A Multicenter Study of the Presentation, Treatment, and Outcomes of Cervical Dural Tears.

STUDY DESIGN: Retrospective multicenter case series study. OBJECTIVE: Because cervical dural tears are rare, most surgeons have limited experience with this complication. A multicenter study was performed to better understand the presentation, treatment, and outcomes following cervical dural tears. METHODS: Multiple surgeons from 23 institutions retrospectively identified 21 rare complications that occurred between 2005 and 2011, including unintentional cervical dural tears. Demographic data and surgical history were obtained. Clinical outcomes following surgery were assessed, and any reoperations were recorded. Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA), Nurick classification (NuC), and Short-Form 36 (SF36) scores were recorded at baseline and final follow-up at certain centers. All data were collected, collated, and analyzed by a private research organization. RESULTS: There were 109 cases of cervical dural tears among 18 463 surgeries performed. In 101 cases (93%) there was no clinical sequelae following successful dural tear repair. There were statistical improvements (P < .05) in mJOA and NuC scores, but not NDI or SF36 scores. No specific baseline or operative factors were found to be associated with the occurrence of dural tears. In most cases, no further postoperative treatments of the dural tear were required, while there were 13 patients (12%) that required subsequent treatment of cerebrospinal fluid drainage. Analysis of those requiring further treatments did not identify an optimum treatment strategy for cervical dural tears. CONCLUSIONS: In this multicenter study, we report our findings on the largest reported series (n = 109) of cervical dural tears. In a vast majority of cases, no subsequent interventions were required and no clinical sequelae were observed.

Anterior Cervical Discectomy and Fusion for Adjacent Segment Disease: Clinical Outcomes and Cost Utility of Surgical Intervention.

STUDY DESIGN: Retrospective review. OBJECTIVE: Determine clinical outcomes and cost utility of anterior cervical discectomy and fusion (ACDF) for the treatment of adjacent segment disease (ASD). SUMMARY OF BACKGROUND DATA: The incidence of symptomatic ASD after ACDF has been estimated to occur in up to 26% of patients. Commonly, these patients will undergo an additional ACDF procedure. However, there are currently no studies available that adequately describe the clinical outcomes or cost utility of performing ACDF for ASD. METHODS: A retrospective review of 40 patients undergoing ACDF for ASD was performed. Baseline and 2-year neck and arm pain (NRS-NP, NRS-AP), neck disability index (NDI), physical and mental quality of life (SF-12 PCS & MCS), and Zung depression score (ZDS) were assessed. Two-year total neck-related medical resource utilization, amount of missed work, and health-state values were determined. Quality-adjusted life years (QALYs) were calculated from EQ-5D assessments with US valuation. Comprehensive costs (indirect, direct, and total cost) and the value (cost-per-QALY gained) of performing ACDF for ASD were assessed. RESULTS: Performing ACDF to treat ASD resulted in significant improvements (P<0.05) in NRS-NP, NRS-AP, NDI, SF-12 PCS, and ZDS outcome measures. Patient-reported health states also significantly improved, with a mean cumulative 2-year gain of 0.54 QALYs. The mean 2-year cost of surgery was $32,616 (direct cost: $25,391; indirect cost: $7225). ACDF for the treatment of ASD was associated with a mean 2-year cost per QALY gained of $60,526. CONCLUSIONS: Performing ACDF for ASD resulted in significant improvements in patient pain, disability, and quality of life. Further, the mean 2-year cost-per-QALY was determined to be $60,526, which suggests surgical intervention to be cost effective. This study is the first to provide evidence that performing an ACDF for ASD is both clinically and cost effective.

Factors associated with long-term patient-reported outcomes after three-column osteotomies.

BACKGROUND CONTEXT: Studies have demonstrated sustained improvements in patient-reported outcomes (PROs) after three-column osteotomies (three-COs), but no study has evaluated what factors impact long-term outcomes. PURPOSE: The aim was to investigate factors associated with PROs in patients who underwent three-CO at minimum 5 years postoperatively. STUDY DESIGN/SAMPLE: This was a retrospective review of prospective database. PATIENT SAMPLE: All patients who had a three-CO at a single institution and completed clinical evaluations after at least 5 years postoperative were included. OUTCOME MEASURES: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) scores, and radiographic parameters were assessed at baseline and a minimum 5 years postoperatively. METHODS: Analysis of 120 patients who underwent three-CO (96-pedicle subtraction osteotomy/24-vertebral column resection) was performed. The mean age was 48 years (range 8-79), and clinical follow-up was 7 years (range 5-14). Separate multivariable linear regression analyses were performed to determine factors associated with ODI, SRS average, and SRS satisfaction while controlling for time since surgery and baseline outcome scores. RESULTS: Average PROs were significantly improved from baseline at a minimum 5-year follow-up (ODI: 48-28, p<.01; SRS: 2.8-3.5, p<.01). The average SRS satisfaction score was 4.0. Average sagittal alignment (C7 plumb) improved 74 mm, with 81% of patients' alignment less than 95 mm. Major surgical complications occurred in 32 patients (27%) with major reoperations in 30 patients (25%). Multivariable regression analysis found that prior surgery and major reoperations were risk factors for worse ODI scores. A diagnosis of adult idiopathic scoliosis and final sagittal alignment less than 95 mm were associated with improved SRS scores. Improvement in major coronal Cobb and final pelvic tilt less than 30° were associated with increased SRS satisfaction. CONCLUSIONS: With a minimum 5-year follow-up, PROs in patients undergoing three-CO were associated with improvements in radiographic alignment but negatively affected by prior surgery and complications necessitating revision surgery.

Bupivacaine for pain reduction after iliac crest bone graft harvest.

Iliac crest bone graft remains the gold standard in achieving spinal arthrodesis, but chronic pain from graft harvest occurs in up to 39% of patients. Studies have shown that a single administration of local anesthetic reduces short-term pain, but they have not adequately investigated possible longer-term benefits. The goal of this study was to determine whether local administration of bupivacaine after iliac crest bone graft harvesting reduces pain and improves patient-reported outcomes. In this prospective, randomized, controlled, and blinded clinical study, 40 patients were identified who underwent posterior spine fusion with iliac crest bone graft and were randomized to receive either bupivacaine (treatment group, n=20) or saline (control group, n=20) at the iliac crest bone graft site. Pain at the harvest site was determined by a series of 12 visual and numeric pain scale assessments. Short Form-12 mental and physical component scores, EuroQol-5D, and Oswestry Disability Index assessments were made, along with determination of patient satisfaction and self-reported outcome of surgery. Baseline pain and outcome assessments were statistically similar (P>.05). Average pain scores were lower for all 12 assessments in the treatment group at mean follow-up of 5 weeks (significant differences in 6 assessments) and 20 weeks (significant differences in 2 assessments). No significant differences were found in Short Form-12 and EuroQol-5D scores. For patients who underwent lumbar fusion, the treatment group had significantly improved Oswestry Disability Index scores (mean±SD=10.8±7.1 vs 18.7±5.9, P=.012). Significantly more patients in the treatment group reported that surgery met all expectations (90% vs 50%, P=.016). This study is the 1st to show that a single administration of bupivacaine at the iliac crest bone graft harvest site during posterior spine fusion surgery can result in improved outcomes and reduced pain far beyond the anesthetic duration of activity.

Risk factors for postoperative retropharyngeal hematoma after anterior cervical spine surgery.

STUDY DESIGN: Retrospective review of prospective database. OBJECTIVE: To investigate risk factors involved in the development of anterior cervical hematomas and determine any impact on patient outcomes. SUMMARY OF BACKGROUND DATA: Postoperative (PO) hematomas after anterior cervical spine surgery require urgent recognition and treatment to avoid catastrophic patient morbidity or death. Current studies of PO hematomas are limited. METHODS: Cervical spine surgical procedures performed on adults by the senior author at a single academic institution from 1995 to 2012 were evaluated. Demographic data, surgical history, operative data, complications, and neck disability index (NDI) scores were recorded prospectively. Cases complicated by PO hematoma were reviewed, and time until hematoma development and surgical evacuation were determined. Patients who developed a hematoma (HT group) were compared with those that did not (no-HT group) to identify risk factors. NDI outcomes were compared at early (<11 mo) and late (>11 mo) time points. RESULTS: There were 2375 anterior cervical spine surgical procedures performed with 17 occurrences (0.7%) of PO hematoma. In 11 patients (65%) the hematoma occurred within 24 hours PO, whereas 6 patients (35%) presented at an average of 6 days postoperatively. All underwent hematoma evacuation, with 2 patients (12%) requiring emergent cricothyroidotomy. Risk factors for hematoma were found to be (1) the presence of diffuse idiopathic skeletal hyperostosis (relative risk = 13.2, 95% confidence interval = 3.2-54.4), (2) presence of ossification of the posterior longitudinal ligament (relative risk = 6.8, 95% confidence interval = 2.3-20.6), (3) therapeutic heparin use (relative risk 148.8, 95% confidence interval = 91.3-242.5), (4) longer operative time, and (5) greater number of surgical levels. The occurrence of a PO hematoma was not found to have a significant impact on either early (HT: 30, no-HT: 28; P = 0.86) or late average NDI scores (HT: 28, no-HT 31; P = 0.76). CONCLUSION: With fast recognition and treatment, no long-term detriment from PO anterior cervical hematoma was found. We identified risk factors to be (1) presence of diffuse idiopathic skeletal hyperostosis, (2) presence of ossification of the posterior longitudinal ligament, (3) therapeutic heparin use, (4) longer operative time, and (5) greater number of surgical levels. LEVEL OF EVIDENCE: 4.

Comparative effectiveness and cost-benefit analysis of local application of vancomycin powder in posterior spinal fusion for spine trauma: clinical article.

OBJECT: Surgical site infection (SSI) is a morbid complication with high cost in spine surgery. In this era of health care reforms, adjuvant therapies that not only improve quality but also decrease cost are considered of highest value. The authors introduced local application of vancomycin powder into their practice of posterior spinal fusion for spine trauma and undertook this study to determine the value and cost benefit of using vancomycin powder in surgical sites to prevent postoperative infections. METHODS: A retrospective review of 110 patients with traumatic spine injuries treated with instrumented posterior spine fusions over a 2-year period at a single institution was performed. One group (control group) received standard systemic prophylaxis only, whereas another (treatment group) received 1 g of locally applied vancomycin powder (spread over the surgical wound) in addition to systemic prophylaxis. Data were collected on patient demographic characteristics, clinical variables, surgical variables, and 90-day morbidity. Incidence of infection was the primary outcome evaluated, and billing records were reviewed to determine total infection-related medical cost (cost of reoperation/wound debridement, medications, and diagnostic tests). The payer's cost was estimated to be 70% of the total billing cost. RESULTS: A total of 110 patients were included in the study. The control (n = 54) and treatment groups (n = 56) were similar at baseline. Use of vancomycin powder led to significant reduction in infection rate (13% infection rate in the control group vs 0% in the treatment group, p = 0.02). There were no adverse effects noted from the use of vancomycin powder. The total mean cost of treating postoperative infection per patient was $33,705. Use of vancomycin powder led to a cost savings of $438,165 per 100 posterior spinal fusions performed for traumatic injuries. CONCLUSIONS: The use of adjuvant vancomycin powder was associated with a significant reduction in the incidence of postoperative infection as well as infection-related medical cost. These findings suggest that use of adjuvant vancomycin powder in high-risk patients undergoing spinal fusion is a cost-saving option for preventing postoperative infections, as it can lead to cost-savings of $438,165 per 100 spinal fusions performed.

Biomechanical evaluation of physeal-sparing fixation methods in tibial eminence fractures.

BACKGROUND: Tibial eminence fractures occur most commonly in skeletally immature children. Several techniques using physeal-sparing fracture fixation have been described, but their structural properties have not been evaluated. PURPOSE: To determine the strength and resistance to displacement of physeal-sparing techniques used to fix tibial eminence fractures. STUDY DESIGN: Controlled laboratory study. METHODS: Skeletally immature porcine knees were randomized into 4 treatment groups: (1) ultra-high molecular weight polyethylene suture-suture button (UHMWPE/SB), (2) suture anchor, (3) polydioxanone suture-suture button (PDS/SB), and (4) screw fixation. A prospective analysis of bone mineral density using dual-energy x-ray absorptiometry was performed on all specimens. Fracture fragments were created in a standardized manner and measured for size comparison. After fracture fixation, biomechanical testing was performed with cyclical and load-to-failure protocols by loading the tibia with an anterior shear force. RESULTS: In load-to-failure testing, screw fixation had a significantly lower median peak failure load (186.4 N; lower quartile [LQ], 158.4 N; upper quartile [UQ], 232.6 N) than did UHMWPE/SB (465.8 N; LQ, 397.8 N; UQ, 527.8 N), suture anchors (440.5 N; LQ, 323.0 N; UQ, 562.3 N), and PDS/SB (404.3 N; LQ, 385.9 N; UQ, 415.6 N). UHMWPE/SB demonstrated a significantly higher median yield load (465.8 N; LQ, 397.8 N; UQ, 527.8 N) than did PDS/SB (306.7 N; LQ, 271.4, N; UQ, 405.7 N) and screw fixation (179.0 N; LQ, 120.2 N; UQ, 232.5 N). During cyclical testing, screw fixation demonstrated significantly lower percentage survival of specimens (0%) compared with the other groups (UHMWPE/SB, 100%; suture anchor, 78%; PDS/SB, 78%). After 1000 cycles of loading, PDS/SB fixation had significantly more median creep (6.76 mm; LQ, 6.34 mm; UQ, 8.28 mm) than did UHMWPE/SB (4.43 mm; LQ, 3.80 mm; UQ, 4.73 mm) and suture anchor fixation (3.06 mm; LQ, 2.59 mm; UQ, 4.28 mm). The lowest median stiffness was observed in the PDS/SB group (48.6 N/mm; LQ, 45.3 N/mm; UQ, 54.2 N/mm). UHMWPE/SB fixation demonstrated a significantly higher median peak failure load after cyclic testing (469.0 N; LQ, 380.6 N; UQ, 507.2 N) than did PDS/SB (237.7 N; LQ, 197.3 N; UQ, 298.3 N) and screw fixation (132.4 N; LQ, 123.7 N; UQ, 180.9 N). Suture anchor fixation had significantly more variance, as demonstrated by width of interquartile range, in peak failure load, yield load, and creep than did other techniques. CONCLUSION: Physeal-sparing fixation of tibial eminence fractures with UHMWPE suture-suture button is biomechanically superior to both PDS suture-suture button and a single screw at the time of surgery and provides more consistent fixation than do suture anchors. CLINICAL RELEVANCE: Suture anchors provide inconsistent fixation for tibial eminence fractures.

Implant contamination during spine surgery.

BACKGROUND CONTEXT: Postoperative spine infections have been reported to occur in 1% to 15% of patients and subsequently lead to significant morbidity and cost, with an elevated risk for instrumented cases. Every effort should be made to minimize the risk of intraoperative wound contamination. Consequently, certain practices are followed in the operating room to prevent contamination, many of which are not evidence based. Conversely, certain objects believed to be sterile are frequently overlooked as potential sources of contamination. PURPOSE: To assess to what degree contamination of spinal implants occurs during spine surgery and evaluate whether coverage of implants alters the rate of contamination. STUDY DESIGN: Prospective study. STUDY SAMPLE: This study included 105 consecutive noninfection surgical cases performed by a single spine surgeon that required the use of instrumentation. OUTCOME MEASURE: Spinal implant contamination. METHODS: Cases were randomized to have all implant trays either remain uncovered (n=54) or covered (n=51) with sterile surgical towels on opening until implants were required for the case. After the last implant was placed, a sterile culture swab was used to obtain a sample from all open implants that had been present at the start of the case. The paper outer wraps of the implant trays were sampled in each case as a positive control, and an additional 105 swabs were capped immediately after they were opened to obtain negative controls. Swab samples were assessed for bacterial growth on 5% sheep blood Columbia agar plates. Of note, only departmental funding was used and no applicable financial relationships exist with any author. RESULTS: No growth was observed on any of the 105 negative controls, whereas 99.1% of positive controls demonstrated obvious contamination. Cultures from implant samples demonstrated a 9.5% overall rate of contamination with 2.0% (n=1) of covered implants versus 16.7% (n=9) of uncovered implants demonstrating contamination. Length of time implant trays were open before sample collection; implant type (plate, rods, vs. polyetheretherketone), number of scrubbed personnel, and number of implants used were all not found to be significantly associated with implant contamination (p>.05). However, coverage of implants was found to significantly reduce the implant contamination rate (p=.016). CONCLUSIONS: The contamination of sterile implants during spine surgery was found to occur. However, this contamination was independent of the amount of time the implant trays remained open. Coverage of implants significantly reduces this contamination. Therefore, no matter the expected duration of a case, implant coverage is a simple modifiable way to reduce the risk of intraoperative wound contamination and potentially reduce postoperative infections.

Coagulopathies in orthopaedics: links to inflammation and the potential of individualizing treatment strategies.

Orthopaedic patients are at risk for developing pathologic imbalances of coagulation factors characterized by phases of both hypocoagulability and hypercoagulability. Complications from "hypocoagulability" include life-threatening hemorrhage, wound hematoma, and poor wound healing. Complications due to "hypercoagulability" include deep venous thrombosis, pulmonary embolus, and disseminated intravascular coagulation. In addition, coagulation imbalance that favors the production of procoagulant factors may lead to excessive inflammation and contribute to systemic inflammatory response syndrome, acute respiratory distress syndrome, multiple organ dysfunction syndrome, and death. Optimally, the goal of individualized treatment of coagulopathies in orthopaedic patients should be to achieve efficient healing while avoiding the morbidities associated with imbalance of coagulation and inflammation. Such individualized and time-sensitive measures of coagulation status require rapid, accurate, qualitative, and quantitative assessment of the critical balance of the coagulation system. Commonly used coagulation tests (prothrombin time and activated partial thromboplastin time) are incapable of determining this balance. An alternative to is to perform thrombin generation assays. The greatest advantage of thrombin generation assays over traditional coagulation tests is their ability to detect hypercoagulability, the balance of procoagulant and anticoagulant factors, and the effect of all pharmaceutical anticoagulants. Further clinical investigations are warranted to develop and refine the thrombin generation assays to help predict clinical complications related to coagulation imbalances. In addition, future testing will help define the prothrombotic period allowing for appropriate initiation and cessation of anticoagulant pharmaceuticals. These subsequent studies have the potential to allow the development of a real-time coagulation monitoring strategy that could have paramount implications in the management of postoperative patients.

Whole-body vibration: is there a causal relationship to specific imaging findings of the spine?

STUDY DESIGN: Systematic review. OBJECTIVE: To perform a systematic review of the available literature for those studies that evaluated the role of whole-body vibration (WBV) on the spine, using imaging modalities as well as an estimation of WBV exposure. SUMMARY OF BACKGROUND DATA: Numerous comparative studies have reported a possible association between the occurrence of spinal symptoms and exposure to WBV. These exposures have commonly been examined in the work environment largely through self-reported questionnaires only. From a scientific perspective, the majority of studies emphasize symptoms and lack objective medical evidence, such as spinal imaging, to help establish a specific spinal disorder. Because both neck and low back pain comprise symptoms that can arise from a host of factors including age, a casual link between spinal disorders and WBV cannot be affirmed. METHODS: MEDLINE and EMBASE were searched for studies related to WBV and spinal symptoms, diagnosis, and/or disorders. Our searches were limited to studies published prior to August 2011. The resulting 700 citations (after excluding 354 duplicates) were then screened by 3 independent reviewers on the basis of the following predetermined inclusion and exclusion criteria: inclusion-clinical studies with imaging evaluation (radiographs, computed tomographic scans, and/or magnetic resonance images) and documented WBV exposure (occupation, amount of WBV, and/or duration); exclusion-reliance solely on self-reporting of symptoms (neck pain, low back pain, and/or sciatica), those articles based on a clinical diagnosis without use of imaging, and in vitro/animal/biomechanical studies. RESULTS: Only 7 studies met the inclusion criteria for this systematic review. Included were 5 retrospective cohort and 2 cross-sectional studies. Although mixed results and conclusions were found, the majority of studies did not identify an association between WBV exposure and an abnormal spinal imaging finding indicating damage of the spine. We should also stress that each included study has limitations secondary to quantifying WBV exposure accurately, both as a single encounter and as a total exposure over years. CONCLUSION: Based on our results from this systematic review, no causality can be shown between WBV and abnormal spinal imaging findings. With the conflicting data available in the literature, WBV has not been established as a cause for objective spinal pathological changes on a scientific basis.

Utility of postoperative radiographs for cervical spine fusion: a comprehensive evaluation of operative technique, surgical indication, and duration since surgery.

STUDY DESIGN: A retrospective study. OBJECTIVE: To assess the utility of postoperative radiographs in patients across a spectrum of cervical fusion procedures, surgical indication, and time since surgery. SUMMARY OF BACKGROUND DATA: Postoperative radiographs are routinely obtained after cervical spine fusion despite lack of evidence supporting such practice. Studies assessing postoperative radiographical utility in the cervical spine have been limited. To date, no study has comprehensively evaluated the utility of obtaining such radiographs across multiple cervical fusion procedures. METHODS: A total of 972 clinic notes from 301 patients during a 10-year period at a single institution were retrospectively reviewed. Patients in this study underwent an anterior cervical discectomy and fusion, anterior corpectomy and fusion, a combined anterior cervical discectomy and fusion and anterior corpectomy and fusion (hybrid), posterior spine fusion, or 360° fusion. All postoperative clinic notes and radiographs were reviewed for abnormalities and changes in treatment course. It was determined whether an abnormal radiograph alone led to a change in treatment course among the various operative techniques, surgical indication, or time since surgery. RESULTS: No statistical significant difference in radiograph utility between anterior cervical discectomy and fusion (0 changes in treatment course due to radiograph alone out of 332 clinic notes), anterior corpectomy and fusion (0 of 140), hybrid procedure (1 of 72), posterior spine fusion (5 of 357), and 360° fusion (0 of 71) was found. Surgical indication (trauma vs. degeneration) and duration from surgery yielded no statistical significant difference in radiograph utility. The overall sensitivity, specificity, and positive and negative predictive values of radiographs were 33.8%, 87.6%, 19.0%, and 93.9%, respectively. CONCLUSION: Regardless of operative techniques performed, surgical indication, and time since surgery, routine postoperative radiographs provide low utility in guiding treatment course in asymptomatic patients. Although radiographs may provide important diagnostic utility in certain individual cases, the results of this study provide further evidence that radiographs should not be considered routine during postoperative visits, thus minimizing unnecessary radiation exposure and medical costs.

Micro-computed tomography assessment of the progression of fracture healing in mice.

The mouse fracture model is ideal for research into the pathways of healing because of the availability of genetic and transgenic mice and the ability to create cell-specific genetic mutations. While biomechanical tests and histology are available to assess callus integrity and tissue differentiation, respectively, micro-computed tomography (µCT) analysis has increasingly been utilized in fracture studies because it is non-destructive and provides descriptions of the structural and compositional properties of the callus. However, the dynamic changes of µCT properties that occur during healing are not well defined. Thus, the purpose of this study was to determine which µCT properties change with the progression of fracture repair and converge to values similar to unfractured bone in the mouse femur fracture model. A unilateral femur fracture was performed in C57BL/6 mice and intramedullary fixation performed. Fractured and un-fractured contralateral specimens were harvested from groups of mice between 2 and 12 weeks post-fracture. Parameters describing callus based on µCT were obtained, including polar moment of inertia (J), bending moment of inertia (I), total volume (TV), tissue mineral density (TMD), total bone volume fraction (BV/TV), and volumetric bone mineral density (vBMD). For comparison, plain radiographs were used to measure the callus diameter (D) and area (A); and biomechanical properties were evaluated using either three-point bending or torsion. The µCT parameters J, I, TV, and TMD converged toward their respective values of the un-fractured femurs over time, although significant differences existed between the two sides at every time point evaluated (p<0.05). Radiograph measurement D changed with repair progression in similar manner to TV. In contrast, BV/TV and BMD increased and decreased over time with statistical differences between callus and un-fractured bone occurring sporadically. Similarly, none of the biomechanical properties were found to distinguish consistently between the fractured and un-fractured femur. Micro-CT parameters assessing callus structure and size (J, I, and TV) were more sensitive to changes in callus over time post-fracture than those assessing callus substance (TMD, BV/TV, and BMD). Sample size estimates based on these results indicate that utilization of µCT requires fewer animals than biomechanics and thus is more practical for evaluating the healing femur in the mouse fracture model.

Fracture healing in protease-activated receptor-2 deficient mice.

Protease-activated receptor-2 (PAR-2) provides an important link between extracellular proteases and the cellular initiation of inflammatory responses. The effect of PAR-2 on fracture healing is unknown. This study investigates the in vivo effect of PAR-2 deletion on fracture healing by assessing differences between wild-type (PAR-2(+/+)) and knock-out (PAR-2(-/-)) mice. Unilateral mid-shaft femur fractures were created in 34 PAR-2(+/+) and 28 PAR-2(-/-) mice after intramedullary fixation. Histologic assessments were made at 1, 2, and 4 weeks post-fracture (wpf), and radiographic (plain radiographs, micro-computed tomography (µCT)) and biomechanical (torsion testing) assessments were made at 7 and 10 wpf. Both the fractured and un-fractured contralateral femur specimens were evaluated. Polar moment of inertia (pMOI), tissue mineral density (TMD), bone volume fraction (BV/TV) were determined from µCT images, and callus diameter was determined from plain radiographs. Statistically significant differences in callus morphology as assessed by µCT were found between PAR-2(-/-) and PAR-2(+/+) mice at both 7 and 10 wpf. However, no significant histologic, plain radiographic, or biomechanical differences were found between the genotypes. The loss of PAR-2 was found to alter callus morphology as assessed by µCT but was not found to otherwise effect fracture healing in young mice.

Microscope sterility during spine surgery.

STUDY DESIGN: Prospective study. OBJECTIVE: Assess the contamination rates of sterile microscope drapes after spine surgery. SUMMARY OF BACKGROUND DATA: The use of the operating microscope has become more prevalent in certain spine procedures, providing superior magnification, visualization, and illumination of the operative field. However, it may represent an additional source of bacterial contamination and increase the risk of developing a postoperative infection. METHODS: This study included 25 surgical spine cases performed by a single spine surgeon that required the use of the operative microscope. Sterile culture swabs were used to obtain samples from 7 defined locations on the microscope drape after its use during the operation. The undraped technician's console was sampled in each case as a positive control, and an additional 25 microscope drapes were swabbed immediately after they were applied to the microscope to obtain negative controls. Swab samples were assessed for bacterial growth on 5% sheep blood Columbia agar plates using a semiquantitative technique. RESULTS: No growth was observed on any of the 25 negative control drapes. In contrast, 100% of preoperative and 96% of postoperative positive controls demonstrated obvious contamination. In the postoperative group, all 7 sites of evaluation were found to be contaminated with rates of 12% to 44%. Four of the 7 evaluated locations were found to have significant contamination rates compared with negative controls, including the shafts of the optic eyepieces on the main surgeon side (24%, P = 0.022), "forehead" portion on both the main surgeon (24%, P = 0.022) and assistant sides (28%, P = 0.010), and "overhead" portion of the drape (44%, P = 0.0002). CONCLUSION: Bacterial contamination of the operative microscope was found to be significant after spine surgery. Contamination was more common around the optic eyepieces, likely due to inadvertent touching of unsterile portions. Similarly, all regions above the eyepieces also have a propensity for contamination because of unknown contact with unsterile parts of the surgeon. Therefore, we believe that changing gloves after making adjustments to the optic eyepieces and avoid handling any portion of the drape above the eyepieces may decrease the risks of intraoperative contamination and possibly postoperative infection as well.

Reduced surgical site infections in patients undergoing posterior spinal stabilization of traumatic injuries using vancomycin powder.

BACKGROUND CONTEXT: Despite improvements through the use of prophylactic systemic antibiotics, surgical site infections remain a significant problem in the treatment of traumatic spine injuries. Infection rates as high as 10% have been reported in this population. The impact on patients and cost of treating such infections is profound. Local delivery of antibiotics has been found to be efficacious in animal and human studies as an adjunct to systemic antibiotics in surgical site infection prophylaxis. PURPOSE: To evaluate the efficacy of using vancomycin powder in surgical sites to prevent infections. STUDY DESIGN: Retrospective case review. PATIENT SAMPLE: Patients who underwent posterior spine fusions for traumatic injuries over a 2-year period at a single academic center. OUTCOME MEASURES: Clinical outcome determined was the incidence of either superficial or deep postoperative wound infections. METHODS: A retrospective review of 110 patients with traumatic spine injuries treated with instrumented posterior spine fusions over a 2-year period at a single academic center was performed. One group (control group) received standard systemic prophylaxis only, whereas another (treatment group) received vancomycin powder in the surgical wound in addition to systemic prophylaxis. Patient demographics and perioperative information obtained included history of previous spine surgeries, substance use, diabetes, body mass index, level of injury, presence of neurologic deficit, operative time, and estimated blood loss. Incidence of infection was the primary outcome evaluated. RESULTS: The control (N=54) and treatment groups (N=56) were statistically similar. A statistically significant difference in infection rate was found between the treatment group (0%) and control group (13%, p=.02) without any adverse events. No adverse effects were noted from use of the vancomycin powder. CONCLUSIONS: The use of vancomycin powder in surgical wounds may significantly reduce the incidence of infection in patients with traumatic spine injuries treated with instrumented posterior spine fusion. Applying vancomycin powder to surgical wounds is a promising means of preventing costly and harmful postoperative wound infections in high-risk populations.

Mechanism by which a sustained inflation can worsen oxygenation in acute lung injury.

BACKGROUND: Sustained lung inflations (recruitment maneuvers [RMs]) are occasionally used during mechanical ventilation of patients with acute lung injury to restore aeration to atelectatic alveoli. However, RMs do not improve, and may even worsen, gas exchange in a fraction of these patients. In this study, the authors sought to determine the mechanism by which an RM can impair gas exchange in acute lung injury. METHODS: The authors selected a model of acute lung injury that was unlikely to exhibit sustained recruitment in response to a lung inflation. In five sheep, lung injury was induced by lavage with 0.2% polysorbate 80 in saline. Positron emission tomography and [13N]nitrogen were used to assess regional lung function in dependent, middle, and nondependent lung regions. Physiologic data and positron emission scans were collected before and 5 min after a sustained inflation (continuous positive airway pressure of 50 cm H2O for 30 s). RESULTS: All animals showed greater loss of aeration and higher perfusion and shunting blood flow in the dependent region. After the RM, Pao2 decreased in all animals by 35 +/- 22 mmHg (P < 0.05). This decrease in Pao2 was associated with redistribution of pulmonary blood flow from the middle, more aerated region to the dependent, less aerated region (P < 0.05) and with an increase in the fraction of pulmonary blood flow that was shunted in the dependent region (P < 0.05). Neither respiratory compliance nor aeration of the dependent region improved after the RM. CONCLUSIONS: When a sustained inflation does not restore aeration to atelectatic regions, it can worsen oxygenation by increasing the fraction of pulmonary blood flow that is shunted in nonaerated regions.