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
Sensitivity of erythrocyte sedimentation rate and C-reactive protein in childhood bone and joint infections.
In addition to the examination of clinical signs, several laboratory markers have been measured for diagnostics and monitoring of pediatric septic bone and joint infections. Traditionally erythrocyte sedimentation rate (ESR) and leukocyte cell count have been used, whereas C-reactive protein (CRP) has gained in popularity. We monitored 265 children at ages 3 months to 15 years with culture-positive osteoarticular infections with a predetermined series of ESR, CRP, and leukocyte count measurements. On admission, ESR exceeded 20 mm/hour in 94% and CRP exceeded 20 mg/L in 95% of the cases, the mean (+/- standard error of the mean) being 51 +/- 2 mm/hour and 87 +/- 4 mg/L, respectively. ESR normalized in 24 days and CRP in 10 days. Elevated CRP gave a slightly better sensitivity in diagnostics than ESR, but best sensitivity was gained with the combined use of ESR and CRP (98%). Elevated ESR or CRP was seen in all cases during the first 3 days. Measuring ESR and CRP on admission can help the clinician rule out an acute osteoarticular infection. CRP normalizes faster than ESR, providing a clear advantage in monitoring recovery. ⋯ Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
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Clin. Orthop. Relat. Res. · Mar 2010
Shoulder arthroplasties have fewer complications than hip or knee arthroplasties in US veterans.
Total shoulder arthroplasties (TSA) are being performed more commonly for treatment of arthritis, although fewer than either hip (THA) or knee (TKA) arthroplasties. Total shoulder arthroplasty also provides general health improvements that are comparable to THA. One study suggests TSAs are associated with lower morbidity and mortality than THAs and TKAs. To confirm and extend that study, we therefore examined the association of patient characteristics (sociodemographics, comorbid illness, and other risk factors) with 30-day complications for patients undergoing TSAs, THAs, or TKAs. We used data from the Veterans Administration (VA) National Surgical Quality Improvement Program (NSQIP) for fiscal years 1999 to 2006. Sociodemographics, comorbidities, health behaviors, operative factors, and complications (mortality, return to the operating room, readmission within 14 days, cardiovascular events, and infections) were available for 10,407 THAs, 23,042 TKAs, and 793 TSAs. Sociodemographic features were comparable among groups. The mean operative time was greater for TSAs (3.0 hours) than for TKAs (2.2 hours) and THAs (2.4 hours). The 30-day mortality rates were 1.2%, 1.1%, and 0.4% for THAs, TKAs, and TSAs, respectively. The corresponding postoperative complication rates were 7.6%, 6.8%, and 2.8%. Adjusting for multiple risk factors, complications, readmissions, and postoperative stays were less for TSAs versus THAs and TKAs. In a VA population, TSAs required more operative time but resulted in shorter stays, fewer complications, and fewer readmissions than THAs and TKAs. ⋯ Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.