Two patients with Marinesco-Sjögren syndrome had striking orthopaedic abnormalities that seemed to arise from multiple areas of physeal growth arrest. Major involvement was seen in the distal femora, where bilateral hypoplasia of the lateral condyles resulted in progressive valgus, patellar dislocation, and quadriceps dysfunction. Marinesco-Sjögren syndrome seems to arise from an error in lysosomal handling of lipids. Timely orthopaedic intervention may be helpful in prolonging ambulation in these patients.