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External fixation of pelvic fractures
External Fixation of Pelvic Fractures
S. Olerud ---__
---
Introduction External fixation had been used for fractures of the extremities for almost a century, but it was not until 1958 that its use in pelvic fractures was first reported, by Pennal’ in Toronto. In the 1970s there were a few reports from different trauma groups in France,‘.3 Switzerland4. s and Finlandb%7 concerning the advantages of using external fixation for unstable and displaced pelvic fractures. It was also observed, however. that there were some pelvic fractures that were not very well treated with this technique. To improve the outcome of external fixation of pelvic fractures even further, biomechanical studies were undertaken with the aim of ascertaining the best external fixation techniques for these injuries. Such an investigation has been carried out by Gunterberg8 and also by McBroom and Tile.9~10 The results show that external fixation has its limitations.
Indications There is no doubt that external skeletal fixation of pelvic ring fractures restores stability, but the effect is dependent upon the degree and nature of the pelvic injury. Empirically some major advantages of external fixation have been found, namely a reduced tendency to bleeding and relief of severe pain. By stabilizing the fracture and holding together the displaced fragments, the oozing of blood from the large open bone surfaces will be prevented. The fixed pelvis will remain within a certain volume. thus producing a tamponade effect on the bleeding. An unstable fracture is a major indication for external fixation, even though this may not be the ______Sven Olerud MD, Department of Orthopaedic Hospital. S-751 85 Uppsala, Sweden. ___-___
Surgery.
University
definitive treatment. An external frame should be applied as early as possibIe after the injury, for the reasons mentioned above. A stable or partially unstable fracture is also a good indication for use of an external fixation frame. In some of these cases this can be the definitive treatment as the external fixation will give good alignment and sufficient stability for walking. A third purpose of using external fixation of the pelvis is to aid reduction of displacements, especially a fixed lateral compression deformity. An external fixation frame may also be applied in cases of insufficient internal fixation to provide supplementary stability.
Method of External Fixation The effect of the external fixation will depend upon two factors, namely the fixation of the anchoring screw into the pelvis, and the type of connecting bar-frame system between the bone-anchored screws. Anchoring of screws into the pelvis
It is very important that the screws are reliably anchored into the pelvis, and the screws should therefore be placed with utmost care and also into the part of the pelvis where the bone is strongest. Four millimetre screws are too weak, and 5 mm or, even better, 6 mm screws should be used. There are three main sites of fixation : (1) Iliac crest bone screw fixation; (2) The anterior approach for bone screws; and (3) Transiliac pin fixation. General anaesthesia is preferred, but local anaesthesia is also possible. The bone screws can be applied transcutaneously or after exposing the bone into which they are to be applied. In the former case it is difficult _~~
34
CURRENT
ORTHOPAEDICS-TRAUMA
Fig. l-(A) Diagram showing the positioning of a Hoffmann half pin cluster group. (E) Diagram showing the two bone screw fixation system in the iliac crest with the pins angled between 20” and 30”. (C) The anterior approach for bone. (D) Transiliac pin fixation as described by Mears.
to find the right direction for the screws, especially if the pelvic ring is disrupted. If any question arises as to how the bone screws should be inserted, it is advisable to make an incision and introduce the screws under direct vision. If possible, some reduction of fragments should be performed before making a skin incision. It is important that the screws exert no pressure on the skin, as otherwise necrosis will develop very quickly and may jeopardise subsequent internal fixation. The anterior approach usually needs a wider incision. The anterior edge of the ilium is rather sharp here and the bone screw may slip very easily unless an appropriate site of insertion is chosen. When the ilium is underdeveloped (in children) or fractured, the anterior approach may be the only alternative. Iliac crest bone screw fixation. (a) Insertion of a Hoffmann half pin cluster group (Fig. 1A). The iliac crest is palpated between the thumb and the index finger. A small incision is made against the iliac crest, and a 4 mm half pin is driven down into the ilium between the two laminae. Using the Hoffman pin guide, another two half pins are driven into the iliac crest. The parallelism of the screws is not always an advantage, as they have to go into partly spherically shaped bone. In patients with thicker soft tissue, palpation of the iliac crest is difficult. In these cases the inner side and the outer side of the ilium are each
marked with a 2 mm Steinmann pin. The incision is made in between these two pins down to the bone. The bone screw is driven home by manual power. Care must be taken to see that the screw tip does not come outside the lamina, but it is better for anchoring if the tip passes inside of the pelvis, as the clusters are usually pressed against each other. It is important to handle the soft tissues gently to prevent any soft tissue reaction and infection. (b) Two bone screw fixation in the iliac crest (Fig. 1B). With this technique the thicker parts of the ilium are used. One screw is placed just behind the anterior superior iliac spine and another one is placed in the iliac tubercle. In these thicker parts of the ilium 56 mm pins can be used without difficulty and be driven home between the laminae of the ilium about 5-6 cm, and with this location they give a very good bone grip. The angle between the screws should be about 20-30”. The anterior approach for bone screws (Fig, 1C). This technique utilizes the very good bone stock of the ilium just above the acetabulum. Because of the rather sharp anterior border at this site, it is difficult to apply the bone screw without opening up the skin. Using a drill sleeve as a guide, it should be possible to place a screw almost completely in the sagittal plane. As it is difficult to know the distance to the hip joint, an image intensifier should be used to ensure that no penetration occurs into that joint. Transiliac pin $.xation (Fig. 1D). This technique has been described by Mears.’ ‘. ’ 2 Through incisions made by the anterior approach and also over the posterior iliac spine, a jig is placed in contact with the bone on both sides and two 4 or 5 mm pins are driven through the iliac bone. The surgical procedure is illustrated in Figure 4. The bone screws and pins on each side are all connected to each other, making a unit for subsequent connection of the two sides of the pelvis for the purposes of stabilization. The bar and/or frame connection of the pins and clusters
The connection between the two sides can be achieved in different ways: by a single bar (Connes) (Fig. 2A); by a double bar-the rectangular system (Tile) (Fig. 2B); by a ‘trapezoid’ frame system (Slatis, Karaharju) (Fig. 2C); by a ‘double cluster’ connection as described to Mears (Fig. 2D); or by a full circumference fixation to transiliac pins (Mears). The different mounting systems give rather better stability when more bars and frames are used. The single bar and double bar hold the two halves of the pelvis together, using the posterior ligament as a tension band when this structure is not damaged. The rectangular mounting with triangular enforcementlO gives even better stability in cases where the primary stability is worse. The trapezoid system provides compression over the posterior parts of the pelvis as well as stability. An example of trapezoid fixation is shown in Figure 5.
F-XTFRNAL
FIXATION
Fig. 2-(A) Single bar connection. (6) Double bar---the rectangular system of connection circumference fixation to transiliac pins.
However, here the pins are placed anteriorly and in the crests. If the bone is not severely damaged or if the fracture fragments grip into each other, this compression system can be very useful. But, if the posterior elements are not injured, these ligaments cannot work as a tension band with this method. In cases of complete sacroiliac joint displacements, or fracture dislocations the compression effect of the trapezoid
OF PELVIC
FRACTURES
(C) Double cluster connection
35
;D) Full
system will very likely cause the sacrum to be pressed downwards. increasing the primary dislocation. In the most unstable posterior pelvic injuries, care must be taken not to increase any dislocation. However, there is a possibility of preventing such an increase by applying femoral traction on the dislocated side to counterbalance the instability. The double cluster fixation is a combination of bars
Fig. 3-Biomechanical tests of external fixation of pelvic injuries. An anteroposterior compression injury is fairly well stabilized by different mounting systems. An anterior plate over the symphysis, however, gives far better stability. The vertical shear injury is not very stable with an external fixation frame placed only in the crests or anteriorly. Note the differently marked scales on the Y axis. With addition of internal fixation the stability is much improved, as seen in the graph to the right.. To ensure stability of fixation, combined treatment is advisable To ensure reduction with external fixation a combination with traction is recommended.
__^..
_ _ - -~-
-.__ __
__~
--__
36
CURRENT
ORTHOPAEDICS-TRAUMA
between bone screws placed in the crista and anteriorly placed ones. A cross link from the crista on one side to the anterior group of pins on the other may theoretically provide the best stabilization in this type of anterior fixation. The full circumference fixation by transiliac pins as described by Mearsi l, l 2 gives the best prerequisites for an effective external fixation technique, as it works as a complete ring. However, the procedure is surgically very demanding and these cases are already difficult to manage. The nursing care is also complicated by the presence of metal bars around the whole body. The most thorough investigation concerning the stability of different mounting systems has been made by McBroom and Tile.9 The effects of some different systems are shown in Figure 3. It is amazing how little the more sophisticated systems increase the stabilizing effect as long as no internal fixation is used. For comparison, the effects of some different types of internal fixation are included.
Clinical Aspects
Fig. &The transiliac pins are placed with the aid of a guide, which is secured against the lower anterior iliac spine and the posterior iliac spine after freeing these prominencesof soft tissue.
In clinical practice the best way to decide when external fixation should be used is to understand the major classification of injuries and to have knowledge of the pathophysiology of the injury and fracture. The advantage or disadvantage of external fixation and the best type to choose will then become clear.
Anteroposterior compression injury
Fig. 5-A well-fitted trapezoid frame may allow very early weight bearing, in 1 to 3 weeks in cases of partly unstable pelvic fractures.
This injury can be divided into three degrees: The first degree consists solely of rupture of the symphysis ligament; the posterior elements are unaffected, as are the sacrospinous and sacrotuberous ligaments. This injury is only a relative indication for external fixation when the symphyseal diastasis is less than 2.5 cm. The second degree is recognised by rupture of the symphysis ligaments and rupture of the anterior sacroiliac, the sacrospinal and sacrotuberous ligaments. This injury is relatively stable in the vertical direction. It is an ideal indication for external fixation with a single-bar or a double-bar system. A second degree anteroposterior compression injury is shown in Figure 6. This treatment also allows free walking. However, if it is difficult to get the pubic bones anatomically aligned, internal fixation with a plate is an easy operation. A third degree anteroposterior compression injury involves rupture of all the posterior elements, which means that the pelvis is 3-dimensionally unstable. External fixation may be helpful but a single bar or a rectangular frame may not be sufficient. The trapezoid system presses the posterior parts together and may therefore be theoretically superior. However, if during treatment displacement occurs, internal fixation will be required.
EXTERNAL
FIXATION
OF PELVIC
FRACTURES
37
Fig. 6-(A) An anteroposterior pelvic fracture probably of third degree, a sacral fracture is also noticed. (B) Satisfactory stabilization is achieved with an anterior frame. Because of communition of the left pubic bone, only the symphysis was fixed. In this case weight bearing was postponed until the sixth week.
Latera/ compression injtq, Again this injury can be divided in three grades: An anterior injury may involve the symphysis pubis or the superior and inferior ischio-pubic rami on one or both sides. The first degree means an internal rotation of the ilium and also a compression fracture of the sacrum with the posterior elements unaffected. If the deformity is too great and includes leg shortening of more than 1.5 cm, reduction has to be performed. With external screw fixation in the inwardly rotated ilium it is possible to reduce the deformity. However, the relatively stability of the deformed pelvis may then change into an unstable situation. A second degree lateral compression type injury causes further deformity of the sacrum or a fracture through the ilium or sacroiliac joint. With a compressed sacrum the nerves, especially Sl and S2, may be affected and a reduction with outward rotation, with external fixation in the ilium, followed by fixation to the other side of pelvis, may be appropriate. In the third degree of a lateral compression injury there will be complete instability of the entire posterior ring of the pelvis External fixation will certainly not always be a sufficient method for achieving stability. Femoral traction together with external fixation may sometimes hold the pelvic ring in an adequate anatomical position until healing occurs but this also means an extended time in bed. Probably in no case of the lateral compression type injury will the stability provided by an external frame be sufficient for weight bearing and walking during the healing period.
often causes a fracture of the transverse process of L5. The injury line will follow the sacral foramina or pass through the sacroiliac joint, or possibly in the medial part of the ilium. In the anterior part of the injury there will also be a major displacement. Very early external fixation will probably be of great value in preventing pain and bleeding. However. the instability is very pronounced and external fixation may not be sufficient for proper alignment of the fractures. On the other hand, there is a great risk that external fixation will increase the displacement, especially with use of the trapezoid system with compression posteriorly. External fixation is most useful as a temporary measure until definitive internal fixation is possible. A lesion through the sacroiliac joint is very often considered to be suitable for external fixation in combination with femoral traction. After having explored many sacroiliac joint dislocations from the anterior aspect, we have found that in most of these cases there is major damage to cartilage. Stable healing of this injury by external fixation alone does not seem probable, and internal fixation from the anterior aspect is therefore necessary with removal of the cartilage. If necessary the alignment of the sacroiliac joint can be restored with bone grafting. A double sacroiliac joint dislocation is not at all suitable for external fixation, which should only be used as a temporary measure. A further dislocation will very easily occur (Fig. 7). Internal fixation may solve the problem.
How to take care oj’the skin and pins Vertical shear injut-!, In a vertical shear injury, the most serious pelvic fracture, there is displacement cranially. This also
A prerequisite for sound care of patients with external fixation is that the bone screws exert no pressure on the skin. If such pressure is observed. further releasing
38
CURRENT
ORTHOPAEDICS-TRAUMA
Fig. 7-(A) A bilateral dislocation of the sacroiliac joint. (B) This was treated with a Slatis-Karaharju frame from the day of the accident. Further dislocation occurred. (C) Reduction was performed by an anterior approach and the square plate method was used for fixation.13
incisions are required. Too large skin openings may be sutured, but a free drain should always be present. Skin motion against pins and screws should be minimised. Cotton bandage encircling the bone screw may exert slight pressure on the soft tissue and thus reduce skin motion. This pressure will also prevent oedema. In patients with thick soft tissue, irritation of this tissue may be minimised by the use of an antibiotic locally and systemically. Most bone screws will loosen after some time and will then not fulfil their purpose and may need to be replaced. But before doing this, it may be possible to press the screws against each other, where the anchoring effect will very often be restored. The first reason for bone screw loosening is always micromotion between the screw and the bone. This will be reduced by using perpendicular loads on the bone over the screw threads. Weight bearing and when to remove the external Jixation frames
Only when there is complete stability should the patient be allowed to bear weight and begin to walk. For partially stable fractures such as open book injuries and some lateral compression injuries walking exercises can probably be started early, after lo-15 days. Pain is usually not a limiting factor but would be a reason for postponing weight bearing.
Concerning the unstable fractures, these need a rather extended immobilization period, the length of which should be decided according to individual judgement. In less severe cases 6 weeks of non-weight bearing may be enough but in the more severe situations 3 months are required. With these long periods of external fixation problems with the bone screws very often arise. When walking is begun, pain and also the patient’s own feeling of instability are good signs that weight-bearing has been started too early. These may also be indications for internal fixation.
Conclusion External fixation of pelvic ring fractures is a very good choice of treatment if the fractures are stable or only partly unstable. For very unstable fractures of the pelvis, external fixation is not always a satisfactory method. When the patient’s general situation has been stabilized, the question of the fracture alignment has to be considered. If displacement has occurred, external traction may be helpful in achieving an acceptable reduction; otherwise internal fixation should be considered for adequate alignment and healing of the pelvic injury.
EXTERNAL
References 1. Pennal G F. The use of external fixation. Presented at the Canadian Orthopaedic Association Annual Meeting, 1958 2. Carabalona P, Rabichong P, Bonnel F. Apports due fixateur exteme dans les dislocations du pubis et d l’articulation sacroiliaque. Montpelier Chir, 1973; 29-61 Paris: 3. Connes H. Hoffman’s double frame external anchorage. Gead. 1973 4. Miiller J H, Bachmann B, Berg H. Malgaigne fracture of the pelvis. Treatment with percutaneous pin fixation. report of 2 cases. J Bone Joint Surg 1978; 60A : 992-993 J K. Die osteosynthese mit dem 5. Miiller K H, Miiller-Farber fixateur externe am becken. Arch Orthop Trauma Surg 1978. 92: 273 283 6. Slltrs P, KaraharJu E 0. External fixation of the pelvic girdle with a trapezoid compression frame. Injury 197.5 : 7. 53356 I. Karaharju E 0. Slatis P. External fixation of double vertical fractures wrth a lntpe/oid compression frame. Injury 1978: IO: I42
FIXATION
OF PELVIC
FRACTURES
B, Goldie I, Slatis P. Fixation of pelvic fractures 8. Gunterberg and dislocation. An experimental study on the loading of pelvic fractures and sacroiliac dislocations after external compression fixation. Acta Orthop Stand 1978: 49: 278-286 9. McBroom R. Tile M. Disruption of the pelvic ring. Presented 31 the Canadian Orthopaedic Research Society Convention. Kingston, Ontario, June 1982 10. Tile M. Fractures of the pelvis and acetabulum. Williams and Wilkins. 1984
Baltimore:
11. Mears D C. Fu F H. Modern concepts of external skeletal tivation of the pelvis. Clin Ortho 1980: 151 65- 77 I2
Mears D D External and Wilkins. 1981
skeletal fixation.
Baltrmore
Williams
13 Olerud S. Hamberg M. The anterior approach to the dlslocatcd sacroiliac joint. Reduction and fixation with a square plate In: Noble J. and Galasko C S. B. (eds!. Recent developments in orthopaedic surgery. Manchester Manchester University Press, 1987
39
S. Olerud ---__
---
Introduction External fixation had been used for fractures of the extremities for almost a century, but it was not until 1958 that its use in pelvic fractures was first reported, by Pennal’ in Toronto. In the 1970s there were a few reports from different trauma groups in France,‘.3 Switzerland4. s and Finlandb%7 concerning the advantages of using external fixation for unstable and displaced pelvic fractures. It was also observed, however. that there were some pelvic fractures that were not very well treated with this technique. To improve the outcome of external fixation of pelvic fractures even further, biomechanical studies were undertaken with the aim of ascertaining the best external fixation techniques for these injuries. Such an investigation has been carried out by Gunterberg8 and also by McBroom and Tile.9~10 The results show that external fixation has its limitations.
Indications There is no doubt that external skeletal fixation of pelvic ring fractures restores stability, but the effect is dependent upon the degree and nature of the pelvic injury. Empirically some major advantages of external fixation have been found, namely a reduced tendency to bleeding and relief of severe pain. By stabilizing the fracture and holding together the displaced fragments, the oozing of blood from the large open bone surfaces will be prevented. The fixed pelvis will remain within a certain volume. thus producing a tamponade effect on the bleeding. An unstable fracture is a major indication for external fixation, even though this may not be the ______Sven Olerud MD, Department of Orthopaedic Hospital. S-751 85 Uppsala, Sweden. ___-___
Surgery.
University
definitive treatment. An external frame should be applied as early as possibIe after the injury, for the reasons mentioned above. A stable or partially unstable fracture is also a good indication for use of an external fixation frame. In some of these cases this can be the definitive treatment as the external fixation will give good alignment and sufficient stability for walking. A third purpose of using external fixation of the pelvis is to aid reduction of displacements, especially a fixed lateral compression deformity. An external fixation frame may also be applied in cases of insufficient internal fixation to provide supplementary stability.
Method of External Fixation The effect of the external fixation will depend upon two factors, namely the fixation of the anchoring screw into the pelvis, and the type of connecting bar-frame system between the bone-anchored screws. Anchoring of screws into the pelvis
It is very important that the screws are reliably anchored into the pelvis, and the screws should therefore be placed with utmost care and also into the part of the pelvis where the bone is strongest. Four millimetre screws are too weak, and 5 mm or, even better, 6 mm screws should be used. There are three main sites of fixation : (1) Iliac crest bone screw fixation; (2) The anterior approach for bone screws; and (3) Transiliac pin fixation. General anaesthesia is preferred, but local anaesthesia is also possible. The bone screws can be applied transcutaneously or after exposing the bone into which they are to be applied. In the former case it is difficult _~~
34
CURRENT
ORTHOPAEDICS-TRAUMA
Fig. l-(A) Diagram showing the positioning of a Hoffmann half pin cluster group. (E) Diagram showing the two bone screw fixation system in the iliac crest with the pins angled between 20” and 30”. (C) The anterior approach for bone. (D) Transiliac pin fixation as described by Mears.
to find the right direction for the screws, especially if the pelvic ring is disrupted. If any question arises as to how the bone screws should be inserted, it is advisable to make an incision and introduce the screws under direct vision. If possible, some reduction of fragments should be performed before making a skin incision. It is important that the screws exert no pressure on the skin, as otherwise necrosis will develop very quickly and may jeopardise subsequent internal fixation. The anterior approach usually needs a wider incision. The anterior edge of the ilium is rather sharp here and the bone screw may slip very easily unless an appropriate site of insertion is chosen. When the ilium is underdeveloped (in children) or fractured, the anterior approach may be the only alternative. Iliac crest bone screw fixation. (a) Insertion of a Hoffmann half pin cluster group (Fig. 1A). The iliac crest is palpated between the thumb and the index finger. A small incision is made against the iliac crest, and a 4 mm half pin is driven down into the ilium between the two laminae. Using the Hoffman pin guide, another two half pins are driven into the iliac crest. The parallelism of the screws is not always an advantage, as they have to go into partly spherically shaped bone. In patients with thicker soft tissue, palpation of the iliac crest is difficult. In these cases the inner side and the outer side of the ilium are each
marked with a 2 mm Steinmann pin. The incision is made in between these two pins down to the bone. The bone screw is driven home by manual power. Care must be taken to see that the screw tip does not come outside the lamina, but it is better for anchoring if the tip passes inside of the pelvis, as the clusters are usually pressed against each other. It is important to handle the soft tissues gently to prevent any soft tissue reaction and infection. (b) Two bone screw fixation in the iliac crest (Fig. 1B). With this technique the thicker parts of the ilium are used. One screw is placed just behind the anterior superior iliac spine and another one is placed in the iliac tubercle. In these thicker parts of the ilium 56 mm pins can be used without difficulty and be driven home between the laminae of the ilium about 5-6 cm, and with this location they give a very good bone grip. The angle between the screws should be about 20-30”. The anterior approach for bone screws (Fig, 1C). This technique utilizes the very good bone stock of the ilium just above the acetabulum. Because of the rather sharp anterior border at this site, it is difficult to apply the bone screw without opening up the skin. Using a drill sleeve as a guide, it should be possible to place a screw almost completely in the sagittal plane. As it is difficult to know the distance to the hip joint, an image intensifier should be used to ensure that no penetration occurs into that joint. Transiliac pin $.xation (Fig. 1D). This technique has been described by Mears.’ ‘. ’ 2 Through incisions made by the anterior approach and also over the posterior iliac spine, a jig is placed in contact with the bone on both sides and two 4 or 5 mm pins are driven through the iliac bone. The surgical procedure is illustrated in Figure 4. The bone screws and pins on each side are all connected to each other, making a unit for subsequent connection of the two sides of the pelvis for the purposes of stabilization. The bar and/or frame connection of the pins and clusters
The connection between the two sides can be achieved in different ways: by a single bar (Connes) (Fig. 2A); by a double bar-the rectangular system (Tile) (Fig. 2B); by a ‘trapezoid’ frame system (Slatis, Karaharju) (Fig. 2C); by a ‘double cluster’ connection as described to Mears (Fig. 2D); or by a full circumference fixation to transiliac pins (Mears). The different mounting systems give rather better stability when more bars and frames are used. The single bar and double bar hold the two halves of the pelvis together, using the posterior ligament as a tension band when this structure is not damaged. The rectangular mounting with triangular enforcementlO gives even better stability in cases where the primary stability is worse. The trapezoid system provides compression over the posterior parts of the pelvis as well as stability. An example of trapezoid fixation is shown in Figure 5.
F-XTFRNAL
FIXATION
Fig. 2-(A) Single bar connection. (6) Double bar---the rectangular system of connection circumference fixation to transiliac pins.
However, here the pins are placed anteriorly and in the crests. If the bone is not severely damaged or if the fracture fragments grip into each other, this compression system can be very useful. But, if the posterior elements are not injured, these ligaments cannot work as a tension band with this method. In cases of complete sacroiliac joint displacements, or fracture dislocations the compression effect of the trapezoid
OF PELVIC
FRACTURES
(C) Double cluster connection
35
;D) Full
system will very likely cause the sacrum to be pressed downwards. increasing the primary dislocation. In the most unstable posterior pelvic injuries, care must be taken not to increase any dislocation. However, there is a possibility of preventing such an increase by applying femoral traction on the dislocated side to counterbalance the instability. The double cluster fixation is a combination of bars
Fig. 3-Biomechanical tests of external fixation of pelvic injuries. An anteroposterior compression injury is fairly well stabilized by different mounting systems. An anterior plate over the symphysis, however, gives far better stability. The vertical shear injury is not very stable with an external fixation frame placed only in the crests or anteriorly. Note the differently marked scales on the Y axis. With addition of internal fixation the stability is much improved, as seen in the graph to the right.. To ensure stability of fixation, combined treatment is advisable To ensure reduction with external fixation a combination with traction is recommended.
__^..
_ _ - -~-
-.__ __
__~
--__
36
CURRENT
ORTHOPAEDICS-TRAUMA
between bone screws placed in the crista and anteriorly placed ones. A cross link from the crista on one side to the anterior group of pins on the other may theoretically provide the best stabilization in this type of anterior fixation. The full circumference fixation by transiliac pins as described by Mearsi l, l 2 gives the best prerequisites for an effective external fixation technique, as it works as a complete ring. However, the procedure is surgically very demanding and these cases are already difficult to manage. The nursing care is also complicated by the presence of metal bars around the whole body. The most thorough investigation concerning the stability of different mounting systems has been made by McBroom and Tile.9 The effects of some different systems are shown in Figure 3. It is amazing how little the more sophisticated systems increase the stabilizing effect as long as no internal fixation is used. For comparison, the effects of some different types of internal fixation are included.
Clinical Aspects
Fig. &The transiliac pins are placed with the aid of a guide, which is secured against the lower anterior iliac spine and the posterior iliac spine after freeing these prominencesof soft tissue.
In clinical practice the best way to decide when external fixation should be used is to understand the major classification of injuries and to have knowledge of the pathophysiology of the injury and fracture. The advantage or disadvantage of external fixation and the best type to choose will then become clear.
Anteroposterior compression injury
Fig. 5-A well-fitted trapezoid frame may allow very early weight bearing, in 1 to 3 weeks in cases of partly unstable pelvic fractures.
This injury can be divided into three degrees: The first degree consists solely of rupture of the symphysis ligament; the posterior elements are unaffected, as are the sacrospinous and sacrotuberous ligaments. This injury is only a relative indication for external fixation when the symphyseal diastasis is less than 2.5 cm. The second degree is recognised by rupture of the symphysis ligaments and rupture of the anterior sacroiliac, the sacrospinal and sacrotuberous ligaments. This injury is relatively stable in the vertical direction. It is an ideal indication for external fixation with a single-bar or a double-bar system. A second degree anteroposterior compression injury is shown in Figure 6. This treatment also allows free walking. However, if it is difficult to get the pubic bones anatomically aligned, internal fixation with a plate is an easy operation. A third degree anteroposterior compression injury involves rupture of all the posterior elements, which means that the pelvis is 3-dimensionally unstable. External fixation may be helpful but a single bar or a rectangular frame may not be sufficient. The trapezoid system presses the posterior parts together and may therefore be theoretically superior. However, if during treatment displacement occurs, internal fixation will be required.
EXTERNAL
FIXATION
OF PELVIC
FRACTURES
37
Fig. 6-(A) An anteroposterior pelvic fracture probably of third degree, a sacral fracture is also noticed. (B) Satisfactory stabilization is achieved with an anterior frame. Because of communition of the left pubic bone, only the symphysis was fixed. In this case weight bearing was postponed until the sixth week.
Latera/ compression injtq, Again this injury can be divided in three grades: An anterior injury may involve the symphysis pubis or the superior and inferior ischio-pubic rami on one or both sides. The first degree means an internal rotation of the ilium and also a compression fracture of the sacrum with the posterior elements unaffected. If the deformity is too great and includes leg shortening of more than 1.5 cm, reduction has to be performed. With external screw fixation in the inwardly rotated ilium it is possible to reduce the deformity. However, the relatively stability of the deformed pelvis may then change into an unstable situation. A second degree lateral compression type injury causes further deformity of the sacrum or a fracture through the ilium or sacroiliac joint. With a compressed sacrum the nerves, especially Sl and S2, may be affected and a reduction with outward rotation, with external fixation in the ilium, followed by fixation to the other side of pelvis, may be appropriate. In the third degree of a lateral compression injury there will be complete instability of the entire posterior ring of the pelvis External fixation will certainly not always be a sufficient method for achieving stability. Femoral traction together with external fixation may sometimes hold the pelvic ring in an adequate anatomical position until healing occurs but this also means an extended time in bed. Probably in no case of the lateral compression type injury will the stability provided by an external frame be sufficient for weight bearing and walking during the healing period.
often causes a fracture of the transverse process of L5. The injury line will follow the sacral foramina or pass through the sacroiliac joint, or possibly in the medial part of the ilium. In the anterior part of the injury there will also be a major displacement. Very early external fixation will probably be of great value in preventing pain and bleeding. However. the instability is very pronounced and external fixation may not be sufficient for proper alignment of the fractures. On the other hand, there is a great risk that external fixation will increase the displacement, especially with use of the trapezoid system with compression posteriorly. External fixation is most useful as a temporary measure until definitive internal fixation is possible. A lesion through the sacroiliac joint is very often considered to be suitable for external fixation in combination with femoral traction. After having explored many sacroiliac joint dislocations from the anterior aspect, we have found that in most of these cases there is major damage to cartilage. Stable healing of this injury by external fixation alone does not seem probable, and internal fixation from the anterior aspect is therefore necessary with removal of the cartilage. If necessary the alignment of the sacroiliac joint can be restored with bone grafting. A double sacroiliac joint dislocation is not at all suitable for external fixation, which should only be used as a temporary measure. A further dislocation will very easily occur (Fig. 7). Internal fixation may solve the problem.
How to take care oj’the skin and pins Vertical shear injut-!, In a vertical shear injury, the most serious pelvic fracture, there is displacement cranially. This also
A prerequisite for sound care of patients with external fixation is that the bone screws exert no pressure on the skin. If such pressure is observed. further releasing
38
CURRENT
ORTHOPAEDICS-TRAUMA
Fig. 7-(A) A bilateral dislocation of the sacroiliac joint. (B) This was treated with a Slatis-Karaharju frame from the day of the accident. Further dislocation occurred. (C) Reduction was performed by an anterior approach and the square plate method was used for fixation.13
incisions are required. Too large skin openings may be sutured, but a free drain should always be present. Skin motion against pins and screws should be minimised. Cotton bandage encircling the bone screw may exert slight pressure on the soft tissue and thus reduce skin motion. This pressure will also prevent oedema. In patients with thick soft tissue, irritation of this tissue may be minimised by the use of an antibiotic locally and systemically. Most bone screws will loosen after some time and will then not fulfil their purpose and may need to be replaced. But before doing this, it may be possible to press the screws against each other, where the anchoring effect will very often be restored. The first reason for bone screw loosening is always micromotion between the screw and the bone. This will be reduced by using perpendicular loads on the bone over the screw threads. Weight bearing and when to remove the external Jixation frames
Only when there is complete stability should the patient be allowed to bear weight and begin to walk. For partially stable fractures such as open book injuries and some lateral compression injuries walking exercises can probably be started early, after lo-15 days. Pain is usually not a limiting factor but would be a reason for postponing weight bearing.
Concerning the unstable fractures, these need a rather extended immobilization period, the length of which should be decided according to individual judgement. In less severe cases 6 weeks of non-weight bearing may be enough but in the more severe situations 3 months are required. With these long periods of external fixation problems with the bone screws very often arise. When walking is begun, pain and also the patient’s own feeling of instability are good signs that weight-bearing has been started too early. These may also be indications for internal fixation.
Conclusion External fixation of pelvic ring fractures is a very good choice of treatment if the fractures are stable or only partly unstable. For very unstable fractures of the pelvis, external fixation is not always a satisfactory method. When the patient’s general situation has been stabilized, the question of the fracture alignment has to be considered. If displacement has occurred, external traction may be helpful in achieving an acceptable reduction; otherwise internal fixation should be considered for adequate alignment and healing of the pelvic injury.
EXTERNAL
References 1. Pennal G F. The use of external fixation. Presented at the Canadian Orthopaedic Association Annual Meeting, 1958 2. Carabalona P, Rabichong P, Bonnel F. Apports due fixateur exteme dans les dislocations du pubis et d l’articulation sacroiliaque. Montpelier Chir, 1973; 29-61 Paris: 3. Connes H. Hoffman’s double frame external anchorage. Gead. 1973 4. Miiller J H, Bachmann B, Berg H. Malgaigne fracture of the pelvis. Treatment with percutaneous pin fixation. report of 2 cases. J Bone Joint Surg 1978; 60A : 992-993 J K. Die osteosynthese mit dem 5. Miiller K H, Miiller-Farber fixateur externe am becken. Arch Orthop Trauma Surg 1978. 92: 273 283 6. Slltrs P, KaraharJu E 0. External fixation of the pelvic girdle with a trapezoid compression frame. Injury 197.5 : 7. 53356 I. Karaharju E 0. Slatis P. External fixation of double vertical fractures wrth a lntpe/oid compression frame. Injury 1978: IO: I42
FIXATION
OF PELVIC
FRACTURES
B, Goldie I, Slatis P. Fixation of pelvic fractures 8. Gunterberg and dislocation. An experimental study on the loading of pelvic fractures and sacroiliac dislocations after external compression fixation. Acta Orthop Stand 1978: 49: 278-286 9. McBroom R. Tile M. Disruption of the pelvic ring. Presented 31 the Canadian Orthopaedic Research Society Convention. Kingston, Ontario, June 1982 10. Tile M. Fractures of the pelvis and acetabulum. Williams and Wilkins. 1984
Baltimore:
11. Mears D C. Fu F H. Modern concepts of external skeletal tivation of the pelvis. Clin Ortho 1980: 151 65- 77 I2
Mears D D External and Wilkins. 1981
skeletal fixation.
Baltrmore
Williams
13 Olerud S. Hamberg M. The anterior approach to the dlslocatcd sacroiliac joint. Reduction and fixation with a square plate In: Noble J. and Galasko C S. B. (eds!. Recent developments in orthopaedic surgery. Manchester Manchester University Press, 1987
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