CORR®Tumor Board: Is There Benefit to Free Over Pedicled Vascularized Grafts in Augmenting Tibial Intercalary Allograft Constructs?
Megan E. Anderson MD
Orthopaedic Oncology Surgeon
Beth Israel Deaconess Medical Center and Boston Children's Hospital
The development of effective chemotherapy and improved imaging techniques in the 1970s and 1980s ushered in the current era of limb surgery. Massive bone allografts are now reliable options for reconstruction of bone defects following sarcoma resection, with improved function in intercalary allografts compared to allograft fusion and osteoarticular allografts [4, 5]. However, because complications, such as infection, nonunion, and fracture, are common in these reconstructions , we still need to develop improvements in surgical techniques. Free vascularized fibula transfer has been applied to salvage allograft fracture and nonunion, but more recently it has supplemented the original allograft reconstruction in an effort to decrease these complications at the outset. The added surgical complexity, longer operative time, and risk for donor-site morbidity have led many to reserve free vascularized fibula transfer only as an effort to salvage the original construct after allograft complications; the decrease in nonunion provided is seen as not worth the added negatives.
In their study, Manfrini and colleagues seek to achieve the general benefits of a vascularized fibula, but decrease the surgical risks, using the pedicled transfer technique. By eliminating the need for microvascular anastomosis and surgery on the contralateral leg, the pedicled transfer may be more broadly applicable and carry less risk.
Manfrini and colleagues found that an experienced team could perform pedicled transfers with similar risks of complications and shorter surgical times compared to free vascularized fibular transfers. In order to assess whether pedicled fibula transfer is truly superior to free transfer and allograft without transfer, longer followup with surveillance for later-term complications, especially infection and fracture, and greater numbers and types of patients are warranted. If a pedicled fibula transfer decreased risk of nonunion, fracture, and infection in the short- and long-term compared to allograft without transfer, and had acceptable perioperative and donor site risks, shorter surgical time, and was simpler to learn than free vascularized fibula transfer, then it would certainly behoove surgical teams to teach and train this technique.
What issues does this study raise in terms of musculoskeletal imaging?
Jim S. Wu MD
Beth Israel Deaconess Medical Center
Imaging of a patient with a tibial sarcoma can be divided into three phases, each with its own important considerations. Preoperative imaging constitutes the first phase where the radiologist must identify for the surgeon the full extent of the tumor and whether there is tumor involvement of important structures such as the joint space or neurovascular bundle. With accurate information, the surgeon can size the allograft appropriately and determine the type of treatment to best restore function. MRI should be performed to best assess full tumor extent.
The next phase is imaging during the immediate postoperative period. In this phase, one must assess for correct positioning of hardware and allograft and determine that the entire tumor has been resected. It is imperative for the radiologist to be familiar with the surgery that has been performed by reading the operative note or contacting the surgeon directly.
The third and final imaging phase is delayed postoperative imaging. During this phase, one needs to assess for incorporation of the allograft with the native tibia, any hardware/allograft complications, and tumor recurrence. This phase can last indefinitely and the radiologist must recognize the imaging appearance of these potential complications. An important pitfall in this phase is overcalling delayed or nonunion of the fibular allograft with the host tibia. For fractures in a healthy patient, healing with mature bridging bone is typically seen in 6 weeks to 12 weeks.