Pauwels2 firmly believed that pseudarthrosis results in part from unfavorable mechanical demands on the fracture. Citing examples of pseudarthroses of the femoral neck and of the tibia, Pauwels proved that by improving the local biomechanics of the fracture, disturbing forces can be eliminated and pseudarthroses united.
The biomechanics of tibial pseudarthroses have also been influenced by the advent of stable internal fixation. The external fixator, the intramedullary nail, and the tension band or compression plate are examples of fixation devices that may be used to correct limb axes and maintain them in an exact and stable position until healing has occurred.
Mueller1 of Berne, Switzerland has been a leader in the preoperative planning of osteotomies, and the present paper illustrates the clinical application of his techniques in the planning of surgical correction of tibial nonunions and malunions.
All construction centers around a plan. The builder and architect have at their fingertips a plan, i.e., a blueprint. The construction of ships, automobiles, airplanes, etc., involves sophisticated plans rendered in drawings to the most minute detail. These systems are designed to discover flaws in the project beforehand. A similar system in orthopedic surgery, utilizing roentgenograms, simple tracing paper, templates, and a ruler–goniometer to plan and perform reconstructive bone surgery, is also possible.
The present paper illustrates these simple techniques, with special reference to tibial nonunions and malunions. In general, three sets of drawings are necessary: (1) The deformity. The deformity must be drawn accurately in the frontal and sagittal planes. Since axial views are not available in most cases, the horizontal plane must be determined by clinical examination of the patient. (2) The desired end result. The desired end result is worked out with tracing paper in each plane of reference. For visualization of the end result considerable “playing with the possibilities” is necessary. Usually, a drawing of the unaffected side is useful: superimposition of drawings of the normal on those of the abnormal side may disclose such details as the amount of correction needed and the best location for the correction; by superimposition of the final drawing on the unaffected limb drawing, the patient may be informed prior to operation of changes in length or deviations from limb alignment that would result from the proposed procedure. (3) The surgical tactic. This drawing usually is a simplification of the method that evolved during the period of experimentation that led to the finished drawing of the desired end result. In other words, the same methods by which the final drawing was achieved are delineated by guide pins, allowing the final surgical correction to be planned in about the same manner as the final drawing. It is a method based on backtracking from the finished rendering.
Precise roentgenograms of the limbs are essential. They must be accurate projections of the anteroposterior (frontal) and lateral (sagittal) planes. Oblique views are sometimes necessary to delineate a deformity fully. These roentgenograms must be of sufficient quality to allow tracing of the bony contours. A consistent 1-m distance between cathode and cassette is desirable.
An X-ray viewbox with good illumination, preferably one that can be placed horizontally like a drawing board, is essential. The viewbox produced by Protek3 (Indianapolis, Indiana) is particularly well suited for this purpose.
Tracing paper in abundance (Monroe “Triple T” parchment tracing paper 14 × 17 inches) is necessary and convenient for drawing in the deformities of long bones. The paper is used liberally, as breaking the problem down to its basic elements and then inter-relating them is the essential part of the “discovery” process.
A goniometer long enough to use as a straight edge and a centimeter ruler are essential. The author prefers the goniometer designed by Mueller (available from Protek) because of its useful adjunctive features. With felt-tip ink pens in multiple colors lines can be drawn and viewed again on superimposition without difficulty. Overlays of almost all implants are available through Protek.3
In general, roentgenograms are evaluated, and the deformity or problem is defined as being confined to one, two, or three planes. In the latter situation the clinical appearance of the patient must be considered, as the horizontal plane is difficult to reproduce by conventional roentgenography. The deformity or problem then becomes simple (abnormality in one plane), compound (abnormality in two planes), or complex (abnormality in all three planes).
The derivation of the solution in simple abnormalities is started in the plane of the problem (Figs. 1 and 2). In compound or complex abnormalities the plane studied is that containing the greatest or most difficult abnormality. It is in this plane that the bony contours are traced and the joint axis marked using a straight edge. The tibial shaft axis is then derived relative to the contiguous joints using the centering device on the goniometer.
In most cases it is helpful to trace the contours of the unaffected limb. Superimposition of proximal or distal contours allows determination of the exact location of the deviation in this plane and of the exact distance of the change from the corresponding joint. Lengthening, with correction if necessary, can be anticipated at this point.
The fragments are then created on separate pieces of tracing paper. Each one is complete in its rendering with the shaft axis. The tracing paper is rotated in the frontal (or, if applicable, sagittal plane) until the axis corresponds or at least becomes parallel. At this point a third tracing paper is placed over the first two in their corrected position, and the contours are traced in detail. It is as though a closed manipulation under image intensification is being performed.
If correction in more than one plane is needed, pins should be drawn at right angles to the tibial shaft axis to delineate the correction. Pins act as points and as such may be used for complex corrections, the actual correction being mitigated through them by means of an external fixator or a femoral distractor (AO/ASIF) and the definitive correction being maintained by external fixation, nail, or appropriate plate.
The sagittal (or frontal) plane is then drawn using appropriate roentgenograms and tracing paper. The pins used (drawn) in the opposite plane are introduced into the drawing of the bone in the second plane. Use of pins to delineate corrections in the second plane is then clear (Fig. 3).
Finally, a definitive drawing that features the desired correction is achieved. Using templates (available through Protek) the definitive fixation may be drawn as well. Attention to metric detail allows preplanning the location of the level of the plate from the subchondral bone line, the location of lag screws, etc. By backtracking the exact number of steps of the procedure, consecutively from beginning to end, may be anticipated. In addition, each instrument and each implant needed may be noted, along with the anticipated order of their appearance. This is of great benefit to nursing personnel, usually unfamiliar with the procedure in this type of case.
1. Muller M. E.. Planning of internal fixation procedures. Presented at International Symposium on Musculoskeletal Trauma, San Francisco, 1982.
2. Pauwels F., Weber B. G., Cech O.: Pseudarthrosis. Trans. Konstam P. Bern, Hans Huber, 1976, pp. 12–13.
3. Protek, Inc., 2601 Fortune Circle East, Ste. 105 B, Indianapolis, Indiana.