In the proximal and distal femur, modular metallic replacement prosthetic joint devices are used. Often a wafer of greater trochanter bone (if uninvolved in the tumor process) can be preserved and a “cable-claw” attachment to the metal component can be accomplished instead of using an allograft.
Since the proximal humerus is not weight-bearing and because of the importance of the rotator cuff, use of an APC in the proximal humerus can be most helpful. Function is not good with a metallic proximal humerus implant alone, and the dislocation rate is high over long-term follow-up, owing to lack of healing of the rotator cuff remnant to the metal prosthesis.
In patients with scapular sarcomas, allograft or prosthetic reconstruction has not been consistently better than simply repairing the remaining muscles to each other, so we generally do not use allografts or prostheses after sarcoma resection in these patients.
Growing bones of youth pose special challenges
In growing children, who represent a large share of bone sarcoma patients, reconstruction after resection in the lower extremity is challenging, particularly in terms of addressing leg length inequality. In general, a prosthesis is used and if the end growth discrepancy will be greater than 3 cm, use of an expandable prosthesis is considered. Use of these expandable prostheses has been fraught with complications, however, and by their nature they require revision because of breakage. An alternative is reoperation to disconnect the modular prosthesis and insert an additional 1- to 2-cm segment to increase length when necessary. Allograft bones are a common method of reconstruction when the resection does not involve the joint.
Rotationplasty—which involves saving the portion of the extremity distal to the resection site and reattaching it after being rotated 180 degrees—is rarely performed for leg reconstruction, in light of the disfiguring nature of the surgery as a result of the 180-degree rotation.
When rotationplasty is performed, the lower tibia and foot generally are brought up to the middle or proximal femoral area and attached to the short proximal femur. Rather than a short above-knee amputation, the reversed foot functions as a knee, allowing for better prosthetic function (ideally similar to a short below-knee prosthesis), and adds length to a short above-knee amputation.
Another alternative is a tibial turn-up to add length to a very short above-knee amputation if the vessels are not involved with the tumor and limb salvage is otherwise not practical. In this procedure the ankle can be turned up to the hip and the proximal tibia ends up distal to the ankle.
When curative surgery is possible and limb-salvaging resection is unlikely to obtain a negative margin or a functionally viable extremity, amputations are still performed. For example, amputation is recommended in a patient with a high-grade calcaneal (heel bone) sarcoma with a large soft-tissue mass. However, amputation is not the usual approach for most bone sarcomas today and it is not benign in outcome. Notably, phantom limb pain and stump pain have been reported after amputation in the typically sensate tumor patient.