| 摘要 |
Objective: Rationales of using interbody fusion cages in posterior lumbar interbody
fusion (PLIF) are enhancement of the fusion rate and prevention of postoperative disc
height loss. However, the prevalence of postoperative disc height loss and its
influences on clinical outcomes have not been clearly understood. The objective of
this study was to clarify and the incidence and clinical consequences of postoperative
disc height loss in instrumented PLIF with keystone grafts and packed bone chips but
without an interbody fusion cage.
Methods: From July 1999 to August 2002, 20 patients who underwent at a total of 23
levels of PLIF by a single surgeon were evaluated. Preoperative diagnosis included
degenerative spondylolisthesis in 11 patients, isthmic spondylolisthesis in 5 patients
and failed back surgery syndrome in 4 patients. During surgery, the anterior half or
two-thirds of the disc space was first filled and packed with bone chips, and then
cubic keystone grafts approximately 1 cm3 in size were tamped into the disc space.
Fusion status was assessed according to sequential postoperative radiographs, and
clinical outcomes were evaluated at least 24 months after surgery.
Results: The fusion rate and clinical outcome in this study were comparable with
those in the literature. Collapsed fusion with disc height loss of more than 2 mm was
observed in 3 levels and pseudarthrosis developed in one level. Postoperative loss of
disc height was not associated with occurrence of radiculopathy secondary to
foraminal narrowing and was not associated with unsatisfactory clinical outcomes.
Factors associated with postoperative loss of disc height included focal kyphosis at
preoperative flexion radiographs and invasion of transpedicular screws into the disc
space. Both situations may jeopardize initial solid packing of bone chips, may lead to
inadequate stability of the anterior bone graft, and then predispose to subsequent loss
of disc height. No other radiographic or demographic factors were found to be
contributive.
Conclusion: Postoperative loss of disc height developed only in the presence of
certain risk factors when single-stage instrumented circumferential fusion was
performed without using interbody fusion cage and would not lead to unsatisfactory clinical outcomes. |
