Local harvest bone graft volume measured by 3 dimensional reconstructed CT in posterior lumbar interbody fusion

Abstract

Posterior lumbar interbody fusion (PLIF) has been widely performed to treat the various degenerative lumbar spinal diseases. Although the autogenous iliac bone graft remained the golden standard, many complications have been reported in many literatures. The autogenous local bone obtained at decompression site would be also good bone graft source with less complications. Recently, the instrumented posterolateral lumbar fusion (PLF) and PLIF with local bone graft alone reported excellent fusion rate. In previous studies, the number of patients was small and the amount of decompression and the reported local bone graft volume varied considerably in different surgeons. The purpose of this study is to evaluate the local bone graft volume during decompression and the volume of bone graft recipient site, disc space with 3D-reconstructed CT, and simulation program. Twenty male and twenty female patients between 21 to 40 years old, 41 to 60 years old, and 61 to 80 years old were enrolled in this study, respectively. The average local bone graft volume in one, two, and three level-decompression is 13.2 cc, 22.9 cc, and 29.8 cc, respectively. The average disc space volume at L3-L4, L4-L5, and L5-S1 is 9.9 cc, 10.1 cc, and 9.7 cc. Bone loss during decompression and preparation and impaction into disc space could decrease volume of bone graft. The use of interbody cages which occupied disc space has been frequent, the actual needed bone graft volume would be decreased. The thorough disc preparation was impossible. Because local bone graft had less cancellous portion than autogenous iliac bone, impaction would not be expected too much. Bone packing dorsal to interbody cage or around nerve root was seldom done. The amount of local bone graft without any bone substitutes was sufficient to fill disc spaces in 1- and 2-level PLIF. As local bone graft volume could not be 2 times or 3 times as disc space volume due to overlapped area of decompression, the amount of local bone graft was not enough in 3-level PLIF. This study presented the evidence that the amount of local bone graft was sufficient without expensive bone substitutes in 1- and 2-level PLIF.