This case study documents an example of inquiry learning and teaching during a summer institute for elementary and middle school teachers. A small group constructed an explanatory model for an intriguing optical phenomenon that they were observing. Research questions included: What physics thinking did the learners express? What aspects of scientific inquiry were evident in what the learners said and did? What questions did the learners ask one another as they worked? How did these learners collaborate in constructingCorrespondence to:
Intraoperative range of motion (ROM) assessment can be challenging during total knee arthroplasty (TKA) surgery. As computer assisted surgery is costly and not readily available to many surgeons, we have developed a simple, cost-effective intraoperative device to precisely measure knee flexion and extension. A simple knee goniometer system was constructed consisting of a digital level mounted to a base that rigidly attaches two standard needles. The needles are pushed through the overlying soft tissue of the distal femur. The device is then applied to the proximal tibia, where an angle measurement of the knee is registered. A validation study for this device was conducted on two pairs of intact cadaveric lower limbs at 0 deg, 10 deg, 15 deg, 20 deg, 25 deg, and 30 deg. Two orthopedic surgeons experienced with the system performed three measurements at each angle. Systematic error, defined as the goniometer reading at 0 deg flexion anatomically as determined by the navigation system, ranged from −9.1 deg to 3.0 deg, consistent for each operator on every case. Measurement error, defined as the variability in repeated, fixed angle measurements made with the goniometer, was 1.5 ± 1.0 deg across all surgeons, cases, and prescribed flexion angles. For both surgeons and all imposed flexion angles, measurement errors were below the 4 deg clinical threshold. The simple knee goniometer system generated accurate, repeatable measures of changes in flexion angle intraoperatively with measurement error comparable to errors obtained using the commercial navigation system (1 deg–2 deg). However, the knee goniometer is less complex, less time intensive, and less costly than currently available computer assistive devices. Taken together, our results are very promising for the continued development of this device.
Intra-operative range of motion (ROM) assessment can be challenging during total knee arthroplasty (TKA) surgery. Measurement accuracy is often compromised by patient draping and anatomy, particularly when assessing knee extension. Accurate ROM assessment is important, as ROM after total knee arthroplasty is an important indicator of clinical outcome. Computer assisted surgery has been shown to accurately determine intra-operative range of motion; however, navigation systems are costly and not readily available to many surgeons. We have developed a simple, cost-effective intraoperative device to precisely measure knee flexion and extension that is efficient and easy to use.
In total hip arthroplasty (THR) cases, it can be technically challenging to achieve the correct inclination angle for the acetabular component. Commercial intra-operative navigation systems have been successfully used to precisely guide acetabular orientation [1]; however, these systems are costly, time consuming, and have a steep learning curve for new users [2]. In an effort to simplify the procedure, McGann et al. have developed a laser-guided system to address the inclination angle [3]. In preliminary clinical trials, this system has been used successfully, but its accuracy and repeatability have never been quantified.
Conclusions: MCA-PSV is a useful parameter to assess fetal cerebral hemodynamics, showing high peak systolic velocity before birth in fetuses with more severe compromise in twin pregnancies complicated by placental dysfunction and fetal growth restriction.
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