Does irradiation affect the clinical outcome of patellar tendon allograft ACL reconstruction?

The clinical implications of using irradiation to sterilize allograft bone-patellar tendon-bone (BPTB) remains unknown. The purpose of this study was to compare the clinical outcome of anterior cruciate ligament (ACL) reconstruction with irradiated allograft versus autograft BPTB. We hypothesized that patients undergoing ACL reconstruction with irradiated BPTB allograft would have no significant differences in patient-reported and objective parameters compared to those undergoing autograft BPTB reconstruction. Patients who underwent ACL reconstruction with either irradiated allograft or autograft BPTB from 1996 to 2002 were eligible for this study. One hundred and two patients (39 allograft, 63 autograft) met the study criteria and were available for follow-up. The BPTB allografts were obtained from a single tissue bank and were sterilized with 2.5 Mrad of irradiation prior to distribution. Participants completed the International Knee Documentation Committee (IKDC) subjective knee form and returned for physical and radiographic examinations, instrumented measurement of laxity, and functional testing. Patients were evaluated at an average follow-up of 4.2 years (range 1.8-8.4). Those undergoing allograft reconstruction were older (44±8.4 vs. 25.3±9.3 years, p<0.001) and had a longer median time from injury to surgery (17.1 weeks vs. 9.7 weeks, p=0.04). There was no difference in IKDC Subjective Knee Scores between groups (86.7 allograft vs. 88.0 autograft, p=0.65). The average maximum manual KT-1000 side-to-side difference was 1.3 and 2.2 mm for allograft and autograft, respectively (p=0.04); however, after adjusting for age, this difference was no longer significant. 90.6% of the allograft and 82.8% of the autograft had normal/nearly normal overall IKDC physical examination rating (p=0.37). 66.7% of the allograft and 77.8% of the autograft returned to the same or more strenuous level of sports (p=0.25). Patients undergoing ACL reconstruction with irradiated allograft BPTB had similar clinical outcomes compared to those reconstructed with autograft BPTB. These data suggest that irradiation can be used to sterilize BPTB allograft without adversely affecting clinical outcome.