Case: A 25-year-old woman underwent osseointegration surgery as treatment for an amputation that had been performed because of congenital femoral deficiency. The undersized custom-designed implant for the congenitally hypoplastic femur subsequently loosened, causing substantial pain and loss of function. The patient underwent revision surgery with a larger standard-sized osseointegration implant, and experienced no additional complications. Conclusion: This case demonstrates the possibility of stimulating a hypertrophic response in underdeveloped bone, which allows the subsequent insertion of a larger implant with greater stability. Similar procedures can be considered for the treatment of patients who had amputations because of congenital deficiencies, in order to produce improved outcomes and reduce the risk of additional complications.