History and exam

Key diagnostic factors

common

limp

The gait is a painless limp that can be described as a gluteus medius lurch, though may be antalgic during acutely painful episodes.

limited range of motion at the hip joint

There is a flexion deformity of the hip in the acute setting. With progression of the disease, adduction in flexion, internal rotation, and abduction in extension are limited due to impingement lesions. The later stage of the disease may be characterized by a global reduction in all ranges of motion with associated pain indicative of joint arthritis.

Other diagnostic factors

common

short stature

Most of the children are shorter than peers in height. However, they attain puberty and a normal final height by their mid teens.

muscle wasting

Wasting of gluteal muscles and quadriceps may be evident.

hyperactivity

Children with this disease tend to be hyperactive and indulge in several sporting activities, unless symptomatic.

Trendelenburg sign

This may be positive (pelvis drops toward the unsupported side during unilateral weight bearing) due to the muscle wasting.

asymmetric limb length

The presence of an adduction contracture may account for an apparent decrease in limb length, although there may also be true shortening from loss of femoral head height as collapse progresses.

uncommon

knee pain

The pain may have a varied radiation based on the different nerves that innervate the hip joint; it may radiate to the suprapatellar portion of the knee through the femoral nerve. This can lead to mistaken evaluation of the knee and a delay in diagnosis.

thigh pain

The pain may have a varied radiation based on the different nerves that innervate the hip joint; it may radiate to the medial aspect of the thigh via the obturator nerve. This can lead to a delay in diagnosis.

groin/buttock pain

The pain may have a varied radiation based on the different nerves that innervate the hip joint; it may radiate to the buttocks via the sciatic nerve. This may occasionally lead to a delay in diagnosis.

synovitis

Some studies have reported synovitis to be the first symptom, although this has not been proven, and the association may be incidental.[32][33]

minor trauma

There may be an associated history of trauma at presentation. Legg-Calvé-Perthes disease is a nontraumatic condition, although a history of minor trauma may be noted.

Risk factors

strong

male sex

Legg-Calvé-Perthes disease is about 4 or 5 times more common in males than females. The unique vascular anatomy of boys between 4 to 8 years makes them particularly vulnerable in the presence of hypercoagulable states and other factors.[23][24][25]

age 4 to 8 years

Typically, Legg-Calvé-Perthes disease affects 4- to 8-year-olds, the mean age being 7 years, although it can affect children between 2 to 12 years of age and can also affect adolescents.

low socioeconomic background

Poverty and social deprivation are associated with Legg-Calvé-Perthes disease.

hypercoagulable states

Vascular thrombosis is uncommon at a young age but may occur due to a genetic defect, such as resistance to activated protein C.[18] Protein C is a vitamin K dependent anti-thrombotic protein that leads to curtailment of procoagulant enzymes, factors Xa and thrombin, via factors V and VIII.[26] Factor V Leiden is implicated in the prothrombotic process by virtue of a substitution that blocks the binding of activated protein C to factor V.[27][28] It is not clear whether the deficiency is due to conversion or resistance to the activated form. However, protein C deficiency causes thrombosis in medium-caliber veins resulting in bone and cartilage ischemia.[17][18][19][20][21][29][30]

weak

urban population

The incidence of Legg-Calvé-Perthes disease is higher in inner city populations.[1][4][5][50][51][52][53][54][55][56]

race and northern latitude

Studies of incidence demonstrate that South Asians have 3 times the rate of East Asians, and that white people have 9 times the rate of East Asians. It is much less common in black people. The incidence per 100,000 in South Africa varies between 10.8 in white people, 1.7 in those of mixed ancestry and 0.45 in black people. More northerly latitudes, independent of race, appear to have greater disease incidence.[7]

transient hip synovitis

Although some have reported this to be the first symptom of Legg-Calvé-Perthes disease, this has not been proven, and the association may be incidental.[32][33] There may be an associated increase in intra-articular pressure, with a concomitant vascular event.[20]

hip joint effusion

The femoral head relies on lateral epiphyseal vessels for its blood supply between 4 and 7 years of age. These vessels run in the retinacula and are susceptible to stretching and pressure in the event of an effusion.[23][24][25]

passive smoking

Passive smoking in the household and maternal smoking during pregnancy may be contributory factors.[17][21][44][45][46]

skeletal dysplasias

Legg-Calvé-Perthes disease is more common in patients with skeletal dysplasias.

congenital anomalies

Genitourinary tract and inguinal anomalies have been demonstrated to have an association with Legg-Calvé-Perthes disease.[57]

trisomy 21

This genotype has an increased incidence of concurrent hip pathologies including Legg-Calvé-Perthes and slipped capital femoral epiphysis.[58]

behavior disorders

There is an association between Legg-Calvé-Perthes disease and generalized behavioral disorders and ADHD.[36][43][57]

endocrinopathy

An associated phenotype is small stature, delayed bone age and prepubertal skeletal arrest, leading to a hypothesis that an underlying endocrinopathy may be present.

Elevated somatomedin A or insulin-like growth factor (IGF) 2 levels suggest that Perthes may be a disease of growth transition.[37][38][39] However, somatomedin C (IGF1) levels are normal in these patients.[40]

One large, cross-sectional, longitudinal study of clinically euthyroid children with Legg-Calvé-Perthes disease found significantly elevated levels of free thyroxine (T4) and triiodothyronine (T3) compared with normal controls, particularly in patients with a greater extent of femoral head involvement.[12][41]

A reduced bone turnover is also noted, although it is not clear whether this is the cause or effect.[42]

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