Legg-calvé-perthes disease

The sphericity deviation score: a quantitative radiologic outcome measure of Legg-Calvé Perthes disease applicable at the stage of healing and at skeletal maturity

AIM

This study aimed to determine if a new measure of sphericity of the femoral head, the Sphericity Deviation Score (SDS), could be estimated reliably at the stage of healing of Legg-Calvé-Perthes disease (LCPD) and to determine if the SDS at the healing stage reflects the outcome at skeletal maturity.

METHODS

The SDS was measured with image analysis software on radiographs of 120 children with unilateral LCPD at healing of the disease and at skeletal maturity. The reproducibility of measurement was assessed. SDS values for hips in different Stulberg classes were calculated. On the basis of SDS values at healing of 82 children, a logistic regression model was developed to determine the probability of a good outcome at skeletal maturity. The validity of the model was tested on another 38 children.

RESULTS

The SDS values at the stage of healing and at skeletal maturity were comparable. The SDS values were lowest for Stulberg Class I hips and highest for Class IV and V hips. The validated regression model showed a very high probability of a good outcome (Stulberg Class I or II) at skeletal maturity if the SDS at the stage of healing was below 10.

CONCLUSIONS

A reliable estimate of the outcome of LCPD at skeletal maturity can be made by computing the SDS as soon as the disease heals.

[Bed rest and skin traction for Perthes' disease: review of the literature]

Long-term bed rest with skin traction, which isolates children with Perthes' disease from their social and educative environment, could be considered as incompatible with the ethics of modern therapeutics. Adaptation for home care has been proposed, but remains burdensome. We searched the literature in order to ascertain the real advantages and disadvantages of bed rest with skin traction and to evaluate the statistical value of published results. Considering that poor outcome is the natural course of the disease in 10-20% of patients, and that the number of patients in this group is further divided according to age and treatment, the number of patients in each treatment arm is rarely sufficient to validate any given treatment. For hips with limited abduction, traction does not appear to be warranted. Conversely, traction could be useful if the aim is to modify the natural course of the disease in precise situations, for example for Herring group B and or B/C patients with bone age above 6 years with a stiff hip. In this case, skin traction should not last more than two weeks and, to be considered useful, should achieve 30 degrees abduction documented on the ap view.

The spherical index. A measure of the roundness of the femoral head

The sperical index is introduced as a new, simple method of measuring the roundness of the femoral head and capital epiphysis. The index may be applied both in children and adults. Means and standard deviations are presented for both sexes in different age groups. The index increases with age until maturation. In adults the index is constant.