Open Reduction and Internal Fixation of Distal Femoral Fractures in Children

Updated: Sep 12, 2013
  • Author: Jeffrey D Thomson, MD; Chief Editor: Dinesh Patel, MD, FACS  more...
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Overview

Overview

Background

Open reduction and internal fixation (ORIF) is a commonly used treatment for fractures throughout the body, including the distal femur. [1] Supracondylar nonphyseal femur fractures are rare in the pediatric population. Although the exact definition of the supracondylar region of the femur is unclear in the pediatric patient, it is often determined by measuring the width of the distal femoral physis, then using that distance to measure proximal to the physis to create a square. This region has been dubbed the supracondylar region of the femur. [6, 7]

Various studies have described the incidence of distal femur fractures to be from 7-12%. [2, 3] These injuries are usually the result of direct trauma to the thigh or knee. It is very important to assess for other associated injuries when presented with a supracondylar femur fracture. Often, patients who sustain these injuries may have pathologic bone from diseases such as osteogenesis imperfect or presence of neuromuscular disease. Also, of utmost importance, with a supracondylar femur fracture in a child less than 1 year of age, the physician should be suspicious of child abuse.

Indications

Indications for treatment include an open fracture, a fracture associated with neurovascular compromise, all displaced fractures, ipsilateral lower extremity fractures, irreducible fractures, and pathologic fractures. Careful examination of a distal pulse is important in supracondylar femur fractures because the fracture may injure the nearby superficial femoral artery.

Treatment of supracondylar femur fractures depends on fracture displacement. Nondisplaced fractures may be treated in a long leg cast, whereas most displaced fractures require operative intervention for fracture reduction.

Contraindications

Patients who are hemodynamically unstable and polytrauma patients may benefit from provisional stabilization of the fracture instead of open reduction and internal fixation. Infections and medical conditions that could pose a life-threatening surgical or anesthetic risk are also contraindications.

Technical Considerations

Best Practices

In preparing for surgical treatment of a supracondylar femur fracture, it is essential to have the necessary tools and equipment in place. It is also essential to have a preoperative template in hand as to what the step-by-step approach to the case will be.

Procedure Planning

For polytrauma patients in whom ORIF is precluded, external fixators may be used to maintain overall length and alignment of the limb.

Solid intramedullary nails may be reamed or unreamed. They are ideally suited for children who are older than 12 years of age because their intramedullary canal is close to adult proportions. Intramedullary nails are load-sharing devices that may be locked proximally and distally to control rotation of the femur.

Flexible intramedullary nails are typically used in children between 6 and 12 years of age. They can be used in children who are too large for a spica cast and too immature for a solid intramedullary nail. Advantages of flexible intramedullary nails include sparing the growth plate proximally or distally, as well as avoiding the blood supply to the femoral head.

K-wires and Steinmann pins may also be used to stabilize supracondylar femur fractures in children who are 6-10 years of age or who weigh less than approximately 50 kg. This method of fixation is not as strong as a nail or plate construct. However, it is feasible for low supracondylar fractures close to the physis, where other forms of fixation such as nails would be difficult. The drawback of using K-wire fixation is that a long-leg cylinder cast is necessary to protect the construct and to aid in fracture healing.

Plate fixation of supracondylar femur fractures may require open reduction and internal fixation or can be done through percutaneous techniques. The plate construct is a stress shielding construct. The implant will eventually need to be removed in growing children. This method of fixation is one of the most common methods employed for supracondylar femur fractures in children.

In general, due to the limited options of surgical fixation of pediatric supracondylar femur fractures, external fixation may be a viable option. A lateral frame or Ilizarov frame may be used. This technique allows the maintenance of overall length and alignment of the limb, but it is cumbersome for patients and is associated with complications such as, pin tract infections.

Complication Prevention

Complications specific to children include malunion and injury to the distal femoral physis, potentially leading to growth arrest and further limb-length discrepancy.

Thromboembolic complications and wound complications are less likely in children.

Complications of solid intramedullary nails include avascular necrosis of the femoral head and greater trochanter physeal injury. It is imperative to determine how much bone is present in the distal fragment of supracondylar femur fractures. Based on anecdotal evidence, if there is insufficient bone present for a distal interlocking screw, then a solid intramedullary nail is not possible. Other feasible options at this time include flexible intramedullary nails or ORIF with a plate. The ideal length of bone needed in the distal fragment of supracondylar femur fractures is unknown at this time.

Complications of flexible intramedullary nails include growth arrest and intraarticular pin placement.

Similar to flexible intramedullary nails crossing the physis, there is always a risk of physeal damage and growth arrest with K-wires and Steinmann pins.

With plate fixation, plate removal is essential after the fracture has healed in a growing child. A greater exposure is necessary with plate fixation and patients need to not bear weight after surgery, as opposed to the solid intramedullary nail, with which weight bearing is permitted if a stable fracture construct is achieved.

Also, the plates should not cross the growth plate unless required. If so, early plate removal is necessary.

Complications of any external fixation device include pin tract infection, loss of reduction, and misalignment of the limb.

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Periprocedural Care

Equipment

Depending on the quality of bone, the surgeon’s experience, and the patient’s clinical scenario, the necessary equipment for fixation for supracondylar femur fractures includes the following:

  • Solid intramedullary nails
  • Flexible intramedullary nails
  • K-wires
  • Steinmann pins

This equipment is discussed further in Technical Considerations.

Patient Preparation

Anesthesia

General anesthesia is used for complete muscle relaxation to facilitate anatomic fracture reduction.

Positioning

Patient is positioned supine on a flat top radiolucent table to allow C-arm imaging. An ipsilateral bump is placed underneath the hip to allow some internal rotation to gain lateral exposure to the distal femur. This positioning is suitable for plating, crossed K-wires or external fixation procedures of the distal femur.

For cases involving flexible or solid intramedullary nails, a fracture table can be used.

Monitoring & Follow-up

Radiographs at regular intervals are necessary to assess fracture healing. Patients may be seen initially at 2 weeks postoperatively followed by monthly intervals until fracture is healed.

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Technique

Solid Intramedullary Nails – Trochanteric Entry Nails

The patient is placed supine on a fracture table. With radiographic imaging, appropriate reduction of the fracture is obtained. A longitudinal skin incision is made 2-3 cm proximal to the greater trochanter to allow easy passage of the nail in the femur. A guide wire is used to get the accurate starting point. The ideal starting point is at the tip of the middle third of the greater trochanter. Care must be taken to avoid the piriformis fossa as this may lead to avascular necrosis.

Once the starting point is confirmed on lateral and anteroposterior views of the hip, reaming of the proximal femur may begin. The femur should be reamed to a diameter 1.5 mm greater than the diameter of the nail.

With the fracture reduced, a long beaded guide wire is passed along the femur, while ensuring that the guide wire passes to the distal fragment confirmed by radiography on all views. The nail may then be passed over the guide wire. Interlocking screws are placed proximally and distally in the nail to control rotation of the femur.

Complications of solid intramedullary nails include avascular necrosis of the femoral head and greater trochanter physeal injury. It is imperative to determine how much bone is present in the distal fragment of supracondylar femur fractures. Based on anecdotal evidence, if there is insufficient bone present for a distal interlocking screw, then a solid intramedullary nail is not possible. Other feasible options at this time include flexible intramedullary nails or ORIF with a plate. The ideal length of bone needed in the distal fragment of supracondylar femur fractures is unknown at this time.

Flexible Intramedullary Nails

Transverse fracture patterns are best suited for this technique; segmental and comminuted fractures are not. Ideally the nails should be close together and provide a snug fit in the femur medullary canal.

The patient is placed supine on a radiolucent table. The standard technique for flexible intramedullary nails for midshaft femur fractures is the retrograde technique, in which the nails should enter the bone approximately 2.5 cm proximal to the distal femoral physis. However, for supracondyla fractures, the nails are entered from proximal to distal for a more stable construct. [4]

A longitudinal incision is made at the lateral subtrochanteric area. The surface of bone distal to the greater trochanter is exposed. An appropriately sized drill (eg, a 4.5-mm drill for 4.0-mm nails) is used to broach the cortex of the femur. The drill should be angled obliquely within the medullary canal, aiming distally to create a sharply angled track for the nail to follow.

The nails are then bent with a gentle contour to allow easy passage. Both nails are tapped up to the fracture site. Once the fracture is reduced, the nails are tapped proximal to distal so that the distal tips of the nails cross the physis, ensuring one enters each femoral condyle but is few millimeters away from the articular surface. [4] Crossing the physis with two small diameter nails should not damage the physis. However, care must be taken not to have repeated attempts at tapping the nails into the epiphysis because this may cause physeal damage.

K-Wire/Steinmann Pin Fixation

The patient is positioned supine on a radiolucent table. The fracture is localized with the aid of radiographic imaging. Small percutaneous incisions are made on the medial and lateral aspect of the distal femur.

With the fracture reduced, the K-wires are then driven through the fracture site from proximal to distal into the femoral condyles. Be careful to have few attempts in driving the K-wires across the physis to prevent physeal damage.

K-wires should be crossed, with the medial wire extending to the lateral femoral condyle and lateral wire extending into medial femoral condyle. A long-leg cylinder cast is then applied with the knee in approximately 30 degrees of flexion. However, note that a long-leg cast can act as a lever arm and displace the fracture. A long-leg cast needs to go as high as possible up on the thigh and the foot section (if used) should be light.

Plate Fixation

Plate fixation of supracondylar femur fractures may require open reduction and internal fixation or can be done through percutaneous techniques. The plate construct is a stress shielding construct. The implant will eventually need to be removed in growing children. This method of fixation is one of the most common methods employed for supracondylar femur fractures in children.

The patient is positioned supine on a radiolucent fracture table. A bump is placed under the ipsilateral hip for proper position of the distal femur. A lateral approach to the distal femur is used. An incision is made on the lateral aspect of the distal femur. The vastus lateralis is exposed and retracted posteriorly or anteriorly based on fracture pattern. The fracture is then exposed and provisional reduction is obtained, which is confirmed by radiography.

A compression plate or distal femur buttress plate may be used depending on fracture pattern. A simple transverse or non comminuted fracture may be repaired with a compression plate. If comminution is extensive or involves a spiral component, a buttress plate is a better option. Ideally six cortices are necessary proximal and distal to the fracture for secure fixation; otherwise fracture stability is further supplemented by cast application.

For percutaneous plating, a small incision is made on the lateral femur. The plate is then slid onto the bone in a submuscular fashion. Percutaneous incisions are made for inserting screws. This technique offers less blood loss, less dissection for exposure, and arguably lower infection rates.

Weight bearing of the limb is avoided after surgery until fracture callus has formed. Protection in a knee brace is also an option.

External Fixation

In general, due to the limited options of surgical fixation of pediatric supracondylar femur fractures, external fixation may be a viable option. A lateral frame or Ilizarov frame may be used. This technique allows the maintenance of overall length and alignment of the limb, but it is cumbersome for patients and is associated with complications such as pin tract infections.

The technique and results of an Ilizarov external fixator have been described by Sabharwal et al. [5] The patient is positioned supine on a radiolucent Jackson table with a bump under the ipsilateral hip. The entire leg, including the lower abdomen, is included in the sterile field.

Two reference pins are used: a proximal reference pin 90 degrees to the proximal axis and a distal reference pin 90 degrees to the distal axis. An imaginary line is drawn from the tip of the greater trochanter to the center of the femoral head. A proximal half-pin is placed parallel and distal to this line.

Typically two or three 5-mm or 6-mm half-pins are placed in each fragment. For distal fractures, a 1.8-mm Ilizarov reference wire is placed as well. As a general guideline for size of the half-pin, it should not exceed one-third of the diameter of the underlying bone. Each half pin is checked by radiography after insertion.

Proximal arch and a distal complete ring are typically used for distal fractures. Once the proximal and distal reference pins have been placed, the half-pin connection to the corresponding arch or ring is firmly secured. Care should be taken that the individual arches or rings are placed orthogonal to the corresponding fracture segments in all planes. Avoid placing components too far posterolaterally (causing a problem with lying supine) or too anteriorly in the proximal thigh (causing a problem with sitting up).

Once all the half-pins have been placed and secured to individual arches or rings, a closed reduction of the fracture is performed under fluoroscopic guidance. If the proximal and distal fixation constructs have been appropriately placed, normal bony alignment should be restored when the 2 arches or rings are brought parallel to each another. Once an acceptable reduction is achieved, 3 evenly spaced threaded rods are inserted between the 2 arches or rings, which should be essentially parallel to each other.

To prevent significant loss of knee mobility related to tethering of the adjacent skin or underlying iliotibial band by the half-pins and wires, one should confirm near full flexion of the knee after final fracture reduction. If needed, limited skin and fascial release can be performed at the individual pin insertion sites.

Overall alignment of the limb should also be checked. Placing an electrocautery cord firmly stretched on the skin from the center of the femoral head to the center of the tibial plafond reproduces the mechanical axis of the entire limb. On average, the bovie cord should project 10 (range, 3–17) mm medial to the midpoint of the knee joint, in line with the medial tibial spine.

The application of a lateral frame is similar in concept to the Ilizarov frame. Two 5-mm or 6-mm pins are placed proximal and distal to the fracture site. Pin location should be approximately 2 cm from the fracture and avoid the femoral neck calcar proximally and the femoral physis distally. Once appropriate reduction is achieved, these pins are then secured by a bar construct.

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