American Society for Peripheral Nerve

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Restoration of Spinopelvic Continuity with the Free Fibula Flap after Limb-Sparing Oncologic Resection
Stefanos Boukovalas, MD1; Margaret S. Roubaud, MD2; Carrie K. Chu, MD2; Justin E. Bird, MD3; Valerie O. Lewis, MD4; Laurence D. Rhines, MD5; Ed Chang, MD3; David M Adelman, MD, PhD3; Matthew M. Hanasono, MD3; Alexander F. Mericli, MD2
1The University of Texas Medical Branch, Galveston, TX, 2University of Texas M.D. Anderson Cancer Center, Houston, TX, 3The University of Texas M.D. Anderson Cancer Center, Houston, TX, 4Department of Orthopedic Surgery, University of Texas MD Anderson Cancer Center, Houston, TX, 5Department of Neurosurgery, MD Anderson Cancer Center, Houston, TX

Oncologic hemipelvectomy can cause significant mechanical instability, requiring reconstruction of the pelvic ring in order to restore spinopelvic continuity. Previously described methods include autografts, allografts and implants, with poor long-term outcomes. We hypothesize that the free fibula flap (FFF) after oncologic hemipelvectomy is safe and effective, resulting in a high bone union rate and good functional outcomes.

We performed a retrospective review of all patients who received FFF after hemipelvectomy with or without sacrectomy at MD Anderson Cancer Center from 2003-2017. Surgical complications included seroma, hematoma, dehiscence, infection, and flap loss. Bony union and time to union was based on imaging. Functional outcomes included ability and time to ambulation. Univariate analyses were performed using the independent t-test, Mann-Whitney test, or Fisher's Exact test depending on data type.

31 patients received 31 FFF (21 males vs. 10 females). The median follow-up was 3.96 years. The most common pathology was chondrosarcoma (38.7%). 29% underwent pre-operative radiation and 65% required neoadjuvant chemotherapy. 10 patients received single-strut reconstructions and 21 had a double-strut. The most common recipient vessels were the external iliac artery (16.1%) and common iliac vein (16.1%). All patients were able to ambulate with assistance at a median of 9.5 days and 90% achieved fusion at a median of 330 days. The nonunion rate was 10% and hardware breakage rate was 23%. Only 1 patient required hardware removal; there were no flap losses. A total of 11 patients (35.4%) developed surgical complications. Nonunion was associated with cardiovascular disease (OR=11.5;p=0.03), re-operation (OR=10.9;p=0.009), tobacco use (OR=9.2;p = 0.01), surgical complications (OR=5.7;p=0.01), and advanced age (56.2 vs. 36.7 years; p<0.001). Hardware breakage was associated with tobacco use (OR=4.3;p=0.04) and increased fusion time (807 vs. 193 days;p=0.05), but not time to ambulation (16 vs. 12 days, p=0.46) or nonunion (OR=1.7;p=1). The presence of a surgical complication was associated with increased BMI (28.7 kg/m2 vs. 25.5 kg/m2; p=0.04). When comparing single and double-strut designs, there was no difference in nonunion, hardware breakage, hardware loss, time to ambulation, or time to fusion.

FFF for pelvic reconstruction is a safe procedure, acting to restore spinopelvic continuity and preserve ambulation. Caution should be exercised with greater BMI, smokers, and in patients with cardiovascular disease, as these factors exhibited an increased complication rate and rate of nonunion. Our data suggests there is no difference in complications or ambulatory function when comparing single vs. double-strut design.

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