Abstract
Introduction
The reconstruction of the knee in growing children considers many options and the chosen solution is often patient (or surgeon) based. Megaprostheses represent a reliable solution but quite expensive in the non-invasive growing version and not free from complications. In an Italian reference center for Bone and Soft tissue sarcomas, following the experience of Rizzoli Institute in Bologna, we performed the reconstruction with a resurfaced allograft for the distal femur or the proximal tibia in selected patients. The aim of the study is to confirm the reliability of this technique and to identify its potential advantages and indications.
Methods
Among 60 children below 16 years old with bone sarcomas (39 osteosarcomas, 21 Ewing's sarcomas, age range 4–16) treated since 2007, 35 cases were around the hip and the knee. 7 pediatric knees (age range 5–12 ys) with the tumor involving the epiphysis were reconstructed using a resurfaced allograft for distal femur (2) or proximal tibia (6) leaving intact the other half of the joint. Functional outcome (MSTS score), complication rate, and oncologic follow up were evaluated.
Results
Oncologic follow up has been regularly conducted (range 2–9 years). No patient died of disease or developed a local recurrence. Two patients are alive with stable lung disease. Mean MSTS score was 32. No complications such as delayed union at the junction allograft-host bone, segmental deformities, fractures of the allograft, or infection have been observed. No prosthesis-related complications occurred. One limb length discrepancy with secondary scoliosis and 2 requiring a contralateral epiphysiodesis were also observed.
Conclusions
In children older than 12 years old and with an expected lower limb discrepancy within 5 cm an adult megaprostheses eventually oversized is the gold standard; in children younger than 6 years old with an expected limb discrepancy longer than 10 cm the big choice is between an amputation (conventional or rotantionplasty) or a temporary reconstruction for the future implant of a growing megaprostheses. In the range 6–12 years old with an expected limb length discrepancy of 5–10 cm one of the options is the resurfaced allograft. It has been found a reliable solution in our case series with an excellent functional result probably derived from the capsule and ligaments reconstruction. Applying this protocol we observed a low mechanical-implant related complication rate. Comparing our results to Literature data of other techniques (induced membrane technique, distraction epiphysiolisis, custom-made or growing prostheses) we observed a lower reintervention rate. It is not possible to evaluate the infection rate among the different techniques used because of the low number of cases. A revision with a conventional first implant or revision total knee arthroplasty is always feasible reducing mechanical complications from megaprostheses. Further studies with longer follow up are mandatory to obtain an international consensus on reconstructive techniques in children with bone sarcomas around the knee.
