Is a patient with minimally displaced fractures of the patella and significant joint effusion representing hemarthrosis safe to be placed in a knee immobilizer and follow up outpatient with orthopedics?

Management of Minimally Displaced Patellar Fractures with Hemarthrosis

Yes, a patient with minimally displaced bilateral lateral patellar fractures and hemarthrosis can safely be placed in a knee immobilizer with outpatient orthopedic follow-up, provided the extensor mechanism is intact and there are no contraindications to conservative management.

Key Clinical Assessment Required

Before discharge with immobilization, you must verify:

• Intact extensor mechanism: The patient must demonstrate active knee extension against gravity with no extension lag 1, 2
• Minimal displacement: Fracture fragments should have <2-3mm displacement and no articular step-off 1
• Hemodynamic stability: No signs of compartment syndrome or vascular compromise 1
• Ability to comply: Patient can follow weight-bearing restrictions and immobilization instructions 1

Immediate Management Protocol

Aspiration Considerations

• Tense hemarthrosis developing within 12 hours of injury should be aspirated to relieve pain and allow better clinical examination 3
• Aspiration confirms hemarthrosis (versus simple effusion) and provides symptomatic relief 3, 4
• In acute traumatic hemarthrosis, 89.4% of cases have significant intraarticular pathology requiring surgical intervention, making careful assessment critical 4

Immobilization Strategy

• Place knee in full extension in a knee immobilizer (removable brace) 1
• Immobilization should be initiated immediately once diagnosis is confirmed 1
• The immobilizer must be worn at all times except for hygiene and skin checks 1

Weight-Bearing Status

• Non-weight bearing or touch-down weight bearing with crutches initially 1
• Consider assistive devices to reduce weight-bearing on the affected limb 1

Critical Pitfalls to Avoid

Hidden Injuries Requiring Surgery

Hemarthrosis indicates serious injury until proven otherwise 3. In patients with acute traumatic hemarthrosis:

• 71% have ACL injuries (complete or partial rupture) 3
• 40% have osteochondral defects not visible on plain radiographs 5
• Associated meniscal tears occur in 24% of ACL injuries with hemarthrosis 3
• Sleeve fractures in children may show minimal bony avulsion but represent significant soft tissue injury 6, 7

When Conservative Management Fails

Absolute indications for urgent orthopedic consultation or surgical referral include:

• Extension lag present: Indicates extensor mechanism disruption requiring surgical repair 2, 6
• Displacement >3mm or articular incongruity: Requires open reduction and internal fixation 6, 7
• Patellar dislocation with osteochondral fragments: 40% have significant fragments requiring removal 5
• High-riding patella (patella alta): Suggests complete tendon disruption or large sleeve fracture 2, 6, 7

Outpatient Follow-Up Timeline

• First follow-up within 5-7 days: Reassess extensor mechanism, check for displacement progression on repeat radiographs 1
• Serial radiographs at 1-2 week intervals for first 3-4 weeks to monitor for late displacement 1
• Clinical re-evaluation: Any development of extension lag mandates immediate surgical consultation 2, 6

Special Populations

Pediatric Patients

• Sleeve fractures are unique to children and easily missed radiographically 6, 7
• High index of suspicion needed when hemarthrosis and high-riding patella present, even with minimal bony fragment 6, 7
• MRI is most accurate for confirming diagnosis and assessing extent of injury in equivocal cases 2

Patients with Neuropathy

• Clinical decision rules (Ottawa/Pittsburgh) do not apply to patients with diabetes, paraplegia, or altered mental status 1
• These patients may have no pain despite significant fracture and require radiographs regardless of clinical findings 1

Thromboprophylaxis Consideration

• Pharmacologic VTE prophylaxis with LMWH should be considered for lower extremity immobilization, particularly with risk factors present 1
• Recent evidence shows VTE rates of 4.3-40% in leg injuries immobilized ≥1 week without prophylaxis, reduced to 0-37% with LMWH 1
• The frequency of bleeding does not increase significantly with LMWH in this population 1