Authors of section

Author

Denis Marcellin-Little

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

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K-wire and figure of 8 technique

1. General considerations

This fracture type is rare. The fracture occurs along the line of tension; therefore, fragment displacement is minor and maintaining fracture reduction is easy.
K-Wire and figure 8 skewer technique

2. Preparation and approach

The patient is positioned in dorsal recumbency. The pelvic limb is extended.

Dog in dorsal recumbency
A sagittal or parasagittal skin incision is made over the patella.
Sagittal or parasagittal skin incision

A lateral parapatellar or medial parapatellar approach is performed along the patellar ligament and patella proximally to the quadriceps muscle.

An arthroscopic assisted minimally invasive approach can be used for some fractures.

Lateral parapatellar dissection

3. Reduction

The stifle is extended.
The stifle is extended
The fragments are temporarily anatomically reduced and stabilized using small pointed reduction forceps.
Fragments reduction and stabilization

4. Fixation

A K-wire is introduced centrally from the smaller fragment, cranial to the articular cartilage. A power drill is used at low speed (less than 300 rpm), using irrigation to minimize heat generation.
As a guideline, the dimension of the K-wire for a German shepherd is 0.062'' (1.55 mm). Smaller K-wires are used in medium and small breeds. For example, 0.045'' (1.15 mm) is used in a border collie, and a 0.032'' (0.8 mm) is used in a miniature poodle or a cat.
K-wire introduction
Both ends of the K-wire should be accessible.
2-3 cm of K-wire should be accessible to facilitate wire placement and K-wire bending.
Both ends of the K-wire should be accessible
Orthopedic wire is wrapped in a figure of 8 pattern over the ends of the K-wire and twisted.
As a guideline, the dimensions of the wire for a German shepherd breed is 18 gauge (1.25 mm). 
Smaller wires are used in medium and small breeds. For example, 20 gauge wire (1.0 mm) is used in a border collie, and a 22 gauge wire (0.8 mm) is used in a miniature poodle or a cat.
Orthopedic wire is wrapped in a figure of 8 pattern
Note: The K-wire is directed perpendicular to the main fracture line, making sure to avoid the articular surface. The K-wire should be placed as caudal as possible, to minimize distraction of the articular surface.
The K-wire is directed perpendicular to the main fracture line
The articular surface is evaluated to make sure that it is anatomically reduced.
Articular surface evaluation
The K-wire ends are cut and bent away from the articular surface.
K-wires ends are cut and bent

5. Closure

The stifle joint is sutured using monofilament absorbable suture material. The wound is closed in layers.
The stifle joint is sutured

6. Aftercare

General considerations

Limb disuse after the repair of a patellar fracture is unusual. Most dogs start weight bearing within 3 days of surgery.

The focus of physical rehabilitation is to:

  • Avoid loss of stifle joint motion, particularly loss of extension
  • Avoid excessive stress on the surgical repair during the healing period
  • Promote low-impact weight bearing pelvic limb exercise

The stifle joint is protected and partially immobilized if deemed necessary for approximately 14 days.

Cryotherapy and passive range of motion are indicated but not possible if immobilization is used.

Activity is limited to leash walks until bone healing is radiographically evident.

Phase 1: 1-3 days after surgery

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

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

Phase 2: 4-14 days after surgery

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

Anti-inflammatory and analgesic medications may still be needed.

If the dog is not starting to use the limb within a few days after surgery, re-evaluation is recommended.

Phase 3: 14 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.

Implant removal

If the implants interfere with soft tissues, they should be removed after the fracture is healed.