The fracture or osteotomy is reduced and secured with pointed reduction forceps.
Two K-wires are driven perpendicular to the fracture line and parallel to each other.
Insertion starts at the dorsal ridge of the greater trochanter. The pins are anchored distally in the medial cortex of the femur.
Tension band wire application
A hole is drilled from cranial to caudal below the fracture line for anchorage of the wire. A pin or small drill bit can be used for that purpose.
The hole is made below the fracture plane at an equal distance from the point of insertion of the K-wires to the fractures.
The wire is passed through that hole and around the pins creating a figure-of-eight pattern.
A loop is created in the long arm of the wire. The free ends of the wire and the “loop” are alternately tightened, so that both arms of the wire are twisted equally.
It is important for the wire to be in contact with the pins and underneath any muscle or tendon. Placing the wire above the tendon would result in necrosis of the tendon and loosening of the tension band.
The pins are bent to sit close to the bone, and cut short. This avoids soft tissue irritation.
Validation of fixation
Postoperative orthogonal radiographs are taken to assess fixation.
4. Case example A1
2-year-old Shih Tzu presented for treatment of a distal femoral fracture and trochanteric avulsion fracture (31-A1).
The distal femoral fracture was repaired with a plate-rod fixation while the trochanteric fracture was repaired with a tension band wire.
Activity restriction is indicated until evidence of bone union is detected on radiographic examinations.
Implants may cause discomfort of the adjacent soft tissue. If this occurs, implants are removed after radiographic evidence of bone healing is complete. In case of infection, implants must be removed after complete bone healing.
Phase 1: 1-3 day after surgery
Aim is to reduce the edema, inflammation, and pain.
Integrative medical therapies, anti-inflammatory and analgesic medications.
Phase 2: 4-10 days after surgery
Aim is to resolve the hematoma, edema and control pain, and prevent muscle contracture.
Anti-inflammatory 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 dog is not starting to use the limb within a 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 complete bone healing is confirmed.
If there is no implant failure or infection, there is no need for implant removal.