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Authors of section


Tomas Guerrero

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

Open all credits

Plate fixation with lag screws and pins

1. Principles

Reducible A3 fractures should be anatomically reduced with lag screws to reconstruct the bone column. Pins may be used to provide temporary stabilization.

A plate is used in a neutralization fashion.

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

Read more about lag screw fixation.

31 A3

2. Patient positioning

This procedure is performed with the patient in lateral recumbency.

combined treatment options

3. Approach

A craniolateral approach is performed in combination with the lateral approach to the femoral shaft.

The length of the incision will depend on the extent of the fracture.

craniolateral approach combined with a dorsal approach

4. Surgical technique


The main fracture fragments are reduced with the help of bone holding forceps, starting from proximal to distal.

plate fixation with lag screws and pins

Preliminary fixation

K-wires or bone holding forceps may be used to provide temporary stabilization.

plate fixation with lag screws and pins

Fixation of the fragments

The fragments are secured with lag or position screws.

plate fixation with lag screws and pins

Plate selection

The plate is perfectly contoured over the lateral aspect of the greater trochanter to allow placement of at least three screws in the proximal fragment.

Note: the plate bending is difficult and needs to be well preplanned. Make sure that one screw hole is positioned to allow screw placement up to femoral head and neck.

Read more about plate preparation.

plate fixation with lag screws and pins

Plate placement

The plate is positioned as proximal as possible to maximize the number of screws in the short proximal fragments.

plate fixation with lag screws and pins

Plate application

Following contouring, the plate is applied to the lateral surface of the reconstructed bone.

The plate position and contouring to the bone is checked thoroughly, and adjusted if required.

plate fixation with lag screws and pins

Plate fixation

The plate is fixed in a neutralization fashion. A screw is inserted obliquely in the plate hole that was positioned specifically to engage the femoral neck and head. The largest diameter screw that will fit the plate should be used for that purpose.

plate fixation with lag screws and pins

A second neutral screw is inserted on the distal part of the bone.

plate fixation with lag screws and pins

Additional lag screws may be inserted through the plate holes where needed. All remaining plate screws are inserted in a neutral mode.

plate fixation with lag screws and pins

Validation of fixation

Postoperative orthogonal radiographs are taken to assess fixation.

31 A3

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 to the surface of the bone is not necessary; however, contouring and perfect positioning is required to ensure that the screws adequately engage the femoral neck and head as the orientation of the screws is dictated by the plate and cannot be altered.

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 cortex screws must be inserted and tightened before any locking screws are placed.

plate fixation with lag screws and pins

5. Aftercare

Activity restriction is indicated until radiographs indicate bone healing of the fracture.

Phase 1: 1-3 day after surgery

Aim is to reduce the edema, inflammation and pain.

Integrative medical therapies, anti-inflammatory and analgesic medications.

Note: Nonsteroidal anti-inflammatory medications can be toxic in the cat and should only be used as labeled for the cat.

Phase 2: 4-10 days after surgery

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

Anti-inflammatory (see nonsteroidal warning) and analgesic medications may still be 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. Rehabilitation is strongly recommended to help prevent quadriceps muscle contracture.

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

10-14 days after surgery the sutures are removed.

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

Implant removal

Implants may cause discomfort of the adjacent soft tissue. If this occurs, implants can be removed after bone healing is observed. In case of infection, implants must be removed after healing.

If there is no implant failure or infection, there is no need for implant removal.