Lag screw fixation

Due to the pulling force of the patellar tendon most of these fractures are displaced and need to be reduced. Reduction may be achieved by extending the knee. If this is not enough, consider pushing the fragment into place with a ball-spiked pusher.

Reduction is not necessary in undisplaced fractures.

To lessen the possibility of damaging the popliteal neurovascular structures when you drill the proximal tibia in an anteroposterior direction, flex the knee at least 15–20°. In full extension the neurovascular bundle is closer to the bone.

There are two important reasons for countersinking:

1. To produce a lower profile of the screw head and thus avoid soft-tissue irritation
2. To ensure that the screw head has the maximum contact area of cortical bone to resist the traction force generated by the threads of the screw advancing across the far cortex and thus compressing the fracture surface

Care should be taken not to excessively thin the cortex during countersinking.

This procedure is normally performed with the patient in a supine position.

• Supine position

For this procedure a midline approach (if in isolation) or an anterolateral approach can be used, depending on any associated injuries or soft-tissue conditions.

• Anterolateral/extended anterolateral approach

After direct exposure of the avulsed tibial tuberosity in an open procedure, reduction may be achieved by using a small clamp placed on the anterior tibial cortex and the bone fragment. The reduction may additionally be secured by temporary K-wires.

A ball-spiked pusher might also be used for the reduction.

Fixation of the tibial tuberosity is achieved by lag screw fixation in an anterior–posterior direction through the main fragment.

Countersunk and overdrilled 3.5 mm cortical screws are preferred. These screws are usually left in place after fracture healing.

In elderly people with osteopenia fully threaded screws should be used. Perforation of the posterior tibial cortex should be limited and visualized under image intensifier to avoid damage of nerves and vessels in the popliteal fossa.

More information is provided in the Cancellous lag screw insertion basic technique.

This fixation can be reinforced, with a tension band wire, but preferably a small plate, acting as a tension band, is employed.

Close monitoring of the tibial compartments should be carried out, especially during the first 48 hours after injury and again after surgery to rule out compartment syndrome. More information is provided here:

• Compartment syndrome

The neurovascular status of the extremity must be carefully monitored. Impaired blood supply or developing neurological loss must be investigated as an emergency and dealt with expediently.

Oral or subcutaneous administration of DVT prophylaxis for six weeks should be strongly considered.

Optimal stability should be achieved at the time of surgery, in order to allow early range of motion exercises. Unless there are other injuries or complications, mobilization may be performed on post OP day 1. If available, continuous passive motion (CPM) splints can be very helpful in the early phase of rehabilitation. Static quadriceps exercises with passive range of motion of the knee should be encouraged. Afterwards special emphasis should be given to active knee and ankle movement.

The goal is to achieve as full range of motion as possible within the first 4–6 weeks.

Weight-of-leg weight bearing is initiated depending on patient comfort. Depending on the severity of the articular displacement, weight bearing can begin as early as 6 weeks postoperatively. In situations where articular displacement was significant weight bearing should be delayed for 10–12 weeks.

Wound healing should be assessed within the first two weeks. Subsequently, a 6- and 12-week follow-up with radiographic assessment is usually performed. If a delayed union is recognized, further surgical care may be necessary and should be carried out as soon as possible. Residual knee instability may require delayed reconstruction.

Implant removal is not mandatory and should be discussed with the patient.