Fixed Angle Devices

Steven Papp, M.D., FRCSC
Ottawa, ON

Supracondylar femur fractures remain a challenge for the orthopaedic surgeon. Most fractures occur as a result of a high-energy accident in young patients or in elderly patients with poor bone quality. Because of these challenges, several treatment options have evolved over time.

First, patient factors and other injuries must be considered. Second, the fracture "personality" (as Dr. Schatzker has taught many) must be examined. Metaphyseal comminution, fracture displacement and articular involvement must be carefully examined in planning the operative procedure. For example, the involvement of a "Hoffa" fragment (an associated coronal fracture of the posterior condyle - lateral being more common) makes the articular reconstruction more complex and it is better handled if known about preoperatively. In one recent study, 38% of all intra-articular distal femur fractures had a Hoffa fracture1. If any concern exists for intra-articular involvement, a CT Scan should be obtained. Preoperative planning is a very important factor in achieving surgical goals.

Once the surgical plan is in place, one hopes there will be fewer intra-operative surprises. The first step entails anatomic reduction of the articular surface. One of the more important goals of surgery is to obtain appropriate axial alignment in the AP and lateral planes while minimizing soft tissue dissection at the meta-diaphyseal junction. Vascular studies have shown that percutaneous plate insertion disrupts the blood supply less than traditional open plating2. Clinical studies using indirect reduction techniques have demonstrated lower complication rates3. For surgeons not used to percutaneous techniques, an open lateral approach is acceptable but understanding and respecting the biology of fracture healing and avoiding excessive stripping are essential.

The debate on the appropriate fixation for these fractures also remains an important consideration. For fractures with comminution and loss of medial support, a fixed angle device remains a solid choice of implant. The Angled Blade Plate (ABP) and the Dynamic Condylar Screw (DCS) have the longest history and remain good implants for this fracture. In fact, recent publications continue to support their use4. The ABP is an excellent choice but insertion of the blade must be correctly done in three planes. The DCS offers a little more "forgiveness" in insertion and the plate/screw construct comes in two pieces for easier insertion but the screw does take up a large volume of bone in the distal femoral condyles. The entire technique for insertion is beyond the scope of this text but insertion of both of these implants must be precise. For example, the insertion of the central hole of either the blade or DCS must be made in the anterior half of the distal femoral condyles at two cm above the level of the joint line (Figure 1). The guide wire should be inserted parallel to the joint surface in the AP plane. The direction of insertion of the guide pin in the lateral plane is also very important. The correct insertion is perpendicular to the surface of the anterior femur. Insertion parallel to a pin inserted along the patellofemoral joint (as originally described in the AO manual) will lead to rotational deformity (Figure 2). When done correctly, these implants have shown reliable results. The use of locking plates has exploded recently; in particular for these difficult supracondylar fractures. The argument for locked plate technology comes from the ability to use multiple locked screws and thereby obtain multiple points of fixation.

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Figure 1a
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Figure 1b

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1a,b - Preop and postop X-rays of an elderly female with a comminuted femur fracture treated by insertion of a dynamic condylar screw. Courtesy of G. Johnson.

The C3 supracondylar fracture pattern with multiple articular pieces is particularly difficult to handle. But if the articular fractures are fixed under compression with small fragmentary screws first, the C3 fracture pattern is converted into a more simple supracondylar fracture and standard fixed angle devices can be used in most instances.

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Figure 2a
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Figure 2b

 

 

 

 

 

 

 

 

 

 

Figure 2 a,b - Insertion of guide pin according to traditional technique can lead to an external rotation deformity.

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Figure 2c
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Figure 2d

 

 

 

 

 

 

 

 

 

 

 

Figure 2c,d - Insertion of guide pin must be precise in AP and lateral planes in order to get appropriate axial alignment with insertion of fixed angle device. With permission - Karunakar M.A., Kellam M.F. Avoiding Malunion With a 95 Fixed-Angle Distal Femoral Implants. J Orthop Trauma 2004; 18: 444.

Recent review by the Evidence-Based Study Group in the Journal of Orthopaedic Trauma looked at distal femur fractures and compared the older fixed angle devices to newer locking plates. There was a trend toward higher rates of fixation failure and higher re-operation rates in the group treated with a newer locked plate5. Duffy et al has shown the DCS to be superior to the LISS plate in biomechanical testing6. Admittedly, I find I am using locked plates more routinely for these fracture patterns. The companies manufacturing these plates have put much more time and engineering into these newer devices and they are constantly evolving and improving. In particular, the reduction clamps and other instruments that come "on the set" with these newer devices make the procedure easier. The older fixed angle devices have not had the benefit of constantly improving instrumentation.

The current standard of care for treatment of displaced supracondylar femur fractures involves open reduction and internal fixation. Indirect reduction techniques (rather than soft tissue stripping and direct reduction) decreases complication rates and should be learned if dealing with these fractures. Obtaining proper axial alignment and stable fixation is important and in most cases, this can be achieved with a standard fixed angle device like the dynamic condylar screw or blade plate. The equipment associated with new locked plates is making their application easier and therefore they have become a popular choice to deal with these fractures.

References

  1. Nork S.E., Segina D.N., Aflatoon K., Barei D.P., Henley B.M., Holt S., Benirschke S.K. The Association Between Supracondylar-Intercondylar Distal Femur Fractures and Coronal Plane Fractures. J Bone Joint Surg 2005; 87A: 564-569.
  2. Farouk O., Krettek C., Miclau T., Schandelmaier P., Guy P., Tscherne H. Minimally Invasive Plate Osteosynthesis: Does Percutaneous Plating Disrupt Femoral Blood Supply Less Than The Traditional Technique? J Orthop Trauma 1999; 13(6): 401-406.
  3. Bolhofner B.R., Carmen B., Clifford P. The Results of Open Reduction and Internal Fixation of Distal Femur Fractures Using Biologic (Indirect) Reduction Technique. J Orthop Trauma 1996; 10(6): 372-377.
  4. Huang H.T., Huang P.J., Su J.Y., Lin S.Y. Indirect Reduction and Bridge Plating of Supracondylar Fractures of the Femur. Injury 2003; 34: 135-140.
  5. Zlowodzki M., Bhandari M., Marek D., Cole P.A, Kregor P.H. Operative Treatment of Acute Distal Femur Fractures: Systemic Review of 2 Comparative Studies and 45 Series (1989 to 2005). J Orthop Trauma 2006; 20(5): 366-371.
  6. Duffy P., Trask K., Hennigar A., Barron L., Leighton R.K., Dunbar M.J. Assessment of Fragment Micromotion in Distal Femur Fracture Fixation with RSA. Clin Orthop Rel Res 2006; 448: 105-113.

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