Long-term follow-up after limb salvage in skeletally immature children with a primary malignant tumor of the distal end of the femur

Background: Skeletally immature children with a primary malignant tumor in the distal end of the femur are candidates for limb-salvage surgery; however, functional impairment due to subsequent limb-length discrepancy must be considered. Our aim was to evaluate the long-term clinical outcome of limb salvage in patients with a sarcoma of the distal end of the femur who were eleven years old or less, focusing on limb-length discrepancy and complications. Methods: The cases of forty children were retrospectively reviewed in a multicenter study based on the responses to a questionnaire. Twenty-eight patients had had endoprosthetic reconstruction, and twelve had had biological reconstruction. Functional evaluation was based on the Musculoskeletal Tumor Society scoring system, with numerical values from 0 to 5 points assigned for each of the following six categories: pain, function, emotional acceptance, use of supports, walking ability, and gait. These values were added, and the functional score was presented as a percentage of the maximum possible score. Limb-length discrepancy was measured with orthoroentgenograms. Complications and their treatment were analyzed. Patient survival and the survival of the reconstructions were analyzed with use of the Kaplan-Meier method. Results: Seven patients died and thirty-three remained alive, for a survival rate of 82% at ten years postoperatively. For the surviving patients, the mean follow-up periods (and standard deviations) were similar for the twenty-two who had endoprosthetic reconstruction (13.2 +/- 3.9 years) and the eleven who had biological reconstruction (10.4 +/- 4.4 years). All patients had reached skeletal maturity. The mean final functional score was 74% +/- 18% in the endoprosthetic reconstruction group and 68% +/- 17% in the biological reconstruction group (p = 0.37). For the nineteen patients who underwent limb-lengthening, the mean functional score increased significantly from 65% +/- 21% before the procedure to 81% +/- 11% after the lengthening (p = 0.0016). There were five early and twenty-eight late complications. In the endoprosthetic reconstruction group, the most frequent complications were deep infection and aseptic loosening. In the biological reconstruction group, the most frequent complications were implant breakage and nonunion. Revision surgeries were required in seventeen patients, including five who had an amputation. The rate of survival of the endoprosthetic reconstructions was 77% at five years and 51% at ten years postoperatively, whereas the rate of survival of the biological reconstructions was 46% at both five and ten years postoperatively. Conclusions: Endoprosthetic or biological reconstructions as limb salvage provided good functional outcome in skeletally immature children with a malignant bone tumor of the distal aspect of the femur despite a high rate of revisions and limb-lengthening procedures.