A Review of Emerging Evidence for Utilization of a Percutaneous Interspinous Process Decompression Device to Treat Symptomatic Lumbar Adjacent-Segment Degeneration.

OBJECTIVE: Postlaminectomy syndrome diagnoses secondary to adjacent segment degeneration are a substantial and rising cause of morbidity in the United States. Emerging spinal cord neuromodulation technologies have produced successful outcomes for postlaminectomy neuropathic pain but are less effective in treating neurogenic claudication secondary to recurrent lumbar stenosis. Percutaneous interspinous process decompression systems can be used as a salvage treatment modality for persistent structural neurogenic claudication in postlaminectomy syndrome or after spinal cord stimulator implantation. METHODS: This paper is a review of emerging evidence for efficacious utilization of percutaneous interspinous process decompression. RESULTS: A recent pragmatic trial of subjects who underwent percutaneous interspinous process decompression for lumbar stenosis with intermittent neurogenic claudication reported that 63% (26/41) maintained minimal clinically important improvement in visual analog scale (VAS) leg pain, 61% (25/41) in VAS back pain, 78% (32/41) in function objective values, and 88% (36/41) reported satisfaction with treatment at 12 months postop. All subjects in a small case series of seven individuals with postlaminectomy adjacent-segment disease reported postoperative satisfaction scores of 3 or 4 on a 0-4 scale and were also able to decrease or wean completely off controlled pain medications. In another study, there was a significant decrease in average leg pain (60% improvement, P < 0.0001, N = 25) and axial low back pain (58% improvement, P < 0.0001, N = 25) in patients who underwent one- or two-level percutaneous interspinous process decompression as a rescue treatment for reemerging neurogenic claudication after spinal cord stimulator implantation. CONCLUSIONS: The spine often is a focus of progressive disease. Furthermore, mechanical changes associated with spinal instrumentation can lead to additional disease at adjacent levels. Many individuals will present with symptomatic neurogenic claudication recalcitrant to multimodal management strategies, including even the most sophisticated neuromodulation technologies. Implementation of salvage percutaneous interspinus process decompression implantation in cases of adjacent segment degeneration or incomplete spinal cord stimulation can decompress structural causes of neurogenic claudication while sparing the patient from more invasive surgical reoperation techniques.

Brief topical sodium nitrite and its impact on the quality of life in patients with sickle leg ulcers.

Cutaneous ulceration from sickle cell disease negatively impacts quality of life. Topical sodium nitrite has previously been shown to reduce the size of sickle leg ulcers. This study examined how topical sodium nitrite impacted the quality of life scores in patients with sickle leg ulcers.We prospectively collected data in patients enrolled in a leg ulcer study (n = 17) or an allogeneic hematopoietic cell transplant study (nonulcer group, n = 15). Both groups completed a pretreatment Short Form-36 questionnaire; the ulcer group completed a second questionnaire after 4 weeks of topical sodium nitrite applications. Data were analyzed by age, sex, >50% area improvement postintervention, and sickle-related complications (vaso-occlusive crises, pulmonary hypertension, or avascular necrosis). Physical and mental component summary scores were analyzed with Student t test.Physical summary scores were lower than mental summary scores in all groups, indicating leg ulcers among other sickle related complications negatively impacted physical quality of life measures. After sodium nitrite use, physical summary scores improved in the leg ulcer group (34.5 ±â€Š9.4 to 39 ±â€Š10.3, P = .03), and mental summary scores improved more in ulcerated patients ≤35 years old (40.7 ±â€Š6.9 to 51.7 ±â€Š9.7, P = .01).Brief topical sodium nitrite has the potential to improve quality of life, especially in younger individuals. Longer treatment duration and randomized-controlled trials are needed to confirm the efficacy of this topical therapy.

Arthrodesis Rate and Patient Reported Outcomes After Anterior Lumbar Interbody Fusion Utilizing a Plasma-Sprayed Titanium Coated PEEK Interbody Implant: A Retrospective, Observational Analysis.

BACKGROUND: Anterior lumbar interbody fusion (ALIF) is utilized in symptomatic spinal disc destabilization due to degenerative lumbar disc disease, isthmic and degenerative spondylolisthesis, internal disc disruption, or pseudarthrosis after non-operative treatments fail. The addition of a plasma-sprayed titanium coating (PTC) to polyether ether ketone spacers (PEEK) may reduce the rate of implant subsidence or non-union secondary to poor osseous-integration of non-coated PEEK or metal interbody systems. METHODS: A retrospective, non-randomized, single-center chart review, evaluated the post-surgical follow-up data of patients receiving a PTC PEEK implant during single or multi-level ALIF procedures to determine the clinical efficacy and rate of arthrodesis after utilization of a coated spacer. Standard roentgenographs or computed tomography were used to identify successful arthrodesis following the ALIF procedure and longitudinal clinical improvements were determined by scores on the Visual Analog Scale (VAS) for low back and leg pain. RESULTS: Forty-four subjects (48% male, mean=53 years) were included in this chart review. Follow-up radiology demonstrated radiographic union with bridging bone formation across the interbody space for 42/44 (96%) individuals with solid arthrodesis occurring at an average of 7.3 ± 2.3 months. Subjects demonstrated significant improvement in VAS low back pain (4.5 ± 2.4 point improvement, p=0.0001) and VAS leg pain (4.1 ± 3.3 point improvement, p=0.0001). While there was a significant reduction in the improvement of VAS low back pain of Worker's Compensation claimants as compared to other patients (3.9 ± 2.4 vs. 5.3 ± 2.1), there was no difference in VAS low back pain or leg pain when the data was stratified by gender, age, tobacco use, comorbidities, prior surgery, fusion construct length, use of supplemental posterior instrumentation, BMI, or diagnosis. CONCLUSIONS: This study provides support that the addition of a PTC coating to a zero-profile PEEK lumbar interbody spacer facilitates rapid and stable fixation at the bone-implant interface. This facilitated osteogenesis is associated with significantly improved pain outcomes, low implant subsidence and a high definitive rate of arthrodesis. Future studies should include a prospective, randomized, controlled, multi-center approach to directly compare arthrodesis rates and clinical outcomes longitudinally between standard PEEK and biomaterial-coated PEEK interbody spacer systems.

The effect of anterior longitudinal ligament resection on lordosis correction during minimally invasive lateral lumbar interbody fusion: Biomechanical and radiographic feasibility of an integrated spacer/plate interbody reconstruction device.

BACKGROUND: Lateral lumbar interbody fusion is powerful for correcting degenerative conditions, yet sagittal correction remains limited by anterior longitudinal ligament tethering. Although lordosis has been restored via ligament release, biomechanical consequences remain unknown. Investigators examined radiographic and biomechanical of ligament release for restoration of lumbar lordosis. METHODS: Six fresh-frozen human cadaveric spines (L3-S1) were tested: (Miller et al., 1988) intact; (Battie et al., 1995) 8mm spacer with intact anterior longitudinal ligament; (Cho et al., 2013) 8mm spacer without intact ligament following ligament resection; (Galbusera et al., 2013) 13mm lateral lumbar interbody fusion; (Goldstein et al., 2001) integrated 13mm spacer. Focal lordosis and range of motion were assessed by applying pure moments in flexion-extension, lateral bending, and axial rotation. FINDINGS: Cadaveric radiographs showed significant improvement in lordosis correction following ligament resection (P<0.05). The 8mm spacer with ligament construct provided greatest stability relative to intact (P>0.05) but did little to restore lordosis. Ligament release significantly destabilized the spine relative to intact in all modes and 8mm with ligament in lateral bending and axial rotation (P<0.05). Integrated lateral lumbar interbody fusion following ligament resection did not significantly differ from intact or from 8mm with ligament in all testing modes (P>0.05). INTERPRETATION: Lordosis corrected by lateral lumbar interbody fusion can be improved by anterior longitudinal ligament resection, but significant construct instability and potential implant migration/dislodgment may result. This study shows that an added integrated lateral fixation system can significantly improve construct stability. Long-term multicenter studies are needed.

Descriptive Analysis of Spinal Neuroaxial Injections, Surgical Interventions, and Physical Therapy Utilization for Degenerative Lumbar Spondylolisthesis Within Medicare Beneficiaries from 2000 to 2011.

STUDY DESIGN: A retrospective, observational study. OBJECTIVE: The aim of this study was to determine the utilization of various treatment modalities in the management of degenerative spondylolisthesis within Medicare beneficiaries. SUMMARY OF BACKGROUND DATA: Degenerative lumbar spondylolisthesis is a condition often identified in symptomatic low back pain. A variety of treatment algorithms including physical therapy and interventional techniques can be used to manage clinically significant degenerative spondylolisthesis. METHODS: This study utilized the 5% national sample of Medicare carrier claims from 2000 through 2011. A cohort of beneficiaries with a new International Classification of Diseases 9th edition (ICD-9) diagnosis code for degenerative lumbar spondylolisthesis was identified. Current procedural terminology codes were used to identify the number of procedures performed each year by specialty on this cohort. RESULTS: A total of 95,647 individuals were included in the analysis. Average age at the time of initial diagnosis was 72.8 ±â€Š9.8 years. Within this study cohort, spondylolisthesis was more prevalent in females (69%) than males and in Caucasians (88%) than other racial demographics. Over 50% of beneficiaries underwent at least one injection, approximately one-third (37%) participated in physical therapy, one in five (21%) underwent spinal surgery, and one-third (36%) did not utilize any of these interventions. Greater than half of all procedures (124,280/216,088) occurred within 2 years of diagnosis. The ratio of focal interventions (transforaminal and facet interventions) to less selective (interlaminar) procedures was greater for the specialty of Physical Medicine and Rehabilitation than for the specialties of Anesthesiology, Interventional Radiology, Neurosurgery, and Orthopedic Surgery. The majority of physical therapy was dedicated to passive treatment modalities and range of motion exercises rather than active strengthening modalities within this cohort. CONCLUSION: Interventional techniques and physical therapy are frequently used treatment modalities for symptomatic degenerative spondylolisthesis. Understanding utilization of these techniques is important to determine relative clinical efficacies and to optimize future health care expenditures. LEVEL OF EVIDENCE: N/A.

Validity and reliability of a novel patient reported outcome tool to evaluate post-operative dysphagia, odynophagia, and voice (DOV) disability after anterior cervical procedures.

BACKGROUND: Existing evaluative instruments for dysphagia, odynophagia, and voice disturbance are cumbersome, focus pre-dominately on dysphagia, and often require administration by a certified Speech Pathologist. This study was conducted to utilize widely accepted instruments such as the American Speech and Hearing Association's National Outcomes Measurement System (NOMS) and VAS pain scales to validate a novel, patient-reported instrument that quantifies the severity of post-operative dysphagia, odynophagia, and voice disabilities (DOV). METHODS: The DOV was developed and subjected to multiple rounds of face and content validation by representative patient cohorts and a panel of clinical experts. An established, prospective clinical registry was utilized to collect pre and post-operative VAS-swallow related pain and DOV measurements for subjects with recent anterior cervical procedures (n=25 content validation, n=20 criterion validation), or recent lumbar decompressions (n=33). NOMS evaluations were performed by a certified Speech Language Pathologist on the first post-operative day after minimally invasive anterior approaches to cervical reconstruction were performed in the criterion validation cohort. RESULTS: Content validity: Subjects with a recent anterior cervical procedure reported a significant increase in post-operative dysphagia (pre-op: 0.13±0.35, post-op: 1.08±1.41, p=0.01), odynophagia (pre-op: 0.24±0.69, post-op: 0.84±0.90, p=0.001), and voice (pre-op: 0.10±0.41, post-op: 0.88±0.92, p=0.0004) disturbance. In contrast, subjects with a recent lumbar procedure did not demonstrate a significant increase in post-operative dysphagia, odynophagia, or voice disturbance (p>0.05).Criterion validity: Chi-squared contingency testing for independence between converted NOMS and DOV instrument scores accepted linkage between the two instruments for dysphagia X2(DF: 12, n=20, Expected: 21.03, Observed: 24.4, p: 0.02) and voice X2(DF: 6, n=20, Expected: 12.60, Observed: 21.28, p: 0.002) dimensions. Similarly, converted swallow related VAS and DOV odynophagia instruments demonstrated linkage X2(DF: 9, n=20, Expected: 16.92, Observed: 24.21, p: 0.004).Internal Reliability: Chronbach's alpha coefficient of reliability was 0.74 between all DOV survey dimensions. CONCLUSIONS: The DOV survey is a valid patient-reported instrument to rapidly and reliably detect post-operative swallow and voice dysfunction.

Clinical Outcomes After Cervical Transcorporeal Microdecompression and Vertebral Body Access Channel Repair.

BACKGROUND: Although anterior cervical decompression and fusion (ACDF) can be performed using minimally invasive techniques, the extensive removal of anatomical keystones during decompression requires a segmental fusion to restore biomechanical stability. Treatment with arthrodesis techniques may result in a prolonged recovery time, loss of motion, and the need for further treatment if a pseudarthosis or adjacent segment disease occur. Transcorporeal micro decompression (TCMD) is a newly developed motion sparing, minimally invasive anterior cervical spine decompression procedure that utilizes a small channel through the cervical vertebral body to decompress areas of central or foraminal stenosis while preserving the native disc. Cervical decompression with TCMD can be performed as a stand-alone or hybrid procedure with ACDF at the adjacent levels. This study retrospectively assesses patient based clinical outcome measures in patients treated with TCMD. METHODS: A retrospective, non-randomized, single-center chart review of single surgeon experience with patients undergoing TCMD both with and without adjacent level ACDF using both a trajectory control guide and access channel repair. Statistical analyses were performed on pre and post-operative data collected using visual analog scale (VAS) and neck disability index (NDI) outcome measures. RESULTS: Among 62 patients, there were no cases of neurovascular injury, CSF leak, transfusion, or migration of repair implement. Revision surgery was required in 6.4% (n=4) patients. A subanalysis of outcome metrics was performed for patients that underwent standalone TCMD (TCMD group, n=42) and TCMD with concurrent ACDF at one or more levels (TCMD+ACDF group, n=20). TCMD group NDI improved from 20.0 to 2.7 at 1 year (p=0.0001); Axial VAS improved from 5.5 to 0.6 (p=0.0001); and Radiating VAS improved from 7.0 to 0.7 (p=0.0001). TCMD+ACDF group NDI improved from 22.0 to 4.0 at 1 year (p=0.004); Axial VAS improved from 7.1 to 1.2 (p=0.01); and Radiating VAS trended towards significant improvement from 6.4 to 2.3 (p=0.09). Mean return to work was 10 days in the TCMD group and 57 days in the TCMD+ACDF group. CONCLUSIONS: Within the limits of a retrospective, single-surgeon study, patients did experience both functional improvement and pain relief as measured by NDI and VAS respectively from standalone TCMD or combined ACDF / TCMD procedures. Definitive statements on long-term efficacy, disc space preservation, and motion preservation await further study.

Outcome Measures of an Intracanal, Endoscopic Transforaminal Decompression Technique: Initial Findings from the MIS Prospective Registry.

BACKGROUND: Minimally invasive transforaminal endoscopic procedures can achieve spinal decompression through either direct or indirect techniques. Subtle variations in trajectory of the surgical corridor can dictate access to the pathologic tissue. Two general strategies exist: the intradiscal "inside-out" technique and the extradiscal, intracanal (IC) technique. The IC technique utilizes a more lateral transforaminal approach than the intradiscal technique, which allows for a more direct decompression of the spinal canal. OBJECTIVE: This study is an assessment of IC patient outcome data obtained through analysis of a previously validated MIS Prospective Registry. METHODS: Post-hoc analysis was performed on the MIS Prospective Registry database containing 1032 patients. A subgroup of patients treated with the endoscopic IC technique was identified. Patient outcome measures after treatment of symptomatic disk herniation and neuroforaminal stenosis were evaluated. RESULTS: A total of 86 IC patients were analyzed. Overall, there was significant improvement in employment and walking tolerance as soon as 6 weeks post-op as well as significant one year VAS and ODI score improvement. Subanalysis of IC patients with two distinct primary diagnoses was performed. Group IC-1 (disc herniation) showed improvement in ODI and VAS back and leg outcomes at 1 year post-op. Group IC-2 (foraminal stenosis) showed VAS back and leg score improvement at one year post-op but did not demonstrate significant improvement in overall ODI outcome at any time point. The one year re-operation rate was 2% (1/40) for group IC-1 and 28% (5/18) for group IC-2. CONCLUSIONS: The initial results of the MIS Registry IC subgroup show a significant clinical improvement when the technique is employed to treat patients with lumbar disc herniation. The treatment of foraminal stenosis can lead to improved short-term clinical outcome but is associated with a high re-operation rate at 1 year post-op.

Complications associated with the initial learning curve of minimally invasive spine surgery: a systematic review.

BACKGROUND: There is an inherently difficult learning curve associated with minimally invasive surgical (MIS) approaches to spinal decompression and fusion. The association between complication rate and the learning curve remains unclear. QUESTIONS/PURPOSES: We performed a systematic review for articles that evaluated the learning curves of MIS procedures for the spine, defined as the change in frequency of complications and length of surgical time as case number increased, for five types of MIS for the spine. METHODS: We conducted a systematic review in the PubMed database using the terms "minimally invasive spine surgery AND complications AND learning curve" followed by a manual citation review of included manuscripts. Clinical outcome and learning curve metrics were categorized for analysis by surgical procedure (MIS lumbar decompression procedures, MIS transforaminal lumbar interbody fusion, percutaneous pedicle screw insertion, laparoscopic anterior lumbar interbody fusion, and MIS cervical procedures). As the most consistent parameters used to evaluate the learning curve were procedure time and complication rate as a function of chronologic case number, our analysis focused on these. The search strategy identified 15 original studies that included 966 minimally invasive procedures. Learning curve parameters were correlated to chronologic procedure number in 14 of these studies. RESULTS: The most common learning curve complication for decompressive procedures was durotomy. For fusion procedures, the most common complications were implant malposition, neural injury, and nonunion. The overall postoperative complication rate was 11% (109 of 966 cases). The learning curve was overcome for operative time and complications as a function of case numbers in 20 to 30 consecutive cases for most techniques discussed within this review. CONCLUSIONS: The quantitative assessment of the procedural learning curve for MIS techniques for the spine remains challenging because the MIS techniques have different learning curves and because they have not been assessed in a consistent manner across studies. Complication rates may be underestimated by the studies we identified because surgeons tend to select patients carefully during the early learning curve period. The field of MIS would benefit from a standardization of study design and collected parameters in future learning curve investigations.

Clinical outcomes of a polyaxial interspinous fusion system.

BACKGROUND: Early interspinous process fixation constructs utilize rigid fixation plates with immobile spikes which increase the difficulty of device implantation when anatomic variations are encountered. Second generation systems have been designed with polyaxial properties with the goal of accommodating natural osseous anatomic variations to achieve optimal implant placement and fixation integrity. The purpose of this study was to evaluate clinical outcomes in patients treated with this device to supplement the biomechanical data from previous studies. METHODS: A retrospective, non-randomized, single-center chart review at or beyond the one year postoperative time point was conducted to collect preoperative and perioperative data on patients treated with a polyaxial intraspinous fixation system. A postoperative numerical pain rating scale and modified MacNab classification score were obtained from each patient in the cohort via phone survey. RESULTS: A total of 53 patients were included in the study. Median hospital stay was 2 days (range 1-7 days). There were no reported perioperative blood transfusions or cases of radiographic fracture/migration of the device at the 6 week post-operative time point. There was a significant improvement in pain index score in the overall patient study group and a satisfactory (excellent or good) MacNab result was obtained in 48% of all patients. Patients with preoperative pain scores greater than 8/10 reported more pain improvement than patients with preoperative pain scores less than 5 (0 points, p = 0.96, n = 8). Patients with a BMI less than 30 had significantly better MacNab outcome classifications than patients with a BMI greater than 30. CONCLUSIONS: The polyaxial interspinous fusion system produces significant clinical improvement when employed to treat patients with stenosis, herniated disc, or low grade spondylolisthesis. This device can be implanted with a low complication rate and short postoperative hospital admission time. Patients with high pre-operative pain score and BMI under 30 can be predictors of better clinical outcome and should be considered prior to implantation.

Validation and analysis of a multi-site MIS Prospective Registry through sub-analysis of an MIS TLIF Subgroup.

STUDY DESIGN: Retrospective analysis of multi-site, prospectively collected database. OBJECTIVE: To assess the validity and utility of a prospective spine registry by sub-analysis of patients treated with MIS TLIF. BACKGROUND: The MIS registry is a large-scale, multi-center series of prospectively collected clinical information on outcomes, complications, and adverse events for minimally invasive spine procedures for the treatment of degenerative lumbar conditions. METHODS: Analysis was performed on the MIS Prospective Registry database. A subgroup of patients treated by MIS TLIF technique was identified. Statistical analyses were performed on pre and post-operative data collected using validated health related quality of life outcome tools. Missing 1-year patient follow-up data was obtained through progressive correspondence modalities. RESULTS: Data analysis was performed on 98 MIS TLIF patients (56 female, 42 male) with a median age of 64.5 years (range 25-91 years) which were extracted from a total registry population of 478 patients. The one year follow-up rate was 87%. A total of 64 single-level, 23 two-level, 3 three-level, and 3 combined TLIFs staged with an MIS lateral procedure were included. The primary surgical indications were spondylolisthesis (27%), central stenosis (25%), foraminal stenosis (14%), post-laminectomy syndrome (14%) and degenerative scoliosis (6%). The peri-operative blood transfusion rate was 3%. Complications included intraoperative dural tear (n = 3), deep wound infection (n = 2), superficial dehiscence/cellulitis (n = 2). There was a 4% re-operation rate at the 1 year post-operative time point. Half of patients were discharged within 2 days (range 1-11 days, mean 2.97 days, median 2 days). All patients that were discharged on the first post-operative day (n = 14) underwent a single-level MIS TLIF procedure and had significantly lower pre-op disability index score than those discharged on POD 3-5 (43.7 ± 15.5 vs. 56.0 ± 18.3, p = 0.04). Average ODI scores in the subgroup of patients that had reached the one year postoperative time point were 46.5 pre-op (n = 46), and 26.2 at 1 year post-op (n = 40, p = 0.0001). There was significant improvement in VAS scores: pre-operative (back = 6.7, leg = 5.4, n = 46), and 1 year post-operative (back = 3.2, leg = 1.7, n = 40, p = 0.0001). Patients with pre-operative ODI scores greater than 50 demonstrated significant improvement starting at the 6 week post-operative time point (24 point improvement, n = 46, p < 0.001). A pre-operative ODI between 35-50 showed significant improvement starting at 3 months (15.5 point improvement, n = 29, p = 0.05). Patients with a pre-operative ODI score less than 35 had an initial period of increased disability with a trend towards significant improvement by 3 months post-op (n = 20). CONCLUSIONS: Initial findings of the MIS Prospective Registry show patients can be enrolled in a relatively short time period and patient based questionnaires can successfully be obtained through a combination of clinic follow-up appointments and remote correspondence. Outcomes of the MIS Registry MIS TLIF subgroup were consistent with previously published MIS TLIF studies. Sub-analysis of data collected through level-specific patient diagnosis and treatment modalities permits outcome analysis of a wide breadth of spinal conditions and interventions.

Discovery and process synthesis of novel 2,7-pyrrolo[2,1-f][1,2,4]triazines.

The synthesis of a new kinase inhibitor template 2-anilino-7-aryl-pyrrolo[2,1-f][1,2,4]triazine is described which includes a late stage orthogonally reactive key intermediate amenable to rapid diversification as well an optimized in situ triflate displacement to install the C2-aniline. Furthermore, an efficient scalable process approach will be highlighted which begins with tert-butyl carbazate to provide the key N-N bond and generates the pyrrolotriazine core through a stable bromoaldehyde intermediate followed by condensation with ammonium carbonate.

Use of a quantitative pedicle screw accuracy system to assess new technology: Initial studies on O-arm navigation and its effect on the learning curve of percutaneous pedicle screw insertion.

BACKGROUND: A quantitative screw accuracy system is proposed that allows for high-fidelity discrimination between various methods of pedicle screw insertion. Our purpose was to study the utility of a quantitative screw accuracy scoring system to assess new imaging technologies and their effects on the minimally invasive spine learning curve. METHODS: By use of a hypothetical "perfect screw," a scoring system is proposed that may be used to compare the position of a small number of screws inserted according to a desired optimal position. This study incorporates a retrospective review of imaging studies for 10 patients who underwent percutaneous pedicle screw placement with either navigation-assisted O-arm imaging or navigation-assisted C-arm imaging. For the learning-curve portion of the study, 2 cadaveric adult torsos were used for instrumentation. Computed tomography imaging studies were used in both studies to assess screw position in the pedicle and vertebral body in relation to an optimal screw by use of a quantitative scoring system to rate accuracy. RESULTS: The quantitative scoring system allowed a statistically significant accuracy difference to be ascertained between 2 different technologies using fewer data points than previously published methods. When this screw scoring system is applied to minimally invasive percutaneous pedicle screw insertion, an optimal screw position can be achieved with greater accuracy through navigation-assisted technology (O-arm with computer-assisted navigation). When the O-arm with computer-assisted navigation was used by a novice surgeon learning the technique of percutaneous screw insertion, screws were inserted in a shorter period without loss of accuracy. In contrast, use of the traditional C-arm fluoroscopy leads to a loss of accuracy with faster insertion times. Increased accuracy can be seen clinically when compared with fluoroscopic navigation. CONCLUSIONS: The use of a quantitative scoring system allows for rapid assessment of screw accuracy. As additional technologies and new teaching techniques for pedicle screw insertion are developed, this scoring system may be useful as an early assessment tool.

Direct asymmetric Zn-aldol reaction of methyl vinyl ketone and its synthetic applications.

A direct catalytic asymmetric aldol reaction of methyl vinyl ketone is described using our dinuclear zinc catalyst. The obtained aldol adduct functions as a bifunctional building block by utilization of the vinyl functionality. For example, convergent fragment coupling methods have been demonstrated via highly diastereoselective cycloaddition of nitrile oxide after reduction into 1,3-diol or via cross-metathesis reaction.