Complications and solutions
1 Introduction 123
2 Malalignment—prevention and correction 123
2.1 Malrotation 123
2.2 Varus-valgus malalignment 126
2.3 AP angulation: sagittal plane malalignment 128
3 Limb-length discrepancy 130
3.1 Prevention of shortening 130
4 Neurovascular injuries 131
4.1 Humerus 131
4.2 Femur 132
4.3 Tibia 132
5 Early postoperative complications 133
5.1 Infection 133
5.2 Prevention of infection after external fixation 135
5.3 Wound complications from hardware 135
6 Late postoperative complications 136
6.1 Implant failure 136
6.2 Delayed union 138
7 Further reading 139
Introduction
Both minimally invasive plate osteosynthesis (MIPO) and conventional plating have their own distinct complications. In MIPO, the fracture site is not exposed during reduction and plate application. Therefore, malrotation, axial malalignment, and limb-length discrepancy are more common. Infection, disturbed bone healing, and hence implant failure are less frequent by virtue of the preservation of biology at the fracture site.
To reduce the problems of malrotation, axial malalignment, and limb-length discrepancy, the surgeon may find these points helpful:
Always be mindful of the possibility of these complications occurring
Be familiar with the various techniques of detecting their occurrence
Be familiar with the common pitfalls and the best ways to prevent them Despite the best efforts of the surgical team complications sometimes occur. In such cases it is essential that they are discovered and corrected early, preferably intraoperatively, or, within 2 weeks postoperatively. Correction should certainly take place before fracture union because correction becomes more difficult and complicated once malunion has occurred, especially if adaptive changes in the anatomy have taken place.
In general, the complications in MIPO may be divided into three phases:
Intraoperative: rotational and axial malalignment, limb-length discrepancy, and neurovascular injuries
Early postoperative: acute infection, wound complication
Late postoperative: implant failure, delayed union, and nonunion
Malalignment—prevention and correction
Malrotation
This complication commonly occurs in MIPO but is often overlooked as it is not always obvious on plain x-rays. Gross malrotation can be recognized clinically but lesser degrees are more difficult to detect. Therefore, it is important to be familiar with the various techniques of evaluating rotational deformities and the steps necessary to prevent their occurrence.
Femur
In the femur, malrotation occurs most commonly with proximal femoral and subtrochanteric fractures. The deforming forces of the iliopsoas, gluteus medius, and short external rotators pull the proximal fragment into flexion, abduction, and external rotation, respectively. Performing fracture reduction and fixation without understanding these deforming forces will lead to malreduction, including malrotation (see Fig 9-5 ).
There are several intraoperative techniques of assessing whether a proximal femoral fracture is fixed in the correct rotational alignment. These may be by clinical assessment or radiological imaging:
Hip rotation test ( Fig 9-1 )
Lesser trochanter shape sign ( Fig 9-2 )
Cortical step sign ( Fig 9-3 )
Diameter difference sign ( Fig 9-4 )
The hip rotation test is a clinical method that compares internal and external hip rotation with that of the contralateral unaffected side. This technique is easily performed and it is radiation independent. However, clinical judgment may be inaccurate, and the test is also dependent on the position of the pelvis, which may change during the course of the operative procedure. Putting a bump or sandbag under the buttock will make evaluation of the hip rotation incorrect. In case there is a need to elevate the buttock to facilitate surgery, it is recommended to place a bump under the sacrum.
The hip rotation test cannot be used if the patient has a bilateral femoral fracture or is on a traction table. In such cases, radiological methods of assessing rotation will have to be used. These include the lesser trochanter shape, cortical step, and diameter difference signs ( Fig 9-2 , Fig 9-3 , Fig 9-4 ).
For multifragmentary fractures of the proximal femur with an intact lesser trochanter, the lesser trochanter shape sign is most useful. When the lesser trochanter is fractured, the rotation should be assessed by clinical means.
In simple transverse or oblique fractures, the correct rotation may be judged by the thickness of the cortices of the proximal and distal fragments (cortical step sign). The cortical step sign and the diameter difference sign cannot be used in multifragmentary fractures, as the area of comminution makes comparison of the cortical step and diameter impossible.
In the midshaft and distal femur, the deforming forces from muscle pull are less, and malrotation is therefore less common. However, the rotation after fixation still has to be checked intraoperatively, both clinically and radiographically.
Prevention of femoral malrotation (Fig 9-5)
It is advisable to use a radiolucent operating table rather than a traction table. Although the traction table maintains limb length, the rotation cannot be assessed clinically during the operation. If a traction table is used, the lesser trochanter shape sign must be used for comparison with the uninjured limb.
If a radiolucent operating table is used, a sandbag or bump must not be placed under the buttock. Rotation is checked after preliminary fixation of both proximal and distal fragments by flexing the hip and knee to 90° (hip rotation test).
Both lower limbs are draped free, if possible, to compare the rotation and to measure the length.
Early revision or correction of any malrotational deformity is essential. Early revision is much easier than correcting a malunited fracture as it is less time consuming. In addition, the patient can return early to normal function.
Tibia
Malrotation of the tibia is easier to assess than malrotation of the femur because there is less soft-tissue coverage and the anteromedial surface of the tibia is easily palpated. Tibial rotation can be determined both clinically and radiographically by comparison with the uninjured limb.
Clinical assessment of tibial rotation is performed on the uninjured side by placing the patient in supine position with the knee flexed at about 45° and the patella in neutral position. The rotation of the tibia of the uninjured side is recorded as a reference by checking the degree of external rotation of the foot. This is used as the reference to compare after fixing the injured side.
Rotational malalignment of the tibia occurs most commonly after MIPO of distal tibial fractures due to the peculiar anatomy of that part of the bone. The distal tibia is flared medially and the smooth anteromedial surface to which the plate is applied twists posteriorly to end at the medial malleolus. This flare and twist must be considered when the plate is contoured, or it will result in malrotation and axial malalignment.
Prevention of tibial malrotation
Precise plate contouring is necessary for MIPO of proximal and distal tibial fractures when using the dynamic compression plate (DCP) or limited-contact dynamic compression plate.
Preliminary reduction of the fracture is essential, if possible before preparing the tunnel. This is especially important on the medial side of the tibia where the soft tissues are tight. If the tunnel is prepared improperly, it will cause malpositioning when the plate is inserted. Slightly oversizing the tunnel may be helpful to adjust the plate position.
The precontoured plate must be placed in the correct position.
Rotation of the tibia must be checked clinically by flexion of the hip and the knee to 90° while keeping the ankle dorsiflexed.
Varus-valgus malalignment
Frontal plane malalignment occurs most commonly in metaphyseal fractures. This is because the metaphyseal cortex is not straight as in the diaphysis. The plate therefore needs to be precisely precontoured or a precontoured anatomical plate may be used. For example, when the 95° condylar plate is used for fixation of proximal or distal femoral fractures, and the blade is inserted in the correct position, indirect reduction of the shaft to the plate will usually provide correct frontal plane alignment. This can also be seen with the distal femoral locking compression plate (LCP).
When a distal femoral fracture is fixed with a distal femoral LCP or less invasive stabilization system (LISS) that has more than 11 holes, valgus malalignment may occur from an anatomical mismatch. This happens when the proximal part of the plate, particularly above the seventh hole, is forced to fit the plate to the shaft. This problem most often occurs in Asians ( Fig 9-6 ) (see also chapter 18 Femur, distal).
The cable technique is an intraoperative technique for checking frontal plane malalignment of the lower extremity. Under image intensification, a cautery cable is placed between the center of the femoral head and the center of the tibial plafond. The cable should pass slightly medial over the center of the knee joint indicating the correct mechanical axis in the frontal plane. This is a reliable method for checking frontal plane malalignment, however, it does expose the patient and operating room personnel to radiation ( Fig 9-7 ).
A variation of the cable technique places the cautery cable from the anterior superior iliac spine to the first web space of the ipsilateral foot. If the frontal plane alignment is correct, the cable should pass through slightly medial to the center of the patella ( Fig 9-8 ). This technique is easier but less precise and many errors can occur depending on the foot rotation, ankle position, and position of the hip in abduction or adduction.
Femur
Varus malalignment can occur during plate insertion when MIPO is applied to fix a proximal femoral fracture using a 95° condylar plate. The channel for the blade of the blade plate is first prepared using a seating chisel inserted via a standard technique. The 95° condylar plate is then slipped into a submuscular tunnel alongside the lateral cortex of the femur with the blade pointing laterally. The blade is then turned medially for insertion into the prepared canal. However, the direction of the blade and the prepared channel frequently do not align. The blade has a tendency to go in the wrong direction and create a false passage, resulting in the proximal fragment being fixed in a varus position. The reason for this is that the lateral thigh muscles tend to push the blade plate into a varus position. This complication can be avoided by inserting a joystick into the proximal fragment to bring it into proper alignment with the blade during blade insertion (see chapter 16.1 Femur, proximal, Fig 16.1-8 ). Also, the guide wire used initially to guide the direction of the seating chisel should be left in place to guide the direction of blade insertion. Another useful tip is to allow the distal part of the plate to come out from the distal incision while introducing the blade into the prepared channel.
Tibia
Varus or valgus malalignment of the tibia can be evaluated by using a tibial alignment grid which has multiple parallel K-wires 3–5 cm apart mounted between two plastic plates. The grid is placed beneath the tibia extending from the knee to the ankle. An AP view of the knee is taken with the image intensifier, with a K-wire parallel to the knee joint. The C-arm is then moved distally to take an AP view of the ankle joint. If the K-wire beneath the ankle joint is also parallel to the ankle joint line, there is no varus or valgus malalignment of the tibia. The unilateral external fixator with the two Schanz screws constructed in parallel frame can also be applied using the same principle.
Varus deformity of the proximal tibia can occur in comminuted or bicondylar fractures. To prevent deformity in this situation, bilateral support of both columns is recommended through a single lateral locking plate or application of conventional buttress plates on both columns.
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