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

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.