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Supplement Article

Preoperative Planning in the Surgical Correction of Tibial Nonunions and Malunions

Mast, Jeffrey W. M.D.*

Author Information
Journal of Orthopaedic Trauma: February 2018 - Volume 32 - Issue - p S1-S4
doi: 10.1097/BOT.0000000000001077

Abstract

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.

MATERIALS

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

METHODS

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.

FIGURE 1A–1G.
FIGURE 1A–1G.:
Tibial nonunion, simple deformity, in a 40-year-old surgeon with a 2-year hypertrophic nonunion of the distal tibia secondary to a skiing injury.(A) Roentgenograms of the fracture and deformity. (B) Drawings of the roentgenograms showing a 20° varus deformity combined with shortening of 0.5 cm. (C) Drawing of the coupling bolts that will be used with the femoral distractor to correct angulation and length. (1) The joint line in the frontal plane; arthrotomy will be necessary to place the Kirschner wire. (2) A 2.0-mm Kirschner wire parallel to (1) and placed into the bone 1 cm proximal to the joint line. (3) The distal coupling bolt placed 2 cm proximal to the joint line parallel to (2). (4) The 90° triangular guide used to place (5) coupling bolt 9 cm proximal to the nonunion site along the medial border. It is perpendicular to the tibial shaft axis. (D) Drawing of the reduced nonunion obtained by drawing the proximal fragment with its axis aligned with the axis of the distal fragment. The fibula, which is not affected in this case, is drawn in after correction of the tibial axis. Its distal reference point remains unchanged because of the intact distal syndesmotic ligaments. At this point the effect of a mild shaft displacement can be viewed and anticipated. Since this is a hypertrophic nonunion, osteoclasis with an attempt at complete anatomic reduction would be contraproductive. (6) Distraction to produce length. (E) Composite drawing of the fracture showing plate location. The distal extent is within 1 cm of the joint line for maximal fixation. (8) A 10-hole plate will suffice, with (9, 10) screws inserted through a plate as lag screws. (7) The gap that must be filled with autogenous cancellous graft. If length were not to be regained or if there were no gap, bone grafting would not be necessary. (F) Roentgenograms showing postoperative result. (G) Roentgenograms showing final result.
FIGURE 2A–2H.
FIGURE 2A–2H.:
Malunion of a distal tibial fracture in a 24-year-old woman, simple abnormality. She complained of pain in the left ankle and had limited plantar flexion and hyperdorsiflexion.(A) Roentgenograms. (B) Drawing of the deformity in anteroposterior and lateral views and the lateral view of the normal side. Note that the deformity exists in both tibia and fibula only in the sagittal plane. (C) Drawing of the tibial deformity superimposed on the lateral view of the uninjured side. In the sagittal plane there is no shift of the posterior cortex at a point 4 cm from the posterior joint line (CR). If the osteotomy of the tibia is hinged at this point, no shaft displacement will occur along the posterior cortex in the sagittal plane. It is the center of rotation for the osteotomy. (D) The desired correction, 30° wedge based anteriorly and starting 4 cm from the distal anterior joint line. (E) The method. (1) Fibular osteotomy; in this case the fibula is part of the deformity and therefore must be corrected with the tibia. (2) Kirschner wire (2.0 mm) at 90° to the tibial shaft axis in the sagittal plane. (3) Kirschner wire (2.0 mm) placed 30° cephalad to (2). (5) The sagittal plane deformity of the distal joint surface, the same as Kirschner wires (3) and (4). (6) The osteotomy 4 cm from the anterior joint surface parallel to Kirschner wire (4) and perpendicular to the tibial shaft axis in the frontal plane. (F) Procedure continued with the application of a spoon plate 1 cm proximal and parallel to the anterior joint line. Fixation to the distal fragment is accomplished with 3 cancellous screws and 1 screw on the proximal side of the osteotomy in the slot of the plate, i.e., a single cortex screw. Distraction of the osteotomy is done until the opening wedge base measures 1 cm, a slight overcorrection. A 30° bone wedge obtained from the iliac crest is inserted. Compression of the osteotomy is done. The most important instrument in this case is the articulating tensioner/compression device (AO/ASIF), which may affect the opening of the osteotomy indirectly. Instability should not become a problem in this case. (G) Intraoperative roentgenograms showing pin placement. (H) Final result at 6 months. A fibular plate was added to secure rigid fixation and early motion.

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).

FIGURE 3.
FIGURE 3.:
Nonunion of the distal tibia in a 27-year-old male motorcycle rider, complex abnormality. The deformity is in 3 planes, with valgus of 16°, anterior angulation (apex posteriorly) of the distal fragment of 30°, and external torsion of the distal fragment of 25°. In this case correction of the deformity is best performed with the femoral distractor or external fixator. In this case the external fixator was used for correction as well as for definitive treatment because infection was present.(A) Roentgenograms of the deformity. (B) Tracing of the deformity in the frontal and sagittal planes. (C) Rendition of the proximal and distal fragments for each plane and superimposition of the deformity and correction with alignment of the axes. (D) Drawing of end result. (E) Drawing of the tactic. A fibular osteotomy is first accomplished at the site of the deformity. A limited arthrotomy is then necessary to place (1) a 2.0-mm guide pin that is parallel to the joint axis in the frontal plane. (2) The drill hole is parallel to (1) in the frontal plane and 3 cm proximal to the joint. In this hole a centrally threaded Schanz screw is inserted. (3) A 2.0-mm Kirschner wire 9 cm proximal to the nonunion is placed parallel to the tibial crest using a 90° angle guide. (4) With a limited incision a drill hole is made 9 cm proximal to the pseudarthrosis with the drill and guide at 90° to the tibial shaft axis in the frontal plane and 105° (90° + 15°) of external rotation relative to the pin (3) in the horizontal plane. Through this drill hole another centrally threaded Schanz pin is placed. These two pins are used as a guide to the correction in the sagittal plane. A connecting tube or stiff long Kirschner wire is laid on the pins, depicted by (5) the dotted line. (6 and 7) Pins may be inserted using appropriate angle guides of 20° distally and 10° proximally, maintaining parallel relations. Schanz pins are inserted by hand, and the “H” frame is assembled with single clamps. In the frontal plane, pins (2) and (4) must remain parallel as the drill holes are made. The pseudarthrosis is manipulated to align the pins in all three planes. If the pseudarthrosis is too “sticky” to move, a minimal osteoclasis may be performed. The procedure is performed open as bone graft must be added to the nonunion site after correction of the axis. (F) Result after operation. (G) Final result.

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.

REFERENCES

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.
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