Norman B. Chutkan

Avoiding wrong site surgery: a systematic review.

Study Design. Systematic review. Objective. To report the incidence and causes of wrong site surgery and determine what preoperative measures are effective in preventing wrong site surgery. Summary of Background Data. From 1995 to 2005, the Joint Commission (JC) sentinel event statistics database ranked wrong site surgery as the second most frequently reported event with 455 of 3548 sentinel events (12.8%). Although the event seems to be rare, the incidence of these complications has been difficult to measure and quantify. The implications for wrong site surgery go beyond the effects to the patient. Such an event has profound medical, legal, social, and emotional implications. Methods. A systematic review of the English language literature was undertaken for articles published between 1990 and December 2008. Electronic databases and reference lists of key articles were searched to identify the articles defining wrong site surgery and reporting wrong site events. Two independent reviewers assessed the level of evidence quality using the Grading of Recommendations Assessment, Development, and Evaluation criteria and disagreements were resolved by consensus. Results. The estimated rate of wrong site surgery varies widely ranging from 0.09 to 4.5 per 10,000 surgeries performed. There is no literature to substantiate the effectiveness of the current JC Universal Protocol in decreasing the rate of wrong site, wrong level surgery. Conclusion. Wrong site surgery may be preventable. We suggest that the North American Spine Society and JC checklists are insufficient on their own to minimize this complication. Therefore, in addition to these protocols, we recommend intraoperative imaging after exposureand marking of a fixed anatomic structure. This imaging should be compared with routine preoperative studies to determine the correct site for spine surgery.

Evaluation of the cervical spine in the polytrauma patient.

Study Design. Two-part study. Part One: the analysis of surveys distributed to members of the Orthopaedic Trauma Association (OTA) and 1000 surgeon members of NASS. Part Two: a prospective clinical study evaluating a new algorithm to evaluate the cerivcal spine in polytrauma patients. Objectives. To determine if there is a consensus of the optimal method for “clearing the cervical spine”; to assess the safety and efficacy of a newly proposed algorithm. Summary of Background Data. There is no uniformly accepted algorithm for “clearing the cervical spine” in the polytrauma patient or those patients with altered mental status secondary to the influence of alcohol, drugs or a closed head injury. Methods. All members of the OTA and 1000 surgeon members of NASS were sent questionnaires to assess their methods of “clearing the cervical spine” in the polytrauma patient. Their answers were collated, analyzed and compared to standard ATLS protocol guidelines. A new protocol, which includes a surgeon, controlled stretch test and flouroscopically visualized flexion-extension views, was initiated and evaluated for safety and efficacy. Results. Survey: Fifty-five percent of the members of the OTA and 31% of the NASS surgeons responded to the questionnaire. Among the responses from the NASS members, the ratio of orthopaedic spine surgeons to neurosurgeons accurately parallels the society’s membership (77% ortho, 23% neuro). Sixty-nine of the OTA and 54% of the NASS responders replied that they followed ATLS guidelines. Analysis of their responses showed only 40% compliance. Eighty-one percent of the OTA respondents utilize the standard three view cervical spine trauma series, only 31% of the NASS members adhere to this guideline. Nearly 90% of all respondents identified the presence of neck pain or retropharygeal soft tissue swelling as an indicator to expand their initial radiographic evaluation. There was no consensus as to management of the polytrauma patient with a closed head injury. Eighty-two percent of all respondents has seen or treated a purely ligamentous injury of the c-spine. Spective Study. Prospective clinical protocol. 35-monthperiod: enrolled 153 patients, 12,000 patients seen in trauma unit. Completed data 149/153. 8/153 unable to be cleared due to poor visualization of cervical-thoracic junction. 3/153 positive findings identified during fluoro examination. All three instability patterns verified in surgery (true positives). No untoward events to date.— Conclusions. A standardized protocol to safely and effectively clear the cervical spine has yet to be established. Preliminary results of a new protocol to safely evaluate the cervical spine in the polytrauma patient are promising.

Age-Related Changes in the Osteogenic Differentiation Potential of Mouse Bone Marrow Stromal Cells

Age‐dependent bone loss has been well documented in both human and animal models. Although the underlying causal mechanisms are probably multifactorial, it has been hypothesized that alterations in progenitor cell number or function are important. Little is known regarding the properties of bone marrow stromal cells (BMSCs) or bone progenitor cells during the aging process, so the question of whether aging alters BMSC/progenitor osteogenic differentiation remains unanswered. In this study, we examined age‐dependent changes in bone marrow progenitor cell number and differentiation potential between mature (3 and 6 mo old), middle‐aged (12 and 18 mo old), and aged (24 mo old) C57BL/6 mice. BMSCs or progenitors were isolated from five age groups of C57BL/6 mice using negative immunodepletion and positive immunoselection approaches. The osteogenic differentiation potential of multipotent BMSCs was determined using standard osteogenic differentiation procedures. Our results show that both BMSC/progenitor number and differentiation potential increase between the ages of 3 and 18 mo and decrease rapidly thereafter with advancing age. These results are consistent with the changes of the mRNA levels of osteoblast lineage‐associated genes. Our data suggest that the decline in BMSC number and osteogenic differentiation capacity are important factors contributing to age‐related bone loss.

Impact of Glucose-Dependent Insulinotropic Peptide on Age-Induced Bone Loss†

GIP is an important hormonal link between nutrition and bone formation. We show for the first time that BMSCs express functional GIP receptors, that expression decreases with aging, and that elevations in GIP can prevent age‐associated bone loss.

Video-assisted thoracoscopic surgery in the prone position.

Study Design. Review of 27 consecutive patients who underwent video-assisted thoracoscopic surgery (VATS) in the prone position for anterior release and discectomy. Objectives. To convey the benefits and safety of this new technique for treating spinal deformities through VATS. Summary of Background Data. All reports using VATS for spinal deformities describe the patient in the lateral position. This is the first study to demonstrate the benefits and safety of the prone position. Methods. The patient is positioned prone, prepared, and draped allowing room for lateral portals on the convexity of the curve. Traditionally, a double-lumen endotracheal tube is used to deflate the ipsilateral lung. Prone positioning eliminates this need, because gravity aids in retraction of the lung. Results. All procedures were successfully performed using the VATS technique with the patient prone. After the anterior release and discectomy, posterior instrumentation (n = 27), costoplasty (n = 16), and fusion (n = 27) were performed. The time (n = 20) and blood loss (n = 16) for the anterior approach averaged 129 ± 35 minutes and 221 ± 231 mL, respectively. The mean number of disks resected was 3.3 ± 0.7 (range, 2–5). Conclusion. The prone position is both safe and effective for VATS when treating spinal deformity. The current results confirm that there is no need to insert a double-lumen tube, there is gravity-assisted correction of kyphosis when the patient is prone, and significant operative time is saved with the elimination of repositioning and redraping before the posterior procedure. Surgical times and blood loss compare very favorably with those reported for VATS in the lateral position.

Odontoid Fractures: Evaluation and Management

&NA; Fractures of the odontoid process are uncommon injuries. Fracture displacement, compromised blood supply, comminution, and iatrogenic distraction have all been implicated in the reported high rates of nonunion. Plain radiography, polytomography, and computed tomography are all useful in delineating the fracture pattern. Magnetic resonance imaging has been recommended for evaluating associated ligamentous injuries and may be helpful in detecting occult cervical spine fractures. Type I fractures are avulsion fractures of the tip of the odontoid process. These rare injuries require only external immobilization with an orthosis if there is no associated ligamentous injury. Type II fractures occur at the junction of the odontoid process and the body of the axis. These are the most common odontoid fractures and are associated with a high incidence of nonunion. Nondisplaced fractures should be treated with halo immobilization for 8 to 12 weeks, with careful clinical and radiographic monitoring. Displaced fractures should be considered for operative treatment, either with atlantoaxial arthrodesis or anterior screw fixation. Type III fractures, which extend into the body of the axis through cancellous bone, are treated with closed reduction and halo immobilization.

Effects of facetectomy and crosslink augmentation on motion segment flexibility in posterior lumbar interbody fusion.

STUDY DESIGN Biomechanical assessment using calf lumbar motion segments. OBJECTIVE To determine whether facetectomy affects the primary stability of posterior lumbar interbody fusion. SUMMARY OF BACKGROUND DATA To improve visualization and access to the disc space, the facet joints frequently are removed. Previous biomechanical studies have indicated a fundamental role for the facet joints in maintaining spinal segment stability. METHODS Single motion segments from calf lumbar spines were tested for pure-moment flexibility in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). After testing intact, an interbody cage and pedicle screw system were implanted. Next, a bilateral facetectomy was performed, and finally a crosslink was added. Flexibility testing was repeated at each stage of implantation. Data are reported for range of motion (ROM), neutral zone (NZ), and a new compliance parameter (COM), based on the slopes of the moment-angle curve in the neutral and elastic regions. RESULTS With posterior lumbar interbody fusion implantation, ROM in FE was reduced 82% +/- 4% (mean +/- standard deviation) and NZ 78% +/- 7% over intact (P < 0.015: Wilcoxon). Reduction in LB was slightly more, whereas reduction in AR was considerably less and did not achieve statistical significance for NZ. After facetectomy, ROM in FE increased 0.3 degrees (P < 0.05), on average, and NZ did not change. In LB neither changed significantly. In AR, ROM increased 0.6 degrees (P < 0.05), and NZ increased 0.2 degrees (P < 0.05). The addition of a crosslink changed ROM and NZ less than 0.1 degrees in FE and LB, whereas in AR it restored half of the stability lost due to facetectomy in ROM (P < 0.05), and had a similar trendwise effect on NZ. The new compliance measure, COM, was found to agree with the direction of change in ROM more consistently than did NZ. CONCLUSION Facetectomy causes a nominal increase in ROM and NZ in FE and LB, which are not affected by the addition of a crosslink. Although the effect of facetectomy is greater in AR-and crosslink has a measurable restoring effect-all differences are within a few tenths of a degree under this loading paradigm. Thus, the clinical utility of adding a crosslink may not be justified based on these small biomechanical changes. COM can serve as a complement to ROM and NZ, or even as a surrogate when its 2 components are reported together, as it shows strong agreement with ROM, effectively distinguishes between lax and elastic region behaviors, and provides a measure of flexibility independent of the load range.Study Design. In vitro testing of vertebroplasty techniques including pulsed jet-lavage for fat and marrow removal in human cadaveric lumbar and thoracic vertebrae. Objective. To develop jet-lavage techniques for vertebroplasty and investigate their effect on cement distribution, injection forces, and fat embolism. Summary of Background Data. The main complications of cement vertebroplasty are cement leakage and pulmonary fat embolism, which can have fatal consequences and are difficult to prevent reliably by current vertebroplasty techniques. Methods. Twenty-four vertebrae (Th8–L04) from 5 osteoporotic cadaver spines were grouped in triplets depending on bone mineral density (BMD). Before polymethylmethacrylate (PMMA) vertebroplasty, a pulsatile jet-lavage for removal of intertrabecular fat and bone marrow was performed in 2 groups with 8 specimens each, performing radial and axial irrigation from the biopsy needles. One hundred mL of Ringer solution were injected through 1 pedicle and regained by low vacuum via the contralateral pedicle. Eight control vertebrae were not irrigated. All specimens underwent standardized PMMA cement augmentation injecting 20% of the vertebral volume. Injection forces, cement distribution, and extravasations were quantified. Results. All irrigation solution could be retrieved with the vacuum applied. A Kruskal-Wallis test revealed significantly higher injection forces of the control group as compared with the irrigated groups (P = 0.021). Dilatation of the syringe at forces above 300 N occurred in 75% of the untreated compared with 12.5% of the lavaged specimens. CT distribution analysis showed more homogenous cement distribution of the cement and significantly less extravasation in the irrigated specimens. Conclusion. The developed lavage technique for vertebroplasty showed to be feasible and reproducible. The reduction of injection forces would allow the use of more viscous PMMA cement lowering the risk for cement embolization and results in a safer procedure. The wash-out of bone marrow and the possible reduction of pulmonary fat embolism have to be verified with in vivo models.

Comparative study of biocompatibility of newly developed calcium phosphate-based root canal sealers on fibroblasts derived from primary human gingiva and a mouse L929 cell line

AIM To determine biocompatibility of three calcium phosphate cement (CPC) sealers, and to compare the cytotoxic response of human gingival fibroblasts (HGF) and one mouse fibroblast cell line (L929) to these materials. METHODOLOGY Monocalcium phosphate, calcium oxide and synthetic hydroxyapatite were combined with one of three aqueous solutions: modified polyacrylic acid, glass-ionomer liquid or 35% w/w polymethyl vinyl ether maleic acid to obtain Types I, IIa and III CPCs, respectively. Commercial Ca(OH)(2) sealer was used as a control. The materials were packed into Teflon molds (5.5 x 3 mm), and cellular function was assessed using MTT assay. The specimens were placed immediately in contact with cells, then evaluated at (24 h, 1 week, 2 week, 3 week, 4 week, 5 week). RESULTS All materials showed significant cytotoxicity for both L929 and HGF cells at 24 h except for Type III. Type I was severely toxic initially, but improved significantly (P < 0.05) over the 5 week evaluation. Types II and Ca(OH)(2) were both cytotoxic over the 5 weeks. Type III CPC was equivalent to Teflon the entire time. The results showed the same rank of cytotoxicity in both cultures. The cytotoxic response decreased in the order of Type II > Ca(OH)(2) > Type I > Type III overtime. L929 cells were generally more sensitive than HGF cells to the calcium hydroxide-based sealer (Acroseal). CONCLUSION Types I and III have acceptable biologic properties for endodontic applications.

Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations

New polymeric calcium phosphate cement composites (CPCs) were developed. Cement powder consisting of 60 wt% tetracalcium phosphate, 30 wt% dicalcium phosphate dihydrate, and 10 wt% tricalcium phosphate was combined with either 35% w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15 min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications.

Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs) were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control). Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12 min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications.