CASE 6137 Published on 07.09.2007

A case of osteitis condensans ilii

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Marco Santoro1, Salvatore Alaimo2 1 Dipartimento di Scienze Cliniche e Bioimmagini, Sezione di Scienze Radiologiche, Università degli Studi “G.d’Annunzio”, Ospedale “SS. Annunziata”, Chieti, Italy. 2 Istituto di Radiodiagnostica e Radioterapia, Azienda Ospedaliero-Universitaria Policlinico “Gaspare Rodolico” di Catania, Italy.

Patient

28 years, female

Clinical History
History of low back pain, gradually started after pregnancy. The pain was localized in the lumbo-sacral area, and occasionally radiated to the hips; It was persistent, not alleviated by analgesics or anti-inflammatory drugs.
Imaging Findings
A 28-year-old mild Caucasian woman presented to our department with a two months history of low back pain, gradually started after her pregnancy. The pain was localized in the lumbo-sacral area, and occasionally radiated to the hips; It was persistent, not alleviated by analgesics or anti-inflammatory drugs, and worsened by sudden movements and physical activities involving the sacro-iliac joints. There was no history suggestive of morning stiffness or other joint involvement. The young woman had no family history of joint disorders and she did not suffer of any relevant pathology; She had no trauma. Physical examination revealed tenderness over sacro-iliac joints, with restricted spinal movements; Power, tone, reflexes, and sensation were normal bilaterally. Baseline blood investigations were all normal, including erythrocyte sedimentation rate. The plain radiographs of the lumbar spine and sacrum showed a triangular shaped dense sclerosis in the right ilium and stops sharply at the sacroiliac joints, with apparently normal joint spaces. CT confirmed the bony eburnation involving the iliac portion of both sacro-iliac joints, with a well-defined subchondral bone. No significant joint erosive change was found. At unenhanced MR examination, the iliac aspect of both sacroiliac joints showed a markedly decreased signal intensity on T1 weighted images and a moderately high signal intensity on T2 weighted images; No fluid collection was appreciable. Bone scintigraphy, performed with Tc-99, showed increased uptake in both sacroiliac joints. The patient underwent a conservative treatment with physiotherapy, resulting in a satisfactory recovery.
Discussion
Low back pain is a common symptom experienced by women during pregnancy and post-partum period. As a result of the increased weight, the degree of lumbar lordosis increases and sliding movement at the sacroiliac joint becomes accentuated. The increased levels of the hormone relaxin, may be associated with generalized articular laxity, softening and relaxation of ligaments, which might be stretched or torn, with subsequent periosteal damage1. Most backaches regress after pregnancy, but in some cases the pain may persist in the post-partum period, and it may hind common daily practice. It is important to diagnose the cause of the pain as soon as possible, in order to plan the most appropriate treatment. Osteitis condensans ilii (OCI) is a rare benign condition, typically seen after pregnancy2. It was described for the first time by Sicard, Gally, and Haguenau in 1926 and named by Bairsony and Polgar in 19283-4. Characteristically, this condition causes a bilateral and symmetric sacroiliac joint involvement and it is more common in women of childbearing age; Rarely, it may affect nulliparous women and men and it can be unilateral. The symptoms of OCI are usually mild, and in some cases the pathology may be clinically silent. As a matter of facts, OCI is mainly a radiological diagnosis; The imaging findings consist of a triangular area of subchondral sclerosis located at the anteroinferior aspect of the iliac side of the sacro-iliac joint, not associated with erosions or joint space narrowing. These radiological features may vary in extent and may even resolve with time. The cause of OCI is not clear; The predominant theory suggests that it is secondary to an abnormal mechanical stress over the sacroiliac joints coupled with increased vascularity during pregnancy, resulting in an exaggerated zone of hyperostosis on the iliac margin of sacroiliac joints5. Urinary tract infections reaching the ilium via nutrient vessels were also considered the cause of this disorder, but this theory was not supported by a scientific probe. Another theory suggested that osteitis condensans ilii is an inflammatory condition, related to ankylosing spondylitis, as supported by histologic studies that showed similar pathologic alterations in these two pathologies6. This hypothesis was not confirmed by other studies: As a matter of fact the two conditions have different aetiopathological, clinical and radiological features. It is possible to differentiate clinically between patients suffering from spondyloarthopathy with sacroiliitis simulating osteitis condensans ilii and those with “true” osteitis condensans ilii by using the clinical criteria proposed by the European Spondyloarthropathy Study Group (ESSG) for the classification of spondyloarthropathy: The clinical criteria include a history of inflammatory spinal pain or lower limb synovitis together with any of one psoriasis, inflammatory bowel disease, alternate buttock pain, and enthesopathy or a positive family history of spondyloarthropathy. However OCI and ankylosing spondylitis are characterized by bilateral, symmetric sacroiliac joint abnormalities; However, osseous erosion, joint space narrowing, sacral involvement, and ligamentous ossification are usually prominent in ankylosing spondylitis and absent in OCI7-8.
Differential Diagnosis List
Osteitis condensans ilii
Final Diagnosis
Osteitis condensans ilii
Case information
URL: https://www.eurorad.org/case/6137
DOI: 10.1594/EURORAD/CASE.6137
ISSN: 1563-4086