The Effect of Geometric Variations in Posterior-stabilized Knee Designs on Motion Characteristics Measured in a Knee Loading Machine

Background

In different posterior-stabilized (PS) total knees, there are considerable variations in condylar surface radii and cam-post geometry. To what extent these variations affect kinematics is not known. Furthermore, there are no clearly defined ideal kinematics for a total knee.

Questions/purposes

The purposes of this study were to determine (1) what the kinematic differences are caused by geometrical variations between PS total knee designs in use today; and (2) what design characteristics will produce kinematics that closely resemble that of the normal anatomic knee.

Methods

Four current PS designs with different geometries and one experimental asymmetric PS design, with a relatively conforming medial side, were tested in a purpose-built machine. The machine applied combinations of compressive, shear, and torque forces at a sequence of flexion angles to represent a range of everyday activities, consistent with the ASTM standard test for measuring constraint. The femorotibial contact points, the neutral path of motion, and the AP and internal-external laxities were used as the kinematic indicators.

Results

The PS designs showed major differences in motion characteristics among themselves and with motion data from anatomic knees determined in a previous study. Abnormalities in the current designs included symmetric mediolateral motion, susceptibility to excessive AP medial laxity, and reduced laxity in high flexion. The asymmetric-guided motion design alleviated some but not all of the abnormalities.

Conclusions

Current PS designs showed kinematic abnormalities to a greater or lesser extent. An asymmetric design may provide a path to achieving a closer match to anatomic kinematics.

Clinical Relevance

One criterion for the evaluation of PS total knees is how closely the kinematics of the prosthesis resemble that of the anatomic knee, because this is likely to affect the quality of function.     

Multinational data on cumulative radiation exposure of patients from recurrent radiological procedures: call for action

European Radiology - To have a global picture of the recurrent use of CT imaging to a level where cumulative effective dose (CED) to individual patients may be exceeding 100 mSv at which organ...     

The oblique plane deformity in slipped capital femoral epiphysis

Background

Slipped capital femoral epiphysis (SCFE) is commonly treated with in situ pinning. However, a severe slip may not be suitable for in situ pinning because the required screw trajectory is such that it risks perforating the posterior cortex and damaging the remaining blood supply to the capital epiphysis. In such cases, an anteriorly placed screw may also cause impingement. It is also possible to underestimate the severity of the slip using conventional radiographs. The aim of this study was to describe and evaluate a novel method for calculating the true deformity in SCFE and to assess the interobserver and intraobserver reliability of this technique.

Methods

We selected 20 patients with varying severity of SCFE who presented to our institution. Cross-sectional imaging [either axial computed tomography (CT) scans or magnetic resonance imaging (MRI) scans] and anteroposterior (AP) pelvis radiographs were assessed by four reviewers with varying levels of experience on two occasions. The degree of slip on the axial image and on the AP pelvis radiographs were measured and, from this, the oblique plane deformity was calculated using the method as popularised by Paley. The intraclass correlation coefficient (ICC) was calculated to determine the interobserver and intraobserver reliabilities between and amongst the raters.

Results

The interobserver reliability for the calculated oblique plane deformity in SCFE ICC was 0.947 [95 % confidence interval (CI) 0.90–0.98] and the intraobserver reliability for the calculated oblique plane deformity of individual raters ranged from 0.81 to 0.94. The deformity in the oblique plane was always greater than the deformity measured in the axial or the coronal plane alone.

Conclusion

This method for calculating the true deformity in SCFE has excellent interobserver and intraobserver reliability and can be used to guide treatment options. This technique is a reliable and reproducible method for assessing the degree of deformity in SCFE. It may help orthopaedic surgeons with varying degrees of experience to identify which hips are suitable for in situ pinning and those which require surgical dislocation and anatomical reduction, given that plain radiographs in a single plane will underestimate the true deformity in the oblique plane.

Level of evidence

Level II diagnostic study.     

Controlled Exposures to Air Pollutants and Risk of Cardiac Arrhythmia

Background: Epidemiological studies have reported associations between air pollution exposure and increases in cardiovascular morbidity and mortality. Exposure to air pollutants can influence cardiac autonomic tone and reduce heart rate variability, and may increase the risk of cardiac arrhythmias, particularly in susceptible patient groups.Objectives: We investigated the incidence of cardiac arrhythmias during and after controlled exposure to air pollutants in healthy volunteers and patients with coronary heart disease.Methods: We analyzed data from 13 double-blind randomized crossover studies including 282 participants (140 healthy volunteers and 142 patients with stable coronary heart disease) from whom continuous electrocardiograms were available. The incidence of cardiac arrhythmias was recorded for each exposure and study population.Results: There were no increases in any cardiac arrhythmia during or after exposure to dilute diesel exhaust, wood smoke, ozone, concentrated ambient particles, engineered carbon nanoparticles, or high ambient levels of air pollution in either healthy volunteers or patients with coronary heart disease.Conclusions: Acute controlled exposure to air pollutants did not increase the short-term risk of arrhythmia in participants. Research employing these techniques remains crucial in identifying the important pathophysiological pathways involved in the adverse effects of air pollution, and is vital to inform environmental and public health policy decisions.Citation: Langrish JP, Watts SJ, Hunter AJ, Shah AS, Bosson JA, Unosson J, Barath S, Lundbäck M, Cassee FR, Donaldson K, Sandström T, Blomberg A, Newby DE, Mills NL. 2014. Controlled exposures to air pollutants and risk of cardiac arrhythmia. Environ Health Perspect 122:747–753; http://dx.doi.org/10.1289/ehp.1307337     

Method development and validation of potent pyrimidine derivative by UV-VIS spectrophotometer

Background

A rapid and sensitive ultraviolet-visible (UV-VIS) spectroscopic method was developed for the estimation of pyrimidine derivative 6-Bromo-3-(6-(2,6-dichlorophenyl)-2-(morpolinomethylamino) pyrimidine4-yl) -2H-chromen-2-one (BT₁₀M) in bulk form.

Results

Pyrimidine derivative was monitored at 275 nm with UV detection, and there is no interference of diluents at 275 nm. The method was found to be linear in the range of 50 to 150 μg/ml. The accuracy and precision were determined and validated statistically. The method was validated as a guideline.

Conclusions

The results showed that the proposed method is suitable for the accurate, precise, and rapid determination of pyrimidine derivative.

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Graphical Abstract Method development and validation of potent pyrimidine derivative by UV spectroscopy.

     

Impact of a structured training program to enhance skills in phacoemulsification surgery

Purpose:The aim of this study was to determine whether the introduction of a structured short-term phacoemulsification training program improved the ICO-OSCAR (International Council of Ophthalmology’s Ophthalmology Surgical Competency Assessment Rubric) score and the learning curve of the trainees and decreased the complication rates of the cases.Methods:This study was a retrospective, observational study conducted in a tertiary eye care hospital in India. The study was conducted from March 2018 to October 2019 based on a structured phacoemulsification training program introduced in January 2019. The trainees enrolled in the phacoemulsification training program were divided into two groups: Group 1 (n = 33), who underwent training before the introduction of the structured program, and Group 2 (n = 29), who underwent the training after the introduction of the structured training program. Each trainee performed 20 cases. Group 1 training consisted of wet-lab and phacoemulsification surgeries. Group 2 training program comprised three modules over 5 weeks and a preassessment examination. Premodule 1 imparted cognitive skills; Module 1 was on structured wet-lab, Module 2 was about phacoemulsification step surgery, and Module 3 had independent complete surgeries. Group 2 also underwent compulsory Observation of cases being performed in the operation theater, surgical video recording review, and formative feedback. Mean OSCAR score comparison was done for both the groups. The OSCAR score was also calculated case-wise to obtain the learning curve with respect to the entry and exit levels, by classifying the trainees in each group as Novice, Beginner, Advanced Beginner, or Competent. A comparison of the posterior capsular rupture (PCR) rates and vision at discharge of all the cases was done.Results:Group 2 had a significantly better mean OSCAR score than Group 1 (4.03 and 3.43, respectively; P < 0.001). The PCR rate of the cases was significantly lower in Group 2 than in Group 1 (9.14% and 20.30%, respectively; P < 0.001). Group 2 had a significantly better visual acuity outcome of the cases than Group 1. Group 1 started as Novice (OSCAR score: 2), whereas Group 2 started as Beginner (OSCAR score: 3). Group 2 reached the Advanced Beginner level eight to 10 cases prior to Group 1.Conclusion:A structured training curriculum can make a significant difference in the training experience of the trainees and enable better surgical outcomes and a decrease in the complication rates.     

Extent of re-excision,sequence/timing of salvage re-irradiation,and disease-free interval impact upon clinical outcomes in recurrent/progressive ependymoma

Journal of Neuro-Oncology - To report clinical outcomes of salvage re-irradiation (re-RT) in recurrent/progressive ependymoma. Medical records of patients treated with curative-intent re-RT as...