Co-ordinatesWhile construction of the atlas of positions for transosseous element insertion the co-ordinate system of the "Method of Unified Designation of External Fixation" (www.aotrf.org/site/metod.html) was used: each segment was divided into eight principal levels, and at each level twelve positions were marked.
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Fig. 1-8-1. Diagram of division of long bones into levels.
Levels I and VIII are located in the projection of metaphyses of long bones, that is in the place where the proximal and distal basic transosseous elements are passed during performance of the absolute majority of operations of external fixation.
On the humerus level I is located at level of the greater tuberculum of the humerus (40mm distal to acromion), and level VIII - in the projection of the epicondylus lateralis. On the forearm level I is located in the projection of the collum of radial bone (40-50mm distal from the apex of the olecranon), and level VIII - 30mm proximally from the apex of the styloid process of the radial bone. On the femur level I is located in the projection of the most prominent lateral part of the greater trochanter, and level VIII - in the projection of the epicondylus lateralis. For the shin proximal level (I) is located at level of the tibial tuberosity, and distal level (VIII) - at level of the distal tibiofibular syndesmosis.
Levels 0 and IX located in the projection of the proximal and distal epiphyses of the bones of each segment are rarely used in practice of external fixation. The distance between levels 0 and I (as well as the distance between levels VIII and IX) is less than the distance between the principal levels. Levels 0 and IX were not included into the atlas.
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Fig.1-8-2. The device is used for rapid designation of all the levels or any one of them. It consists of hinge joints of 14 laths; the dimensions of them are 80x10mm. During the work it is enough to set the marginal joints of the device into the projections of levels I and VIII, and the whole segment will be divided into 8 segments remoted equally. With the same aim the elastic tape with 8 marks of levels can be used.
Each of theoretical cuttings made in transverse plane at each of ten levels is divided into twelve equal sectors (similar to the clock-face); the sectors are limited with positions 1 to 12. The long axis of the bone is the centre of division of each level into twelve positions. According to this principle the positions are projected on the skin (Fig. 1-8-3).
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Fig. 1-8-3. Diagram of designation of the positions of right (1) and left (2) femur at level IV. Conventionally, position "3" is always located along medial surface of the segment, and "12" -anteriorly. The maintenance of this guideline allows to avoid a failure during the designation of positions on the right and left extremity. According to the topographico-anatomical features of the humerus, positions 2, 3, 4, and 5 can only be imagined theoretically at levels 0 and I (in some individuals - at level II due to the constitutional features).
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Fig 1-8-4. At each of 10 levels of the forearm 24 positions are indicated: 12 positions relative to each bone segment. Diagram of designation of positions relative to radial (1) and ulnar (2) bones at level IV of forearm (right forearm, in the middle between supine and prone position) is represented.
On the anatomic functional cuttings of the forearm the sign designates only the positions where (in case of K-wire or S-screw insertion there) we can expect the complete functional duration of post-op period: with the restoration of rotation function during the fixation period. The sign «
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means that the application of the external fixation device with the insertion of transosseous elements into the mentioned places will provide the early restoration of only flexion and extension in elbow and wrist joints.
Next to the figure of the recommended transosseous elements their ciphered designations are located according to the "Method of Unified Designation of External Fixation" (www.aotrf.org/site/metod.html). As the angle of console transosseous element insertion is defined by the optimal biomechanics for the concrete clinical situation, the numerical value of the degrees are not represented on the schemes.
While planning the external fixation frame one should pay attention to the reference positions represented at this level symmetrically relative to the bone, for example, 2 and 8, 3 and 9, 6 and 12, etc. In the projection of these positions one can insert K-wire. However, the insertion of S-screw is possible as well - from the side of any of the reference positions. For example, if at the
level V of the humerus the reference positions are 4 and 10, then either K-wire V,4-10, or one of the following S-screws V,4,90 or V,10,90 can be used (the angle of S-screw insertion is mentioned arbitrarily).
In the cases when at the level there were RP located symmetrically relative to the bone, then K-wire was drawn on the scheme instead of two S-screws "inserted" in the proceeding from opposite direction.
In case when at the level there are no any reference positions located symmetrically relative to the bone, then at this level it is expedient to apply S-screws. For example, at the level I of the femur the reference positions are 8 and 9, that causes the application of S-screws I,8,90 and (or) I,9,90 (the angle of S-screw insertion is mentioned arbitrarily).
The application of the safe positions side by side with the reference positions enlarges the number of variants of transosseous element insertion at each level. However, in this case the danger of pin-induced joint stiffness and infectious complication occurrence increases.
On the upper extremities the following meridians pass (Fig. 1-9-1): lung (P), large intestine (GI), triple heater (TR), small intestine (IG), heart (C), pericardium (MC).
On the lower extremities the following meridians pass: stomach (E), liver (F), spleen (Rp), kidneys (R), bladder (V), gall bladder (VB).
In the atlas schemes the projection of acupuncture points and meridians on the skin is shown. The zones of crossings of the levels by meridians in the scaled cuttings are designated according to the recommendation of Volkov M.V. et al (1986). In the case of level coincidence with the acupuncture point it was designated according to the French transcription. Only the designations in letters correspond to the crossing of the level by meridian. While identification of the "safe positions" and "reference positions", the projections of acupuncture points and meridians were not accounted because the data concerning the meaning of the transosseous element passing via reflex zones are differ at present (Nechushkin A.I. et al, 1976; Volkov M.V. et al., 1986; Shpilevsky I.E. et al., 1994; Prokin B.M. et al., 1994; Verkhozina T.K. et la., 1998; Ivannikov S.V. et la., 2003).
One should account that the diagrams given in atlas are oriented on the anatomical-topographical norm. That is why before the transosseous element insertion the elimination of severe displacement of bone fragments and restoration of limb axis are obligatory. In case of deformities, shortenings, dysplasia of the extremities, to define more precisely the forbidden positions one should apply the additional examinations in the post-op period: computer tomography, MRI, angiography.
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Fig.1-9-1. Diagrams of meridians according to G.Luvsan (1990)