Object Although it improves rates of fusion in surgical arthrodesis, conventional spinal instrumentation is associated with several risks, including hardware extrusion that injures adjacent anatomical structures, and disuse osteopenia as a result of stress shielding. The long-term effects of indwelling spinal instrumentation, although incompletely documented, may be detrimental. One way to avoid such problems would be to use bioabsorbable implantation devices. In this pilot study, performed in 1998 and 1999, the authors evaluated the use of a bioabsorbable interbody fusion device in a goat cervical spine model. Methods Forty-two goats underwent two-level anterior cervical discectomy and fusion: eight received iliac crest autograft; 16 received a cage implant composed of 70:30 poly(L-lactide-co-D,L-lactide)/polyglycolic acid (70:30 PLDLLA/PGA) filled with either autograft or recombinant human bone morphogenetic protein–2 (rhBMP-2); and 18 received a cage implant composed of 85:15 PLDLLA/PGA filled with either autograft or rhBMP-2. Animals were killed at 3, 6, and 12 months postsurgery, and their cervical spines were evaluated histologically, radiographically, and physically for fusion. A primarily fibrous union was demonstrated in all animals killed at 3 months. At 6 months, bone trabeculae had become more prominent and the fibrous response less so in all cohorts. This occurred most frequently in the animals that underwent fusion with the 70:30 PLDLLA/PGA cages filled with rhBMP-2, in which 63% attained a histologically confirmed union that contained quantitatively more bone and less fibrous tissue than in the other cohorts; 63% of the unions in the aforementioned cohort were graded quantitatively as being stable. Conclusions In this study the authors have established that the 85:15 PLDLLA/PGA cages are absorbed too quickly to be functionally useful in this model. The 70:30 PLDLLA/PGA cages worked as well as tricortical autograft when filled with cancellous autograft, and better when filled with rhBMP-2. At 6- and 12-month follow-up review, the 70:30 PLDLLA/PGA cages had not yet begun to be absorbed. There was little if any inflammatory response to these cages at 6 months. Future studies should include biomechanical and microradiographic testing, and a longer follow-up period is necessary in this model to determine when the 70:30 PLDLLA/PGA cages are absorbed.

✓ This case of a 68-year-old woman with a low-thoracic intramedullary neurenteric cyst is notable for clinical presentation, cyst location, intraoperative findings, and imaging characteristics. The patient's postoperative course was complicated by neurological deterioration and a neuropathic pain syndrome. Potential causes of these complications are discussed, as are possible ways to reduce the risk of their occurrence.

Objective and Importance: Aneurysmal bone cysts (ABC) are benign bone neoplasms which typically involve the spine and long bones. We present a rare case of an ABC in the temporal bone with significant cerebellar compression. Clinical Presentation: The patient was a young boy who presented with several weeks of left posterior auricular pain. Computed tomography, magnetic resonance imaging and angiogram showed an expansile bone neoplasm involving the left petrous temporal bone. Intervention: A retrosigmoid-transmastoid craniectomy was performed, and total removal of the bone lesion was achieved. The pathological examination revealed the diagnosis of ABC. Conclusion: The postoperative course was uneventful, and the imaging studies demonstrated total removal of the neoplasm. This case represents the imaging and surgical management of a rare ABC in the temporal bone. This diagnosis should be considered in the differential of bone neoplasms in this region.

Object Adult scoliosis is a pathologically different entity from adolescent idiopathic scoliosis. The curves are more rigid, and rotational deformity and multilevel sagittal vertebral slippages compound the coronal malalignment. To correct these deformities, a surgical anterior release procedure is usually required, as well as posterior instrumentation-assisted fusion. This exposes the patient to the risks of a second procedure and of a thoracotomy or laparotomy. To decrease these risks, the authors have performed an anterior release, posterior release, and reduction via a posterior-only approach. The purpose of this study was to analyze quantitatively the degree of pre- and postoperative coronal deformity, the extent of correction, and related complications. Methods Data obtained in 20 patients with adult scoliosis were retrospectively studied. Patients presented with persistent back or lower-extremity pain, progressive deformity, or progressive neurological deficit. Sixteen patients underwent Gill-type laminectomy, radical discectomy (including fracture of any anterior and lateral osteophytes), and posterior lumbar interbody fusion (PLIF) of all apical and adjacent segments. One to four anterior release procedures were performed in each patient. Posterior instrumentation was placed over three to 15 levels. Autograft was obtained from the laminectomy sites and posterior iliac crest for fusion. There were no deaths; all patients were followed for a minimum of 1 year. The mean coronal Cobb angle improved from 36° to 14.7°. All spondylolisthetic lesions were reduced to at least Grade I. At the most recent follow-up examination, evidence of fusion was demonstrated in all patients. Reoperation for adjacent-segment failure, cephalad to the highest level of fusion, was required in two cases. Conclusions In many cases of adult scoliosis, a satisfactory multiplanar correction may be obtained via a single posterior approach and by using extended PLIF techniques. Cephalad adjacent-segment failure remains a significant problem in patients with osteoporosis, and routine extension of posterior instrumentation to the upper thoracic spine should be considered in these cases.

The purpose of this technical note is to describe our salvage technique of iliac bolt placement as an adjunct to lumbar-sacral fusions in a previously harvested iliac crest.