Sharon E. Mace, MD, FACEP, Cleveland Clinic Foundation, Ohio State University School of Medicine, and MetroHealth Medical Center, Cleveland, Ohio
Published Online: May 17, 2007 - 11:48:20 PM (CDT)
Sharon E. Mace, MD, FACEP Clinical Director, Observation Unit Director, Pediatric Education/Quality Improvement Cleveland Clinic Foundation Associate Professor Department of Emergency Medicine Ohio State University School of Medicine Faculty, MetroHealth Medical Center Emergency Medicine Residency Cleveland, Ohio
Legg-Calv?-Perthes disease is the most common serious hip disorder in school-aged children. The usual manifestation is a limp. Evaluation of the child with a limp begins with a comprehensive history and physical examination. Plain radiographs are generally the initial diagnostic study and can often determine the underlying etiology. Referral to a pediatric orthopedist is mandatory whenever the diagnosis of Legg-Calv?-Perthes disease is likely. Early identification and appropriate treatment of this condition may make the difference between normal function and lifelong pain and disability.
A limp is a common complaint in the pediatric population and is responsible for about 2 of every 1000 emergency department visits by children.1 Limping is often a manifestation of pain. The differential diagnosis of a child presenting with a limp and/or lower-extremity pain is extensive and ranges from benign conditions to serious and even life-threatening diseases. Legg-Calv?-Perthes (LCP) disease accounts for about 2% of cases of childhood limping.1 If left undiagnosed and untreated, it can lead to significant permanent disability.
The typical patient with LCP disease is a child aged 3 to 12 years (mean age, 6.6 years for boys and 7.1 years for girls)2 who is short for relative age and who presents with a limp and/or hip pain (Table 1). The boy-to-girl ratio is about 4.5:1.3 Whites are affected more often than Asians and Asians more often than blacks.4 About 10% to 13% of patients have bilateral involvement.5 A positive family history of LCP disease is noted in 10% to 20% of cases.6
Illustrative Cases Case 1: A 6-year-old white boy presents with a complaint of right knee pain. His medical history is unremarkable. Physical examination reveals a limp and pain on palpation over the right hip. There is decreased internal rotation of the right hip, which the child holds in external rotation. Radiographs demonstrate fragmentation and joint-space widening (Figure 1), findings that are characteristic of LCP disease.
Case 2: A 9-year-old white boy presents with a limp. His medical history is unremarkable. Physical examination reveals pain on palpation over both hips, along with limited rotation. Radiographs of the pelvis show widening of the joint space, as well as flattening, fragmentation, and sclerosis of the left hip (Figure 2). A subchondral fracture and sclerosis of the right hip are also seen. All these findings are consistent with bilateral LCP disease.
Case 3: An 18-year-old white boy complains of right hip pain that is so severe he is unable to walk. Multiple doses of ibuprofen have not helped. He has a history of right hip problems since age 11, when he was diagnosed with LCP disease. Physical examination reveals that the severe right hip pain is aggravated by movement. He has been followed by an orthopedist, who has discussed the possibility of hip replacement surgery. Radiographs show avascular necrosis of the right femoral head, with deformity of the right hip joint (Figure 3).
Pathophysiology and Etiology LCP disease is an osteochondrosis of the capital femoral epiphysis. Osteochondroses occur when the blood supply to the epiphysis is interrupted. In LCP disease, disruption of blood supply to the capital femoral epiphysis causes infarction of the bone (ie, avascular necrosis) and subsequent cessation of growth of the ossific nucleus. The infarcted epiphyseal bone softens, dies, and is gradually absorbed. Left untreated, the epiphysis will eventually collapse from the pressure of the body?s weight. The body?s reparative processes work to replace the dead bone with new bone and cartilage that grows in from the adjacent nonaffected viable bone. Complete healing generally does occur, but it may take up to 3 to 4 years.7
The newly healed epiphysis may be left with residual deformity and never regain a totally normal shape and appearance. Residual deformity can lead to serious disability later in life. Some flattening of the epiphysis, referred to as ?coxa plana,? can occur.7 In more severe disease, complete collapse can occur, with the femoral head mushrooming around the femoral neck. Because younger patients have more growth potential for reformation and remodeling of bone, they tend to have better outcomes.8
Vascular insufficiency in the form of recurrent episodes of ischemia to the proximal femoral epiphysis causes infarction and necrosis of bone.9 There has been much speculation recently that clotting abnormalities associated with vascular thrombosis may be responsible for the impaired blood supply in LCP disease.10 Some evidence suggests that affected children have a greater incidence of disorders that increase clotting (thrombophilias) or decrease the ability to dissolve clots (hypofibrinolysis).11 Although the current theory regarding etiology points to thrombophilia, the use of anticoagulant therapy for patients with LCP disease is not recommended.11
Clinical Presentation LCP disease typically affects short, active boys with a delayed bone age whose skeletal maturity lags behind their peers by approximately 15 to 32 months.2,12
The limp is often accompanied by mild, usually dull and chronic, pain lasting weeks to months.1 As with other pediatric hip disorders, pain may be referred to the knee or the thigh or even to the groin or the abdomen by cutaneous branches of the obturator and/or femoral nerves. The pain generally improves with rest, and there are no associated systemic symptoms.
The pain may be mild or even absent initially, and the onset of limp is often insidious. In the acute phase, the child may have an antalgic gait (ie, short-stance phase secondary to pain in the weight-bearing extremity).13 In long-standing cases, a Trendelenburg gait (downward pelvic tilt away from the affected hip during the swing phase), hip flexion contracture, or even atrophy of the thigh, calf, and/or buttock muscles can occur because of lack of use.13,14
Physical examination generally reveals decreased range of motion of the affected hip in abduction and internal (medial) rotation.15 However, all physical examination findings-including establishing a position of comfort for the affected leg, eliciting pain with movement of the affected hip, positive log roll test, antalgic limp, and Trendelenburg gait-are nonspecific and can be present in almost any pediatric hip disorder, from toxic synovitis to septic arthritis to slipped capital femoral epiphysis.
Diagnosis Plain radiographs remain the initial diagnostic test of choice when LCP disease is being considered in any child and generally in any child with a limp; these radiographs are frequently diagnostic.13 The series should include films of the pelvis in addition to the hip to assess for bilateral involvement, detect associated pelvic abnormalities, and compare findings with the opposite hip.13 In addition to standard views, radiographs with the femurs abducted and externally rotated (frog?s leg or Lauenstein view) should be obtained if hip pathology is being considered.
Ancillary studies are generally not part of initial diagnostic testing but are reserved for specific indications, such as preoperative evaluation. Advanced imaging techniques do have advantages; magnetic resonance imaging (MRI), scintigraphy, and sonography can all demonstrate early findings, and ultrasonography can identify joint effusion or abscess.13 Nevertheless, current diagnostic and prognostic classifications rely on plain films.16 If the diagnosis is in doubt or the plain radiographs are normal, bone and MRI scans may be useful.
Differential Diagnosis The differential diagnosis of hip pain in childhood includes many inflammatory and infectious causes (Table 2). In the age-group usually affected by LCP disease (ie, 3-12 years), transient synovitis is included in the differential. Also called toxic synovitis, this common cause of nontraumatic hip pain in children shares many features with LCP disease. Both conditions generally affect children aged 3 to 8 years (peak, 6 years for transient synovitis, 7 years for LCP disease6), are more common in boys, are usually heralded by unilateral hip pain, are not associated with systemic symptoms, and present with an antalgic limp and limited range of hip motion, with the hip held in abduction and external rotation.
Children with transient synovitis will usually have hip effusion, but the white blood cell count and erythrocyte sedimentation rate (ESR) will be normal or minimally elevated. Unlike in LCP disease, the symptoms of transient synovitis resolve within 1 week in most patients.17
Hip pain and a limp may be manifestations of septic arthritis or juvenile rheumatoid arthritis (RA). Associated features of juvenile RA include fever, rash, and joint pain; septic arthritis does not have a rash.13
Laboratory studies are helpful in distinguishing these conditions from LCP disease. The ESR and C-reactive protein levels are elevated with infectious and inflammatory conditions and are normal with toxic synovitis and LCP disease. When suspecting bacterial infection, aspiration of a hip effusion, perhaps guided by ultrasound or fluoroscopy, should be performed.
Other causes of hip pain and/or a limp in children include slipped capital femoral epiphyses, other rheumatologic or inflammatory disorders (eg, lupus, lyme disease), malignancies (bone tumors and blood neoplasias, such as leukemia or histiocytosis), metabolic disorders (often with bone disease secondary to conditions such as renal disease or hyperparathyroidism), nutritional or toxicologic disorders, referred pain from the spine or abdomen, neurologic diseases, infections, and trauma.1,13
Bilateral symmetric involvement with femoral head fragmentation and collapse of both hips is a clue that another condition may be responsible for the signs and symptoms.The bilateral disease that occurs in about 1 in 10 patients with LCP disease is usually not symmetric. The disease will be noticeably more severe in one hip than in the other, and progression in the less severely affected hip will lag behind the other, as demonstrated in Figure 2.
When bilateral symmetric avascular necrosis of the femoral head is encountered in a black child, a complete blood cell (CBC) count, with testing for sickle-cell anemia, should be considered.13 The history and physical examination are helpful in ruling out other conditions, such as a history of chronic steroid use, the stigmata of hypothyroidism, manifestations of hepatosplenomegaly suggestive of Gaucher?s disease, or a strong family history of hip/bone problems that suggests epiphyseal/spondyloepiphyseal dysplasias.
The distinguishing features on imaging studies are (1) evidence of dysplasia in other joints on radiographs in children with congenital epiphyseal/ spondyloepiphyseal dysplasia, and (2) effusion and/ or synovial thickening on ultrasound in children with transient synovitis.1 Occasionally, additional testing, including CBC count and differential, hemoglobin electrophoresis, thyroid function tests, and radiographs of other joints are useful if bilateral symmetric avascular necrosis is seen on radiography or the diagnosis of LCP disease is in doubt.
Disease Course The natural history of LCP disease consists of a destructive phase, a relatively stable phase, and a remineralization/healing phase. Reossification and remodeling may take 3 to 4 years.7 Generally, any of the osteochondroses, including LCP disease, are self-limited disorders that affect the pressure epiphyses during the growth period. With LCP disease, healing may reconstitute the normal shape and size of the femoral head, although more often some residual deformity remains that can result in the early onset of severe, often disabling arthritis in adulthood because of the progressive destruction of the articular cartilage of the hip joint.18 Without treatment, about 24% of patients will be left with a spherical femoral head and 52% with an irregularly shaped femoral head.18
The long-term prognosis of LCP disease varies. About 50% of patients will recover from their early childhood symptoms and be left with little disability.19 The remaining 50%, after an initial 1 to 2 years of symptoms, will do fairly well as young adults and will have only occasional pain. In their 40s and 50s, pain and disability will progress. Most patients with LCP disease will develop degenerative joint disease by their 60s or 70s19 and may require a hip replacement. However, a long-term prospective study showed that only 12 of 51 hips had been replaced at 50 years after disease onset.20 A few patients with severe LCP disease will have early persistent pain and disability and will require hip surgery in young adulthood, even as early as their 20s.
Treatment The treatment of LCP disease is a subject of debate, at least in part because the disease is so variable, and the response to treatment is often unpredictable.21 In general, patients with LCP disease should be referred to a pediatric orthopedist, since prompt treatment and close follow-up may improve long-term outcome. No therapy can immediately restore blood flow to the affected femoral head. Management includes symptomatic treatment to control pain; minimize or eliminate limping; improve range of motion; and prevent or limit complications, such as subluxation, extrusion, and hinging of the femoral head.
The principle of containment (ie, reducing the forces through the hip by actual or relative varus positioning) underlies the various nonsurgical and surgical methods for maintaining the femoral head within the acetabulum. This allows the body?s own reparative processes to remodel the capital femoral epiphysis as it reossifies, thus achieving a more normal shape and configuration and providing better outcomes. Patients with milder forms of the disease may be treated with conservative measures, including exercise or traction; those with more severe disease have better outcomes when treated surgically with varus femoral osteotomy.9,21
Age of onset appears to be a particularly important prognosticator and has been correlated with the extent of femoral head damage.20 The shape of the femoral head is generally normal when onset is at 5 years, flattened and spherical with onset at 6.3 years, and irregular with onset at 9.5 years.20 A good outcome (based on improved radiologic findings or clinical symptoms), however, cannot be guaranteed, even in children diagnosed at a young age. A 2003 meta-analysis of patients who were younger than 5 years at diagnosis showed a wide variation in outcomes by radiologic findings (using Mose and Stulberg radiologic classification systems), with 28% (Mose rating) to 45% (Stulberg classification) rated as good and 42% (Mose rating) to 45% (Stulberg classification) rated as poor at skeletal maturity.22 Such statistics have led some authors to suggest that it is bone age, not chronologic age, that determines prognosis.8 It was once thought that prognosis was worse for girls than for boys, but this is probably a reflection of the earlier age of growth-plate closure in girls.23
Conclusion LCP disease is the most common serious hip disorder in school-aged children. Urgent referral to a pediatric orthopedist is indicated when the diagnosis of LCP disease is being considered. The goal of therapy is to prevent the residual deformity of the hip joint that can leave the patient with lifelong pain and disability.
Self-assessment test 1. Which of these features is NOT characteristic of LCP disease? A. Male gender B. Black race C. Unilateral involvement D. No systemic symptoms
2. Which of the following characteristics is true of LCP disease? A. Painless, normal gait B. More common in females C. Usual onset in late teenage years (eg, age 16) D. Lack of systemic symptoms (eg, fever)
3. Which of the following findings is NOT suggestive of septic arthritis? A. Fever B. Elevated white blood cell count C. Elevated C-reactive protein and ESR levels D. Normal ESR and C-reactive protein levels
4. Which condition usually does NOT cause bilateral, symmetrical avascular necrosis of the femoral capital epiphysis? A. Gaucher?s disease B. Sickle-cell anemia C. Juvenile RA D. Hypothyroidism
5. All these are associated with a poor prognosis in a child with LCP disease, except: A. Age of onset >12 years B. Early growth-plate closure C. Normal-shaped femoral head D. Flattened femoral head
(Answers at end of reference list)
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23. Guille JT, Lipton GE, Szoke G, et al. Legg-Calve-Perthes disease in girls. A comparison of the results with those seen in boys. J Bone Joint Surg Am. 1998;80:1256-1263.
