Can you provide a diagram of the cerclage wire repair technique for a transverse or comminuted patellar fracture in an adult with an intact extensor mechanism?

Cerclage Wire Repair of Patella: Technical Overview

I cannot provide a diagram as I am a text-based AI system, but I can describe the cerclage wire repair technique in detail to guide your understanding and clinical application.

Technical Description of Cerclage Wire Fixation

The cerclage wire technique for patellar fractures involves circumferential wire placement around the patella combined with anterior tension band wiring, creating a stable construct that allows early mobilization. 1, 2

Wire Configuration

The technique utilizes two main components:

• Circumferential cerclage wire: A single wire (typically stainless steel or titanium) is passed completely around the perimeter of the patella, encircling the entire bone 1, 2
• Figure-of-eight anterior tension band: The same wire or an additional wire is configured in a figure-of-eight pattern on the anterior surface of the patella, passing through the quadriceps tendon proximally and the patellar tendon distally 1, 2

Step-by-Step Technique

• Wire placement begins with circumferential passage: The wire is passed around the entire patella, staying close to bone to minimize soft tissue irritation 1
• Anterior figure-of-eight configuration: The wire is then passed through the quadriceps tendon superiorly and patellar tendon inferiorly, creating a figure-of-eight pattern that provides anterior compression 1, 2
• Tension application: The wire is tightened to approximately 35 kg of tension to achieve adequate compression and stability 2
• No K-wires required: This technique eliminates the need for Kirschner wires, thereby avoiding K-wire-related complications such as migration, skin irritation, and need for removal 1

Anatomical Landmarks

• Superior anchor point: Wire passes through the quadriceps tendon approximately 1-2 cm above the superior pole of the patella 1
• Inferior anchor point: Wire passes through the patellar tendon approximately 1-2 cm below the inferior pole of the patella 1
• Lateral wire position: The circumferential wire should sit in the groove between the articular and non-articular surfaces of the patella to avoid articular surface damage 1

Visual Conceptualization

Imagine the construct as follows:

• A complete circle of wire around the patella's perimeter (like a belt)
• An "8" pattern on the front surface, with the crossing point at the fracture site
• The superior and inferior loops of the "8" anchored in the quadriceps and patellar tendons respectively

Fracture Types Suitable for This Technique

• Transverse fractures: The most common indication, often associated with patellar maltracking 3, 1
• Simple comminuted fractures: Multiple fragments can be compressed together with the circumferential wire before applying the figure-of-eight component 1, 4
• Displaced fractures with intact extensor mechanism: The technique relies on tendon integrity for anchoring 1

Clinical Outcomes

• Fracture healing: Union achieved by 16 weeks in 100% of cases in recent series 1
• Early mobilization: 92% of patients achieved 90 degrees of active flexion within one week postoperatively 1
• Complication rates: Significantly lower than traditional K-wire techniques, with hardware removal rarely needed 1, 2
• Functional scores: Average Böstman score of 28.5 at 12 months (excellent to good range) 1, 2

Key Technical Pitfalls to Avoid

• Insufficient tension: Under-tightening leads to loss of reduction and delayed union 2
• Wire placement too anterior: Can cause skin irritation and soft tissue problems 1
• Inadequate soft tissue protection: The wire should be buried beneath fascia where possible to minimize irritation 1
• Failure to assess extensor mechanism: This technique requires intact quadriceps and patellar tendons for anchoring 1

Postoperative Protocol

• Immediate mobilization: Isometric quadriceps exercises begin on postoperative day 1 5
• Progressive range of motion: Active flexion to 30 degrees initially, progressing to full range by 4-6 weeks 5
• Weight bearing: Full weight bearing with crutches and hinged brace initially, transitioning to unassisted ambulation by 6 weeks 5