Facial grimace testing as an assay of neuropathic pain-related behavior in a mouse model of cervical spinal cord injury.

A major portion of individuals affected by traumatic spinal cord injury (SCI) experience one or more types of chronic neuropathic pain (NP), which is often intractable to currently available treatments. The availability of reliable behavioral assays in pre-clinical models of SCI-induced NP is therefore critical to assess the efficacy of new potential therapies. Commonly used assays to evaluate NP-related behavior in rodents, such as Hargreaves thermal and von Frey mechanical testing, rely on the withdrawal response to an evoked stimulus. However, other assays that test spontaneous/non-evoked NP-related behavior or supraspinal aspects of NP would be highly useful for a more comprehensive assessment of NP following SCI. The Mouse Grimace Scale (MGS) is a tool to assess spontaneous, supraspinal pain-like behaviors in mice; however, the assay has not been characterized in a mouse model of SCI-induced chronic NP, despite the critical importance of mouse genetics as an experimental tool. We found that beginning 2 weeks after cervical contusion, SCI mice exhibited increased facial grimace features compared to laminectomy-only control mice, and this grimace phenotype persisted to the chronic time point of 5 weeks post-injury. We also found a significant relationship between facial grimace score and the evoked forepaw withdrawal response in both the Hargreaves and von Frey tests at 5 weeks post-injury when both laminectomy-only and SCI mice were included in the analysis. However, within only the SCI group, there was no correlation between grimace score and Hargreaves or von Frey responses. These results indicate both that facial grimace analysis can be used as an assay of spontaneous NP-related behavior in the mouse model of SCI and that the information provided by the MGS may be different than that provided by evoked tests of sensory function.

Third-Ray and Capitate Resection with Limited Midcarpal Fusion for Recurrent Giant Cell Tumor: A Case Report.

CASE: We describe a 23-year-old man who had multiple recurrences of a giant cell tumor (GCT) of the third metacarpal. Initial treatments consisted of curettage without the use of an adjuvant and bone-grafting. At the time of the latest recurrence, the lesion had extended into the capitate and the trapezoid. Treatment included third-ray resection and limited midcarpal fusion. No local recurrence was identified at more than 1 year after surgery. CONCLUSION: GCTs of the hand should be aggressively treated, but care should be taken to preserve function whenever possible.

Just a little bit more: when sports scientists cross the line.

Sports science has attracted controversy for the role it plays in an athlete's career and health, but Australian jurisprudence lacks any discussion of their criminal and civil liability when athletes suffer personal or professional harm. This article explores how liability may attach to both sports doctors and sports scientists in the future based on principles from current case law. It finds that criminal and civil liability attaching to personal harm could be proven, provided that consent to the risks or the treatment has not been given. Establishing professional harm caused by negligent advice regarding whether a substance does not comply with the World Anti-Doping Code is arguable considering the athlete's vulnerability to be exposed to sanctions. Expert evidence regarding what, and how a substance, is taken will be crucial to establishing causation in manslaughter prosecutions.

Radiographic survival in total shoulder arthroplasty.

BACKGROUND: Glenoid component loosening is thought to be a major cause of failure. This study assesses radiographic and clinical failure in shoulder arthroplasty, identifying factors predictive of loosening. METHODS: Three-hundred two shoulder arthroplasties were implanted utilizing a cemented, keeled glenoid component, mean clinical follow-up 8.6 years. One-hundred fifty one shoulders had preoperative, early postoperative, and most recent radiographs, mean radiographic follow-up 8.0 years, minimum 4 years or less if revision was performed (2 cases). RESULTS: Fifty-two of 151 glenoid components (34%) showed a shift in position or a complete lucent line ≥1.5 mm. Four humeral components (3%) shifted or showed a 2-mm lucency in 3 zones. Component survival (Kaplan-Meier) free from radiographic failure at 5 and 10 years were 99% (95% CI) (98-100%) and 67% (95% CI) (58-78%). Glenoid components with lines at the keel on initial radiographs were at risk for radiographic failure, hazard ratio 4.6 95% CI 1.2-17.2, P = .02. No associations were found between radiographic survival and age, gender, diagnosis, glenoid erosion, and preoperative or early subluxation. Late subluxation superiorly was associated with the glenoid at risk for radiographic failure (P = .006). Glenoid component survivals free from revision at 5 and 10 years for the 302 shoulders were 99% (95% CI) (97-100%) and 93% (95% CI) (90-97%). CONCLUSION: Glenoid radiolucencies are seldom seen early, except beneath the faceplate. Glenoid radiolucencies develop, with notable changes 5 or more years following surgery. Humeral components seldom loosen. Revision rates remain low. The high frequency of late radiographic changes dictates the need for innovation.

Clinical meaning of unexpected positive cultures (UPC) in revision shoulder arthroplasty.

PURPOSE: This study analyzed the prevalence and clinical meaning of unexpected positive cultures (UPCs) in revision shoulder arthroplasty for causes different than infection. METHODS: Between 1976 and 2007, 107 consecutive patients with UPCs, no previous suspicion of infection, and fulfilling inclusion criteria were identified. Forty-five partial (PSA) and 62 total shoulder arthroplasties (TSA) with different preoperative diagnoses were reviewed. Cases were classified as true infections, possible infections, contaminants, and undetermined. Mean follow-up was 5.6 ± 5.3 years. RESULTS: The prevalence of UPC was 15%. Male sex was a risk factor for UPC. Results of preoperative blood tests and intraoperative pathology were negative in 94 and 97 cases, respectively. Most prevalent bacteria were Propionibacterium acnes (n = 68) and Staphylococcus epidermidis (n = 21). Fifty-three patients received treatment with antibiotics and 54 did not. In 11 patients, a postoperative arthroplasty infection during follow-up was diagnosed by culture and was produced by the same microorganism as the one isolated on the UPC (true infection). Risk factors for true infection vs contamination included revision of a TSA vs a PSA and the number of previous surgeries. Antibiotic use and number of positive cultures did not influence the rate of true infections. CONCLUSIONS: UPCs are a prevalent condition in revision shoulder arthroplasty for causes different than infection. In at least 25% of cases, UPC had no clinical relevance. In 10% of cases, a persistent infection was demonstrated.

A FRAMEWORK FOR EVALUATING REGIONAL-SCALE NUMERICAL PHOTOCHEMICAL MODELING SYSTEMS.

This paper discusses the need for critically evaluating regional-scale (~200-2000 km) three-dimensional numerical photochemical air quality modeling systems to establish a model's credibility in simulating the spatio-temporal features embedded in the observations. Because of limitations of currently used approaches for evaluating regional air quality models, a framework for model evaluation is introduced here for determining the suitability of a modeling system for a given application, distinguishing the performance between different models through confidence-testing of model results, guiding model development, and analyzing the impacts of regulatory policy options. The framework identifies operational, diagnostic, dynamic, and probabilistic types of model evaluation. Operational evaluation techniques include statistical and graphical analyses aimed at determining whether model estimates are in agreement with the observations in an overall sense. Diagnostic evaluation focuses on process-oriented analyses to determine whether the individual processes and components of the model system are working correctly, both independently and in combination. Dynamic evaluation assesses the ability of the air quality model to simulate changes in air quality stemming from changes in source emissions and/or meteorology, the principal forces that drive the air quality model. Probabilistic evaluation attempts to assess the confidence that can be placed in model predictions using techniques such as ensemble modeling and Bayesian model averaging. The advantages of these types of model evaluation approaches are discussed in this paper.

Survival of the glenoid component in shoulder arthroplasty.

INTRODUCTION: This study was conducted to determine the survival of different glenoid component designs, assess the reasons for revision surgery, and identify patient and diagnostic factors that influence this need. METHODS: Between January 1, 1984, and December 31, 2004, 1337 patients underwent 1542 total shoulder arthroplasties with 6 types of glenoid components: Neer II all-polyethylene, Neer II metal-backed, Cofield 1 metal-backed bone-ingrowth, Cofield 1 all-poly keeled, Cofield 2 all-poly keeled, and Cofield 2 all-poly pegged. RESULTS: Revision was required in 125 shoulders for glenoid component failure. Survival rates free of revision by glenoid implant type at 5, 10, and 15 years were, respectively, 96%, 96%, and 95% for 99 Neer II all-poly; 96%, 94%, and 89% for 316 Neer II metal-backed; 86%, 79%, and 67% for 316 Cofield 1 metal-backed; 94%, 94%, and 87% for 18 Cofield 1 all-poly; 99%, 94%, and 89% for 497 Cofield 2 all-poly keeled; and 99% at 5 years for 358 Cofield 2 all-poly pegged. Glenoid component type was significantly associated with component revision (P < .001). Male gender was associated with a higher risk of revision (P < .001). Compared with degenerative arthritis, posttraumatic arthritis (P = .02) and avascular necrosis (P = .06) were associated with increased risk of revision. CONCLUSIONS: Survival is improved with cemented all-polyethylene glenoid components. Revision of cemented all-polyethylene components may be lessened with the use of pegged components in early follow-up. Male gender and the operative diagnoses of posttraumatic arthritis or avascular necrosis are associated with an increased risk of failure. LEVEL OF EVIDENCE: Level IV, Case Series, Treatment Study.

Biomechanical analysis of posterior fixation techniques in a 360 degrees arthrodesis model.

STUDY DESIGN: A biomechanical study to assess the ability of posterior fixation techniques to stabilize a functional spine unit (FSU) after insertion of an anterior load-sharing device. OBJECTIVE: The objective of this study is to compare various posterior fixation techniques in combination with an anterior load-sharing implant. SUMMARY OF BACKGROUND DATA: Pedicle screws and translaminar facet screws have been shown to improve the stiffness of an FSU in combination with an anterior load-sharing device. No published studies, to our knowledge, have compared translaminar facet screw fixation versus bilateral and unilateral pedicle screw fixation used with an anterior load-sharing device. METHODS: Ten cadaveric FSUs were potted using methylmethacrylate and attached to a spine simulator mounted to an MTS Mini-Bionix testing machine. The simulator was configured to control compressive loading, axial torque, flexion, extension, and lateral bending. Each specimen was tested in the intact state and following the application of each of four stabilization techniques: custom cage alone, cage plus translaminar facet screw fixation, cage plus unilateral pedicle screw and plate fixation, and cage plus bilateral pedicle screw and rod fixation with transverse coupling. Compressive stiffness and total range of motion (ROM) between +/-8 Nm of torque were extracted from the raw data. RESULTS: Each fixation method decreased ROM in torsion, flexion-extension, and lateral bending compared with the intact state. Unilateral pedicle fixation offered less stability than either of the other posterior fixations in all modes of testing except axial loading, where it was equivalent. Translaminar facet screw fixation was equivalent to bilateral pedicle screws in all modes tested. CONCLUSIONS: Using a load-sharing interbody implant, translaminar facet screws are equivalent to bilateral pedicle screws in resisting motion in all three planes. Translaminar facet screws and bilateral pedicle screws offer greater stabilization in all three planes compared with unilateral pedicle screws and a single plate.