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INTRA - OPERATIVE CONTROL WITH EXTERNAL FIXATION FOR SUPRACONDYLAR FRACTURE OF FEMUR

Author: Dr. Lee Pei-Yuan
Co - authors: Dr. Ta-Feng Ho, Dr. Ming-Chou Ku.
Country: Taiwan
E-mail: b1208b@ms26.hinet.net

Department of Orthopaedic Surgery, Show Chwan Memorial Hospital , Changhua , Taiwan

Abstract The value of minimally invasive percutaneous (plate) osteosynthesis (MIPO) is well accepted due to its biological benefits. The application in supracondylar fracture of femur shows the advantages of this technique -decreased infection rate and bone grafting, and increased union rate. But the possibility of malreduction is considered. External fixation is temporarily used before definite operation or applied during operation as reduction device. After proper assembling, the external fixation could be used to control, correct and fix the axis or length of femur intra-operatively. This technique is helpful to achieve the reduction and maintain the position of reduction during MIPO procedures. It may avoid the problems that occurs as operator could not handle the fracture via direct exposure.Introduction Indirect reduction and fixation technique with minimally invasive approach have been developed to limit the soft tissue dissection at the fracture site. It focuses on the biological benefits for fracture healing and follows the way of indirect union by callus formation. Although anatomical reduction for the articular surface is still the gold standard, these new techniques don't rely upon anatomical reduction of the fracture fragments. MIPO for distal femur, introduced by Krettek (1, 2), is technique demanded. How to treat the fracture in proper position without direct exposure of the fracture is difficult even for experienced surgeon . The first important step is to achieve the reduction indirectly or percutaneously. Another critical step is to keep the reduction during fixation. Mast, Jakob and Ganz pioneered the indirect reduction technique. (3) Manual traction, distraction devices and tension devices combined with the aids of Schanz screw, Kirschner wire, external fixation and recent pre-contoured anatomical implants had ever been introduced. It becomes more important and essential during the minimally invasive operation. However, these techniques have the disadvantages of not allowing for open alignment. Dealing with the supracondylar fracture of femur, biological approach ensures the preservation of healing potential of fracture. But the restoration of anatomical alignment is equally important to achieve maximal functional outcome. Once the operators become familiar with the MIPO approach, they should pay more attention to overcome the hazard of malalignment. Some intra-operative examinations and radiographic techniques have been introduced.(4) These include: the 'cable technique' for frontal plane, 'Blumensaat's line' and 'Recurvatum sign' for sagittal plane, 'Lesser trochanter shape sign' and 'Hip rotation test' for coronal plane, and 'Meterstick technique' for leg length discrepancy. Conventional external fixation has been used temporally, but it needs to achieve reduction first. The modular technique expands the application of external fixation as reduction tool, but it is hard to control the three dimensional relationship and hold the relatively small distal condylar block during fixation. Therefore, we develop new frame of external fixation for supracondylar fracture of femur to resolve the problems from the initial reduction, through correction to the final fixation stage.Material s and Methods An intact distal block is the basic requirement for this kind of reduction method, therefore, non- articular A.O./O.T.A. 33 A1-A3 is the fracture of choice. For some complete articular A.O./O.T.A. 33 C1 or C2, after anatomical restoration of articular surface and union by interfragmentary fixation, are also indicative. AO external fixation system is selected. We use 4 Schanz screws, 4 clamp bodies, 2 carbon rods and one adjustable clamp to set up the frame. (Fig.1) Two Schanz screws are inserted anteriorly along the femur shaft. Another two Schanz screws are put into the medial and lateral condyles of femur respectively. One long carbon rod is adapted to the upper two screws with clamp bodies and another shorter rod to the lower two screws. These two rods are connected together by adjustable clamp and used as reduction handles.

During the initial stage of reduction, manual traction, femur distracter or traction by fracture table will be helpful. Many adjuvant indirect reduction techniques could be used to approximate or adjust the position of main fragments. Once the external fixator is applied, with the aid of X-ray intensifier and some measurement and comparative methods mentioned above, three axial planes and leg length could be determined. Holding the rods, the frontal plane is controlled by varus-valgus deviation. (Fig.2) and the coronal plane by external-internal rotation. (Fig.3) The sagittal plane, concerning the antecurvatum and recurvatum, is difficult to deal with even during conventional open approach due to the pulling force of lower leg. If we pull the short rod back, not only the sagittal plane but also the length could be controlled.

Discussion It is challenging to deal with the supracondylar fracture of femur. Conventional open approach is easy to reduce the fracture and fix it, but the problems of malunion, nonunion, need for bone grafting and infection persist. Since the last decade, the minimally invasive surgery became the main trend of osteosynthesis. It emphasizes on maintenance of the soft tissue envelop around the fracture, therefore improves the efficacy in bone healing and decreases infection. The MIPO techniques include indirect reduction, separated incisions, submuscular plating and bridging fixation with percutaneous screwing. The biological benefits of MIPO for supracondylar of femur is widely accepted, nevertheless the length and alignment are difficult to determine due to lack of direct visualization of fracture site. Facing the supracondylar fracture of femur, three axial planes ( frontal plane - varus and valgus, sagittal plane - antecurvatum and recurvatum, coronal plane - external and internal rotation ) and leg length discrepancy should be considered as equal important as biological approach concept. Many table techniques have ever been introduced to achieve the reduction, like joy-stick maneuver, modular technique of external fixation or reduction with anatomical implants. Manual traction, femur distracter, fracture table, multiple Kirschner wire and simple frame of external fixation help to maintain the reduction. Several measurement methods have also been developed to check the relationship between femur shaft and distal condylar block with the x-ray intensifier. But these tools are hard to control the fracture at a glance three dimensionally without interference for the further fixation procedures. The purpose of the anatomical restoration of alignment is to achieve maximal functional recovery. Using the new frame of external fixation we introduce, indirect reduction becomes easier. The opposite main fragments, shaft and condyle, could be handled and manipulated by holding the rods. Correction of axis between three planes could be achieved and the frame is fixed by modular method. The temporary external fixator is stable enough during the ongoing MIPO steps.References

1. Krettek C, Schandelmaier P, Miclau T and Tscherne H. Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury 1997;28 Suppl 1:A20-30 Krettek C, Schandelmaier P, Miclau T, Bertram R, Holmes W and Tscherne H. Transarticular joint Reconstruction and indirect plate osteosynthesis for complex distal supracondylar femoral fractures. Injury 1997;28 Suppl 1:A31-41 Mast J, Jakob R, Ganz R. Planning and reduction technique in fracture surgery. Berlin Heidelberg New York : Springer, 1989
2. Krettek C, Miclau T, Grun O, Schandelmaier P, Tscherne H. Intraoperative control of axes, rotation and length in femoral and tibia fractures. Injury 1998;29 Suppl 3: C29-39