Intra-articular deformities of the knee in congenital hypoplasias of the lower limb: an arthroscopic study.

A knowledge of the morphology of the cruciate ligaments in congenital hypoplasias of the lower limb, susceptible to treatment to even the length discrepancy, is of practical importance in the prevention of subdislocation and dislocation of the knee during the distraction phase of femoral and/or tibial lengthening. The authors report their experience with 20 arthroscopies diagnosed in 20 children affected with congenital hypoplasia of the lower limb (shoft congenital femur, longitudinal peroneal hemimelia) performed prior to assembling the Ilizarov external fixator for femoral and/or tibial lengthening. None of the patients had congenital dislocation of the knee or knee with recurvation. In the patients in our study, it is possible to demonstrate that the anatomical cause of instability of the knee in congenital hypoplasias of the lower limb may be constituted by aplasia of one or both cruciate ligaments.