Novel Bioabsorbable Interbody Fusion Spacer
Object: The authors report the cases of 12 patients with medically refractory mechanical low-back pain and intermittent radicular symptoms in whom radiography demonstrated evidence of multilevel lumbosacral degenerative kyphotic and scoliotic deformity and spondylolisthesis.
Methods: These patients underwent multilevel posterior lumbar interbody fusion in which Macropore bioabsorbable spacers were placed. Each patient underwent at least 1 year of clinical and radiographic follow up.
Conclusions: This series illustrates the novel use of bioabsorbable interbody spacers and fusion technique for correction of spinal deformity due to advanced degenerative kyphoscoliosis and spondylolisthesis.
Degenerative spinal deformity is a formidable problem in the aging population. With advancing age, disc dessication and degeneration occur as do osteophyte formation and gradual reduction in the volume of cancellous bone throughout the spinal column. This process may be significantly accelerated in postmenopausal women, smokers, and those with a congenital predisposition such as achondroplasia. When these degenerative processes occur asymmetrically, kyphosis and scoliosis may contribute to a rapidly narrowing lumbar canal. The clinical syndrome associated with these findings is chronic low-back pain that worsens over time and may be exacerbated by standing, walking, or back extension. Radiculopathy or dysesthesias may be present but generally are less prominent features of the pain syndrome.
In the treatment of these deformities, decompressive laminectomy with or without facetectomy and discectomy may provide adequate neural decompression; however, this procedure fails to correct, and may worsen, a developing degenerative spinal deformity. In these instances recurrent pain manifests and revision surgery is often indicated. The PLIF technique provides anterior structural support and foraminal distraction by means of an interbody graft as well as posterior immobilization by pedicle screw/rod-or plate-augmented fixation. Intertransverse onlay autograft is used to augment posterior fusion. This technique allows for the correction of degenerative kyphosis and scoliosis in addition to neural decompression. Excellent fusion rates have been well documented.
Interbody grafts used in PLIF have historically included autograft, cadaveric allograft, titanium and stainless steel implants, and most recently custom devices made of bioabsorbable polymers including polyhydroxy acids. Macropore (Macropore Biosurgery, Inc., San Diego, CA) is a polyhydroxy acid polymer that may prove to be suitable for placement as an interbody graft. It has been approved by the Food and Drug Administration for use as a cement restrictor and has been used in this study in an investigational capacity. Advantages of bioabsorbable materials include biocompatibility with neural tissue, predictable degradation, lack of neuroimaging-related exuberant inflammatory reaction, and lack of neuroimagingrelated artifacts. In addition, there is no significant toxicity because the degradation products are typically carbon dioxide and water. Encouraging preliminary results have previously been reported with the use of Macropore spacers in PLIF constructs. Further investigation is warranted to determine fusion rates, graft durability, and patient selection criteria. We present a small series of 12 cases in which bioabsorbable interbody graft-assisted PLIF resulted in correction of degenerative spinal deformity; patients attended more than 1 year of clinical and radiographic follow up.
Object: The authors report the cases of 12 patients with medically refractory mechanical low-back pain and intermittent radicular symptoms in whom radiography demonstrated evidence of multilevel lumbosacral degenerative kyphotic and scoliotic deformity and spondylolisthesis.
Methods: These patients underwent multilevel posterior lumbar interbody fusion in which Macropore bioabsorbable spacers were placed. Each patient underwent at least 1 year of clinical and radiographic follow up.
Conclusions: This series illustrates the novel use of bioabsorbable interbody spacers and fusion technique for correction of spinal deformity due to advanced degenerative kyphoscoliosis and spondylolisthesis.
Degenerative spinal deformity is a formidable problem in the aging population. With advancing age, disc dessication and degeneration occur as do osteophyte formation and gradual reduction in the volume of cancellous bone throughout the spinal column. This process may be significantly accelerated in postmenopausal women, smokers, and those with a congenital predisposition such as achondroplasia. When these degenerative processes occur asymmetrically, kyphosis and scoliosis may contribute to a rapidly narrowing lumbar canal. The clinical syndrome associated with these findings is chronic low-back pain that worsens over time and may be exacerbated by standing, walking, or back extension. Radiculopathy or dysesthesias may be present but generally are less prominent features of the pain syndrome.
In the treatment of these deformities, decompressive laminectomy with or without facetectomy and discectomy may provide adequate neural decompression; however, this procedure fails to correct, and may worsen, a developing degenerative spinal deformity. In these instances recurrent pain manifests and revision surgery is often indicated. The PLIF technique provides anterior structural support and foraminal distraction by means of an interbody graft as well as posterior immobilization by pedicle screw/rod-or plate-augmented fixation. Intertransverse onlay autograft is used to augment posterior fusion. This technique allows for the correction of degenerative kyphosis and scoliosis in addition to neural decompression. Excellent fusion rates have been well documented.
Interbody grafts used in PLIF have historically included autograft, cadaveric allograft, titanium and stainless steel implants, and most recently custom devices made of bioabsorbable polymers including polyhydroxy acids. Macropore (Macropore Biosurgery, Inc., San Diego, CA) is a polyhydroxy acid polymer that may prove to be suitable for placement as an interbody graft. It has been approved by the Food and Drug Administration for use as a cement restrictor and has been used in this study in an investigational capacity. Advantages of bioabsorbable materials include biocompatibility with neural tissue, predictable degradation, lack of neuroimaging-related exuberant inflammatory reaction, and lack of neuroimagingrelated artifacts. In addition, there is no significant toxicity because the degradation products are typically carbon dioxide and water. Encouraging preliminary results have previously been reported with the use of Macropore spacers in PLIF constructs. Further investigation is warranted to determine fusion rates, graft durability, and patient selection criteria. We present a small series of 12 cases in which bioabsorbable interbody graft-assisted PLIF resulted in correction of degenerative spinal deformity; patients attended more than 1 year of clinical and radiographic follow up.
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