Are Pasteurized Autografts Durable for Reconstructions After Bone Tumor Resections?
Authors: Lee Seung Yong , Jeon Dae-Geun , Cho Wan Hyeong , Song Won Seok , Kim Bum Suk 
Published: June 2018

Abstract

Background
Pasteurized autograft is regarded as a biologic reconstructive option for managing bone defects after tumor resection; however, reports on long-term outcomes from large patient series are scarce. Contrary to previous favorable reports, we have observed many patients with failures, in particular as the duration of followup increased. Because pasteurized autografts are used in many countries as a reconstruction option, we wished to formally evaluate patients who underwent this approach at one specialty center.

Questions/purposes
(1) What is the graft survival and what proportion of patients achieved union when pasteurized autografts were used for bone defects after tumor resection? (2) What are the complications and causes of graft removal? (3) What factors are related to the likelihood of union and graft survival? (4) What is the survival and cause of failure by type of pasteurized autograft reconstruction?

Methods
Over a 26-year period from 1988 to 2013, we performed 1358 tumor resections in our center. Of these, 353 were reconstructed with pasteurized autograft. Other reconstructions included endoprostheses (508 patients), instant arthrodesis using an intramedullary nail and bone cement (286 patients), allografts (97 patients), and resection only (114 patients). During the period in question, we generally used this approach when tumor showed an osteoblastic pattern and less than one-third cortical destruction in osteolytic tumor. We generally avoided this approach when the tumor showed an extensive osteolytic pattern. We excluded 75 (21% [75 of 353]) patients, 21 (6% [21 of 353]) for incomplete clinical data and 54 (15% [54 of 353]) with a followup < 2 years or those lost to followup leaving 278 autografts eligible. The mean followup was 113 months (range, 25–295 months). Of these 278 patients, 242 patients had primary bone sarcomas, 22 patients had soft tissue tumor invading bone, seven patients had metastatic carcinoma, and seven patients had aggressive benign bone tumors. From a chart review, we obtained the age, sex, location, tumor volume, histologic diagnosis, use of chemotherapy, graft length, fixation modality, type of pasteurized bone used, proportion of union, complications, and oncologic outcome of the patients. In total, 377 junctional sites were assessed for union with serial radiographs. We defined junctions showing union < 2 years as union and > 2 years as delayed union. We grouped our patients into type of pasteurized bone use: pasteurized autograft-prosthesis composites (PPCs) were performed in 149, intercalary grafts in 71, hemicortical grafts in 15, osteoarticular in 12, and fusion of a joint in 31 patients. The endpoint of interest included removal of the autograft with implant loosening, infection, fracture of the graft, or any reoperation resulting in removal. Survival of the graft was determined by Kaplan-Meier plot and intergroup differences were determined using log-rank test.

Results
Five, 10-, and 20-year survival of 278 autografts was 73% ± 5.5%, 59% ± 6.7%, and 40% ± 13.6%, respectively. Of 278 autografts, 105 (38%) were removed with complications. Cause of removal included infection in 13% (33 patients), nonunion in 7% (18 patients), fracture of graft in 6% (16 patients), resorption of the graft in 5% (14 patients), and local recurrence in 4% (11 patients). Univariate survival analysis revealed that patient age ≤ 15 years (p = 0.027; hazard ratio [HR], 1.541), male sex (p = 0.004; HR, 1.810), and pelvic location (p = 0.05; HR, 2.518) were associated with graft removal. The 20-year survival rate of osteoarticular and hemicortical methods was 92% (95% confidence interval, -15.6% to +8.3%) and 80% ± 20%, respectively. For intercalary and fusion, it was 46% ± 15% and 28% ± 22%, respectively, although for PPC, it was 37% ± 22%. Log-rank survival analysis showed the osteoarticular and hemicortical groups had better graft survival compared with other types of reconstruction (p = 0.028; HR, 0.499). The most prevalent cause of graft removal in three major types of reconstruction was as follows: (1) PPC type was infection (30% [17 of 56]); (2) intercalary graft was infection, nonunion, and local recurrence in even proportions of 29% (86% [24 of 28]); and (3) fusion was infection (35% [six of 17]). Two hundred ten (56%) of 377 junctional sites showed union within 2 years (average, 14 months), 51 (13%) junctions showed delayed union after 2 years (average, 40 months), and the remaining 116 (31%) junctions showed nonunion. Diaphyseal junction (p = 0.029) and male sex (p = 0.004) showed a higher proportion of nonunion by univariate analysis.

Conclusions
Compared with the favorable short-term and small cohort reports, survival of pasteurized autograft in this long-term large cohort was disappointing. We believe that pasteurized autograft should be used with caution in children and adolescents, in the pelvic region, and in PPC form. When bone stock destruction is minimal, it is worth considering this approach for small intercalary or distal long bone reconstruction. We believe this procedure is best indicated after hemicortical resection of long bone.

Level of Evidence
Level III, therapeutic study.