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Abstract:Mobile power meters allow for cyclists to monitor power output (PO) during training and competition. The Garmin Vector power meter (VPM) measures PO at the pedal compared to the crank and has been tested in only a few limited studies. The purpose of this study was to determine the validity and reproducibility of the VPM by comparing it to the SRM. The VPM validity was tested by (1) a submaximal incremental test, (2) submaximal constant power test, (3) sprint test, and (4) a field test. The reliability of the VPM was tested by repeating the laboratory tests 10 times over a 6 week span. Significant differences (P = 0.046) were found between the mean PO SRM (178 ± 1.8 W) and PO VPM (163.5 ± 14.7 W) for the submaximal constant-power test. No significant differences were found between the PO MAX SRM and the PO MAX VPM. The reproducibility of the VPM was lower than the SRM (CV = 8.52 ± 4.0 vs 3.48 ± 1.9, 10.66% vs 5.50%, and 67.7% vs 55.3% for the submaximal incremental test, submaximal constant-power test, and field test respectively). The PO VPM appears to underestimate the PO SRM and is less valid and reliable across various cycling efforts.

Objective: To compare the sensitivity of gastro-oesophageal reflux (GOR) scintigraphy at 5-s and 60-s frame acquisition rates.Methods: GOR scintigraphy of 50 subjects (1 month-20 years old, mean 42 months) were analysed concurrently using 5-s and 60-s acquisition frames. Reflux episodes were graded as low if activity was detected in the distal half of the oesophagus and high if activity was detected in its upper half or in the oral cavity. For comparison purposes, detected GOR in any number of 5-s frames corresponding to one 60-s frame was counted as one episode.Results: A total of 679 episodes of GOR to the upper oesophagus were counted using a 5-s acquisition technique. Only 183 of such episodes were detected on 60-s acquisition images. To the lower oesophagus, a total of 1749 GOR episodes were detected using a 5-s acquisition technique and only 1045 episodes using 60-s acquisition frames (these also included the high-level GOR on 5-s frames counted as low level on 60-s acquisition frames). 10 patients had high-level GOR episodes that were detected only using a 5-s acquisition technique, leading to a different diagnosis in these patients. No correlation between the number of reflux episodes and the gastric emptying rates was noted. Conclusion:The 5-s frame acquisition technique is more sensitive than the 60-s frame acquisition technique for detecting both highand low-level GOR. Advances in knowledge:Brief GOR episodes with a relatively low number of radioactive counts are frequently indistinguishable from intense background activity on 60-s acquisition frames.

Background: Extraction of a well-fixed femoral stem during revision total hip arthroplasty presents a technical challenge to the operating surgeon. The option of several stem designs during implantation necessitates the availability of extraction tools to be utilised intra-operatively. This study aims to compare the amount of axial force generated from using a threaded-coupled extraction device, loop extraction device, and vice-grip universal extraction set on a potted total hip arthroplasty stem construct. Methods: A size 7 Stryker Accolade® II femoral stem (Stryker, Mahwah, NJ) was potted within a 5.20 cm inner diameter polyvinyl chloride pipe using a potting medium with tensile strength and lap shear of 1000psi. This construct was coupled to a material testing system whose force transducer was calibrated to a recording speed of 1000 frames per second. The extractors were coupled to the potted stem, and a force of 1.32 J was applied ten times sequentially to each construct. Force was recorded in Newtons. Results: The maximum average force for the threaded, loop, and Shukla extractors was 111.46 ± 1.77 N, 90.22 ± 0.87 N, and 64.70 ± 9.03 N (p < 0.01). Loss of coupling was not experienced with any extractor. Conclusion: Within our study, the forces observed per constant load when utilising a threaded-coupled extraction device that attaches to the shoulder of the implant were significantly higher than those seen when using an extraction device that couples to the neck of the femoral stem.

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