Figure 2.

(A) Coronal section MRI image of a bone sarcoma located in the right distal femur of a 10-year-old boy. After the wide resection performed in the first stage, the projected adult limb length discrepancy (LLD) was 9.5 cm. (B and C) Anteroposterior and lateral roentgenograms of the tumor prosthesis placed during the first stage of reconstruction after the patient’s resection. Note the gap formation at the prosthesis’s proximal attachment area. (D) At the 5-year follow-up orthoroentgenogram with 9 cm compensation, a 10 cm LLD was identified, with 6.3 cm originating from the femur and 3.2 cm from the tibia. Despite all infection parameters being negative, radiolucency suggestive of loosening was observed at the bone–implant interface both distally and proximally. (E) The patient’s bone lengthening surgery was planned from the proximal side. Lengthening over nail (LON) was applied via a nail integrated into the proximal stem, along with a circular external fixator. Early postoperative radiography is shown. (F) The orthoroentgenogram taken at the end of the lengthening period. A lengthening of 4 cm was achieved. (G and H) Grafting with a titanium cage at the proximal distraction area of the implant––bone composite for osteointegration purposes after lengthening. (I) The orthoroentgenogram during follow-up showing full consolidation and osteointegration with 6 cm compensation. (J and K) Early postoperative anteroposterior and lateral radiography of the tibial lengthening procedure using a computer-assisted hexapod external fixator. (L) At the end of the final tibial lengthening procedure, an anteroposterior orthoroentgenogram of the patient revealed proper mechanical axis and lower limb alignment. (M) Successful healing of the distraction gap is shown after fixator removal.