What Are the Risk Factors and Management Options for Infection After Reconstruction With Massive Bone Allografts?

BACKGROUND: Massive bone allografts have been used for limb salvage of bone tumor resections as an alternative to endoprosthesis, although they have different outcomes and risks. The use of massive bone allografts has been thought to be associated with a high risk for infection, and there is no general consensus on the management of this complication and final outcome. Because infection is such a devastating complication of limb salvage, at times leading to loss of a limb, recognizing the risk factors for infection and the results of treatment is important. QUESTIONS/PURPOSES: The purposes of this study were (1) to analyze the frequency of infection in a group of patients treated with massive bone allografts; (2) to analyze risk factors such as age, sex, affected bone, type of reconstruction, operative room used, primary or revision procedure, length of postoperative antibiotic administration, and use of chemotherapy; and (3) to determine the likelihood that treatment of an infected allograft will result in a successful reconstruction.
METHODS: We retrospectively analyzed the records of patients treated with massive bone allografts for a benign or malignant bone tumor or as a revision for a previous limb salvage procedure between 1985 and 2011. During this period, 673 patients were reconstructed with massive bone allografts in long bones, which included 272 osteoarticular, 246 intercalary, and 155 allograft-prosthetic composite reconstructions. Using a chart review, we ascertained the frequency of infection and reoperations after the treatment of infected allografts. Minimum followup was 2 years unless death occurred earlier (mean, 106 months; range, 6-360 months), and no patient was lost to followup. The selected variables were analyzed using multivariate logistic regression to identify risk factors for infection. We analyzed survivorship free of infection as the endpoint.
RESULTS: During followup, 60 patients (9%) had a bacterial infection of the allograft with a survivorship free from infection of 92% at 5 years (95% confidence interval [CI], 90%-94%) and 91% at 10 years (95% CI, 89%-93%). We found that tibia allografts (p < 0.001; odds ratio [OR], 3.17; 95% CI, 1.80-5.60), male patients (p < 0.029; OR, 1.92; 95% CI, 1.08-3.49), procedures performed in a conventional operating room (p < 0.002; OR, 3.15; 95% CI, 1.58-6.62), and the use of longer periods of postoperative antibiotics (p < 0.041; OR, 2.25; 95% CI, 1.02-4.88) were patient factors associated with a greater risk of infection. In 11 patients (18%, 11 of 60 infections) the infection was controlled with antibiotics and surgical débridement; however, in 49 patients (82%, 49 of 60 infections), this approach failed, so the allograft was removed and a temporary cement spacer with antibiotic was implanted to control the infection. Forty-one patients subsequently had the spacer removed and were reconstructed after infection control with another bone allograft in 24 and an endoprostheses in 17. Four patients underwent an amputation for infection and four died of disease with the spacer in place. When we analyzed the 41 patients with a second reconstruction, 14 failed with a new infection (34%, 14 of 41 secondary reconstructed) of whom 12 had been reconstructed with bone allograft (29%) and two had endoprostheses (5%).
CONCLUSIONS: Management of infections of massive bone allografts with antibiotics and surgical débridement usually resulted in failure. Infections could be treated with resection of the allograft, antibiotics, a temporary cement spacer with antibiotics, and a repeat reconstruction; however, this approach is unlikely to be successful if a second bone allograft is used. Infections are difficult to treat, and more studies are needed, but we propose that it might be preferable to use endoprosthesis reconstruction for salvage of an infected allograft. LEVEL OF EVIDENCE: Level III, therapeutic study.