Plate Fixation Technique for Reducing Osteoarticular Allograft Fracture: A Preliminary Report.

ABSTRACT

Background: Osteoarticular allograft is now commonly used as a reconstructive biomaterial to replace bone defect following removal of aggressive bone tumors and for revision of failed arthroplasty. Good long-term clinical result of allograft replacement has been demonstrated. However, the rate of complications is high, including deep infection, allograft fracture, delayed union or non-union, and joint instability. Prevalence of allograft fracture ranges from 12-54 percent. Many studies recommend avoiding plate and screw fixation, or they advise the use of a modified screw fixation technique that minimizes the number of screws and changes screw alignment. Objective: The objective of this study was to compare the efficacy of the conventional technique with a new method of plate and screw fixation in osteochondral allograft following removal of aggressive bone tumors. Material and Method: From September 1988 to February 2015, 52 patients with primary aggressive benign or malignant bone tumor underwent massive bone allograft reconstruction. There were 25 males and 27 females with a mean age of 27-years. Giant cell tumor and osteosarcoma comprised most of the diagnoses. Thirty-five of the tumors were located around the knee. Average length of allograft was 12.9 cm. Twenty-nine patients were reconstructed using standard technique and 23 patients were fixed using only one dynamic compression plate with limited and 15-degree divergent-angle screw fixation at the allograft. Results: Mean follow-up time in the group treated by conventional fixation was 84.5 months. There were 13 fractures (44.8%) in the conventional fixation group, with a median time to graft fracture of 4.9 months. The 23 patients with new technique fixation were followed-up for a mean duration of 60.5 months. Six fractures (26.1%) occurred in this group, with a median time to graft fracture of 10.40 months. Differences between groups for incidence of allograft fracture and median time to fracture were not statistically significant (p = 0.163 and p = 0.244, respectively). Most patients with allograft fracture were treated surgically using autogenous bone grafting and revision of internal fixation. Conclusion: The new method of osteochondral allograft fixation using single plate, fewer screws, and divergent screw fixation yielded a lower fracture rate and a longer median time to fracture than the conventional method; however the differences between groups did not achieve statistical significance. The results of this preliminary study should be confirmed in a larger group of allografts over a longer follow-up period.