The goal is to restore:
- Extensor mechanism continuity
- Patellar length
- Articular congruity
- Stable fixation permitting early knee movement
Preserve the patella whenever possible.
Nonoperative treatment
Treat nonoperatively when:
- Extensor mechanism is intact
- Fracture is nondisplaced or minimally displaced
- Articular step is below approximately 2 to 3 mm
- Fracture gap is below approximately 3 to 4 mm.
Immobilise the knee in full extension using a brace.
Allow weight bearing in extension when fracture stability permits.
Begin controlled knee range of motion early, commonly after approximately 1 to 2 weeks, while maintaining extension protection during weight bearing.
Progress strengthening after radiographic and clinical evidence of healing.
Operative indications
Operate for:
- Open fracture
- Disrupted extensor mechanism
- Articular step greater than approximately 2 to 3 mm
- Fracture separation greater than approximately 3 mm
- Unstable displaced fracture
- Osteochondral fragment requiring fixation or removal.
Simple transverse fracture
Options include:
Cannulated lag screws with anterior tension band augmentation
or
Plate fixation
Traditional modified anterior tension band wiring uses parallel Kirschner wires with an anterior figure of eight wire, converting tensile forces into compression during knee flexion.
It remains effective but symptomatic wire prominence and secondary implant removal are common. Contemporary data show high hardware irritation and reoperation rates with classic metallic tension band constructs.
Cannulated screw based constructs and low profile plates increasingly reduce reliance on prominent K wires.
Comminuted fracture
Do not attempt to convert a severely comminuted pattern into a simple two fragment tension band construct.
Use fragment specific fixation, mini fragment screws, circumferential fixation or a low profile locking or mesh plate to reconstruct as much viable patella as possible.
Modern plating is particularly useful for 34C2 and 34C3 injuries because it can capture multiple peripheral fragments and provide multiplanar fixation.
Inferior pole fracture
Preserve and fix the inferior pole whenever technically possible.
Options include:
- Plate fixation
- Transosseous high strength sutures
- Suture anchors
- Cerclage augmentation
- Combined constructs
Partial patellectomy with patellar tendon advancement is reserved for a truly unreconstructible small distal fragment, because shortening the patella alters patellofemoral biomechanics and can reduce quadriceps efficiency.
Total patellectomy
Total patellectomy should be a last resort for unreconstructible catastrophic injury, infection or exceptional salvage circumstances.
Loss of the patella substantially reduces the mechanical advantage of the extensor mechanism.
Open patella fracture
Treat as an open fracture with immediate antibiotics, operative irrigation and debridement followed by stable fixation where possible.
Rehabilitation
Repair the medial and lateral retinacula when disrupted.
Stable fixation should permit early controlled knee motion.
Excessive immobilisation leads to:
- Arthrofibrosis
- Quadriceps atrophy
- Patellar adhesions
- Loss of knee flexion
Major longer term complications are:
- Symptomatic hardware
- Knee stiffness
- Extensor lag
- Nonunion
- Patellofemoral post traumatic osteoarthritis
- Fixation failure
Hardware irritation remains particularly common after traditional tension band fixation, which is one reason contemporary low profile constructs are increasingly used.
