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Diagnostic and Classification of the Early Stages of Legg-Calv-Perthes Diseases.

Role of Ultrasonography and Magnetic Resonance Imaging.Nuno Craveiro Lopes; Carolina Escalda and Carlo Villacreses.

Orthopedic and Traumatologic Department, Pediatric Orthopedic Unit,

Garcia de Orta Hospital, Almada, Portugal

The multifactorial origin of Legg-Calv-Perthes disease (LCPD) is well documented. The same is true

for the existence of two or more ischemic episodes preceding the onset of the disease. After more than 30years of experimental and clinical data analysis about the initial stage of LCPD, the senior Author (NCL)

verified that these episodes are symptomatic. Patients complain of pain and transient limping, and it is

possible to detect those ischemic episodes with imaging techniques. The same Author has also found that

those episodes represent an autonomous disease, which, if some enchained factors are present, can evolve to

LCPD. The Author named this pre-LCPD situation, Ischemic Disease of the Growing Hip (IDGH).

To identify these ischemic episodes and to detect the cases of IDGH at risk of evolution to LCPD, the

Authors have developed a screening protocol. All pediatricians and general doctors of the area of influence

of their hospital have been informed of the protocol and advised to send all children who presented hip,

thigh or knee pain and limping for more than one day of evolution to the emergency unit. From January

1993 to December 1995, the Authors have observed 123 children, with ages between 3 and 12 years,presenting a painful syndrome of the hip. After standard clinical, radiological and laboratorial examination,

32 cases (26%) had a diagnosis, including epiphisiolysis (3), septic arthritis (3), rheuma (3) trauma (2)

LCPD (18) and other causes (3). The protocol was used on the remaining 91 cases and included a first

ultrasound screen to determine the existence of criteria of probability of IDGH. This screen have discarded

48 of the cases (53%), diagnosed as hip toxic synovitis. A second screening was made in the remaining 43

cases that presented ultrasound criteria of IDGH, using a nuclear magnetic resonance. This screening,

detected an ischemic episode in evolution in 6 of those cases (5% of all cases).

IDGH Stage I

Irregular contour

Synovitis, thick cart.

No actual ischemia

IDGH Stage II

Irregular contour

Synovitis, effusionSubchond. ischemia

IDGH Stage III

Porosis (weakening)

+ Synovitis, effusion+ Subchond. ischemia

LCPD Stage I

Dense, subchond. Fr.

+ Synovitis, effusionExtensive necrosis

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The analysis of the data of this screening protocol and of the demography of the area of influence of our

hospital, have shown the existence of a prevalence of 8,5 for LCPD and of 2,8 for active IDGH, for 100.000

children with less than 16 years and per year.

As a guide of the probability of evolution to LCPD, the Authors had developed a classification of IDGH

considering 3 stages: Stage I, represents a hip where one can identify sequel of an old ischemic episode; ithas a low probability of evolution to LCPD. Stage II, shows sequel of an old episode with a new ischemic

episode in evolution; it is considered to have a moderate probability of evolution. Finally, stage III,presenting signs of a recent episode with a new one in evolution, situation that is considered to have almost

100% of probability to evolve to Legg-Calv-Perthes disease.

From the whole of the patients diagnosed as having IDGH, 20 have not been treated and were followed.

From 15 IDGH stage II cases, 3 had evolved to LCPD and from 5 IDGH stage III cases all had evolved to

LCPD.

04/1995 - IDGH Stage III

Porosis, wider medial space

04/1995 - IDGH Stage III

Sub-chondral ischemia

10/1995 Lost from follow-up

6 months later - LCPD Stage I10/1995 LCPD Stage I

Extensive necrosis

The Authors conclude that it is possible to identify the fractional and transitory ischemic events that

precede the beginning of Legg-Calv-Perthes disease, and to define a group of cases at risk of evolution

to LCPD. This allows the introduction of measures to treat IDGH and maybe capable to prevent or to

abort the evolution to Legg-Calv-Perthes disease.