Expanding endoprosthesis for pediatric musculoskeletal malignancy: current concepts and results

Abstract

Surgical treatment and reconstruction of a pediatric patient with a bone malignancy should consider many patient and tumor specific factors. Surgical treatment should be geared first and foremost towards obtaining wide margins. To that end the options can include amputation, rotationplasty and prosthetic reconstruction. Advances in adjuvant chemotherapy for musculoskeletal malignancy in pediatric patients has increased acceptance of limb-salvage procedures as a viable option for treatment, whereas limb ablation was formerly the only acceptable means for attaining disease eradication. The advent of the expandable prosthesis has gained significant interest due to the appeal of improved cosmesis and potential for equal limb length at skeletal maturity. The latest generation implants allow for non-invasive lengthening with an outpatient procedure and are generally very well-tolerated by the patient. Review of current literature demonstrates that this procedure has generally good patient reported outcomes but has a high complication rate. Aseptic loosening and mechanical dysfunction are common modes of failure and often necessitate one or more large revision surgeries. Further improvement in implant design and biomaterials may decrease the incidence of these complications and promising work in these areas is ongoing. When discussing this specific option, patients and family should be counseled regarding the likelihood of future surgeries to manage the expected complications.

Figure 1

Pre-operative coronal STIR MRI demonstrating a Ewing's sarcoma of the distal femur.

Figure 2

Intraoperative photograph demonstrating careful dissection of the distal femur in preparation for en bloc resection of the malignancy.

Figure 3

Gross specimen of Ewing sarcoma of the distal femur. Resection was carefully measured and planned based on pre-operative imaging and implant has be custom made to match resection.

Figure 4

Post-operative anteroposterior and lateral views of the knee demonstrating the implanted Repiphysis prosthesis.