Authors of section

Authors

Arnold Besselaar, Daniel Green, Andrew Howard

Executive Editor

James Hunter

General Editor

Fergal Monsell

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Open reduction; pin or screw fixation

1. General considerations

Reconstruction vs excision

A loose small osteochondral fragment in the knee may cause more symptoms than a small articular defect.

Reasonable attempts should be made to repair the articular surface but there may be small osteochondral defects that are not reconstructable.

Specialist techniques to reconstruct the articular surface are available and include osteochondral autograft and allograft transfer.

Screw fixation of a flake fracture of the distal femur

Associated patellar dislocation

Anterior and lateral flake fractures may be associated with patellar dislocation/subluxation.

Check the retropatellar surface for osteochondral lesions.

Implant selection

Fixation can be achieved using a small fragment screw system (A or B), or absorbable pins (C). In general, screws provide a better compression of the fracture, but require an osteochondral fragment that is sufficiently large to accommodate the screw head.

Cannulated implants are advantageous.

Absorbable pins (C) are preferable for thin and small fragments.

open reduction pin or screw fixation

2. Patient preparation and approaches

Patient positioning

Place the patient supine on a radiolucent table with a C-arm.

Supine patient position

Approaches

When appropriate resources are available, arthroscopically assisted reduction and fixation is recommended.

If arthroscopy is not available, osteochondral fractures can be reduced and fixed via a parapatellar approach.

3. Reduction and temporary fixation

Reduction

Reduce the fracture with an elevator.

A small ball-spiked pusher, K-wire, or dental pick, may also be used.

Reduction of the osteochondral fragment with a small ball-spike pusher

Alternative: reduction under arthroscopic view

Reduce the osteochondral fracture with a hook (illustrated) under arthroscopic control. This may be inserted through a separate portal.

Reduction under arthroscopic view

Fixation with K-wire

Insert a K-wire to secure the reduction. Make sure that it does not interfere with the intended implant position, or alternatively is the correct diameter for cannulated screw insertion.

K-wire fixation

4. Planning for screw/pin fixation

Use two screws, or pins, to prevent fragment rotation.

None of the implants should project above the articular surface.

Take care to modify screw trajectory and length to avoid injury to the distal femoral growth plate.

Planning for screw/pin fixation

5. Sunken screw

Insertion of guide wire

Place the guide wires as near to perpendicular to the fracture plane as possible.

Confirm correct guide wire placement under image intensification.

Insertion of guide wire for sunken screw fixation

Countersinking

It is imperative to countersink for the screw head.

Countersink manually, deep enough to fully bury the screw heads.

Pitfall: Avoid countersinking too deeply into the cancellous bone, which often happens with a power tool.
Countersinking

Screw insertion

Use partially threaded screws so that a gliding hole is not required.

Screw insertion

This illustration shows the completed osteosynthesis using sunken screws.

Completed osteosynthesis using sunken screws

6. Headless compression screw

Insert headless compression screws after predrilling, or over a guide wire.

Neither a gliding hole nor countersinking is required.

It is imperative to insert the headless compression screw until the screw head has completely penetrated the cartilage surface.

Insertion of headless compression screws

This illustration shows the completed osteosynthesis using headless compression screws.

completed osteosynthesis using headless compression screws

7. Absorbable pin

Absorbable pins require predrilling.

Use the insertion device with gentle hammer blows as the pins may deform.

Insertion of absorbable pins

This illustration shows the completed osteosynthesis using absorbable pins.

Completed osteosynthesis using absorbable pins

Intraoperative image of open reduction and internal fixation with absorbable pins

Intraoperative image of open reduction and internal fixation with absorbable pins

8. Final assessment

Check x-rays for correct implant positioning and anatomical reduction.

9. Aftercare

Immediate postoperative care

The patient should get out of bed and begin ambulation with crutches on the day of surgery or the first postoperative day.

In most cases the postoperative protocol will be protected weight bearing in a hinged knee brace.

Hinged knee brace

In some situations, the use of continuous passive motion may be useful.

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Analgesia

Routine pain medication is prescribed for 3–5 days postoperatively.

Discharge care

Discharge from hospital follows local practice and is usually possible after 1–3 days.

Follow-up

Routine clinical follow-up is undertaken, and physiotherapy may be necessary to accelerate recovery.