[Permanent, habitual dislocation and recurrent dislocation of the patella in children: surgical management by patellar ligamentous transfer in 50 knees]. / Traitement chirurgical des luxations et instabilités patellaires chez l'enfant et l'adolescent par transfert ligamento-périosté

ABSTRACT

PURPOSE OF THE STUDY Appropriate treatment of patellar dislocation in children and adolescents remains a subject of debate. Ligamentous transfer or "soft rod" is a technique for realigning the extensor mechanism that can be adapted to children. We analyzed results obtained in our patients. MATERIAL AND METHODS: Between 1979 and 2000, 35 children (50 knees) underwent realignment which was combined in all cases with lateral retinacular release and medial reefing using the Insall procedure. Complementary procedures were needed in certain cases (quadriceps lengthening, femoral sulcus plasty, quadriceps release). Mean age at surgery was 11 years, range 5-15 years. All patients were reviewed at skeletal maturity with a mean follow-up of 7.5 years. The last review included a functional assessment using the IKDC form and standard x-rays (anteroposterior and lateral standing view and tangential view at 30 degrees flexion). A computed tomography scan and/or magnetic resonance imaging series were done preoperatively and at last follow-up. DISCUSSION: We distinguished two groups of patients, those with major (permanent or habitual) dislocation of the patella and those with recurrent dislocation. Functional outcome was good in 76% and 86% of knees respectively. There were eight cases of recurrent dislocation five knees underwent revision surgery with good outcome. The femoral sulcus angle was improved in both groups, but especially in the congenital dislocation group. There was on case of reversed tibial slope (-2 degrees) ant to slopes at 0 degrees. Functional outcome was equivalent to results from earlier series (Grammont, Bensahel, Langeskiold), but comparison was hampered due to the heterogeneous nature of the different series. Femoral sulcus remodeling can enable good patellar stability if the surgery is performed early enough (before age 10 years). In teenagers with major instability, femoral sulcus plasty must be associated with the realignment procedure. We noted a small amplitude reduction of the tibial slope in eleven knees. The procedure appears to have an "epiphysiodesis effect" but with no functional consequence. CONCLUSION: Ligamentous transfer combined with different procedures is a method of choice for stabilizing the extensor system, enabling a normal femoral sulcus angle if the child is operated early. Remodeling of the tibial tuberosity could be related to a transient vascular disorder.