Risikofaktoren beim Morbus Perthes und ihre Auswirkungen auf das klinische und radiologische Ergebnis

Between 1984 and 2001, 94 patients underwent a course of treatment for Legg-Calvé-Perthes disease in the clinic for orthopaedics at the university of Marburg. The intention of this study consisted in retrospectively eliciting prognostically valuable factors for the sickness, the so called risk factors, and verifying their effect on the medium-term clinical and radiological results. The patient population comprised 84 boys and 10 girls. In 10 cases both the left and the right hip were affected in one patient. The chronological age at the time of the initial stage of the disease averaged 7.19 years. Five patients (6.49%) showed an occurrence of the disease among relatives. The majority of cases were treated operatively, predominantly by intertrochanteric varus osteotomy or pelvic osteotomy (Chiari or Salter), and some were treated conservatively. A leg-length-discrepancy of 1 to 3.5 cm was observed in merely 14 patients (17.8%). Severe complications (adduction contractures, osteochondrosis dissecans) during course of treatment and deformities in the state of convalescence were extremely rare. 75 patients (79.8% of the patient population) were examined according to clinically accepted hip scores. Since the time of diagnosis an average of 8.34 years had elapsed and the mean age at the time of examination constituted 15.07 years. 73 patients (97.3%) showed excellent results according to the Harris Hip score and solely one case a good and another a satisfying result. Accordingly, the Merle d’Aubigné Hip score presented excellent values in the majority of cases. Thus, 72 patients (96%) achieved an excellent, two patients a moderate and one patient a poor result. Between the applied Hip scores and the severity of the disease, there was no correlation detectable. The radiological course and outcome of disease was analyzed for 74 patients. The extent of the femur head-affection was measured by means of Catterall-, Salter-Thompson and Herring-classification and the result at recovery was evaluated by dint of Mose- and Stulberg-classification. The presence of radiological risk signs such as Gage’s sign and metaphyseal reaction (including number and volume of the cysts) was scrutinized. After an extensive analysis we subdivided the risk factors into clinical (female gender, age > six years, incidence of the disease in relatives and bilateral disease) and radiological risk factors (severe Catterall-/Salter-Thompson-/Herring-stage, presence of the Gage’s sign and metaphyseal reaction including number and volume of the cysts) and checked the correlation with a poor outcome according to Mose and Stulberg classification. On closer examination of the clinical risk factors, the age proved to be an especially useful indicator with regard to the prognosis since the patients who were older than nine years at time of hip-affection more often tended to develop aspherical femur heads compared to the patients below six years of age. Scilicet the older patients showed poor results with aspherical femur heads in 84,6% of the cases (compared to 28, 6% of the younger patients) and in 16,7% of the cases the older patients generated an aspherical incongruency corresponding to Stulberg type 3 with the risk of evolving a grave arthritis before the age of 50 (whereas all of the younger patients were able to obtain a congruent hip joint). The closer investigation of female gender and bilateral disease showed that female patients and bilaterally affected patients both leaned towards poorer outcomes than boys or unilateral affected patients, although a statistical significance could not be established. Contrary to expectations, patients with increased incidence of the disease among relatives presented excellent clinical and radiological results, which contradicts an assumed disadvantage of these patients. The in-depth analysis of the radiological risk factors revealed a good correlation of the severe stages of Catterall, Salter-Thompson and Herring, which all indicate an extensive infestation of the femur head, with a poor outcome according to Mose and Stulberg. Patients which radiologically demonstrated a Gage’s sign or a metaphyseal reaction were somewhat more often struck by a poor result than patients without existence of these risk signs, although no statistically significant differences could be determined. All in all, there may be summarized that in our patient population most notably an age older than nine years at the time of initial affection of the hip and an extended affection of the femur head showed a good correlation with a poor outcome, wherefore both of these risk factors seem to be qualified for a reliable evaluation of the prognosis.