Outcome of expandable prostheses in children

Expandable prostheses offer the advantages of limb-salvage and limb-length equality at skeletal maturity. However, what is the cost for achieving that goal, and in how many children this is achieved?

We present 32 children (16 boys and 16 girls; mean age, 9 y) with bone sarcomas of the femur treated with limb salvage using expandable prostheses. The Kotz Growing prosthesis and the noninvasive Repiphysis and Stanmore expandable prostheses were used. The mean follow-up was 49 months. Survival analysis of the children and primary implants and functional evaluation were performed.

Survival of the children was 94% and 84% at 48 and 72 months. Survival of the primary prostheses was 78% and 66% at 48 and 72 months; survival was significantly higher only for the Kotz when compared with the Repiphysis prostheses (P=0.026). The rate of implant-related complications was 51.3%; 9 prostheses (23%) were revised because of aseptic loosening, infection, and breakage. A mean total lengthening of 28 mm (4 to 165 mm) was achieved by 84 procedures (2.6 procedures/patient). Three of the 9 children who reached skeletal maturity had limb-length equality and 6 discrepancy of 15 to 30 mm. The mean Musculoskeletal Tumor Society score was excellent (79%) without a significant difference between the type of prostheses (P=0.934).

The Kotz Growing prosthesis, although it requires an open lengthening procedure, has shown higher survival when compared with the noninvasive Repiphysis prosthesis. However, the total lengthening remains small, and the complications rates are high even with the noninvasive prostheses.