Long-Term Outcomes for Cementless Anatomic Femoral Components, Compared by Area of Porous Coating, in Patients Younger Than 50 Years Treated for Hip Dysplasia

We investigated whether the proximal circumferential porous coating of cementless stems would make implant survival of20 years possible in young patients.Data for patients younger than 50 years with hip dysplasia who had an anatomic stem implanted with a proximal porous coating with hydroxyapatite/tricalcium phosphate were reviewed. Noncircumferential porous (non-C-type) stems were used in 17 hips (13 cases), and circumferential porous (C-type) stems were used in 87 hips (68 cases). Acetabular components with conventional polyethylene were used for all hips. The mean ages at surgery for patients with non-C-type stems and those with C-type stems were 43.3 and 44.7 years, respectively. Stems that had not loosened were retained at the time of acetabular revision. The average duration of follow-up for patients with non-C-type stems was 26.9 years and was 22.3 years for those with C-type stems.Mean survival rates as determined by the Kaplan-Meier method were 74.9% at 20 years and 59.9% at 25 years for non-C-type stems and were 100% at 20 years and 94.0% at 25 years for C-type stems. The survivorship for C-type stems was significantly higher than that for non-C-type stems (P.01). Focal osteolysis in the shoulder of 37 hips with C-type stems suppressed the spread of osteolysis to the distal femur.Anatomic femoral stems with a circumferential porous coating provide excellent durability in patients with hip dysplasia who are 50 years of age or younger.Therapeutic Level IV.