De Meester Liesbet1, Gaelle Varkas2, Manouk de Hooge3, Ann-Sophie De Craemer4, Nele Herregods5, Lennart Jans5, Philippe Carron6, Dirk Elewaut7 and Filip Van den Bosch8, 1Department of Rheumatology, Ghent University Hospital, Ghent, Belgium, 2Dept. of Rheumatology, Ghent University Hospital, Ghent, Belgium, 3Ghent University Hospital, Hesperange, Luxembourg, 4Ghent University Hospital, Gent, Belgium, 5Department of Radiology, Ghent University Hospital, Ghent, Belgium, 6UZ Gent, Gent, Belgium, 7Ghent University and VIB Center for Inflammation Research, Ghent, Belgium, 8Department of Internal Medicine and Pediatrics, Ghent University and VIB Center for Inflammation Research, Ghent, Belgium
Background/Purpose: Sacroiliac bone marrow oedema (BMO) on MRI, immediately after childbirth, has been observed in a large proportion of postpartum women and appears to be a transient phenomenon. Although generally attributed to mechanical stress, these postpartum BMO lesions bear a striking resemblance to the inflammatory lesions seen in axial spondyloarthritis (axSpA). In axSpA, active inflammatory lesions are likely to progress to structural lesions, particularly fat metaplasia and erosions. It is not known whether the same is true for mechanical stress-induced BMO. To assess the long-term evolution of postpartum BMO and the potential development of axSpA-like structural lesions, we performed a 5-year follow-up ofour prospective study on sacroiliac MRI lesions in healthy women following an uncomplicated vaginal delivery.
Methods: Seventeen (48.6%) of the original 35 participants underwent a new MRI of the sacroiliac joints (MRI-SIJ) approximately 5 years after delivery. Structural lesions (fat metaplasia, erosions, sclerosis, (partial) ankylosis) and BMO were scored by three well-trained, calibrated readers using the Spondyloarthritis Research Consortium of Canada (SPARCC) scoring system. Agreement with the Assessment of SpondyloArthritis international Society (ASAS) MRI definition of sacroiliitis was assessed. Baseline MRI images were re-evaluated, and compared with the 5-year follow-up MRI data. Demographic, clinical, and obstetric data were updated.
Results: The overall prevalence of fat metaplasia, erosions and sclerosis on baseline and 5-year MRI images was low. No ankylosis was found. Scores for fat metaplasia and erosions did not change significantly between the two time points. A numerical increase in sclerosis score at year 5 was seen in only3 of 17 subjects, all of whom had BMO after delivery. As expected, there was a significant decrease in BMO from baseline to year 5. Six of the 17 subjects (35%) still had BMO at the 5-year follow-up MRI-SIJ,3 of whom met the ASAS definition of sacroiliitis. No deep or intense BMO lesions were observed.
Conclusion: In postpartum women, nosignificant development of axSpA-like structural MRI lesions was observed 5 years after delivery. These results support the hypothesis that transient mechanical stress-induced sacroiliac BMO, while resembling axSpA on MRI,does not evolve into chronic structural lesions.
D. Liesbet: None; G. Varkas: AbbVie/Abbott, 1, 2, 5, 6, Eli Lilly, 6, Novartis, 6, UCB, 1, 2, 6; M. de Hooge: UCB, 6; A. De Craemer: None; N. Herregods: None; L. Jans: None; P. Carron: AbbVie/Abbott, 2, 6, Bristol-Myers Squibb(BMS), 2, 6, Celgene, 2, 6, Eli Lilly, 2, 6, Gilead, 2, 6, Merck/MSD, 2, 5, 6, Novartis, 2, 6, Pfizer, 2, 5, 6, UCB, 2, 5, 6; D. Elewaut: AbbVie/Abbott, 6, Bristol-Myers Squibb(BMS), 5, Eli Lilly, 2, galapagos, 5, Janssen, 6; F. Van den Bosch: AbbVie, 2, 6, Amgen, 2, BMS, 6, Celgene, 6, Eli Lilly, 2, Galapagos, 2, Janssen, 2, 6, Merck, 2, 6, Novartis, 2, 6, Pfizer, 2, 6, UCB Pharma, 2, 6.
