New surgical techniques
The decades since widespread adoption of limb-sparing surgery for primary bone tumors have seen incremental improvements in the ability of surgeons to remove tumors whilst maintaining as much function as possible in the affected limb. In any procedure, surgeons and patients must balance the oncological benefits of wider resections with the morbidity of removing normal tissues, such as muscle, bone and nerves.
To achieve this, surgeons have to define the anatomic location and extent of tumor to enable accurate complete resection. MRI remains the gold standard to identify the intramedullary extent of primary bone tumors, including skip metastases.100,123 Preoperative imaging however, is unfortunately not able to assess the response of tumors to neoadjuvant chemotherapy with sufficient reliability to influence surgical options.124 Intraoperative imaging techniques, such as fluorescence using indocyanine green, offer the prospect of guiding surgeons towards improved surgical margins, but have yet to be proven in large scale clinical trials.125Novel techniques including intraoperative navigation and personalized custom jigs to guide bone resections, are becoming more established, may increase safety, and when matched with implants using additive layer manufacturing and porous ingrowth surfaces, offer the ability to improve margins whilst preserving normal tissue, (Fig. 3).126
For some patients with large tumors where it may not be possible to preserve the limb, or when the expected functional differences between limb-sparing surgery and amputation are small and the risks of limb-sparing surgery high, amputation remains the best option. Reconstruction with the uninvolved part of the limb, for example, by rotationplasty or tibial turn-up may be helpful, particularly in children.127 Advances in prosthetics and other technologies including transosseous fixation devices offer the potential for improved function for some amputees.128
Limb preservation carries a risk of local recurrence. In OS, retrospective studies have evaluated the risk in terms of the surgical margins, chemotherapy response and proximity to major vessels,129,130 but the application of these systems in prospective decision making has yet to be established.
Growth and the long-term complications of surgical reconstructions are further issues for adolescents. Growing endoprostheses contain a mechanism which is activated in outpatients using a magnetic coil. Although these implants have reduced the number of operations required after endoprosthetic reconstruction, patients do not escape further surgery, but the rate of limb preservation remains high. Bone-compatible collars encourage bone growth onto the surface of implants and reduce the risk of aseptic loosening when successful integration occurs. New porous designs may have some advantages but these remain to be proven.131 Antibacterial silver surface treatments have also become widely adopted with the aim of reducing the risk of deep infection. However, studies of their efficacy are retrospective and they have not been subjected to a prospective randomized trial .132