Transient synovitis of the hip refers to a self-limiting acute inflammatory condition affecting the synovial lining of the hip. It is considered one of the most common causes of hip pain and limping in young children. Over 90% of hip joint effusions in children tend to be due to transient synovitis 10.
It typically affects young children (3-8-year-olds). There is a recognised increased male predilection.
Patients typically present with hip pain for one to three days, associated with limping or the refusal to bear weight.
Their exact pathogenesis is not well known. Several theories have been proposed. In some situations, it may follow an upper respiratory tract infection. Some have suggested a viral aetiology (e.g. related to Parvovirus B-19 and /or Herpes simplex virus 6 infections while others have proposed a post-traumatic aetiology with subsequent development of chemical synovitis.
Features are nonspecific although in some cases there may be an increase in medial joint space in the affected hip 5.
Useful at demonstrating a joint effusion which is often seen in the anterior recess. Herniation of the synovial membrane through a joint capsular defect (pseudodiverticulum) between the iliopsoas muscle and the anterior border of the joint capsule may be seen in a very small proportion of patients (~2%) 1.
Described features include 6
- symptomatic hip joint effusion
- synovial enhancement
- contralateral joint effusion
- synovial thickening
- signal alterations and enhancement in surrounding soft tissue
- there is usually no signal alteration in the adjacent marrow.
Treatment and prognosis
It is a self-limiting disorder usually has no residual sequelae. Recurrences are possible. Management is usually supportive.
For imaging appearances, possible considerations include
- septic arthritis: on MRI there is often signal abnormality in marrow 8
For clinical limping there can be much wider differential such as other childhood arthritides (e.g. juvenile rheumatoid arthritis 1, Brucellar arthritis), Perthes disease, epiphysiolysis and osteoid osteoma etc.
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- 2. Kwack KS, Cho JH, Lee JH et-al. Septic arthritis versus transient synovitis of the hip: gadolinium-enhanced MRI finding of decreased perfusion at the femoral epiphysis. AJR Am J Roentgenol. 2007;189 (2): 437-45. doi:10.2214/AJR.07.2080 - Pubmed citation
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- 6. Yang WJ, Im SA, Lim GY et-al. MR imaging of transient synovitis: differentiation from septic arthritis. Pediatr Radiol. 2006;36 (11): 1154-8. doi:10.1007/s00247-006-0289-9 - Pubmed citation
- 7. Lee SK, Suh KJ, Kim YW et-al. Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow. Radiology. 1999;211 (2): 459-65. doi:10.1148/radiology.211.2.r99ma47459 - Pubmed citation
- 8. Caird MS, Flynn JM, Leung YL et-al. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. 2006;88 (6): 1251-7. doi:10.2106/JBJS.E.00216 - Pubmed citation
- 9. Robben SG, Lequin MH, Diepstraten AF, den Hollander JC, Entius CA, Meradji M. Anterior joint capsule of the normal hip and in children with transient synovitis: US study with anatomic and histologic correlation. Radiology. 210 (2): 499-507. doi:10.1148/radiology.210.2.r99fe52499 - Pubmed
- 10. Miralles M, Gonzalez G, Pulpeiro JR, Millán JM, Gordillo I, Serrano C, Olcoz F, Martinez A. Sonography of the painful hip in children: 500 consecutive cases. AJR. American journal of roentgenology. 152 (3): 579-82. doi:10.2214/ajr.152.3.579 - Pubmed