Intraoperative data showed anterior ICBG to yield 20.7 12.8 ( 5-60 ) cm of autograft with an average harvest time of 33.2 16.2 minutes , posterior ICBG yielded 36.1 21.3 ( 20-100 ) cm of autograft in 40.6 11.2 minutes , and RIA yielded 37.7 12.9 ( 5-90 ) cm in 29.4 15.1 minutes .