Noninstrumented facet fusion in patients undergoing lumbar laminectomy for degenerative spondylolisthesis.

The purpose of this retrospective study was to evaluate the radiographic and clinical efficacy of uninstrumented facet fusion in elderly patients undergoing lumbar laminectomy for spinal stenosis due to a single-level degenerative spondylolisthesis. Several studies have clearly demonstrated the beneficial effects of concomitant spinal fusion with laminectomy in degenerative spondylolisthesis. Controversy, however, persists regarding the virtues of fusion in this patient population. This study included 62 patients with a single-level grade I or II degenerative spondylolisthesis who underwent laminectomy and uninstrumented facet fusion for unremitting symptoms of spinal stenosis. Group 1 (39 patients) had a fixed degenerative spondylolisthesis with no measurable translation on flexion/extension radiographs, while group 2 (23 patients) had a mobile degenerative spondylolisthesis with preoperative translation. Postoperatively, the 62 listhetic levels were analyzed for radiographic signs of instability on flexion/extension radiographs for a minimum of 24 months. Clinical outcome was assessed in each patient at the time of final follow-up. In group 1 (patients with no preoperative translation), 64% of the index listhetic facet fusion levels had < or = 2 mm of motion on postoperative flexion/extension radiographs, while the other 36% had > 2 mm to < or = 15 mm of motion. Ninety-six percent of patients with < or = 2 mm of postoperative motion were "much better" after surgery, whereas only 50% of patients with > 10 mm of postoperative motion had similar results. Similar trends were also observed in group 2 with 52% of levels having < or = 2 mm motion and patient "much better" outcomes being observed with less motion postoperatively. The overall postoperative radiographic stabilization rate and improved patient outcomes were higher in group 1 than in group 2. In patients undergoing laminectomy for a grade I or II fixed or mobile degenerative spondylolisthesis, concomitant facet fusion decreases motion and stabilizes the spine via a bony fusion or a stable pseudarthrosis. In general, patients with less motion on postoperative flexion/extension radiographs had a better clinical outcome than those with more motion.

Short-term mortality and its association with independent risk factors in adult spinal deformity surgery.

STUDY DESIGN: Retrospective review. OBJECTIVES: To determine postoperative mortality after adult spinal deformity surgery. To determine whether independent risk factors can predict mortality. SUMMARY OF BACKGROUND DATA: Although mortality after adult spinal surgery is reported to range from 0.03% to 3.52%, there is a general paucity of data on mortality and its associated risk factors after adult spinal deformity surgery. METHODS: Three hundred sixty-one adults with spinal deformity underwent 407 corrective procedures. For patients who died within 30 days of the procedure, the following risk factors were examined to determine if each could independently predict mortality: demographic information, American Society of Anesthesiologists' (ASA) classification, operative time, surgical approach, number of fusion levels, primary versus revision surgery, and intraoperative blood loss. RESULTS: Ten of the 407 procedures resulted in death (2.4% mortality): 1 intraoperatively secondary to cardiac ischemia, 3 secondary to sepsis/multiple organ failure, 2 each secondary to pulmonary embolus, uncal herniation/cerebral edema, and shock. The average preoperative ASA levels for patients who died and patients who survived were 3.0 and 2.3, respectively (P < 0.0001). Age, gender, operative time, surgical approach, number of fusion levels, revision status, and estimated blood loss did not have an independently significant correlation to mortality. CONCLUSION: There was a strong association (P < 0.0001) between increasing ASA class and increasing mortality. The other risk factors could not independently predict postoperative mortality within 30 days after adult spinal deformity surgery.

Pulmonary embolism after adult spinal deformity surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: To determine the incidence and identify the associated risk factors of pulmonary embolism (PE) in patients who receive pharmacologic thromboprophylaxis after adult spinal deformity surgery. SUMMARY OF BACKGROUND DATA: The risk of PE after adult spinal deformity surgery is reported to be as high as 2.2%. However, the incidence and associated risks of PE in the same patient population who receive postoperative pharmacologic thromboprophylaxis is unknown. METHODS: The study included 361 adult patients with spinal deformity who underwent 407 corrective spinal procedures for scoliosis, kyphosis, or kyphoscoliosis. The incidence of PE was determined and compared with a study (historical control) of similar patients undergoing similar surgery but without postoperative pharmacologic thromboprophylaxis. Their demographic information, American Society of Anesthesiologists score, operative time, surgical approach, surgical complexity, and intraoperative blood loss were also analyzed to determine the presence of associated risk factors. RESULTS: Despite universal pharmacologic thromboprophylaxis, 10 pulmonary emboli (2.4%) were diagnosed. Patients undergoing anterior spinal surgery were at a significantly higher risk than those undergoing posterior spinal surgery (P = 0.024). The right-side anterior approach was also associated with a significantly higher incidence of PE compared with the left-sided anterior approach (P = 0.018). Although the rate of PE after posterior spinal surgery did not differ from the historical control, the rate of PE after anterior surgery was reduced by 50% compared with the historical control. Age, gender, estimated blood loss, operative time, revision status, and the number of fusion levels were not significant variables for PE. There were 2 epidural hematomas requiring decompression (0.48%) and 1 wound hematoma (0.24%). CONCLUSION: Although pharmacologic thromboprophylaxis probably does not have a role after posterior spinal surgery, the data in this study suggest that it does lower the incidence of PE after anterior spinal surgery.

Vertebroplasty and kyphoplasty for the management of osteoporotic vertebral compression fractures.

Osteoporotic vertebral compression fractures have previously been treated nonoperatively given the tremendous morbidity associated with open fixation in elderly patients who often have multiple medical comorbidities. With the advent of percutaneous vertebral augmentation techniques, these fractures can now be stabilized using minimally invasive surgical techniques while maintaining a relatively safe risk profile. Vertebroplasty and kyphoplasty provide immediate pain relief in the great majority of patients who have painful, osteoporotic vertebral compression fractures. The balloon used in kyphoplasty may allow for improved height restoration, cavity creation, and decreased cement extravasation rates. The authors discuss the procedural steps, advantages and disadvantages, and results of each technique, recognizing that prospective, randomized controlled studies are necessary to objectively compare the two techniques.

Posterior only versus combined anterior and posterior approaches to lumbar scoliosis in adults: a radiographic analysis.

STUDY DESIGN: Retrospective study. OBJECTIVE: To compare the radiographic lumbar curve correction between a posterior only and combined anterior-posterior approach in patients with adult spinal deformity. SUMMARY OF BACKGROUND DATA: In adolescent idiopathic scoliosis correction, posterior only has been compared with the combined anterior-posterior approach; however, there have been no corollary studies in adult scoliosis. Traditionally, rigid lumbar curves have been treated with a combined anterior and posterior approach; however, the absolute indications for this approach are unclear. MATERIALS AND METHODS: A total of 180 patients with degenerative or adult idiopathic spinal deformity and curves measuring between 40 degrees and 70 degrees who underwent reconstructive spinal fusion. The minimum follow-up period was 28 months and average follow-up was 53 months. Of the 155 patients who underwent surgery, 80 underwent posterior only (35 with idiopathic and 45 with degenerative scoliosis) while 75 patients (30 with idiopathic and 35 with degenerative scoliosis) underwent combined anterior-posterior surgery. The groups were compared by age at operation, preoperative deformity, levels operated and postoperative correction and balance. RESULTS: There were no significant differences in sagittal and coronal plane curve and balance correction between the posterior only and the combined anterior-posterior groups. When the patients were subdivided into degenerative adult scoliosis and idiopathic adult scoliosis, there were again no significant differences in the sagittal and coronal curves or balance between the posterior only and combined anterior and posterior approaches. While the posterior only group and the same-day anterior and posterior surgery group had a similar major complication rate of 24% and 23%, respectively, patients who underwent staged anterior and posterior surgery had a major complication rate of 45%. CONCLUSION: When combined with extensive posterior releases, posterior only approach is just as effective as combined anterior and posterior surgery for adult lumbar scoliosis measuring between 40 degrees and 70 degrees .

Spinal fusion after revision surgery for pseudarthrosis in adult scoliosis.

STUDY DESIGN: A retrospective study. OBJECTIVE.: To decipher the incidence, characteristics, functional outcomes, and complications of spinal fusion after revision surgery for recurrent pseudarthrosis in adult patients with scoliosis. SUMMARY OF BACKGROUND DATA: While the rate of spinal fusion has been examined in the past, there have been no studies that have examined the incidence, characteristics, functional outcomes, and complications of spinal fusion after pseudarthrosis repair in adult patients with scoliosis. MATERIALS AND METHODS: A total of 132 patients with failed spinal fusion surgery for adult scoliosis and painful pseudarthroses were studied. Each patient had an average of 3.7 spinal surgeries before undergoing revision at our institution. In addition to clinical assessment and imaging studies, pseudarthrosis was confirmed intraoperatively in all patients. All patients underwent reinstrumentation and fusion along with adjunctive procedures as needed. Spinal fusion was assessed clinically and radiographically after surgery for a minimum of 40 months. Subjective functional outcomes and complications associated with the procedures were also studied. RESULTS: The overall incidence of spinal fusion after revision surgery for pseudarthrosis in adult scoliosis was 90%. There was a propensity for pseudarthrosis to recur at the thoracolumbar and lumbosacral junctions. Increasing thoracolumbar kyphosis and loss of sagittal balance were significant risk factors for recurrent pseudarthrosis after revision surgery (mean thoracolumbar kyphosis of 23 degrees and mean sagittal balance of 7.9 cm anteriorly associated with persistent pseudarthrosis). Additionally, patients with multiple preoperative sites of pseudarthroses were at a higher risk for continued pseudarthrosis after surgery. Cigarette smoking, age, and surgical approach did not have any significant correlation with pseudarthrosis. Seventy-two percent of patients were satisfied with the outcome and 80% would have chosen to undergo surgery again if necessary. Thirty-three percent of patients who underwent surgery had some complication related to the surgery. CONCLUSION: Revision surgery for pseudarthrosis repair in adult scoliosis is most successful at attaining fusion when thoracolumbar and overall sagittal alignment are restored as much as possible.

Lumbar nerve root palsy after adult spinal deformity surgery.

STUDY DESIGN: A retrospective study was conducted to investigate the incidence and prognosis of postoperative lumbar nerve root palsy after surgical treatment for adult spinal deformity. OBJECTIVE: To decipher the incidence of postoperative lumbar nerve root palsy and recovery in 361 adult spinal deformity patients who underwent 407 spinal fusion surgeries. SUMMARY OF BACKGROUND DATA: Although lumbar nerve root palsy is a known complication of spinal surgery, there are no large studies that have examined its incidence or prognosis. METHODS: Three hundred and sixty-one consecutive patients who underwent 407 procedures for adult deformity spinal surgery were reviewed. Patients in this study did not have spinal cord injury or nerve root compression on the postoperative imaging study (obtained for change in neurologic examination). The incidence of nerve root palsy was based on postoperative muscle strength, which was followed for a minimum of 3 and an average of 7 years. RESULTS: The overall incidence of lumbar nerve root palsy was 2.9% with a 1.4% incidence in primary and 3.8% incidence in revision surgery. The incidence was 0.9, 1.5, and 7.4% for fusion of <5 levels, 5 to 10 levels, and >10 levels, respectively. The incidence of nerve root palsy for posterior only, same day anterior-posterior, and staged posterior was 1.3, 3, and 7.2%, respectively. While L5 was the most commonly injured nerve root, all other lumbar nerve roots were also involved. There were no S1 injuries. Although there was some recovery in most injuries, Grade IV injuries had the best recovery at 1-year follow-up. CONCLUSION: Patients with increasingly complex spinal deformities are at a higher risk for postoperative lumbar nerve root palsy. These injuries can be treated nonoperatively when there is no identifiable cause on postoperative imaging studies.

Parathyroid hormone-related Peptide expression in cartilaginous tumors.

Parathyroid hormone-related peptide is one of the most important regulators of chondrocyte proliferation. Although cartilaginous neoplasms express different collagens, including Types II and X, the pathogenesis of these tumors has not been elucidated. The current study examined the hypothesis that parathyroid hormone-related peptide is expressed in cartilaginous neoplasms and its level of expression may correlate with the proliferative rate of cartilaginous neoplasms with higher levels in more malignant tumors and lower levels in benign lesions. Two hundred thirty-four biopsy and resection specimens of benign and malignant cartilage tumors from 179 patients were retrieved from surgical pathology archival material and analyzed immunohistochemically using an antibody to human parathyroid hormone-related peptide. Most cartilaginous neoplasms had some level of expression of parathyroid hormone-related peptide, and tumors with a more proliferative phenotype had higher levels of parathyroid hormone-related peptide. Although benign lesions such as enchondromas and osteochondromas had low levels of parathyroid hormone-related peptide, malignant neoplasms such as extraskeletal myxoid chondrosarcomas, dedifferentiated chondrosarcomas, and mesenchymal chondrosarcomas expressed high levels of parathyroid hormone-related peptide. Parathyroid hormone-related peptide expression correlated with grade of malignancy in chondrosarcoma. Although there were highly significant differences between Grade I chondrosarcoma versus Grade II and Grade III lesions, the difference between Grade II and Grade III chondrosarcomas approached significance. Parathyroid hormone-related peptide may represent a new tumor marker with potential diagnostic use in classifying cartilaginous neoplasms.

Lead alters parathyroid hormone-related peptide and transforming growth factor-beta1 effects and AP-1 and NF-kappaB signaling in chondrocytes.

The skeletal system is an important target for lead toxicity. One of the impacts of lead in the skeleton, the inhibition of axial bone development, is likely due to its effect on the normal progression of chondrocyte maturation that is central to the process of endochondral ossification. Since little is known about the effect of lead on chondrocyte function/maturation, its impact on (1) growth factor-induced proliferation, (2) expression of maturation-specific markers type X collagen and BMP-6, and (3) the activity of AP-1 and NF-kappaB was examined in chick growth plate and sternal chondrocyte models. Exposure to lead alone (1-30 microM) resulted in a dose-dependent inhibition of thymidine incorporation in growth plate chondrocytes. Lead also blunted the stimulation of thymidine incorporation by parathyroid hormone-related peptide (PTHrP) and transforming growth factor-beta1 (TGF-beta1), two critical regulators of chondrocyte maturation. Lead (1 and 10 microM), TGF-beta1 (3 ng/ml) and PTHrP (10(-7) M) all significantly inhibited the expression of type X collagen, a marker of chondrocyte terminal differentiation. However, when in combination, lead completely reversed the inhibition of type X collagen by PTHrP and TGF-beta1. The effect of lead on BMP-6. an inducer of terminal differentiation. was also examined. Independently, lead and TGF-beta1 were without effect on BMP-6 expression, but PTHrP significantly suppressed it. Comparatively, lead did not alter PTHrP-mediated suppression of BMP-6, but in combination with TGF-beta1. BMP-6 expression was increased 3-fold. To determine if lead effects on signaling might play a role in facilitating these events, the impact of lead on NF-kappaB and AP-1 signaling was assessed using luciferase reporter constructs in sternal chondrocytes. Lead had no effect on the AP-1 reporter, but it dose-dependently inhibited the NF-kappaB reporter. PTHrP, which signals through AP-1, did not activate the NF-kappaB reporter and did not affect inhibition of this reporter by lead. In contrast, PTHrP activation of the AP-1 reporter was dose-dependently enhanced by lead. These findings, which establish that chondrocytes are important targets for lead toxicity, suggest that the effects of lead on bone growth are derived from its impact on the modulation of chondrocyte maturation by growth factors and second messenger signaling responses.

Role of pentoxifylline in preventing radiation damage to epiphyseal growth plate chondrocytes.

Radiation therapy plays an important role as part of multimodality treatment for a number of childhood malignancies. The damaging effects of radiation on bone formation in children have been well documented. Recent work suggests that the postirradiation increase in cytosolic calcium is probably responsible for the deleterious effects of radiation on growth plate chondrocytes because it causes a specific suppression of the mitogen PTHrP. Using an in vitro model of avian growth plate chondrocytes, this study demonstrates that pentoxifylline is effective in increasing basal PTHrP mRNA levels and partially preventing the radiation-induced decrease in PTHrP mRNA. This effect of pentoxifylline is probably due to its ability to lower basal levels of cytosolic calcium and the radiation-induced increase in cytosolic calcium in chondrocytes. Pentoxifylline also prevented the radiation-induced decreases in [3H]thymidine uptake and BCL2 and PTHrP receptor mRNA levels in chondrocytes. The effects of pentoxifylline appear to be specific for the PTHrP signaling pathway because it did not alter basal TGFB mRNA levels or TGFB mRNA expression in irradiated chondrocytes. The results of the current study suggest that by decreasing basal cytosolic calcium levels and curtailing the radiation-induced increase in cytosolic calcium levels in chondrocytes, pentoxifylline is able to sustain PTHrP signaling in chondrocytes and maintains the proliferative signal that is necessary to prevent chondrocytes from undergoing apoptosis.