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Hip Dysplasia Pro App

Hip dysplasia leads to premature osteoarthritis of the hip and accounts for many of total hip replacements in patients. The early diagnosis is extremely important and is based mainly on the radiological findings. In a radiographs  correctly performed  measurements of Indexes like the Hip Value (HV), Acetabular Index (AI), or  the  Acetabular Index of the Weight-Bearing Zone (AIW) , the Center-Edge (CE), the Acetabular Depth-Width Ratio (ADR), the femoral head extrusion index or Reimer Index (RI), the Congruity Index (CI), the Sharp’s angle (SA), Tonnis grade of dislocation (TG), Congruence Index (CG) and the Acetabular Center Margin angle (ACM) are important for an the orthopaedic surgeon who wants objectively to asses and monitor optimally on standard radiographs the hips. These measurements usually performed in one X-ray by the traditional way which is time-consuming and cumbersome. 

The main concern of the orthopedic surgeon especially those treating the dysplastic hip are 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 .A useful sensitive tool also to identify normal hip joints as having  potential prearthritic tendency.
We offer this new app, in which simply by marking certain anatomical landmarks at each hip you measure in an instant, all these indexes. The app also compares the results with normal age, gender and side specific reference databases retrieved from the international literature. Geometric parameters are also taken into account and weight-bearing contact surface, load (R) and stress (P) on the measured hip are being calculated.
The Hip dysplasia PRO 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 way eleven Indexes of hip dysplasia at once. By inserting the gender the age and marking certain anatomical landmarks -points at the same X-ray, at each hip, the App calculates the ten  above mentioned  indexes (AI, AIWB, CE, RI, ADR ,CI, SA,TG, CG,HV,ACM) without to have to repeat each measurement separately. You measure all radiographic Indexes in one picture. Gender age and side-specific normal reference databases are used and in cases where values are out of normal ranges, the hips are categorized according the measured Index normal categorization.
- 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 for all Indexes and measured  data  an export module 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, the measured values and results compared by normal reference databases are exported as txt file, ready to print or to input as cells to numbers or excel ready for chart printing and further research or later review. 
-The app also is independent from errors produced by image inclination. Especially developed module allows the user to measure accurately without to worry about the tilting of the picture or the X-ray.
The software is a class II medical device in the FDA. All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment!  Hip dysplasiaPro  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.
Reference
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
1.Wiberg G. The anatomy and roentgenographic appearance of a normal hip joint. Acta Chir Scand. 1939;83:7-38
2 .Tönnis D. Normal values of the hip joint for the evaluationX-rays in children and adults. Clin Orthop Relat Res 1976; (119):39-47
3. Novais EN1, Pan Z, Autruong PT, Meyers ML, Chang FM.Normal Percentile Reference Curves and Correlation of Acetabular Index and Acetabular Depth Ratio in Children. J Pediatr Orthop. 2016 Jun 2. [Epub ahead of print]
4.Murphy SB, Ganz R, Muller ME: The prognosis  of untreated dysplasia of the hip: A study of radio-graphic factors that predict the outcome. J BoneJoint Surg 77A:985–989, 1995
5.Delaunay S, Dussault RG, Kaplan PA, Alford BA Review Radiographic measurements of dysplastic adult hips  Radiographic measurements of dysplastic adult hips. Skeletal Radiol. 1997 Feb;26(2):75-81.
6.Reimers J. The stability of the hip in children. A radiological study of the results of muscle surgery in cerebral palsy. Acta Orthop Scand Suppl 1980; 184: 1-100 

How to measure with the Hip Dysplasia Pro App.

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 and the radius point (R2) appears. If the coin for example is 10mm you enter the number 10 in the unit 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 of the acetabulum or the triradiate cartilage (if it is still open) - usually at the halfway of the acetabular width - and by clicking the button “point” the A9 point is marked. The acetabulum arc starts drawing.

By the same manner you mark the V10 point which is the lowest and most lateral point on the acetabular teardrop, and subsequently you mark the point where the lower contour of the head intersects the posteroinferior acetabular margin (point D11). Finally, you mark the site of insertion of the hip abductors on the greater trochanter (point T12).


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, you have to choose sequentially and manually the following certain anatomical landmarks -points, which are shown below with the correct order:


Calibration procedure

C1 → center of a known dimension object.

R2 → dynamic cycle radius of the known dimension object (e.g. 10mm, enter 10 in unit 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


RIGHT-SIDE:

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