What is the typical healing time for a knee contusion?

Healing Time for Knee Contusions

Most knee contusions heal within 2-5 days with appropriate immediate management, though bone marrow contusions visible on MRI may take 6-12 weeks to fully resolve radiographically.

Immediate Management and Early Recovery

For simple soft tissue knee contusions (muscle/quadriceps contusions):

• Immediate immobilization in 120 degrees of knee flexion within 10 minutes of injury dramatically shortens recovery time to an average of 3.5 days (range 2-5 days) for return to unrestricted athletic activities 1
• This aggressive early positioning protocol appears superior to traditional approaches and should be maintained continuously for 24 hours 1
• After 24 hours, transition to active pain-free quadriceps stretching and isometric strengthening exercises 1

Bone Marrow Contusions (Bone Bruises)

For deeper bone contusions visible on MRI:

• Bone marrow contusions are present in approximately 28% of acute knee injuries and represent more significant trauma than simple soft tissue contusions 2
• These injuries are commonly associated with ACL tears, meniscal injuries, or occur as isolated lesions 2
• MRI-visible bone contusions can predict associated soft-tissue injuries and have implications for long-term outcomes, including development of focal osteoarthritis within 1 year 3

Timeline for Different Severity Levels

Mild Contusions (Soft Tissue Only)

• Return to full activity: 2-5 days with immediate proper immobilization 1
• Pain severity typically decreases most significantly in the first 3 months 4

Moderate to Severe Contusions (Bone Marrow Involvement)

• Radiographic healing on MRI: 6-12 weeks for most bone contusions 3
• Some contusions may become less visible with increased chronicity beyond 6 weeks 3
• Clinical improvement often precedes complete radiographic resolution 4

Clinical Recovery Expectations

• The majority of patients (76%) report full recovery or major improvement at 12 months following knee injury 4
• Most clinical improvement occurs within the first 3 months, with pain severity decreasing most rapidly during this period 4
• Lysholm knee scores show greatest improvement in the first 3 months post-injury 4

Important Caveats and Pitfalls

Risk of Myositis Ossificans:

• Quadriceps contusions carry risk of myositis ossificans (heterotopic bone formation) if not managed properly 1
• With appropriate immediate immobilization protocol, this complication rate is very low (approximately 4% in one series) 1

Associated Injuries:

• Bone contusions frequently indicate more serious underlying pathology - 50% of patients with bone contusions have associated ligamentous or meniscal injuries 2
• "Kissing contusions" (contusions on both joint surfaces) occur in 6.3% of acute knee injuries and are highly associated with ACL tears 2
• The presence of bone contusion on MRI should prompt careful evaluation for ACL, meniscal, and other ligamentous injuries 3

Long-term Implications:

• Bone contusions are highly predictive of focal osteoarthritis development within 1 year of trauma 3
• This risk necessitates appropriate counseling about long-term joint health and potential need for follow-up 3

When to Consider Advanced Imaging

• If clinical recovery does not follow expected timeline (significant improvement by 3 months) 4
• When there is concern for associated internal derangement (ligament or meniscal injury) 3
• MRI is the gold standard for detecting bone marrow contusions and associated soft tissue injuries 3