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PAPADIMITRIOU ABDUCTION HIP SPLINT APP

An established method of treatment of  developmental dysplasia of the hip (DDH) is the use of abduction splint also in walking children. To achieve a favourable outcome in treatment of DDH, the abduction splint has to place the leg in such abduction thus allowing concentric distribution of  pressure of the femoral head inside the dysplastic  acetabulum and inducing the remodelling of acetabulum towards normal. 

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The surgeon is usually faced with the dilemma how much abduction is necessary to induce the acetabulum modelling. The degree of abduction of the splint is usually chosen according to surgeons’ experience by surmising which is the optimal biomechanical position of the leg in static X-rays. Most of the times, he has to repeat the X-ray with the child in new abduction position and measure again in a trial and error effort to find the most advantageous position.This procedure in busy everyday clinical settings it time and effort consuming

The app is based over the hip dysplasia app pro which has been  developed by our team. In this App we added t the degree of  abduction of  each femur  (ABD), the entry angle (EA), the Neck-shaft angle  (NSA)  and mainly the dynamic component which is to help peadiatric orthopaedic surgeons to apply the best possible way the abduction splint by using the measurements from X-rays. Investigating  virtually by dymamically changing the position of the legs and in second have all new calculated data in a screen. By scrolling a button + or - you can virtual change the position of  virtually schematic  leg  which is extracted from the calibrated data from X-ray and  by clicking the +,- button you add for each click one degree of virtual abduction. By placing more or less virtual abduction, the app concurrently calculates load, pressure and its distribution for the new position, which is printed in real time over the X-ray in the acetabulum. Each time you change the degree of abduction in real time the distribution of pressure is depicted as vectors over the acetabulum  for the corresponding degree of abduction. Within this procedure all Indexes Like Pressure, load, degree of abduction, Entry angle  are recalculated live in front of your screen for the new position of the leg in Abduction, thus allowing  to find easily the biomechanically sound position (concentric distribution of pressure inside the acetabulum). In addition the colour of the pressure vectors adds very important informations about the exerted pressure in the acetabulum - red means not favourable pressure -green means favourable pressure thus stimulating the growth  -green with black colour inside means very potent stimulus to growth. This procedure helps decide in an instant the optimal position of abduction of the extremity by changing the abduction of the brace to the suggested advantageous degree of abduction, without repeating X-rays and not blindly - based only on  surgeon experience. The uniform distribution of pressure over acetabulum and appropriate magnitude of pressure (green vector with black line inside-the optimal magnitude is the result of calculation from basic science see reference 1) will promote the uniformly remodelling of the dysplastic  acetabulum towards normal, saving time for successful outcome and objectively discovering by virtual biomechanical analysis the optimal degree of the abduction of the splint. By simply clicking the the + or - button you change the virtual degree of abduction and using the powerful calculations the whole spectrum and distribution of forces that are developing inside the acetabulum.The changing colours of depicted pressure vectors and the changing magnitude of pressure vectors which are depicted respectively by the changing length of vectors  - arranged over the acetabulum- helps and informs the surgeon both qualitative and quantitative in an instant, if the the distributed forces are  promoting the growth of acetabulum (green vectors) and  helps decide the optimal position of the leg in abduction by the splint making the treatment a simple app game. The difference in the duration of time to measure with the App compared to manual measurements is striking. Imaging to calculate all these models by hand for every 1 degree of  changing of abduction of leg … mission near impossible for a surgeon in clinical settings.
  We believe this is the first time that something like this is  attempted to merge in in one app the image of X-rays, the indexes measured for evaluating the degree  of hip dysplasia, the biomechanical analsyis, turnig the screen of an iPhone or iPad   in a  dynamic tool , by depicting all possibilities  by virtual  changing the position of the leg and  allowing predictions. All these features and after thousands built-in calculation which are integrated in this app taking also into account normal reference data according to age, height, and weight of the patient allow the paediatric orthopaedic surgeon by simply playing with the buttons very vividly, in front of his  screen  to decide which is the optimal treatment .……we must explicitly repeat that 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! The App indicated for assisting healthcare professionals. Clinical judgment and experience are required to properly use the software.
The App seems to be a power full tool for orthopaedic surgeon treating children with hip dysplasia. By marking  few anatomical landmarks developmental dysplasia of the hip can be successfully treated with the help of the App which seems to be an easy answer to monitor, evaluate, store, handle and compare all the measured data in an extreme rapid way and help decide the optimum therapy. We think  that he have made some great contributions to the advancement of orthopedic care by this App.


How it works?

    By choosing a few anatomical landmarks of measurement on  X-rays captured in the screen the Papadimitriou Abduction splint Application calculates the whole range of measurements in seconds offering great aid to the surgeon. Sixteen radiographic indexes like Hip Value (HV), Acetabular Center Margin angle (ACM), Acetabular Index (AI), 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), the Acetabular Index of the Weight-Bearing Zone (AIW), Congruence Index (CG), the degree of  abduction of  each femur  (ABD), the entry angle (EA), the Neck-shaft angle  (NSA), load (R) pressure (P), Surface Weight-Bearing Zone (F0) are measured. The current  abduction or adduction of the hip is measured and by scrolling a button  you can virtual change the position of the legs. By placing more or less Abduction, the app concurrently calculates load, pressure and its distribution in the new position, which is printed in real time over the X-ray. Each time you change the degree in real time the distribution of pressure is printed for the corresponding degree of abduction. Within this procedure all data are recalculated live in front of your screen, thus allowing  to find easily the biomechanically sound position (concentric distribution of pressure inside the acetabulum). This procedure helps decide in an instant the optimal position of abduction of the extremity by changing  the abduction of the brace  to the suggested advantageous degree of abduction, without repeating X-rays. This will promote uniformly remodelling of the dysplastic  acetabulum towards normal, saving time for successful outcome. In addition the colour of the pressure vectors adds very important informations about the exerted pressure in the acetabulum - red means not favourable pressure -green means favourable pressure thus stimulating the growth  -green with black colour inside means very potent stimulus to growth.The changing colours of depicted pressure vectors and the changing magnitude of pressure vectors which are depicted respectively by the changing length of vectors  - arranged over the acetabulum- helps and informs the surgeon both qualitative and quantitative in an instant, if the the distributed forces are  promoting the growth of acetabulum (green vectors) and  helps decide the optimal position of the leg in abduction by the splint .
 

- All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment! The App indicated for assisting healthcare professionals. Clinical judgment and experience are required to properly use the software.

Reference

1. Book -Werner Konermann, Gerd Gruber, Christian Tschauner (1999)
Die Hüftreifungsstörung Diagnose und Therapie  Springer-Verlag
ISBN 978-3-642-58695-8

2. Legal H (1977) Biomechanische Analyse des Hiiftgelenks. Ein Beitrag mit besonderer Berucksichtigung der Druckberechnung und der klinischen Anwendung. Habilitationsschrift, Universitat Erlangen Nurnberg. 

3. Pauwels F (1935) Der Schenkelhalsbruch, ein mechanisches Problem. Grundlagen des Heilungsvorganges, Prognose und kausale Therapie. Z Orthop Chir 63 (Beilageheft).

4. Book- 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

5.Matthiessen H.D.:(1997) Dysplasie- und Therapiefaktor bei der Huftreifungsstorung. Z. Orthop. 135 01 12-13 

6.Wiberg G. The anatomy and roentgenographic appearance of a normal hip joint. Acta Chir Scand. 1939;83:7-38

7 .Tönnis D. Normal values of the hip joint for the evaluationX-rays in children and adults. Clin Orthop Relat Res 1976; (119):39-47

8. 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]

9.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

10 .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.

How to measure with the Papadimitriou Abduction hip splint 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 n

umber 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).

By using the circular template of transparent cycles and you try to fit the best of circles to the two distant sites of the canal and remain at the center of the canal of the neck of the femur. By pressing the button “point” the center of the canal is located (C12). The selected two points are joined automatically, and the resulting straight line (P6 C12) forms the femoral neck axis (orange line segment). By repeating the same task you identify the third point C13 in the femur canal and further distant you choose the fourth point (C14) in the femur canal. The second line segment is drawn C13 C14 (green line segment) and is the axis of femur bone. The angle between lines is calculated and the femoral neck-shaft angle or (NSA angle) appears in degrees in the screen. Finally, you mark the site of insertion of the hip abductors on the greater trochanter (point T15).

 

By finishing marking of points a box appears on screen with - and + sign symbols inside. By clicking over the respective button the virtual femur is depicted and rotates its position over the center of the femoral head (point C6). For every click you notice the dynamic change of all derived calculations on screen and the vectors in the acetabulum, and also that the angle of abduction/adduction in degrees (ABD, ADD) and the entry angle (EA) are changing respectively.  In addition the colour of the vectors may change:

-red colour means not favourable pressure

-green colour means favourable pressure thus stimulating the growth

-green colour with black fill inside means very potent stimulus to growth

 

LEFT-SIDE: Without to recalibrate you start the same procedure from the left side by marking the center of the left femoral head C16, R17 and as mentioned above with the same order you mark the rest of the points at the left side as follows: E18 lateral acetabular margin of acetabulum, A19 deepest point of the roof the acetabulum or the triradiate cartilage, V20 acetabular teardrop, D21 intersection of femoral head at the posteroinferior acetabular margin, C21 femur neck canal, C24 proximal femur canal, C25 distal femur canal, T26 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

C12 → femur neck canal

C13 → proximal femur canal

C14 → distal femur canal

T15 → insertion of the hip abductors on the greater trochanter

 

LEFT-SIDE:

C16 → femoral head center

R17 → dynamic cycle radius of femoral head

E18 → lateral acetabular margin of acetabulum

A19 → deepest point of the acetabulum or the triradiate cartilage

V20 →  acetabular teardrop

D21 → femoral head intersection at the posteroinferior acetabular margin

C22 → femur neck canal

C23 → proximal femur canal

C24 → distal femur canal

T25 → 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.

 

In quick view, the following Indexes and angles are being calculated and printed on screen by the App:

R/G5, load R exerted at the weight bearing F0

F0 Weight-bearing area of hip joint surface

P/G5 compressive stress (P) at the weight bearing F0

Hip Value (HV) - calculated after 5 years of age

Acetabular Center Margin angle (ACM)

Acetabular Index (AI) - after 7 years of age the Acetabular Index of the Weight-Bearing Zone (AIW) is calculated instead

Center-Edge angle (CE)

Acetabular Depth-Width Ratio (ADR)

Femoral head extrusion index or Reimer Index (RI)

Congruity Index (CI)

Sharp’s angle (SA)

Tonnis grade of dislocation (TG)

Congruence Index (CG)

Entry Angle (EA)

Neck-shaft angle or (NSA angle)

Adduction angle (ADD)

Neutral position

Adduction angle (ABD)

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