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Technique using inflatable balloon aids reduction of depressed tibial plateau fractures
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The gold standard technique for reduction of a depressed fracture relies on the use of a cortical window and elevation of the articular fragment with a bone tamp, but more modern, less invasive options are available that use balloon inflation-plasty. Long- or mid-term results are not yet published about the technique, but prospective trials collecting data on the quality of reduction are being performed.
The cost of this innovative technique is higher than other approaches and therefore, until its ability to achieve a better reduction is proven, the procedure should be used with caution. The key to a successful outcome with balloon inflation-plasty is to choose the correct fracture and to accept the steep learning curve associated with the technique.
In this article, we present our surgical technique that involves the use of an inflatable balloon as a tool to reduce depressed tibial plateau fractures. The technique is assisted with arthroscopy and carried out using percutaneous fixation.
Indications, technique limitations
The success of this technique rests with having a good understanding of its limitations. In fact, a number of depressed tibial plateau fractures are not amenable to its use. The ideal fracture is one with a large depressed fragment that is centrally located. More peripheral depressed fragments can be elevated using the balloon, but one has to ensure there is an intact peripheral bony rim around the depressed articular surface. In fact, when a sleeve of cortical bone is also detached, the balloon inflates towards the path of least resistance and displaces the cortical wall further instead of inflating it upwards and achieving reduction of the articular segment.
When the cortex has been breached medially or laterally, a large periarticular clamp can be placed to provide resistance during the inflation phase. When the cortex is breached posterolaterally or posteriorly, this approach is more difficult and more traditional methods of fracture reduction are recommended.
Another important recommendation is to apply this technique in fractures that occurred within the last 2 weeks. An intervention performed more than 2 weeks after the fracture occurred may fail due to inability of the balloon to elevate the depressed fragment. In such situations, a harder metallic bone tamp might be a better option.
Surgical planning is crucial. It is important to understand the fracture configuration based on its CT scan appearance to identify the point of depression and its position in the three planes (coronal, sagittal and axial) (Figure 1). The instruments used include a cannula, a hand drill and the balloon placed at the end of a thin introducer.
CT images of a lateral tibial plateau fracture show it in a coronal cut (a), in a sagittal cut (b) and in the axial cut (c).
Images: Mauffrey C
The cannula should be placed parallel to the joint just beneath the most depressed portion of the articular fragment, coming from the opposite side of the joint. Whether the cannula needs to be angled more anteriorly or posteriorly depends on the location of the depressed fragment in the sagittal plane. If a cortical split is seen on the coronal CT images, then it is advisable to have a large periarticular clamp available during the inflation phase. More traditional instruments also should be available in case the use of balloon inflation-plasty fails.
The patient is consented, marked, anesthetized and placed on a radiolucent operating table in a supine position. Antibiotics are given at induction of anesthesia, and a tourniquet is placed on the thigh. The lower extremity is prepped and draped accordingly.
Introducer, rafting wires
The skin is marked around the knee to identify the joint line, and a line is made to identify the most depressed part of the fragment and the tibial tubercle as landmarks. Based on preoperative planning, if there is a lateral depression, a stab incision is made on the medial side that corresponds to the level of the lowest area of depression. A sharp introducer is then used to breach the proximal cortex, and it is advanced for 1 cm. The cannula is then inserted parallel to the joint line and aimed at the point of the most distal depression in both the sagittal and coronal planes. The hand drill is used through the cannula to advance it to its required position. Under fluoroscopy, confirm that the cannula is placed is an adequate position (Figures 2a and 2b).
The next step involves placement of rafting wires, a concept that is especially useful in patients with osteoporotic bones. These wires, which are placed beneath the cannula in an anterior to posterior direction, create a solid floor for the balloon to rest upon during the inflation phase. One might imagine that without the wires, and in a patient with low bone mineral density, the balloon would follow the path of least resistance, distally, and thus fail to elevate and reduce the articular segment.
The cannula is beneath the depressed fragment in both the coronal plane (a) and sagittal plane (b). In this image (c), the rafting wires shown have been positioned.
We use three 2-mm Kirshner wires placed from anterior to posterior just beneath the cannula. This is done under fluoroscopic control (Figure 2c). The balloon is then inserted through the cannula, and the cannula is then withdrawn a few millimeters to ensure that the two radiological markers identifying the proximal and distal end of the inflation device are positioned just proud of the cannula, but also beneath the fragment that will be elevated.
Arthroscopy optional
The use of the arthroscope is not essential, but there have been a number of occasions when the fluoroscopic images were adequate, but the arthroscopic picture revealed a step-off that could be improved. Therefore, we prefer to assist our reduction technique with the use of direct visualization. The duration of the arthroscopic portion of the procedure has to be kept as short as possible to prevent compartment syndrome from fluid extravasation, hence the preparation of cannulas and the balloon before the introduction of the camera is encouraged. The fluids used are not pressurized, and therefore, gravity is used.
Patience is critical, and the first few minutes are spent washing out the knee joint. A shaver then can be introduced to break up clots and fibrous tissue within the knee. The menisci, ACL and joint surfaces are also assessed for the presence of any associated injuries that can be addressed and this is documented.
Once the depressed area is identified — which is often sub-meniscal — the balloon can be inflated (Figure 3). It may be challenging to perform these steps at the same time as a knee arthroscopy in the lateral compartment, requiring a figure of four, and to take fluoroscopic images to visualize balloon inflation. We have found that a partial figure of four of the lower extremity creates enough varus stress to visualize the lateral compartment, while at the same time make it possible to obtain an anteroposterior fluoroscopic image.
Fluoroscopy can be challenging to perform when used in conjunction with the arthroscope, the rafting wires and balloon instruments, but a good lateral view is obtainable. The joint line depressed prior to balloon inflation (a) and, following inflation, a well-reduced articular surface is noted (b).
For this part of the surgery, at least one — and ideally two — assistants are required. The balloon is inflated. The device that we use (Inflate Fx, Medtronic) includes a monitor to check the volume and pressure within the balloon, which should be kept below 4 mL and 400 psi, respectively. A fluoroscopic image should be checked during inflation to ensure the balloon is inflating in the desired direction.
Second balloon
A second balloon is often required if the amount of depression of the articular fragment is beyond the reach of the volume of one balloon or if the balloon ruptures during the inflation phase. If this occurs, then the process of cannula, drill and balloon insertion is repeated about 1 cm proximal to the site of insertion of the first device (Figure 4a).
Once the articular fragment is reduced, the balloon is deflated partially, leaving room proximally for two 1.6-mm Kirschner wires to be inserted from medial to lateral in the subchondral space supporting the restored articular fragment (Figure 4b). The balloon is then deflated and removed. A bone graft substitute, such as calcium phosphate, is then inserted through the cannula to fill the void left by the balloon and provide mechanical support to the joint surface. Once this hardens, either screws or a plate and screws can be used for permanent fixation of the tibial plateau.
AP fluoroscopic images of the reduced articular surface are shown (a), as well as insertion of wires to temporarily stabilize the fragment (b).
To end the procedure, the wound is irrigated, final fluoroscopy images are taken and the skin is closed. Following dressings application, the patient is placed in a knee immobilizer.
Use of deep vein thrombosis prophylaxis will depend on institutional policies. Patients should remain strictly non-weight bearing until the fracture is healed radiologically. At 2 weeks, we perform a wound check and remove the sutures. At that time, patients are placed in a hinged knee brace and encouraged to range their knee motion from full extension to 90°.
Patients are reviewed at 6 weeks postoperatively. The brace is usually removed at that time, and they are referred to physical therapy for motion and strengthening exercises.
The use of a balloon inflated with a radio-opaque dye as a tool to reduce depressed tibial plateau fractures is becoming more popular. Clinical results are yet to be demonstrated to help justify the cost of the device, but laboratory work on cadavers showed the quality of reduction was improved when compared to more traditional methods. Understanding the limitations of this technique is critical, and good preoperative templating is necessary to ensure adequate positioning of the device at the outset of the procedure. The simultaneous use of arthroscopy to visualize the reduction can be useful. More work is required to better understand which fracture configurations are most amenable to this technique and whether fixation with screws alone is sufficient enough to hold the reduced articular fragment in place until bone healing occurs.
References:
Broome B. J Orthop Traumatol. 2012;doi: 10.1007/s10195-012-0185-z.
Giannoudis PV. Articular step-off and risk of post-traumatic osteoarthritis. Evidence today. Injury. 2010;4(10):986-995.
Heiney JP. Balloon reduction and minimally invasive fixation (BRAMIF) for extremity fractures with the application of fast setting calcium phosphate. J Orthopaedics. 2010;7(2):e8.
Mauffrey C. Patient Saf Surg. 2012;doi: 10.1186/1754-9493-6-6.
For more information:
Robert Jordan, MD, FRCS, can be reached at robert.jordan@doctors.org.uk.
Cyril Mauffrey, MD, FRCS, is assistant professor of orthopedics and director of Orthopedic Research at Denver Health Medical Center, Denver, Colo. He can be reached at email: cmauffrey@yahoo.com.
Michael Messina, MD, can be reached at michael.messina@ucdenver.edu.
Disclosure: Jordan, Mauffrey and Messina have no relevant financial disclosures.