Authors of section

Author

Mary Sarah Bergh

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

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Lag screw and neutralization plate

1. Principles

Anatomic reconstruction is required.

Anatomic reconstruction is required

Note: If anatomical reconstruction cannot be accomplished, a bridging technique should be used. A detailed description of the "Bridging plate" technique is available in the dedicated section.

Bone plates may be placed on the medial or lateral surface of the femur. The normal curve of the distal femur makes it difficult to achieve optimal screw purchase with standard straight plates. Contouring these plates is challenging.

If anatomical reconstruction cannot be accomplished, a bridging technique should be used

2. Positioning and approach

This procedure is performed with the patient placed in either of the two positions:

One of the following approaches is utilized:

3. Surgical technique

Reduction and preliminary stabilization

Reducing the free fragment to one another or one of the main bone segments is recommended. This transforms a complex fracture into a simpler fracture configuration that allows for an easier anatomical fracture reduction.

The fracture of a dog distal femur is reduced with pointed reduction forceps

Preliminary stabilization can be achieved with reduction forceps.

Preliminary stabilization can be achieved with reduction forceps

Lag screw fixation

The large comminuted fragments are reduced and interfragmentary compression is achieved with a lag screw.

The large comminuted fragments are reduced and interfragmentary compression is achieved with a lag screw

Reduction of the remaining fracture line

Bone holding forceps are applied to the proximal and distal major fragments to assist in fracture reduction.

Bone holding forceps are applied to the proximal and distal major fragments to assist in fracture reduction

Perfect anatomical reduction is achieved with the help of one or two pointed reduction forceps placed across the fracture line.

Note: care must be taken not to damage the secured fragment during the reduction manoeuvre.

Note: If the fragment is large enough a second lag screw may be placed for additional stability.

Perfect anatomical reduction is achieved with the help of one or two pointed reduction forceps placed across the fracture line

Plate selection

Numerous plate types can be used. Specially designed plates for the distal femur are available.

Ideally the plate should be long enough to place at least three screws in either side of the fracture. In the distal femur the use of only two screws in the distal fragment is acceptable.

Numerous plate types can be used to repair a type A fracture in a dog distal femur

Plate placement

The plate is contoured to the lateral aspect of the distal femur. The plate position and contouring to the bone is checked thoroughly and adjusted, if required.

Note: Care should be taken to avoid placement of the plate high on the lateral trochlear ridge, where it can impinge on patellar tracking and result in pain and discomfort.

A detailed description of "Plate preparation" can be found here.

The plate is contoured to the lateral aspect of the distal femur

Plate fixation

A screw is inserted in the proximal fragment in the neutral position.

A screw is inserted in the proximal fragment in the neutral position

A screw is inserted in the distal fragment in the neutral position.

Note: Care should be taken to avoid penetrating the articular surface with the screws. Where possible at least one screw should traverse both condyles.

A screw is inserted in the distal fragment in the neutral position

The remaining screw holes are filled. If a screw hole lays over the fracture plane it should be left open.

The remaining screw holes are filled

Note: If the fracture plane does not lay under the bone plate and the obliquity of the plane is amenable, one or two lag screws may be inserted through the plate to achieve interfragmentary compression.

Distal femoral fracture in a dog repaired with a neutralization plate and lag screw

Fixation with a locking plate

If a locking plate is used, only 2-3 locking bicortical screws are needed per main fragment. One advantage of using a locking plate is that precise contouring is not necessary. Great care must be taken when contouring the distal part of the locking plate to avoid directing screws into the joint.

Note: If a combination of cortex and locking screws is used, the plate must be anatomically contoured at the sites of non-locking screw insertion. The non-locking screws must be inserted and tightened before any locking screws are placed.

If a locking plate is used, only 2-3 locking bicortical screws are needed per main fragment

Validation of fixation

Postoperative radiographs should be taken to assess the repair.

Distal femoral fracture in a dog repaired with a neutralization plate

4. Aftercare

Activity restriction and controlled walking is indicated until evidence of bone healing is detected by radiographic examinations.

cross pinning

Phase 1: 1-3 day after surgery

The aim is to reduce the edema, inflammation and pain using anti-inflammatory and analgesic medications.

Passive range of motion of the hip and stifle joint can be initiated to promote mobility and joint health.

cross pinning

Phase 2: 4-10 days after surgery

The aim is to resolve the hematoma, edema and control pain, and prevent muscle contracture.

Anti-inflammatory and analgesic medications are still needed. Rehabilitation and integrative medical therapies can be used.

Special attention should be given to patients less than 1 year of age with a femoral fracture, as they are at risk for developing quadriceps contracture. Early controlled activity and passive range of motion is strongly recommended to help prevent this complication.

If the patient is not starting to use the limb within few days after surgery, a careful evaluation is recommended.

cross pinning

Phase 3: 10 days-8 weeks after surgery

Rehabilitation therapy is continued.

10-14 days after surgery the sutures are removed.

Radiographic assessment is performed every 4-8 weeks until bone healing is confirmed.

cross pinning

Implant removal

Implants may be removed if there is irritation or infection present, however if they are not causing problems for the patient, there is no need for implant removal.