Staged correction of varus knee and lateral thrust in an achondroplastic (ACH) juvenile patient who underwent limb lengthening with IM nails: tips for proper timing and prioritisation of procedures

Abstract

We present the case of a fifteen-year-old achondroplastic (ACH) woman who requested to have her femurs lengthened by intramedullary nails. She had undergone bilateral tibial lengthening at the age of eleven and presented with a varus deformity of the right lower limb, lateral thrust of the right knee and valgus deformity of the left lower limb. We performed deformity analyses based on mechanical axis measurements, and we came with a staged surgical plan. In ACH adolescences, correction of bony deformity needs to encounter continuous fibula growth dynamics. Lateral knee thrust was corrected by gradual distal translation of the fibula head via an Ilizarov frame and the amount of translation we decided clinically. Tibial lengthening and valgus osteotomy of the distal femur accentuate lateral collateral ligament (LCL) complex laxity. In patients with ACH, tibial lengthening and valgus osteotomy of the distal femur—if needed—should precede LCL complex tightening, and femoral lengthening should follow.