Article
Changes in bone density in a lumbar cage filled with local autograft
Veränderungen der Knochendichte in einem mit lokalem Autograft gefüllten lumbalen Cage
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Published: | April 11, 2007 |
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Objective: To date, it is at least debatable if a cage for interbody lumbar fusion should be filled with autologous bone or any type of bone substitute or should remain unfilled. Thus, the objective of the current study was to investigate the fate of a bone graft within and behind of a lumbar fusion cage.
Methods: 16 patients suffering from degenerative disc disease of the lumbar spine received a posterior transforaminal lumbar interbody fusion with pedicle screw rod system and monoportal, bilateral supporting intervertebral cage. Three patients were fused in two adjacent lumbar segments. The cages were filled with bone that has been taken from the hemilaminectomy or arthrectomy, respectively. Three days and again one year after surgery an axial computed tomography scan through the cage was performed. In a standardised manner the density in both apertures of the cage and in the bone seal behind the cage was measured. Each time the mean value of bone density and standard deviation was calculated. The statistical significance was expected if p≤0,05.
Results: Mean density (± standard deviation) was 547.2 (±124.0) Hounsfield Units (HU) on day 3, 612.7 (±142.2) HU one year after surgery. The difference between the values on three days and one year after surgery was not significant (p=0.1). In 73% of the investigated segments was the bone density higher or at least unchanged.
Conclusions: In our opinion filling the lumbar monoportal, bilateral supporting, intervertebral cage with bone received from the approach is an appropriate alternative to the current treatment options.