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Here you will find product info that will help you to successfully use the Akucal to scale your image.

Description

The Akucal x-ray scaling tool is a fully positional marker of known size that can be used to calculate the magnification of a divergent beam. Scaling an x-ray image assures the highest level of accuracy throughout the planning process, especially orthopedic templating.

The Akucal is a must for every x-ray suite and is compatible with all orthopedic software.

Instructions for Use

• Place near anatomy or reposition to not over-stress the flexible arm.

• Use two hands to bend the arm as you are testing for the right distance. Then fine-tune the position or un-suction and try again.

• The flexible arm will last if you are nice to it! Try not to overbend.

• Finger tabs at the base of the suction cup can be utilized for quick release with a squeeze.

• Disengage suction base lever

• Place on a smooth horizontal/vertical surface.

• Engage lever

• Position marker level with the anatomy of study without patient contact

• Rotate marker size indicator towards x-ray tube

• Consult the video above for proper placement.

• Additional lubrication under the lever may be needed periodically for smooth operation.

Warning and Precautions:

• The Akucal x-ray scaling tool is provided UNsterile.

• The sphere, and only the sphere, can be autoclaved AND MUST BE COMPLETELY REMOVED FROM THE DEVICE.

• The entire Akucal must be properly cleaned with disinfectant and should be regularly inspected for any signs of wear or damage.

• Use caution when using the device for any existing pinch points under the lever.

• If the lever is difficult to engage, a bit of lube under the lever is needed.

• The Akucal x-ray scaling tool should not come into direct contact with the patient.

PUB MED ARTICLE ID 29398996 using the Akucal

Scaling Marker Position Determines the Accuracy of Digital Templating for Total Hip Arthroplasty

In this study, we have demonstrated the importance of proper scaling marker position for accurate digital templating for hip surgery. The first part of this study used a known acetabular cup size and varied the position of the scaling marker. This demonstrated that placing the scaling marker at the level of the center of the acetabular implant produces an accurate template. Four additional x-rays were obtained to show the effect of scaling marker position on templated implant size due to magnification. As the scaling marker was moved toward the x-ray detector, the templated implant size increased. Placing the scaling marker 3.5 cm more anterior or posterior than the center of an acetabular implant resulted in a one cup size difference from the known implant size.

The limitations of this study include (1) evaluation of a single hip pathology, (2) a limited number of samples for the BMI evaluation, and (3) variation in patient fat distributions (male vs female) affecting the BMI analysis. Given the large variation in patient anatomy and a lack of a priori knowledge, it is unlikely that a single estimation method will be applicable to all cases including the extremes; however, a practical guide of scaling sphere positioning for x-ray technologists that addresses most patient anatomy is highly desirable. In this study, we did not specifically evaluate hip dysplasia, Perthes disease, hip impingement, and variations in pelvic tilt. We recommend that after these conditions are discovered, scaling sphere position should be modified accordingly to plan for these cases. In the future, we plan to collect a larger number of patients to give recommendations based on specific disease state and also for patient-specific fat distributions. Furthermore, we plan to collect additional CT scans for a reliability study and to increase our sample size for the extremes of BMI to provide recommendations for scaling sphere positioning in these patients.

An anatomic pelvis phantom was used in the second part of this study to demonstrate the effects of magnification based on anatomic landmarks. Clinically, x-ray technologists place scaling markers during image acquisition. The placement of the scaling spheres at the level of the center of the hip joint is difficult, especially given variations in body habitus, fat distribution, pelvic tilt, femoral anteversion, and hip dysplasia. Given a lack of a priori knowledge of patient specific anatomy, x-ray technologists use external palpable landmarks such as the center of the greater trochanter, pubic symphysis, or x-ray table for scaling marker placement. This large variation in scaling marker position is problematic for obvious reasons. In this portion of the study looking at specific anatomic landmarks, we have demonstrated a difference in two acetabular implant sizes when the scaling marker is placed at the level of the table and four sizes when positioned at the level of the pubic symphysis. These findings reinforce the need for a practical method for x-ray technologists to position scaling spheres for accurate hip imaging.

The third portion of this study aimed to establish a practical method for scaling marker positioning for x-ray technologists. The center of the greater trochanter is often a surrogate for the hip center given its ability to be palpated externally; we have demonstrated above that positioning the scaling sphere ± 3.5 cm from the actual hip center will result in a ± one cup size that is templated. This 7-cm window for scaling sphere position allows for some variation in patient-specific anatomy (e.g., variations in femoral version) when the greater trochanter is used as a surrogate for the hip center. However, the greater trochanter is not palpable in all patients, which was the motivation for the third part of this study; herein, we investigated patient BMI as a method to estimate the position of the greater trochanter. Overall, we found that scaling markers can be estimated to be placed mid-thigh in the anterior-posterior direction for patients with a BMI between 25.1 and 40. Patients with a BMI < 25 should have the scaling marker placed posterior to the mid-thigh (53% measured from the anterior thigh surface), and patients with a BMI > 40 should have the scaling marker placed anterior to the mid-thigh (46% measured from the anterior thigh surface).

In conclusion, digital templating relies on accurate scaling marker position to faithfully estimate implant size. We have shown that the most accurate digital templating is achieved when scaling markers are positioned as close as possible to the center of the hip joint. Deviation from this positioning results in inaccuracy in templated acetabular implant size. Based on the findings in this study, scaling markers for hip imaging should be placed laterally, mid-thigh in the anterior-posterior direction for patients with a BMI between 25 and 40 kg/m2. If abnormal hip anatomy is discovered, then scaling sphere positioning should be optimized on a case-by-case basis.

Ramme AJ, Fisher ND, Egol J, Chang G, Vigdorchik JM. Scaling Marker Position Determines the Accuracy of Digital Templating for Total Hip Arthroplasty. HSS J. 2018 Feb;14(1):55-59. doi: 10.1007/s11420-017-9578-0. Epub 2017 Sep 12. PMID: 29398996; PMCID: PMC5786590.