Irritable hip

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Irritable hip
The hip joint is formed between the femur and acetabulum of the pelvis.
ICD-10 M67.3
MedlinePlus 000981
eMedicine ped/1676 

Transient synovitis of the hip, also called toxic synovitis or irritable hip is a self-limiting condition in which there is a inflammation of the inner lining (the synovium) of the capsule of the hip joint.

Transient synovitis usually affects children between three and ten years old (but it has been reported in a 3-month-old infant and in adults[1]). It is the most common cause of sudden hip pain and limp in this age group[2].[3] Boys are affected two to four times as often as girls.[4][3][5] The exact cause is unknown. A recent viral infection (most commonly an upper respiratory tract infection) or a trauma have been postulated as precipitating events, although these are reported only in 30% and 5% of cases, respectively.[5]

Transient synovitis is a diagnosis of exclusion.[2] The diagnosis can be made in the typical setting of pain or limp in a young child who is not generally unwell and has no recent trauma. There is a limited range of motion of the hip joint. Blood tests may show mild inflammation. An ultrasound scan of the hip joint can show a fluid collection (effusion). Treatment is with non-steroidal anti-inflammatory drugs and limited weight-bearing. The condition usually clears by itself within seven to ten days,[3] but a small group of patients will continue to have symptoms for several weeks. The recurrence rate is 4–17%, most of which is in the first six months.[6]

Symptoms and signs

Transient synovitis causes pain in the hip, thigh, groin or knee on the affected side.[3] There may be a limp (or other abnormal movements, such as crawling, in infants) with or without pain. In small infants, the presenting complaint can be unexplained crying (for example, when changing a diaper). The condition is nearly always limited to one side.[3] The pain and limp can range from mild to severe.

Some children may have a slightly raised temperature; high fever and general malaise point to other, more serious conditions. On clinical examination, the child typically holds the hip slightly bent, turned outwards and away from the middle line (flexion, external rotation and abduction).[5] Active and passive movements may be limited because of pain, especially abduction and internal rotation. The hip can be tender to palpation. The log roll test involves gently rotating the entire lower limb inwards and outwards with the patient on his back, to check when muscle guarding occurs. The unaffected hip and the knees, ankles, feet and spine are found to be normal.[6]

Differential diagnosis

Pain in or around the hip and/or limp in children can be due to a large number of conditions. Septic arthritis (a bacterial infection of the joint) is the most important differential diagnosis, because it can quickly cause irreversible damage to the hip joint.[2] Fever, raised inflammatory markers on blood tests and severe symptoms (inability to bear weight, pronounced muscle guarding) all point to septic arthritis[7],[8] but a high index of suspicious remains necessary even if these are not present.[3] Osteomyelitis (infection of the bone tissue) can also cause pain and limp.

Bone fractures, such as a toddler's fracture (spiral fracture of the shin bone), can also cause pain and limp, but are uncommon around the hip joint. Soft tissue injuries can be evident when bruises are present. Muscle or ligament injuries can be contracted during heavy physical activity -however, it is important not to miss a slipped upper femoral epiphysis when there has been a fall. Avascular necrosis of the femoral head (Legg-Calvé-Perthes disease) typically occurs in children aged 4–8, and is also more common in boys. There may be an effusion on ultrasound, similar to transient synovitis.[9]

Neurological conditions can also present with a limp. If developmental dysplasia of the hip is missed early in life, it can come to attention later in this way. Pain in the groin can also be caused by diseases of the organs in the abdomen (such as a psoas abscess) or by testicular disease. Rarely, there is an underlying rheumatic conditions (juvenile idiopathic arthritis, Lyme arthritis, gonococcal arthritis, ...) or bone tumour.


There are no set standards for the diagnosis of suspected transient synovitis, so the amount of investigations will depend on the need to exclude other, more serious diseases. Inflammatory parameters in the blood may be slightly raised (these include erythrocyte sedimentation rate, C-reactive protein and white blood cell count), but raised inflammatory markers are strong predictors of other more serious conditions such as septic arthritis.[7][8]

X-ray imaging of the hip is most often unremarkable. Subtle radiographic signs include an accentuated pericapsular shadow, widening of the joint space, lateral displacement of the femoral epiphyses with surface flattening (Waldenström sign), prominent obturator shadow, diminution of soft tissue planes around the hip joint or slight demineralisation of the proximal femur. The main reason for radiographic examination is to exclude bony lesions such as occult fractures, slipped upper femoral epiphysis or bone tumours (such as osteoid osteoma). An anteroposterior and frog lateral (Lauenstein) view of the pelvis and both hips is advisable.[10]

An ultrasound scan of the hip can easily demonstrate fluid inside the joint capsule, although this is not always present in transient synovitis.[5][11] However, it cannot reliably distinguish between septic arthritis and transient synovitis.[12][13] If septic arthritis needs to be ruled out, needle aspiration of the fluid can be performed under ultrasound guidance.[14] In transient synovitis, the joint fluid will be clear.[3] In septic arthritis, there will be pus in the joint, which can be sent for bacterial culture and antibiotic sensitivity.

More advanced imaging techniques can be used if the clinical picture is unclear; the exact role of different imaging modalities remains uncertain. Some studies have demonstrated findings on magnetic resonance imaging (MRI scan) that can differentiate between septic arthritis and transient synovitis (for example, signal intensity of adjacent bone marrow).[15][16][17] Skeletal scintigraphy can be entirely normal in transient synovitis, and scintigraphic findings do not distinguish transient synovitis from other joint conditions in children.[18] CT scanning does not appear helpful.

Differential Diagnosis of Irritable hip

Cardiovascular No underlying causes
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug Side Effect No underlying causes
Ear Nose Throat No underlying causes
Endocrine No underlying causes
Environmental No underlying causes
Gastroenterologic No underlying causes
Genetic No underlying causes
Hematologic No underlying causes
Iatrogenic No underlying causes
Infectious Disease No underlying causes
Musculoskeletal / Ortho No underlying causes
Neurologic No underlying causes
Nutritional / Metabolic No underlying causes
Oncologic No underlying causes
Opthalmologic No underlying causes
Overdose / Toxicity No underlying causes
Psychiatric No underlying causes
Pulmonary No underlying causes
Renal / Electrolyte No underlying causes
Rheum / Immune / Allergy No underlying causes
Trauma No underlying causes
Miscellaneous No underlying causes


Treatment consists of rest, non-weightbearing and painkillers when needed. A small study showed that the non-steroidal anti-inflammatory drug ibuprofen could shorten the disease course (from 4.5 to 2 days) and provide pain control with minimal side effects (mainly gastrointestinal disturbances).[19] If fever occurs or the symptoms persist, other diagnoses need to be considered.[6]


In the past, there have been speculations about possible complications after transient synovitis. The current consensus however is that there is no proof of an increased risk of complications after transient synovitis.[20]

One such previously suspected complication was coxa magna, which is an overgrowth of the femoral head and broadening of the femoral neck, accompanied by changes in the acetabulum, which may lead to subluxation of the femur.[6][21] There was also some controversy about whether continuous high intra-articular pressure in transient synovitis could cause avascular necrosis of the femoral head (Legg-Calvé-Perthes disease), but further studies did not confirm any link between the two conditions.[22]

Further reading

An illustrated, free full-text review with emphasis on clinical examination of the acutely limping child.



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  2. 2.0 2.1 2.2 Hart JJ. "Transient synovitis of the hip in children." Am Fam Physician 1996; 54(5): 1587–91, 1595–6. PMID 8857781
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Scott Moses, MD. "Transient hip tenosynovitis". Family practice notebook. Revision of August 9, 2007. Retrieved December 22, 2007.
  4. Vijlbrief AS, Bruijnzeels MA, van der Wouden JC, van Suijlekom-Smit LW. "Incidence and management of transient synovitis of the hip: a study in Dutch general practice." Br J Gen Pract 1992; 42(363): 426-8. PMID 1466922 PMC 1466922
  5. 5.0 5.1 5.2 5.3 Irritable hip. General Practice Notebook. Retrieved December 22, 2007.
  6. 6.0 6.1 6.2 6.3 ped/1676 at eMedicine
  7. 7.0 7.1 Caird MS, Flynn JM, Leung YL, Millman JE, D'Italia JG, Dormans JP. "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. PMID 16757758
  8. 8.0 8.1 Kocher MS, Mandiga R, Zurakowski D, Barnewolt C, Kasser JR. "Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children." J Bone Joint Surg Am 2004; 86-A(8): 1629-35. PMID 15292409
  9. radio/387 at eMedicine
  10. Gough-Palmer A, McHugh K. "Investigating hip pain in a well child." BMJ 2007; 334: 1216–1217. PMID 17556478
  11. Nicola Wright, Vince Choudhery. Ultrasound is better than x-ray at detecting hip effusions in the limping child. . Retrieved December 22, 2007
  12. Zamzam MM. "The role of ultrasound in differentiating septic arthritis from transient synovitis of the hip in children." J Pediatr Orthop B 2006; 15(6): 418-22. PMID 17001248
  13. Bienvenu-Perrard M, de Suremain N, Wicart P, Moulin F, Benosman A, Kalifa G, Coste J, Adamsbaum C. "Benefit of hip ultrasound in management of the limping child." (French) J Radiol 2007; 88(3 Pt 1): 377-83. PMID 17457269
  14. Skinner J, Glancy S, Beattie TF, Hendry GM. "Transient synovitis: is there a need to aspirate hip joint effusions?" Eur J Emerg Med 2002; 9(1): 15-8. PMID 11989490
  15. Kwack KS, Cho JH, Lee JH, Cho JH, Oh KK, Kim SY. "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. PMID 17646472
  16. Yang WJ, Im SA, Lim GY, Chun HJ, Jung NY, Sung MS, Choi BG. "MR imaging of transient synovitis: differentiation from septic arthritis." Pediatr Radiol 2006; 36(11): 1154–8. PMID 17019590
  17. Lee SK, Suh KJ, Kim YW, Ryeom HK, Kim YS, Lee JM, Chang Y, Kim YJ, Kang DS. "Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow." Radiology 1999; 211(2): 459-65. PMID 10228529
  18. Connolly LP, Treves ST. "Assessing the limping child with skeletal scintigraphy." J Nucl Med 1998; 39(6): 1056–61. PMID 9627343
  19. Kermond S, Fink M, Graham K, Carlin JB, Barnett P. "A randomized clinical trial: should the child with transient synovitis of the hip be treated with nonsteroidal anti-inflammatory drugs?" Ann Emerg Med 2002; 40(3): 294-9. PMID 12192353
  20. Mattick A, Turner A, Ferguson J, Beattie T, Sharp J. "Seven year follow up of children presenting to the accident and emergency department with irritable hip." J Accid Emerg Med 1999; 16(5): 345-7. PMID 10505915
  21. Sharwood PF. "The irritable hip syndrome in children. A long-term follow-up." Acta Orthop Scand 1981; 52(6): 633-8. PMID 7331801
  22. Kallio P, Ryöppy S, Kunnamo I. "Transient synovitis and Perthes' disease. Is there an aetiological connection?" J Bone Joint Surg Br 1986; 68(5): 808-11. PMID 3782251