Fusion rates and subsidence of morselized local bone grafted in titanium cages in posterior lumbar interbody fusion using quantitative three-dimensional computed tomography scans.
METHODS
Prospective, controlled study.


OBJECTIVE
To determine fusion rates, cage to bone contact area ratios, and subsidences using titanium cages filled with a local bone graft for posterior lumbar interbody fusion (PLIF).


BACKGROUND
PLIF using decompressed local bone inserted in titanium cages combined with pedicle screw fixation is a popular procedure for treating lumbar spine degeneration. There is no report about cage to bone contact area ratios using titanium cages filled with a local bone graft for PLIF.


METHODS
PLIF using a titanium cage filled with excised laminar and facet joint bone with pedicle screw fixation was performed in 54 (78 levels) consecutive patients. Mean age at the time of surgery was 62.5 years. Radiographic assessments of posterior and anterior disc heights were performed. Three-dimensional thin-section computed tomography assessments of cage subsidences, fused area ratios of local bone inside cages, and overall fusion rates were analyzed.


RESULTS
Mean values of anterior and posterior disc heights at 1 year after surgery were significantly greater than mean preoperative disc heights. The fusion rate of cages over both upper and lower segment endplates was 96.2%. The ratios of fused areas of local bone inside cages exposed to upper and lower segment endplates were 46.7% and 52.2% in the coronal plane and 46.4% and 49.9% in the sagittal 3-dimensional computed tomography plane, respectively. And, subsidences of titanium cages at upper and lower segment endplates were 1.26 mm and 0.72 mm in the coronal plane and 1.04 mm and 0.53 mm in the sagittal plane, respectively.


CONCLUSIONS
The ratio of fused area of local bone inside cages at regions exposed to endplates was <50%, which is insufficient for physiologic load transmission. The authors recommend that additional bone should be grafted into the disc space or new bone bonding interbody spacer should be considered.
Lee
Jae Hyup
JH
Department of Orthopedic Surgery, College of Medicine, Seoul National University, Jongno-Gu, Seoul, Korea.
Jeon
Do-Whan
DW
Lee
Suk-Jae
SJ
Chang
Bong-Soon
BS
Lee
Choon-Ki
CK
D000328:Adult; D000368:Aged; D001863:Bone Screws; D016025:Bone Transplantation / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods; D011446:Prospective Studies; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D014025:Titanium; D014057:Tomography, X-Ray Computed / Q000379:methods*
D014025:Titanium