III. Mechanism
- Direct blow to anterior, flexed knee (direct injury)
- High force injury associated with Femur Fracture, Hip Dislocation or Knee Dislocation (secondary Patella Fracture)
- Rapid knee flexion against a eccentrically contracting quadriceps (uncommon, indirect injury)
- May result in sleeve Fracture as below
IV. Types
- Stellate Fracture
- Direct blow to Patella
- Sleeve Fracture
- Distal Patella Fracture due to quadriceps Muscle Contraction against a fixed lower leg
V. Exam
- Tenderness, swelling, Ecchymosis overlying the Patella
- Evaluate for breaks in the skin overlying the Patella
- Suggests Traumatic Arthrotomy (open Fracture)
- Evaluate extension mechanism
VI. Imaging
-
Knee XRay (esp. lateral Knee XRay and sunrise view)
- Evaluate for pneumoarthrosis (air within joint), suggesting a Traumatic Arthrotomy (open Fracture)
-
Knee CT without contrast Indications
- Non-diagnostic Knee XRay (e.g. suspected Tibial Plateau Fracture)
- Surgical planning (or MRI Knee)
- Suspected Traumatic Arthrotomy (open Fracture)
- Test Sensitivity and Test Specificity approaches 100% (better than saline load test)
- Konda (2013) J Orthop Trauma 27(9): 498-504 [PubMed]
VII. Differential Diagnosis
- Bipartite Patella (2% of uninjured patients)
- Congenital Ossification Center that failed to fuse
- Consider Bilateal Knee XRay (expect both Patellas to be bipartite in 50% of cases)
VIII. Management: Surgical versus non-surgical management
- Surgical indications
- Traumatic Arthrotomy (open Fracture) requires emergent Consultation
- Initiate Antibiotics, Tetanus Prophylaxis and send to operating room
- Fracture step-off of >2 mm on articular surface
- Fracture separation of >3 mm
- Associated with Retinacular disruption and active knee extension loss
- Traumatic Arthrotomy (open Fracture) requires emergent Consultation
- Non-surgical Indications
- Non-displaced Patella Fracture with intact articular surface
- Active knee extension against gravity intact
- Minimal Patella Fracture fragment displacement
- Articular surface with minimal involvement
IX. Management: General
- Acute management (for first week)
- Knee Immobilizer (knee in full extension)
- Non-weight bearing (Crutches)
- Ice and elevation
- Non-surgical management
- Week 1
- Start immobilization for 4-6 weeks
- Cylinder cast from groin to above ankle (with knee in full extension) OR
- Knee Immobilizer brace worn at all times except bathing (in highly compliant patients)
- Weight bearing
- Straight leg Exercises
- Start immobilization for 4-6 weeks
- Week 2
- Weeks 4-6
- Repeat Knee XRay and exam
- Continue knee immobilization until XRay demonstrates radiographic union
- Weeks 6-10
- Physical therapy for knee range of motion and quadriceps strengthening
- Repeat exam every 3-4 weeks until fully healed (typically 8-10 weeks from start of immobilization)
- Week 1
X. Complications
- Inability to extend knee
- Disrupted knee extension mechanism (Patellar tendon or quadriceps tendon)
- Premature Knee Osteoarthritis
- Related to articular surface defects (osteochondral defects)
XI. References
- Eiff (1998) Fracture Management for Primary Care, W.B. Saunders, p. 179-83
- Kiel (2022) Crit Dec Emerg Med 36(7): 18
- Spangler and Tollefson (2014) in Herbert 14(6): 9-11
Images: Related links to external sites (from Bing)
Related Studies
Concepts | Injury or Poisoning (T037) |
ICD9 | 822 |
ICD10 | S82.0 |
SnomedCT | 157237006, 208607004, 51037009 |
English | Fracture of patella, NOS, fracture of patella (diagnosis), fracture of patella, Broken knee cap, Patella fracture, fracture patella, patella fracture, fracture patellar, Fracture;patella, fracture knee cap, fractures patellar, fracture knee-cap, fractures patella, patellar fracture, broken knee cap, knee-cap fracture, Fracture of patella, NOS (disorder), Fracture of patella, Fracture of knee-cap, Fracture of patella (disorder), fracture; knee cap, fracture; patella, knee cap; fracture, patella; fracture, fractured patella |
Italian | Frattura della rotula |
Dutch | breuk van knieschijf, gebroken knieschijf, fractuur; knieschijf, fractuur; patella, knieschijf; fractuur, patella; fractuur, Fractuur van patella, knieschijfbreuk |
French | Rotule cassée, Fracture de la rotule |
German | gebrochene Kniescheibe, Fraktur der Patella, Patellafraktur |
Portuguese | Rótula partida, Fractura da rótula |
Spanish | Rótula rota, fractura de la rótula, fractura rotuliana, SAI (trastorno), fractura de rótula (trastorno), fractura de rótula, fractura de la rótula (trastorno), fractura rotuliana, SAI, Fractura de rótula |
Japanese | 膝蓋骨骨折, シツガイコツコッセツ |
Czech | Zlomenina čéšky, Zlomenina pately |
Korean | 무릎뼈의 골절 |
Hungarian | Patellatörés, Törött térdkalács |