Inpatient admission, NPO for at least 8 hours, prophylactic intravenous antibiotics (cefazolin), baseline coagulation profile, type and screen, radiographic assessment (AP/Lateral/Merchant views), and anesthesia consultation for general or spinal block.
Immediate post-operative immobilization in a knee brace in extension. Initiate gentle passive range of motion exercises as directed by physical therapy. Monitor neurovascular status. Manage pain with multimodal analgesia. Initiate weight-bearing as tolerated or per surgeon preference after confirming hardware stability. Scheduled follow-up at 2 weeks for suture removal and repeat radiography.
Comprehensive Clinical Guide: Open Reduction and Internal Fixation (ORIF) of the Patella
1. Introduction and Overview
The patella, or kneecap, is a sesamoid bone embedded within the quadriceps tendon. It serves as a critical fulcrum, increasing the lever arm of the extensor mechanism and protecting the articular surface of the femoral condyles. When the patella sustains a fracture—typically due to direct trauma or forceful eccentric contraction of the quadriceps—the integrity of the knee extensor mechanism is compromised.
Open Reduction and Internal Fixation (ORIF) of the patella is the gold-standard surgical intervention for displaced fractures. The primary objective of ORIF is to achieve anatomical reduction of the articular surface and restore the extensor mechanism’s tension, allowing for early mobilization and the prevention of post-traumatic osteoarthritis.
2. Technical Specifications and Mechanisms
The patella is subject to immense tensile forces. During knee flexion, the patella experiences compression against the femur, while the quadriceps and patellar tendon exert significant distraction forces.
Surgical Principles
- Anatomical Reduction: Restoration of the articular surface is paramount to prevent patellofemoral joint incongruity.
- Stable Fixation: The construct must be rigid enough to withstand cyclic loading during early physical therapy.
- Tension Band Wiring (TBW): The classic mechanism involves converting the distraction forces of the quadriceps into compressive forces at the fracture site.
- Compression Screws/Plating: Modern techniques often utilize cannulated screws combined with tension bands or low-profile locking plates for comminuted fractures.
| Fixation Method | Mechanism | Best Indication |
|---|---|---|
| Tension Band Wiring (TBW) | Converts tensile force to compression | Transverse fractures |
| Cannulated Screws | Interfragmentary compression | Simple transverse/pole fractures |
| Locking Plate | Rigid stabilization | Comminuted/complex fractures |
3. Clinical Indications and Usage
Indications for Surgery
Surgical intervention is indicated when the fracture compromises the extensor mechanism or the articular surface.
* Displacement: Any fracture with >2-3 mm of articular step-off.
* Gap: Any fracture with >3 mm of separation between fragments.
* Extensor Mechanism Failure: Inability of the patient to perform a straight-leg raise (SLR).
* Open Fractures: All open patellar fractures require urgent surgical debridement and stabilization.
Pre-Operative Preparation
- Imaging: Radiographic assessment includes AP, lateral, and sunrise views. A CT scan is often necessary for complex or comminuted fractures to map the articular fragment architecture.
- Physical Assessment: Evaluation of the skin integrity (crucial due to the thin subcutaneous tissue over the patella) and distal neurovascular status.
- Medical Optimization: Management of glycemic control and smoking cessation counseling, as nicotine significantly impairs bone healing.
4. The Procedure: Step-by-Step
Phase I: Exposure
A midline longitudinal incision or a transverse incision is made, depending on the fracture pattern and soft tissue status. Full-thickness skin flaps are developed to expose the patella while preserving the parapatellar retinaculum.
Phase II: Reduction
The fracture hematoma is evacuated. The articular surface is inspected and reduced using pointed reduction forceps. Temporary fixation is achieved using Kirschner wires (K-wires).
Phase III: Fixation
- For Transverse Fractures: Two parallel K-wires are placed longitudinally. A figure-of-eight stainless steel wire is passed around the K-wires, anterior to the patella, creating a tension band.
- For Comminuted Fractures: Fragments are reconstructed using small screws (2.0mm or 2.4mm). A low-profile locking plate may be applied to provide a "rafting" effect to support the articular surface.
Phase IV: Closure
The retinaculum is repaired using absorbable sutures. The integrity of the extensor mechanism is tested intraoperatively via passive flexion.
5. Post-Operative Recovery Protocol
The recovery trajectory is structured to balance healing with joint mobilization.
- Weeks 0–2: Immobilization in a hinged knee brace locked in full extension. Non-weight bearing or toe-touch weight-bearing.
- Weeks 2–6: Gradual increase in active range of motion (ROM). Usually 0–60 degrees, progressing to 90 degrees by week 6.
- Weeks 6–12: Strengthening of the quadriceps and hamstring muscles. Weaning off the brace.
- Month 3+: Return to functional activities, including agility and sport-specific training.
6. Complications and Risks
Despite the high success rate, ORIF of the patella carries specific risks:
1. Hardware Prominence: The most common complaint. The tension band wire may irritate the skin, necessitating secondary removal.
2. Post-traumatic Osteoarthritis: Resulting from articular incongruity or cartilage damage at the time of injury.
3. Non-union/Mal-union: More common in highly comminuted fractures or patients with poor vascular supply.
4. Infection: Risks are elevated due to the subcutaneous nature of the bone.
5. Arthrofibrosis: Stiffness of the knee joint due to prolonged immobilization or aggressive post-op scarring.
7. Alternative Treatments
- Non-Surgical Management: Indicated only for non-displaced fractures with an intact extensor mechanism. Treatment involves a cylinder cast or hinged brace for 4–6 weeks.
- Partial/Total Patellectomy: Reserved for severely comminuted fractures where reconstruction is biologically impossible. This is a salvage procedure and significantly alters knee biomechanics.
8. Frequently Asked Questions (FAQ)
1. How long does the surgery take?
Typically, the procedure lasts between 60 to 120 minutes depending on the complexity of the fracture.
2. Will I need to have the hardware removed?
Hardware removal is common if the patient experiences pain or skin irritation from the prominent wires or screws. It is typically performed 6–12 months post-op.
3. When can I return to driving?
Driving is generally prohibited until the patient can safely operate the vehicle, has adequate range of motion, and is off narcotic pain medications. This usually takes 6–8 weeks.
4. What is the success rate of this surgery?
Success rates are high, with over 90% of patients regaining full extension and functional range of motion.
5. How do I know if my hardware has failed?
Signs include sudden pain, a palpable "click" or gap, loss of ability to perform a straight-leg raise, or visible deformity.
6. Can I walk immediately after surgery?
Usually, weight-bearing as tolerated is permitted in a locked brace, but this varies based on surgeon preference and fracture stability.
7. Why is the patella so difficult to heal?
The patella is subject to high tension and is covered by relatively thin soft tissue, which limits the blood supply compared to other long bones.
8. What exercises should I avoid?
Avoid deep squats, heavy leg presses, or high-impact jumping during the first 3 months of recovery.
9. Is physical therapy mandatory?
Yes. PT is essential to prevent stiffness and to regain the strength required for daily activities.
10. What happens if I don't treat a displaced patella fracture?
Untreated displaced fractures lead to permanent extensor mechanism failure, chronic pain, and significant gait abnormalities.
9. Conclusion
ORIF of the patella is a sophisticated procedure requiring meticulous surgical technique. By prioritizing anatomical reduction and stable fixation, orthopedic surgeons can restore the extensor mechanism, allowing patients to return to their pre-injury quality of life. Success is heavily dependent on the synergy between the surgical intervention and a disciplined, progressive rehabilitation program.