Mathematically directed single-cut osteotomy for correction of tibial malunion

In 1986 and 1987, four patients with tibial malunion involving both angular and torsional misalignment underwent surgical correction by a single-cut technique based on a mathematical model of long bone deformity. The technique involved a single surgical cut, followed by rotation of the two fragments along the osteotomy plane. The orientation of the osteotomy is based on a computer-assisted design. The deformity is measured on radiographs, computed tomography, and clinical exam and is then plotted on graphs to find the osteotomy orientation. The deformity involved varus and extension in four cases, internal rotation in 2, and external rotation in two. The deformities ranged from 9 to 26 degrees. The cutting angle of the osteotomy ranged from 50 to 66 degrees as measured from the transverse plane. Actual lengthening of 1 cm and functional lengthening over 1.5 cm was obtained without the use of bone graft. As no wedge of bone was removed, all corrected bones were easily suited to rigid internal fixation across the cut surface. In all cases, the desired correction was obtained within measurable error, and union was obtained with minimal immobilization. There were no soft tissue or joint contractures, and no neurovascular complications. In one patient, who had had four prior surgical procedures on the involved limb, an infection developed 6 weeks postoperatively that required debridement and delayed primary closure. As the technique involves only one cut, no wedge of bone is removed, no shortening occurs, and the osteotomy is highly suitable for rigid internal fixation. The described technique is the first to integrate in a precise way the correction of torsion with the correction of angular deformity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Can Electrocardiographic Criteria Predict Adverse Cardiac Events and Positive Cardiac Markers?

OBJECTIVES: To determine electrocardiogram (ECG) predictors of positive cardiac markers and short-term adverse cardiac events in an undifferentiated chest pain population presenting to emergency departments (EDs). The authors hypothesized that specific ECG findings, other than those previously identified in higher-risk populations, would be predictive of cardiac outcomes and positive cardiac markers. METHODS: This study used data from a prospectively collected, retrospectively analyzed Internet-based data registry of undifferentiated chest pain patients (i*trACS). Logistic regression modeling was performed to determine the ECG findings that were predictive of 1) positive cardiac markers and 2) short-term adverse cardiac events. RESULTS: ST-segment elevation (STE), ST-segment depression (STD), pathological Q-waves (PQW), and T-wave inversion were associated with increased odds of percutaneous coronary intervention or catheterization, myocardial infarction, or coronary artery bypass grafting. The odds of creatine kinase-MB (CK-MB) measuring positive were increased if STE, STD, or PQW were present [odds ratio (OR) 2.495, 2.582, and 1.295, respectively]. A right bundle branch block tended to decrease the odds of CK-MB measuring positive (OR 0.658). A similar pattern of results was observed for troponin I (OR 3.608 for STE, 3.72 for STD, 1.538 for PQW). Troponin T showed an increased odds of measuring positive if any of STE, STD, left bundle branch block, or T-wave inversion were evident (OR 2.313, 2.816, 1.80, and 1.449, respectively). CONCLUSIONS: Initial ECG criteria can be used to predict short-term cardiac outcomes and positive cardiac markers. These findings can be important aids in the risk-stratification and aggressive treatment regimens of chest pain patients presenting to EDs.     

Combining spin echoes with gradient echoes in the context of the global coherent free precession pulse sequence.

To extend the signal longevity of magnetically excited spins in flowing fluids while in a state of global coherent free precession (GCFP), a refocusing radiofrequency (RF) pulse and bipolar gradient waveforms were combined with the GCFP sequence. The data demonstrate that RF refocusing in the presence of flowing blood is possible, but the improvement in signal amplitude depends on the static magnetic field homogeneity along the direction of motion and the displacement of the spins between the excitation and the RF refocusing pulse, as well as displacement during subsequent RF refocusing pulses. The least amount of phase dispersion and thus the longest lasting signal is obtained with the shortest echo spacing where only one line of data is recorded between two RF refocusing pulses. This approach was successfully used in a phantom and in vivo to image fast and slow blood flow. Depending on the experimental conditions, signal persistence is improved significantly compared to playing the same sequence without RF refocusing, but the improvement is limited by the product of blood flow velocity and the time between RF refocusing pulses.