Treatment of Displaced Inferior Pole Patella Fracture
Surgical fixation is the standard of care for displaced inferior pole patella fractures to restore the extensor mechanism and allow early mobilization, with suture-based techniques offering comparable outcomes to traditional tension band wiring while minimizing hardware-related complications. 1, 2
Initial Assessment and Imaging
- Standard anteroposterior and lateral radiographs should be obtained to assess fracture displacement, articular congruity, and extensor mechanism integrity 3
- CT imaging with metal artifact reduction techniques may be utilized if radiographs are inconclusive or to better characterize comminution 3
- Assess for extensor mechanism disruption by evaluating the patient's ability to perform a straight leg raise against gravity
Surgical Indications
Surgery is indicated for displaced inferior pole fractures because these injuries typically disrupt the extensor mechanism and compromise knee function 1. Specific criteria include:
- Displacement greater than 2-3 mm of articular step-off 1
- Displacement greater than 1-4 mm of fragment separation 1
- Inability to perform active knee extension (extensor mechanism disruption) 1
- Transverse fracture patterns associated with patellar maltracking 3
Surgical Technique Selection
Suture-Based Fixation (Preferred for Inferior Pole)
Non-absorbable braided suture fixation through drill holes is the preferred technique for inferior pole fractures, offering several advantages over traditional metal fixation 2:
- Significantly lower reoperation rate (7.6% vs 30.6% for tension band wiring) due to reduced hardware-related complications 2
- Preserves patellar length and allows fixation of comminuted fragments 4
- Technique involves weaving suture through the patellar tendon and placing through drill holes in the proximal fragment 2
- Allows early knee mobilization without risk of symptomatic hardware 2
Separate Vertical Wiring Technique (Alternative for Comminution)
For comminuted inferior pole fractures, separate vertical wiring demonstrates superior biomechanical strength 4:
- Ultimate load to failure of 250.1 ± 109.7 N compared to 69.7 ± 18.9 N for partial patellectomy 4
- All fractures healed at mean of 7 weeks with no wire breakage or infection 4
- Preserves patellar length and avoids long-term immobilization 4
Tension Band Wiring (For Mid-Pole Fractures)
Traditional tension band fixation with K-wires or cannulated screws is technically demanding and associated with higher complication rates (30.6% requiring hardware removal) 2. This technique is more appropriate for mid-pole rather than inferior pole fractures.
Postoperative Management
- Early mobilization and knee flexion should be encouraged as soon as pain permits 5
- Weight-bearing as tolerated is appropriate following stable fixation 5
- Standard follow-up at regular intervals to assess fracture healing and range of motion 2
- All fractures typically heal radiographically, with mean healing time of 7 weeks for comminuted patterns 4
Expected Outcomes
- Range of motion at one year is comparable across fixation techniques when hardware complications are avoided 2
- Patients requiring reoperation for hardware removal have significantly diminished range of motion (p > 0.005) 2
- Mean functional grading of 29.5 points (out of 30) using the Böstman method for vertical wiring technique 4
Important Caveats
Nonoperative treatment is generally not recommended for displaced inferior pole fractures in active patients, as it results in activity limitations and inferior functional outcomes compared to surgical fixation 5. However, nonoperative management may be considered in:
- Patients with severe medical comorbidities limiting activity 5
- Those with minimal functional demands 5
- When displacement is truly minimal and extensor mechanism is intact 1
Symptomatic hardware remains the most common complication following operative treatment with metal implants, making suture-based techniques particularly attractive for inferior pole fractures 1, 2.