; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D014421:Turkey; D055815:Young Adult
keywords: Ankylosing spondylitis; Bone-forming phenotype; Ultrasonography