Clinical orthopaedics and related research
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Clin. Orthop. Relat. Res. · Mar 2010
P value and the theory of hypothesis testing: an explanation for new researchers.
In the 1920s, Ronald Fisher developed the theory behind the p value and Jerzy Neyman and Egon Pearson developed the theory of hypothesis testing. These distinct theories have provided researchers important quantitative tools to confirm or refute their hypotheses. The p value is the probability to obtain an effect equal to or more extreme than the one observed presuming the null hypothesis of no effect is true; it gives researchers a measure of the strength of evidence against the null hypothesis. ⋯ Perhaps the most common misconception is to consider the p value as the probability that the null hypothesis is true rather than the probability of obtaining the difference observed, or one that is more extreme, considering the null is true. Another concern is the risk that an important proportion of statistically significant results are falsely significant. Researchers should have a minimum understanding of these two theories so that they are better able to plan, conduct, interpret, and report scientific experiments.
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There are few good surgical options that allow for continued spinal growth in patients with early-onset scoliosis. The "Shilla" is a growth guidance system that does not require repeated surgical lengthenings. The Shilla system guides growth at the ends of dual rods with the apex of the curve corrected, fused, and fixed to the rods. ⋯ All of the goat spines grew with the implants in place; growth occurred in both the thoracic and lumbar ends of the rods for a total average of 48 mm. None of the implants failed, although we observed minor wear at the rod/screw interface. Growth guidance with the Shilla rod system allowed for continued growth in this goat model.
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Skeletally immature patients with adolescent idiopathic scoliosis are at risk for curve progression. Although numerous nonoperative methods have been attempted, including physical therapy, exercise, massage, manipulation, and electrical stimulation, only bracing is effective in preventing curve progression and the subsequent need for surgery. Brace treatment is initiated as either full-time (TLSO, Boston) or nighttime (Charleston, Providence) wear, although patient compliance with either mode of bracing has been a documented problem. We review the natural history of adolescent idiopathic scoliosis, identify the risks for curve progression, describe the types of braces available for treatment, and review the indications for and efficacy of brace treatment. ⋯ Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
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Clin. Orthop. Relat. Res. · Mar 2010
Preoperative pain catastrophizing predicts pain outcome after knee arthroplasty.
Psychologic status is associated with poor outcome after knee arthroplasty yet little is known about which specific psychologic disorders or pain-related beliefs contribute to poor outcome. To enhance the therapeutic effect of a psychologic intervention, the specific disorders or pain-related beliefs that contributed to poor outcome should be identified. We therefore determined whether specific psychologic disorders (ie, depression, generalized anxiety disorder, panic disorder) or health-related beliefs (ie, self-efficacy, pain catastrophizing, fear of movement) are associated with poor outcome after knee arthroplasty. We conducted a cohort study of 140 patients undergoing knee arthroplasty at two hospitals. Patients completed a series of psychologic measures, provided various sociodemographic data, and were followed for 6 months. Patients were dichotomized to groups with either a favorable or a poor outcome using WOMAC pain and function scores and evidence-based approaches. After adjusting for confounding variables, we found pain catastrophizing was the only consistent psychologic predictor of poor WOMAC pain outcome. No psychologic predictors were associated consistently with poor WOMAC function outcome. An intervention focusing on pain catastrophizing seems to have potential for improving pain outcome in patients prone to catastrophizing pain. ⋯ Level I, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.