ACETABULAR ANGLE OF SHARP (AA) APP
The diagnosis of hip dysplasia, the prognosis, the evaluation of different methods of treatment is based mainly on X-rays of the hip joint. For the objective evaluation of hip dysplasia in everyday orthopaedic care the acetabular index (AI) or the Centre-edge angle (CE) are frequent measured. But the measurement of AI is not valid index for acetabular Dysplasia in children over 8 years of age and in cases with subluxation of the femoral head where the centre-edge angle (CE) is not accurately calculated. The acetabular angle of Sharp (AA) is especially designed for theses cases.The acetabular angle of Sharp (AA) is formed by a horizontal line connecting the tips of the both pelvic teardrops and by a line connecting the inferior tip of the pelvic teardrop with the most lateral point of the acetabular roof.
Measuring angles X-rays in clinical settings it is time consuming. Accessory instruments like protractors, goniometers, well sharped pencils, rulers or even transparent papers must be available in a busy everyday practice. Usually you miss or you never had one or another. Also after measurement you have to compare the data that you measure with the normal reference values according to patient age, and decide what could be considered normal in an X-ray of the hip and what is considered pathologic. This way is cumbersome and old fashioned.
The SharpAngle app is medical software aimed for orthopaedic surgeons, providing tools that allow doctors to:
-Securely import medical images directly from the camera or stored photos
-Offers a very convenient way to determine the most accurate possibly lines in order to measure the angles. By the aid of a circular transparent template, the points of in-terest are marked accurately. The automatically formed lines, drawn between points, measure automatically the angles of interest. The results are printed in degrees. By inputting the age, of the patient in the App, the measured angle is compared with values from normal reference database according to patient age. In case the measured angle is beyond the normal range for that age, the hips are categorised as borderline dysplastic or dysplastic.
-Save the planned images, for later review or consultation.
All information received from the software output must be clinically reviewed regarding its plausibility before pa-tient treatment! SharpAngle App is indicated for assisting healthcare professionals. Clinical judgment and experience are required to properly use the software. The software is not for primary image interpretation.
The app is a handy tool for an orthopaedic surgeon, radiologist, medical stu-dent or resident who wants objectively monitor and determine the severity of dysplasia of the hip. The build-in comparison feature with the normal reference values according to patient age may help decide what could be considered normal or borderline dysplastic or dysplastic. The app is not a simple goniometer, is an enhanced product which offers the ability to compare all the input data with medical reference database. The results are printed on the screen and the hips are categorised as normal or dysplastic according to the AA angle measures respectively. This feature it is particular useful especially in clinical settings where you need a quick results without losing time in looking for reference data according to age variations in huge textbooks.
Sharp IK. Acetabular dysplasia. The acetabular angle. J Bone Joint Surg Br 1961; 43B:268–272.
How to measure the Sharp Angle ( AA) of the hip joint with the App
The app offers a very convenient way to determine the most accurate lines in order to measure the angle.Once you load or capture the patient’s image and insert the corresponding age, the transparent circular template appears and you aim to locate the right tear drop by moving the template. By clicking the option ‘point’ the first point of measurement (C1 right) appears and by repeating the same task you locate the tear drop of the left hip (C2 left). After that, a horizontal line (C1C2) is drawn. Now you are ready to mark first the right lateral acetabular border- third point (C3 right) – by pressing the ‘point’ option.
The right (AA) angle over the right hip is measured and the values in degrees are printed on the screen with the relevant categorization as normal, borderline dysplastic, or severe dysplastic over the right hip. Similarly, the left lateral acetabular border (C4 left) is marked on the image by the transparent circular template. Then, automatically, the left (AA) angle is measured and the value is printed over the screen after being compared to the reference database based on the age of the patient. The hip is then categorised as normal, borderline dysplastic, dysplastic or severe dysplastic. The evaluation of acetabular development of hip for children older than 5 years old follows a different normal reference database.
Ιn cases where you have leg-length inequality, unilateral luxation of femoral head or THR or obliquity you can choose another way to measure the AA angle. By pressing the option ‘ext’ you activate another method of marking the points. Instead of marking both tear drops (C1,C2) you try to mark two points first right (K1 right) and then left (K2 left) through the ischial tuberosities, or inferior border of the obturator foramina depending on which was more symmetric and accessible. A horizontal line is drawn (K1, K2) and appears on screen. Now you are ready to mark first the right lateral acetabular border (C3 right) – by pressing the option ‘point’ and then the left acetabular border (C4 left) by the same technique as described above. Please see tutorial videos at developer site.