Executive Editor: Chris Colton

Authors: Florian Gebhard, Phil Kregor, Chris Oliver

Patella

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Glossary

Midline longitudinal approach
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Principles

Sensory innervation
The saphenous nerve runs along the medial aspect of the distal femur. The infrapatellar branches of the saphenous nerve lie on the medial and inferior aspects of the patella, and run across to the lateral side. Postoperatively, there is usually minor sensory loss to the lateral side of the scar, but significant saphenous nerve damage is avoidable. Occasionally, there may be postsurgical saphenous nerve neuroma formation which is rarely a significant problem.

Vascular supply
The anterior surface is surrounded by an extraosseous arterial ring, which receives inflow from branches of the genicular arteries. This anastomotic ring supplies the patella through mid-patellar vessels, which penetrate the middle third of the anterior surface, and the polar vessels, which enter the apex.

Longitudinal versus transverse approach
A longitudinal midaxial incision is the preferred approach because it offers excellent exposure of the fracture site, and can be extended proximally or distally. This incision may be re-opened for any further surgery at any stage in the future should it be required.

In the past some surgeons used a transverse approach to the patella. This is not recommended as wound healing is frequently a problem. Additionally, should reconstructive knee surgery be required later in life, a transverse pre-patellar scar may compromise healing.

Parapatellar incisions are also possible, especially in the case of an open fracture. A medial parapatellar arthrotomy is made if it is necessary to inspect the knee joint and intraarticular surgery can still be performed as needed.

Prophylactic antibiotics
Antibiotics are administered according to local antibiotic policy and specific patient requirements.

Many surgeons use gram-positive prophylactic antibiotic cover for closed fractures, adding gram-negative prophylactic cover for open fractures. Always remember that antibiotic therapy will never compensate for poor surgical technique.


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Skin incision

Landmarks
The landmarks are the patella, the patellar tendon and the tibial tubercle, which are easily palpatable.


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Skin incision
Make a longitudinal midaxial incision from 5 cm above the superior pole of the patella to the tibial tubercle.

Full thickness flaps should be developed in order to avoid damage to skin blood supply.


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Approach to the patella

After incision of the superficial fascia, the complete extent of the injury must be identified. There may well be traumatic tears in the lateral and medial retinacula and the knee joint capsule.

In open fractures, or a preexisting chronic bursitis, the prepatellar bursa may be excised.


Fracture assessment

Since the preoperative x-ray may not always reveal all fracture lines any extraarticular fracture lines will be detected by clearing a very small amount of overlapping tissue (1 or 2 mm) at the fracture edges. The joint is explored through the fracture site, steps, gaps, and any destroyed or impacted cartilage are noted and any loose fragments are removed from the knee. The joint is irrigated and the articular surface of the corresponding femoral condyle is examined.


Wound closure

Before closure, irrigate wounds copiously with warm Ringer lactate solution.

Care should be taken to suture any tears in the lateral and medial parapatellar retinacula. The use of suction drains may be considered. Meticulously close the skin with nonabsorbable sutures.

v1.0 2008-12-03