Mark E. Easley and Giles R. Scuderi

1. Extensor mechanism insufficiency

2. Articular incongruency

3. Fracture displacement greater than 3 mm (particularly with a transverse fracture pattern)

4. Open fracture

1. Nondisplaced fracture (nonoperative treatment)

2. Minimally displaced fracture with intact extensor mechanism

3. Fracture of the nonarticular surface with intact extensor mechanism

1. History and physical examination

2. Knee radiographs

a. Anteroposterior (AP) and lateral to assess fracture pattern

b. Sunrise view (may be useful to identify osteo-chondral/marginal fractures)

1. Other imaging studies

a. Rarely CT

b. Rarely arthrography

c. MRI may be useful in identifying osteochondral/marginal fractures.

1. Supine position

2. If extremity tends to externally rotate, place a “bump” under the ipsilateral hip.

3. General, spinal, or epidural anesthesia

a. Relaxes muscles to facilitate repair

b. Permits tourniquet use

1. Intravenous antibiotics

2. Standard instrument set

3. Standard small fragment set

4. Large tenaculum clamps

5. Tension band wire (18 gauge)

6. Cannulated screws (4.0 mm)

7. Kirschner wires (2.0 mm)

8. Nonabsorbable suture (#5)

9. Intraoperative fluoroscopy or X-ray

1. Universal vertical midline incision

a. Allows adequate exposure

b. Functional incision if future surgery is needed

1. Place a tourniquet as proximal as possible on the thigh.

2. Remember to perform a meticulous retinacular repair.

4. Inspect the articular surfaces of the patella and femur because their condition will have a significant effect on the clinical outcome.

5. If necessary, consider lateral release to improve patella tracking.

Tension band principle

a. Converts distraction forces into compressive forces

b. Strongest fixation

c. Wire tension band must be on the anterior aspect of the patella to ensure compression at the articular surface.

Cannulated screws

a. Wire tension band is passed through the cannulated screws.

b. The cannulated screws must be buried within the bone for the tension band principle to act on the bone (otherwise the tension will only be created on the screw ends).

1. If skin contamination is present secondary to either an open injury or skin abrasion, then delay internal fixation until the wound is clean.

2. Avoid creating multiple layers. Attempt to create two full-thickness tissue flaps medially and laterally.

3. If possible, avoid prolonged operative delay. Aim for surgery within the first 10 to 14 days after injury.

4. Avoid intra-articular step-off. If possible, palpate the patella’s articular surface.

5. Avoid improper placement of the wire tension band (otherwise the compressive effect will be forfeited).

6. If possible, avoid performing a patellectomy (only indicated if bone comminution and/or articular surface damage is too extensive for repair).

1. Suction drain for 24 hours may avoid hematoma. Compressive dressing for 24 to 48 hours is also useful.