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 legs 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. 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.
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 Sharps 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 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.
1. Werner Konermann, Gerd Gruber, Christian Tschauner (1999) Die Hftreifungsstrung Diagnose und Therapie Springer-Verlag 2.Tnnis, Dietrich (1987) Dysplasia and Dislocation of the Hip in Children and Adults.