Authors of section

Author

Mary Sarah Bergh

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

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Screw fixation

1. Principles

Anatomic reconstruction of the joint surface is essential.

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

Lag screw fixation in a type B2 fracture in a distal femur of a dog

2. Positioning and approach

This procedure is performed with the patient placed in dorsal recumbency

Through one of the following approaches:

transcondylar lag screw and neutralization plate

3. Surgical technique

Reduction and preliminary stabilization

The fracture is reduced, and preliminary stabilization achieved with pointed reduction forceps. Anatomic reduction is essential in all cases.

The fracture is reduced, and preliminary stabilization achieved with pointed reduction forceps

Fixation

The lag screw is inserted perpendicular to the fracture plane. The screw may be placed in lateral to medial direction.

The lag screw is inserted perpendicular to the fracture plane

The screw may also be placed in medial to lateral direction.

The starting point is variable depending on the fracture configuration. The screw should be directed caudomedially to maximize purchase of the fracture fragment.

Note: Care should be taken not to penetrate the articular surface with the screw. The screw head should be countersunk to avoid soft tissue irritation and maximize contact between the screw head and the bone.

The lag screw is inserted 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

Additional stabilization can be achieved by:

  • A K-wire
  • An additional lag screw in larger fragments
Additional stabilization can be achieved by a K-wire or an additional lag screw in larger fragments

Validation of fixation

Postoperative radiographs should be taken to assess the repair.

Distal femoral fracture in a dog repaired with a screw in lag fashion

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.