Authors of section

Author

Mary Sarah Bergh

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

Open all credits

Transcondylar lag screw and neutralization plate

1. Principles

Anatomic reconstruction of the joint surface is essential, and this step should be performed prior to fixation of the condyles to metaphysis.

Interfragmentary compression is achieved with a lag screw for anatomical reduction of the articular fracture.

Proper alignment of the femur must be obtained with special attention to angulation and torsion, particularly in transverse fractures, where rotational malalignment is more likely to occur.

Comparison with the contralateral unaffected bone can be useful.

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

2. Positioning and approach

This procedure is performed with the patient placed in dorsal recumbency

One of the following approaches is utilized:

transcondylar lag screw and neutralization plate

3. Surgical technique

Reduction and stabilization of the femoral condyles

The articular fracture of the condyles is reduced with pointed reduction forceps. Anatomic reduction is essential in all cases.

Note: Bone in juvenile patients is very soft. Care must be taken not to damage it during reduction.

The articular fracture of the condyles is reduced with pointed reduction forceps

Stabilization is achieved with inserting the lag screw across the condyles perpendicular to the fracture plane. Frequently the screw is placed in lateral to medial direction, starting at the level of the epicondyle.

Note: Care should be taken not to penetrate the condylar fossa to avoid damage to the cruciate ligaments with the screw.

A detailed description of "Lag screw fixation" can be found here.

Stabilization is achieved with inserting the lag screw across the condyles perpendicular to the fracture plane

Note: If the screw is not placed perpendicular to the fracture plane, this will result in loss of anatomic reduction of the articular surface.

If the lag screw is not placed perpendicular to the fracture plane, this will result in loss of anatomic reduction of the articular surface

Reduction and stabilization of the condyles to the metaphysis

The reconstructed femoral condyles are carefully reduced to the metaphysis with pointed reduction forceps. Anatomic reduction is desired in all cases. Under-reduction of the fracture should be avoided as it is less stable, and the cranial aspect of the metaphysis would interfere with the gliding of the patella in the trochlear groove.

Note: Bone in juvenile patients is very soft. Care must be taken not to damage it during reduction.

The reconstructed femoral condyles are carefully reduced to the metaphysis with pointed reduction forceps

Preliminary fixation can be achieved by placement of a K-wire across the fracture.

Preliminary fixation can be achieved by placement of a K-wire across the fracture

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.

Note: The plate should be contoured so the distal holes are positioned away from the lag screw.

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

Note: If a wedge fragment of appropriate size is positioned under the plate, a lag screw may be inserted through the plate to achieve interfragmentary compression.

a lag screw may be inserted through the plate to achieve interfragmentary compression

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

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.

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.