Hip biomehanics App
The app approximate true biomechanical conditions in hip as realistically as possible Now we are able to predict the biomechanical effect on load and pressure of an operative procedure by computational means.
Human hip is a biologic system that obeys purely mechanical laws. The main concern of the orthopedic surgeon especially those treating the dysplatic hip is to improve the biomechanical status of the joint. To accomplish this, the surgeon must be familiar with the biomechanics of the hip. Because of the complexity of biomechanical analysis (trigonometric functions, etc.) is almost impossible to calculate in everyday settings, forces acting on the hip, the directions in which they act, and the associated stresses that develop within the joint. With measurements by the App and having numerical data it is possible to evaluate the efficacy or even predict it of the various procedures not on the basis of experience any more.
The Hip Biomechanics 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.
-By marking certain points in a simple standard AP pelvic radiograph, geometric parameters are being calculated. The App computes weight-bearing contact surface, the load (R) and stress (P) on the measured hip.
Data from load and pressure distribution in the hip - like in a real biomechanicals tests- are being measured and depicted graphically as vectors over the X-ray in the screen over the joint. The distribution also of compressive stresses over the acetabulum, which is usually associated radiographic sclerosis over the acetabular margin, are printed in real time over the screen and thus can be easily and objectively evaluated. Besides that, the App provides data in export for diagrams of load (R) pressure (P), which each can be plotted as a curve allowing easy comparison with normal data and thus help decide the orthopaedic surgeon which procedure is objectively indicated.
-The data are printed over to screen so each case can easily assessed
-Save the planned images, for later review or consultation. Data are exported as txt file, ready to print or to input as cells to numbers or excel ready for chart printing and further research.
All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment! Hip Biomechanics App 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 coverts a standard pelvic X-ray from a simple image into an accurate biomechanical analysis study, involving a calculation of the joint load and pressure. In clinical settings easily assessments of hip load and pressure may help planning operations, modify or monitor objectively treatment strategies in a effort to improve hip biomechanics.
The sound build-in computational methods of the app allows in a blink of an eye in
front of your screen to do complex biomechanical studies. This App is particular useful in clinical settings where you need a quick results without losing time, in a busy everyday practice. Please see tutorial videos at the developer’s web site www.orthopractis.com
1. Legal H (1977) Biomechanische Analyse des Hiiftgelenks. Ein Beitrag mit besonderer Berucksichtigung der Druckberechnung und der klinischen Anwendung. Habilitationsschrift, Universitat Erlangen Nurnberg.
2. Pauwels F (1935) Der Schenkelhalsbruch, ein mechanisches Problem. Grundlagen des Heilungsvorganges, Prognose und kausale Therapie. Z Orthop Chir 63 (Beilageheft).
3. Tönnis, Dietrich (1987) Dysplasia and Dislocation of the Hip in Children and Adults. Chapter 4, Current Knowledge on the Biomechanics of the Hip, page 26-57. Book
HOW TO MEASURE HIP BIOMECHANICS FROM SIMPLE X-RAY WITH THE HIPBIOMECHANICSAPP
The first thing is to load one image from your photo library or capture a photo from x-rays photos of a patient. Next you fill in the empty boxes according the patient’s height in cm and weight in kg. In case the height or the weight of the patient is unknown, by simply entering the age, the build-in feature chooses the exact middle weight and middle height of the person, calculating the 50th percentile according to normal reference data population adjusted for gender and age. The empty boxes are filled automatically with the middle values, respectively. You can also edit one or other directly in case that a value is known
Next you have to fill the calibration unit box in mm after finishing the calibration procedure. With the calibration procedure you try to locate the center of a template - a known dimension in mm object in x ray (for example a coin) - by moving the transparent circular yellow template over the object (coin), trying to fit to a best-fit circle to the contour of the coin circumference. Once you have found the best fit by clicking the “point” button, the center of the coin is marked (C1). Next a dynamic circle appears with the C1 center point marked over the screen.
The radius of the circle is changed dynamically and by moving the attached finger you try to find the best fit circle to the contour of the coin. Once you found the best fit you press the “point” button and the subject (whole coin) is marked by the circle (R2) point appears. If the coin for example is 10mm you enter the number 10 in the box.
Next by clicking the button “point” you mark two points, point S3 (left) and point S4 (right) over the lateral edge of the superior end plate of the S1 vertebra (sacral end plate). The yellow horizontal line S3S4 is drawn. Next by aiming the center of upper middle distance of pubic symphysis with the transparent circular template and clicking the button “point” the point S5 is marked. An erected vertical reference line from S5 is drawn.
RIGHT-SIDE: The transparent circular template appears and you aim to locate the center first of the right femoral head by moving the template over the femoral head, trying to fit to a best-fit circle to the contour of femoral head circumference. By clicking the “point” button the center of the left femoral head is marked (C6 point) and the corresponding radius of the femoral head by clicking the “point” button (R7 point) appears. Aiming with the transparent circular template to the lateral acetabular edge you mark the lateral acetabular edge, by pressing the “point” button (E8 point).
Finally you aim with the transparent circular template the deepest point of the roof the acetabulum or the triradiate cartilage if still open -usually at the halfway of the acetabular width- and by clicking the button ‘point’ the A9 point is marked. A semicircle is printed
By the same manner you mark the V10 point which is the lowest and most lateral point on the acetabular teardrop, and subsequently the point where the lower contour of the head intersects the posteroinferior acetabular margin (point D11) is marked, final the the site of insertion of the hip abductors on the greater trochanter (point T12) is also marked.
LEFT-SIDE: Without to recalibrate you start the same procedure from the left side by marking the center of the left femoral head C13,R14 and as mentioned above with the same order you mark the rest of the points at the left side as follows, E15 lateral acetabular margin of acetabulum, A16 deepest point of the roof the acetabulum or the triradiate cartilage,V17 acetabular teardrop,, D18 intersection of femoral head at the posteroinferior acetabular margin, T19 insertion of the hip abductors on the greater trochanter. In quick view , the following reference points you have to choose sequentially manually are shown below by the following order:
C1 → center of known dimension object.
R2 → dynamic cycle radius of known dimension object (10mm enter 10 in box)
S3 → lateral edge of the superior end plate of the S1 vertebra (left)
S4 → lateral edge of the superior end plate of the S1 vertebra (right)
S5 → center of upper middle distance of pubic symphysis
C6 → femoral head center
R7 → dynamic cycle -radius of femoral head
E8 → lateral acetabular margin of acetabulum
A9—> deepest point of the acetabulum or the triradiate cartilage
V10 → the acetabular teardrop
D11 → femoral head intersection at the posteroinferior acetabular margin
T12 → insertion of the hip abductors on the greater trochanter
C13 → femoral head center
R14 → dynamic cycle- radius of femoral head
E15→ lateral acetabular margin of acetabulum
A16—>deepest point of the acetabulum or the triradiate cartilage
V17 → acetabular teardrop
D18 → femoral head intersection at the posteroinferior acetabular margin
T19 → insertion of the hip abductors on the greater trochanter
The powerful undo feature gives the user the freedom to make corrections without resetting the whole procedure. Simply by clicking the undo button the measurement returns to last chosen point (or state) and you are ready to choose the same point again, without reseting the whole measurement and starting again from the beginning.
Moreover, the sides are independent, thus the user can measure first any side he wants.
A complete report with all detailed calculations and measurements can be extracted and saved in a text file with the “Save” button.
All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment! Hip Biomechanics App indicated for assisting healthcare professionals. Clinical judgment and experience are required to properly use the software.