The Anatomical Relationship Between the Cervical Nerve Roots, Intervertebral Discs and Bony Cervical Landmark for Posterior Endoscopic Cervical Foraminotomy and Discectomy: A Cadaveric Study.

STUDY DESIGN: Cadaveric anatomical studies. OBJECTIVE: This study aims to investigate the anatomical relationship between bony landmark "V point", dural sac, nerve roots, and intervertebral disc for improving operative outcomes and decreasing post-operative complications in posterior endoscopic cervical foraminotomy or discectomy (PECF or PECD). METHOD: 10 soft adult cadavers were studied. We measured the distance of the V point to the lateral margin of dural sac, V point to the inferior border of intervertebral disc, and the inferior border of cervical nerve root to the inferior border of intervertebral disc. Then we calculated the mean of distance from V point to the inferior border of cervical nerve root. RESULT: The mean distance from the V point to the lateral margin of dural sac from C3/4 to C7/T1 ranged from 3.1 ± 1.38 mm to 3.37 ± 1.46 mm. The mean distances from V point to the inferior border of intervertebral disc from C3/4 to C7/T1 were .19 ± 1.16 mm at C3/4, .45 ± 1.23 mm at C4/5, .43 ± 1.01 at C5/6, -.43 ± 1.86 mm at C6/7 and -1.5 ± 1.2 mm at C7/T1. The mean distance between V point and the inferior border of cervical nerve root from C3/4 to C7/T1 showed all positive value, ranging from .06 ± 1.18 mm to 4.45 ± 2.57 mm, increasing caudally. CONCLUSION: In performing PECF or PECD, a 3-4 mm radius of bone removal should be enough for exposure and neural decompression at C3/4 to C5/6. At C6/7 and C7/T1 a more extensive bone cut of more than 4 mm is recommended, especially in cranial direction.

Survey research of patient's preference on choosing microscopic or endoscopic spine surgery for lumbar discectomy.

BACKGROUND: There are several surgical methods of lumbar discectomy which provide the similar clinical outcomes. There is no clear evidence for how to select the procedures. To better understand the patient's opinion and decision process in the selection of surgical methods between microscopic lumbar discectomy (MLD) and endoscopic lumbar discectomy (ELD). METHODS: A cross-sectional survey study. Summary information sheet was created by reviewing the comparative literatures, and tested for quality and bias. Participants read the summary information sheet then were asked to complete the anonymous questionnaire. RESULTS: Seventy-six patients (71%) of patients who had no experience in lumbar discectomy selected ELD while 31 patients (29%) selected MLD. There were significant differences of score between patients who selected MLD and ELD in this group for wound size, anesthetic method, operative time, blood loss and length of stay (P< 0.05). In patients who had experience in discectomy group, 22 patients (76%) who underwent MLD still selected MLD if they could select surgical methods again for themselves, while 24 patients (96%) who underwent ELD still selected ELD if they could select again. The most important factor in patients who selected MLD was outcomes of treatment. The most important factor in patients who selected ELD was wound size. There were significant differences of scores between patients who selected MLD and ELD in this group for wound size, anesthetic method, operative time, complication, cost and length of stay (P< 0.05). CONCLUSIONS: About two thirds of the participants preferred ELD after reading the summary evidence information. The most important factor in MLD group was outcomes of treatment while the most important factor in ELD group was wound size.

Predictive factors for respiratory failure and in-hospital mortality after surgery for spinal metastasis.

PURPOSE: Spinal metastasis surgeries carry substantial risk of complications. PRF is among complications that significantly increase mortality rate and length of hospital stay. The risk factor of PRF after spinal metastasis surgery has not been investigated. This study aims to identify the predictors of postoperative respiratory failure (PRF) and in-hospital death after spinal metastasis surgery. METHODS: We retrospectively reviewed consecutive patients with spinal metastasis surgically treated between 2008 and 2018. PRF was defined as mechanical ventilator dependence > 48 h postoperatively (MVD) or unplanned postoperative intubation (UPI). Collected data include demographics, laboratory data, radiographic and operative data, and postoperative complications. Stepwise logistic regression analysis was used to determine predictors independently associated with PRFs and in-hospital death. RESULTS: This study included 236 patients (average age 57 ± 14 years, 126 males). MVD and UPI occurred in 13 (5.5%) patients and 13 (5.5%) patients, respectively. During admission, 14 (5.9%) patients had died postoperatively. Multivariate logistic regression analysis revealed significant predictors of MVD included intraoperative blood loss > 2000 mL (odds ratio [OR] 12.28, 95% confidence interval [CI] 2.88-52.36), surgery involving cervical spine (OR 9.58, 95% CI 1.94-47.25), and ASA classification ≥ 4 (OR 6.59, 95% CI 1.85-23.42). The predictive factors of UPI included postoperative sepsis (OR 20.48, 95% CI 3.47-120.86), central nervous system (CNS) metastasis (OR 10.21, 95% CI 1.42-73.18), lung metastasis (OR 7.18, 95% CI 1.09-47.4), and postoperative pulmonary complications (OR 6.85, 95% CI 1.44-32.52). The predictive factors of in-hospital death included postoperative sepsis (OR 13.15, 95% CI 2.92-59.26), CNS metastasis (OR 10.55, 95% CI 1.54-72.05), and postoperative pulmonary complications (OR 9.87, 95% CI 2.35-41.45). CONCLUSION: PRFs and in-hospital death are not uncommon after spinal metastasis surgery. Predictive factors for PRFs included preoperative comorbidities, intraoperative massive blood loss, and postoperative complications. Identification of risk factors may help guide therapeutic decision-making and patient counseling.

Validation of Traditional Prognosis Scoring Systems and Skeletal Oncology Research Group Nomogram for Predicting Survival of Spinal Metastasis Patients Undergoing Surgery.

Background: Many scoring systems that predict overall patient survival are based on clinical parameters and primary tumor type. To date, no consensus exists regarding which scoring system has the greatest predictive survival accuracy, especially when applied to specific primary tumors. Additionally, such scores usually fail to include modern treatment modalities, which influence patient survival. This study aimed to evaluate both the overall predictive accuracy of such scoring systems and the predictive accuracy based on the primary tumor. Methods: A retrospective review on spinal metastasis patients who were aged more than 18 years and underwent surgical treatment was conducted between October 2008 and August 2018. Patients were scored based on data before the time of surgery. A survival probability was calculated for each patient using the given scoring systems. The predictive ability of each scoring system was assessed using receiver operating characteristic analysis at postoperative time points; area under the curve was then calculated to quantify predictive accuracy. Results: A total of 186 patients were included in this analysis: 101 (54.3%) were men and the mean age was 57.1 years. Primary tumors were lung in 37 (20%), breast in 26 (14%), prostate in 20 (10.8%), hematologic malignancy in 18 (9.7%), thyroid in 10 (5.4%), gastrointestinal tumor in 25 (13.4%), and others in 40 (21.5%). The primary tumor was unidentified in 10 patients (5.3%). The overall survival was 201 days. For survival prediction, the Skeletal Oncology Research Group (SORG) nomogram showed the highest performance when compared to other prognosis scores in all tumor metastasis but a lower performance to predict survival with lung cancer. The revised Katagiri score demonstrated acceptable performance to predict death for breast cancer metastasis. The Tomita and revised Tokuhashi scores revealed acceptable performance in lung cancer metastasis. The New England Spinal Metastasis Score showed acceptable performance for predicting death in prostate cancer metastasis. SORG nomogram demonstrated acceptable performance for predicting death in hematologic malignancy metastasis at all time points. Conclusions: The results of this study demonstrated inconsistent predictive performance among the prediction models for the specific primary tumor types. The SORG nomogram revealed the highest predictive performance when compared to previous survival prediction models.

Effect of Multimodal Drugs Infiltration on Postoperative Pain in Split Laminectomy of Lumbar Spine: A Randomized Controlled Trial.

STUDY DESIGN: A randomized, double-blinded controlled trial. OBJECTIVE: This study tested the effect of single-dose wound infiltration with multiple drugs for pain management after lumbar spine surgery. SUMMARY OF BACKGROUND DATA: Patients undergoing spine surgery often experience severe pain especially in early postoperative period. We hypothesized that intraoperative wound infiltration with multiple drugs would improve outcomes in lumbar spine surgery. METHODS: Fifty-two patients who underwent one to two levels of spinous process splitting laminectomy of lumbar spine, were randomized into two groups. Infiltration group received intraoperative wound infiltration of local anesthetics, morphine sulfate, epinephrine, and nonsteroidal anti-inflammatory drugs at the end of surgery, and received patient-controlled analgesia (PCA) postoperatively. The control group received only PCA postoperatively. The primary outcome measures were amount of morphine consumption and visual analogue scale (VAS) for pain. The secondary outcome measures were Oswestry Disability Index (ODI), Roland-Morris Low Back Pain and Disability Questionnaire (RMDQ), patient satisfaction, length of hospital stay, and side effects. RESULTS: A total of 49 patients (23 patients for local infiltration group, and 26 patients for control group) were analyzed. There were statistically significant [P < 0.001, the effect size -5.0, 95% CI (-6.1, -3.9)] less morphine consumptions in the local infiltration group than the control group during the first 12 hours, 12 to 24 hours, and 24 to 48 hours after surgery. The VAS of postoperative pain reported by patients at rest and during motion was significantly lower in the local infiltration group than the control group at all assessment times (P < 0.001). The effect size of VAS of postoperative pain at rest and during motion were -2.0, 95% CI (-2.5, -1.4) and -2.0, 95% CI (-2.6, -1.4) respectively. ODI and RMDQ at 2 week and 3 month follow-ups in both groups had significant improvement from baseline (P < 0.001). No significant differences were found between groups (P = 0.262 for ODI and P = 0.296 for RMDQ). There were no significant differences of patient satisfaction, length of stay, and side effects between both groups (P = 0.256, P = 0.262, P = 0.145 respectively). CONCLUSION: Intraoperative wound infiltration with multimodal drugs reduced postoperative morphine consumption, decreased pain score with no increased side effects. LEVEL OF EVIDENCE: 1.

Malposition of Cage in Minimally Invasive Oblique Lumbar Interbody Fusion.

INTRODUCTION: Minimally invasive oblique lumbar interbody fusion is one of the novel lateral lumbar interbody fusion techniques for which the successful early results have been reported. However, new complications were increasingly reported from ongoing studies. CASE PRESENTATION: We report a case of an unusual complication of minimally invasive oblique lumbar interbody fusion associated with contralateral nerve root compression due to deep and posterior position of polyetheretherketone cage and discussion of the operating technique for repositioning polyetheretherketone cage. CONCLUSION: Malposition of polyetheretherketone cage can cause contralateral nerve root compression and neurological complication. The surgical technique to proper pull the polyetheretherketone cage back into the acceptable position should be considered and well prepared.

Prevalence of High-Riding Vertebral Artery and Morphometry of C2 Pedicles Using a Novel Computed Tomography Reconstruction Technique.

STUDY DESIGN: Cross-sectional, matched-pair comparative study. PURPOSE: To determine whether a thin-sliced pedicular-oriented computed tomography (TPCT) scan reconstructed from an existing conventional computed tomography (CCT) scan is more accurate for identifying vertebral artery groove (VAG) anomalies than CCT. OVERVIEW OF LITERATURE: Posterior atlantoaxial transarticular screw fixation and C2 pedicle screws can cause vertebral artery (VA) injury. Two anatomic variations of VAG anomalies are associated with VA injury: a high-riding VA (HRVA) and a narrow pedicle of the C2 vertebra. CCT scan is a reliable method used to evaluate VAG anomalies; however, its accuracy level remains debatable. Literature comparing the prevalence of C2 VAG anomalies between CCT and TPCT is limited. METHODS: A total of 200 computed tomography scans of the upper cervical spine obtained between January 2008 and December 2011 were evaluated for C2 VAG anomalies (HRVA and narrow pedicular width) using CCT and TPCT. The prevalence of C2 VAG anomalies was compared using these two different measurement methods via a McNemar's test. RESULTS: Of the 200 patients studied, 23 HRVA (6.01%; 95% confidence interval [CI], 3.61%-8.39%) were detected with CCT, whereas 66 HRVA (16.54%; 95% CI, 12.85%-20.23%) were detected with TPCT (p<0.001). Sixty-two narrow pedicles (15.58%; 95% CI, 11.99%-19.15%) were detected with CCT, whereas 90 narrow pedicles (22.83%; 95% CI, 18.58%-26.87%) were detected with TPCT (p<0.001). CONCLUSIONS: VAG anomalies are commonly observed. A preoperative evaluation using TPCT reconstructed from an existing CCT revealed a significantly higher prevalence of C2 VAG anomalies than did CCT and showed comparable prevalence to previously published studies using more sophisticated and higher risk techniques. Therefore, we propose TPCT as an alternative preoperative evaluation for C2 screw placement and trajectory planning.

Anatomic Considerations of Intervertebral Disc Perspective in Lumbar Posterolateral Approach via Kambin's Triangle: Cadaveric Study.

STUDY DESIGN: Anatomical study. PURPOSE: To evaluate the anatomy of intervertebral disc (IVD) area in the triangular working zone of the lumbar spine based on cadaveric measurements. OVERVIEW OF LITERATURE: The posterolateral percutaneous approach to the lumbar spine has been widely used as a minimally invasive spinal surgery. However, to our knowledge, the actual perspective of disc boundaries and areas through posterolateral endoscopic approach are not well defined. METHODS: Ninety-six measurements for areas and dimensions of IVD in Kambin's triangle on bilateral sides of L1-S1 in 5 fresh human cadavers were studied. RESULTS: The trapezoidal IVD area (mean±standard deviation) for true working space was 63.65±14.70 mm2 at L1-2, 70.79±21.88 mm2 at L2-3, 99.03±15.83 mm2 at L3-4, 116.22±20.93 mm2 at L4-5, and 92.18±23.63 mm2 at L5-S1. The average dimension of calculated largest ellipsoidal cannula that could be placed in IVD area was 5.83×11.02 mm at L1-2, 6.97×10.78 mm at L2-3, 9.30×10.67 mm at L3-4, 8.84×13.15 mm at L4-5, and 6.61×14.07 mm at L5-S1. CONCLUSIONS: The trapezoidal perspective of working zone of IVD in Kambin's triangle is important and limited. This should be taken into consideration when developing the tools and instruments for posterolateral endoscopic lumbar spine surgery.

Outcomes of fluoroscopically guided lumbar transforaminal epidural steroid injections in degenerative lumbar spondylolisthesis patients.

STUDY DESIGN: A prospective cohort. PURPOSE: To report the short and long term outcomes of fluoroscopically guided lumbar transforaminal epidural steroid injection (TFESI) in degenerative lumbar spondylolisthesis (DLS) patients. OVERVIEW OF LITERATURE: TFESI has been widely used for the treatment of lumbosacral radicular pains. However, to our knowledge, there has been no study which has evaluated the outcomes of TFESI in patients with DLS. METHODS: The DLS patients received fluoroscopically guided lumbar TFESI with 80 mg of methylprednisolone and 2 mL of 1% lidocaine hydrochloride. Patients were evaluated by an independent observer before the initial injection, at 2 weeks, at 6 weeks, at 3 months, and at 12 months after the injections. Visual analog scale (VAS), Roland 5-point pain scale, standing tolerance, walking tolerance, and patient satisfaction scale were evaluated for outcomes. RESULTS: Thirty three DLS patients treated with TFESI, who were completely followed up, were included in this study. The average number of injections per patient was 1.9 (range from 1 to 3 injections per patient). Significant improvements in VAS and Roland 5-point pain scale were observed over the follow up period from 2 weeks to 12 months. However, the standing and walking tolerance were not significantly improved after 2 weeks. At 2 weeks, the patient satisfaction scale was highest, although, these outcomes declined with time. The DLS patients with one level of spinal stenosis showed significantly better outcome than the DLS patients with two levels of spinal stenosis. Five patients (13%) underwent surgical treatment during the 3 to 12 months follow up. CONCLUSIONS: TFESI provides short term improvements in VAS and Roland 5-point pain scale, standing tolerance, walking tolerance and patient satisfaction scale in DLS patients. In the long term, it improves VAS but limits the improvements in Roland 5-point pain scale, standing tolerance, walking tolerance and patient satisfaction scale.

Morphometric evaluation of subaxial cervical spine using multi-detector computerized tomography (MD-CT) scan: the consideration for cervical pedicle screws fixation.

BACKGROUND: Cervical pedicle screw (CPS) insertion is a technically demanding procedure. The quantitative understanding of cervical pedicle morphology, especially the narrowest part of cervical pedicle or isthmus, would minimize the risk of catastrophic damage to surrounding neurovascular structures and improve surgical outcome. The aim of this study was to investigate morphology and quantify cortical thickness of the cervical isthmus by using Multi-detector Computerized Tomography (MD-CT) scan. METHODS: The cervical CT scans were performed in 74 patients (37 males and 37 females) with 1-mm slice thickness and then retro-reconstructed into sagittal and coronal planes to measure various cervical parameters as follows: outer pedicle width (OPW), inner pedicle width (IPW), outer pedicle height (OPH), inner pedicle height (IPH), pedicle cortical thickness, pedicle sagittal angle (PSA), and pedicle transverse angle (PTA). RESULTS: Total numbers of 740 pedicles were measured in this present study. The mean OPW and IPW significantly increased from C3 to C7 while the mean OPH and IPH of those showed non-significant difference between any measured levels. The medial-lateral cortical thickness was significantly smaller than the superior-inferior one. PTA in the upper cervical spine was significantly wider than the lower ones. The PSA changed from upward inclination at upper cervical spine to the downward inclination at lower cervical spine. CONCLUSIONS: This study has demonstrated that cervical vertebra has relatively small and narrow inner pedicle canal with thick outer pedicle cortex and also shows a variable in pedicle width and inconsistent transverse angle. To enhance the safety of CPS insertion, the entry point and trajectories should be determined individually by using preoperative MD-CT scan and the inner pedicle width should be a key parameter to determine the screw dimensions.

Treatment of acute tuberculous spondylitis by the spinal shortening osteotomy: a technical notes and case illustrations.

Surgical treatment for spinal tuberculosis is necessary in particular cases that a large amount of necrotic tissue is encountered and there is spinal cord compression. A spinal shortening osteotomy procedure has previously been described for the correction of the sagittal balance in a late kyphotic deformity, but there have been no reports on this as a surgical treatment in the acute stage. Thus, the aim of this report is to present the surgical techniques and clinical results of 3 patients who were treated with this procedure. Three patients with tuberculous spondylitis at the thoracic spine were surgically treated with this procedure. All the patients presented with severe progressive back pain, kyphotic deformity and neurological deficit. The patients recovered uneventfully from surgery without further neurological deterioration. Their pain was improved and the patients remained free of pain during the follow-up period. In conclusion, posterior spinal shortening osteotomy is an alternative method for the management of tuberculous spondylitis.

Quantitative differences in intervertebral disc-matrix composition with age-related degeneration.

This study was carried out to determine the effect of age on the intervertebral disc, using a rabbit model. Anulus fibrosus and nucleus pulposus tissue from New Zealand white rabbits aged 3 years old (old rabbits) and 6 months old (young rabbits) were used. The water content, the proteoglycan, the DNA content, and the mRNA levels of aggrecan, type I collagen, and type II collagen were all measured for each sample. Water, proteoglycan, DNA, and the mRNA levels of aggrecan and type II collagen were all greater in the nucleus pulposus of the young rabbits as compared to the old. For the anulus fibrosus, the difference between young and old is less marked with only proteoglycan and DNA being greater in the young disc as compared to the old. Clearly, according to our results, it is the nucleus pulposus that suffers the brunt of the changes with age.

A comparison of pedicle and lateral mass screw construct stiffnesses at the cervicothoracic junction: a biomechanical study.

STUDY DESIGN: Biomechanical comparison of five different posterior cervicothoracic junction (C7-T1) fixation constructs in a cadaveric model. OBJECTIVES: To determine whether augmenting C7 lateral mass screws with spinous process wires or additional fixation in the C6 lateral mass can create constructs of similar normalized stiffness to that of C7 pedicle screws. SUMMARY OF BACKGROUND DATA: Cervical pedicle screws are known to provide excellent fixation but are potentially dangerous and technically demanding to insert. Lateral mass screws are safer and easier to insert but have less pullout strength and must often be short at C7. METHODS: Twelve cadaveric cervicothoracic specimens (C5-T2) were randomly assigned to one of three experiments: Experiment A (Part 1 and Part 2), Experiment B, and Experiment C (Part 1 and Part 2) (n = 4 each for each experiment). First, the intact specimens were biomechanically tested according to a seven-part loading protocol. The specimens were then destabilized, and then restabilized with the following constructs in conjunction with bilateral T1 pedicle screws and biomechanically tested again using the same seven-part biomechanical protocol as was applied to the intact specimens. Experiment A: Part 1: lateral mass screw fixation at C7 (C7LM); then Part 2: retested after augmentation with triple wiring (C7LM+W). Experiment B: pedicle screw fixation at C7 (C7PS). Experiment C: Part 1: C6 and C7 lateral mass screws (C6C7LM); then Part 2: retested after augmentation with triple wiring (C6C7LM+W). Thus, five different constructs were biomechanically compared in these three experiments. RESULTS: None of the lateral mass constructs demonstrated a significant increase in normalized stiffness when augmented with wiring in any mode of testing. In axial compression, the C7PS construct showed significantly higher (P < 0.001) normalized stiffness than any of the other four constructs. In extension, there were no significant differences among any of the five constructs. Inflexion, right/left lateral bending and right/left axial torsion, the C7PS construct again showed significantly higher normalized stiffness (P < 0.05) than lateral mass fixation at C7 alone. However, in these five modes of testing, the addition of a secondary point of lateral mass fixation at C6 (C6C7LM) produced a construct with a normalized stiffness similar to that of C7PS with no significant difference (P > 0.05). CONCLUSION: C7 pedicle screw fixation provides the construct with the highest normalized stiffness for stabilizing the cervicothoracic junction. If C7 pedicle fixation is not possible, then performing two-level lateral mass fixation at C6 and C7 will achieve a construct with similar normalized stiffness except in axial compression. The addition of triple wiring to the spinous processes does not significantly increase lateral mass construct normalized stiffness.

The role of the sternum, costosternal articulations, intervertebral disc, and facets in thoracic sagittal plane biomechanics: a comparison of three different sequences of surgical release.

STUDY DESIGN: Eighteen human torsos were used in three experiments (A, B, and C) to determine the changes in sagittal motion due to three different sequences of three surgical releases. OBJECTIVES: To investigate the relative effects of releasing the intervertebral disc, the costosternal joint, the sternum, and the facet joints on sagittal thoracic motion and the consequences of altering the sequence of the releases. SUMMARY OF BACKGROUND DATA: The biomechanics of the thoracic spine are different from the cervical and lumbar spine particularly due to the ribs and sternum, which contribute to stability and control motion. The role of the sternum and costosternal articulation in the biomechanics of thoracic sagittal motion has not been well studied. The effects of releasing each of these structures, whether alone or with discectomy and/or facetectomy, is potentially relevant in the surgical correction of thoracic deformities, such as severe kyphosis, and in the biomechanics of thoracic fracture. METHODS: In Experiment A, the release sequence was back to front: total facetectomy (T4-T8), then radical discectomy (T4-T8), then costosternal release, then sternal osteotomy. In Experiment B, the release sequence was front to back: sternal osteotomy, then costosternal release, then radical discectomy, and finally total facetectomy. In Experiment C, the release sequence was: radical discectomy, then sternal osteotomy, then costosternal release, then total facetectomy. The different sequences allowed separate analysis of each component and the synergistic patterns. In each of the three experiments, the torso was flexed then extended each time by an applied force (25 N) before and after each release. The extent of flexion and the extent of extension were measured each time and compared with the intact condition, after each release. RESULTS: The results obtained for sternal osteotomy were combined with the results obtained for costosternal release to give "sternal release." Radical discectomy provided the greatest increase (P < 0.05) in range of motion (ROM) compared with the other two single releases, no matter what the sequence. For paired release combinations, the radical discectomy and sternal release (as in Experiments B and C) provided a significant (P < 0.05) increase in total sagittal ROM compared with the combination of radical discectomy and total facetectomy (Experiment A). In Experiment A, sternal release accounted for 42% of the total sagittal ROM compared with only 26% related to the total facetectomy (Experiment B). In general, all of the releases allowed more extension than flexion. CONCLUSIONS: Sagittal plane motion in the thoracic spine is influenced by all three structures tested in this experiment. Overall, the radical discectomy provides the greatest increase in total ROM and in extension compared with the other two releases. The second most influential release is the combination of sternal osteotomy plus costosternal release (i.e., sternal release), particularly in extension (correction of kyphosis). When two releases are done in sequence, radical discectomy plus sternal release provides the greatest increase in total ROM and in extension. Overall, total facetectomy is the least effective release. These data have relevance for surgical strategies in the correction of thoracic kyphosis or lordosis and suggest a potential role for sternal osteotomy and costosternal release in severe and rigid upper thoracic kyphosis.

Comparison of Healos/bone marrow to INFUSE(rhBMP-2/ACS) with a collagen-ceramic sponge bulking agent as graft substitutes for lumbar spine fusion.

STUDY DESIGN: A rabbit lumbar intertransverse process arthrodesis model was used to evaluate the efficacy of two different bone substitute materials: 1) collagen-hydroxyapatite sponge (Healos bone void filler) combined with heparinized bone marrow; and 2) recombinant human bone morphogenetic protein-2 delivered in a collagen sponge (INFUSE Bone Graft) wrapped around an additional collagen-ceramic sponge (Mastergraft Matrix) as a "bulking agent." OBJECTIVES: To compare the relative efficacy of two different bone graft substitutes to achieve posterolateral lumbar spine fusion in rabbits. SUMMARY OF BACKGROUND DATA: Autogenous bone graft is considered the gold standard graft material for spine fusion. Complications with its use, however, may occur in as many as 30% of patients. A variety of bone substitutes have been used for spine fusion, but there are few direct comparison experiments to determine the relative efficacy of any two alternatives. METHODS: Adult New Zealand white rabbits (n = 24) were divided into two groups and underwent bilateral posterolateral intertransverse process spine arthrodesis at L5-L6. The fusions were augmented by different bone substitute materials as follows: Group 1 (n = 12) received 3 mL of collagen-hydroxyapatite sponge (Healos bone void filler) (10 x 30 x 5 mm, two per side) with 3.0 mL of heparinized bone marrow on each side of the spine. (ratio 1:1); Group 2 (n = 12) received 1.5 mL of rhBMP-2 (0.43 mg/mL solution) on a Type 1 collagen sponge (INFUSE Bone Graft) wrapped around an additional 1.5 mL collagen-ceramic (15%HA/85%TCP) sponge (Mastergraft Matrix) as a bulking agent to provide 3 mL of graft on each side of the spine. Bone marrow was aspirated from posterior iliac crest, and 1 mL of bone marrow was sent to count number of nucleated cells. The rabbits were killed after 8 weeks; the spines were evaluated by manual palpation, radiographs (plain radiograph and CT scan), tensile mechanical testing, and nondecalcified histology. RESULTS: The bone marrow had average of total nucleated cell count 9 x 10 cells. All rabbits (100%) in Group 2 (INFUSE/Mastergraft Matrix) achieved solid spinal fusions by manual palpation and radiographs, whereas solid spinal fusion was not achieved by manual palpation and radiographs in any of the rabbits treated with Healos combined with heparinized bone marrow (Group 1). The plain radiograph and CT scans of Group 1 showed some minimal new bone formation near the transverse processes, but none of these rabbits formed a continuous fusion mass. In contrast, all of plain radiographs and CT scans in Group 2 showed continuous fusion mass and complete graft incorporation between transverse processes bilaterally. Biomechanically, the relative strength and relative stiffness values of L5-L6 (fusion segment) in Group 2 were statistically significant greater than L5-L6 in Group 1 (P < 0.001). Histologic sections confirmed the palpation and radiographic results. CONCLUSION: From the manual palpation, radiographic and biomechanical assessment of fusion, the results in this study showed that INFUSE (rhBMP-2/collagen sponge) consistently produced spine fusion when wrapped around a collagen-ceramic sponge bulking agent (Mastergraft Matrix). Meanwhile, Healos was ineffective as a bone graft material when combined with heparinized autogenous bone marrow.

The effects of doxorubicin (adriamycin) on spinal fusion: an experimental model of posterolateral lumbar spinal arthrodesis.

BACKGROUND CONTEXT: Malignant spinal lesions may require surgical excision and segmental stabilization. The decision to perform a concomitant fusion procedure is influenced in part by the need for adjunctive chemotherapy as well as the patient's anticipated survival. Although some evidence exists that suggests that chemotherapy may inhibit bony healing, no information exists regarding the effect of chemotherapy on spinal fusion healing. PURPOSE: To determine the effect of a frequently used chemotherapeutic agent, doxorubicin, on posterolateral spinal fusion rates. STUDY DESIGN/SETTING: Prospective animal model of posterolateral lumbar fusion. OUTCOME MEASURES: Determination of spinal fusion by manual palpation of excised spines. Plain radiographic evaluation of denuded spines to evaluate intertransverse bone formation. METHODS: Thirty-two New Zealand White rabbits underwent posterior intertransverse process fusion at L5-L6 with the use of iliac autograft bone. Rabbits randomly received either intravenous doxorubicin (2.5 mg/kg) by means of the central vein of the ear at the time of surgery (16 animals) or no treatment (16 animals; the control group). The animals were euthanized at 5 weeks, and the lumbar spines were excised. Spine fusion was assessed by manually palpating (by observers blinded to the treatment group) at the level of arthrodesis, and at the adjacent levels proximal and distal. This provided similar information to surgical fusion assessment by palpation in humans. Fusion was defined as the absence of palpable motion. Posteroanterior radiographs of the excised spines were graded in a blinded fashion using a five-point scoring system (0 to 4) devised to describe the amount of bone observed between the L5-L6 transverse processes. Power analysis conducted before initiation of the study indicated that an allocation of 16 animals to each group would permit detection of at least a 20% difference in fusion rates with statistical significance at p=.05. RESULTS: Eleven of the 16 spines (69%) in the control group and 6 of the 16 spines (38%) in the doxorubicin group fused. This difference was statistically significant (=.038). There was no significant correlation (p>.05) between the radiographic grade of bone formation (0 to 4) and fusion as determined by palpation. There were four wound infections in the control group and four in the doxorubicin group. However, solid fusions were palpated in three of these four spines in both the control and treatment groups. CONCLUSIONS: No significant differences in wound complications were noted with doxorubicin administration. A single dose of doxorubicin administered intravenously at the time of surgery appears to play a significant inhibitory role in the process of spinal fusion. If similar effects occur in humans, these data suggest that doxorubicin may be harmful to bone healing in a spine fusion if given during the perioperative period. Further investigation will be necessary to determine the effect of time to aid at determining whether doxorubicin administered several weeks pre- or postoperatively results in improved fusion rate, and whether bone morphogenetic proteins can overcome these inhibitory effects.

Results of radiotherapy in non round cell spinal metastasis.

Spinal metastases are commonly encountered by physicians in a variety of clinical fields. There are some controversies in choice of treatment between surgery and radiotherapy. This report is a study of the outcomes of radiotherapy for metastatic nonround cell tumors of the spine. Medical records and films of 31 patients who were treated with radiotherapy at Songklanakarind Hospital were retrospectively reviewed. The most common primary tumors were prostate and breast. One patient had spinal metastases from malignant serous cystadenoma of the fallopian tube of which no previous report has been published. This patient had excellent results after radiotherapy. Back and neck pain were the primary symptoms of the patients, while motor or sensory deficits (or both) were found in 58 per cent of the cases. Seven patients had neurological recovery and 18 patients had pain relief after radiotherapy. Cause of compression is the only factor effecting the result from univariate and multivariate analysis. Spinal cord compressed by a tumor had a better recovery than those which were compressed by a bony fragment or intervertebral disc. The authors concluded that radiotherapy remains a good treatment for patient with non round cell spinal metastasis. Cause of spinal cord compression is the only factor predicting the result of treatment.