What is the initial management of an Anterior Cruciate Ligament (ACL) rupture in the emergency department?

Initial Management of ACL Rupture in the Emergency Department

In the emergency department, aspirate painful, tense knee effusions for symptom relief, immobilize the knee, provide analgesia, and arrange urgent orthopedic follow-up within 1-2 weeks to discuss definitive treatment options before the 3-month window for optimal surgical outcomes closes. 1, 2

Immediate ED Assessment and Intervention

Pain and Effusion Management

• Consider aspiration of tense, painful hemarthrosis for immediate symptom relief, though evidence is limited, this is a reasonable option based on expert consensus 1, 2
• Provide adequate analgesia with NSAIDs or other appropriate pain medications 3
• Apply ice/cryotherapy to reduce pain and swelling 1

Immobilization and Weight-Bearing

• Immobilize the knee in a hinged knee brace or knee immobilizer for comfort and protection 3
• Allow weight-bearing as tolerated with crutches for ambulation 4
• The brace provides temporary stability but is not a long-term treatment solution 1

Diagnostic Confirmation

• Clinical examination is highly sensitive (>80%) when performed properly, with the Lachman test being the most accurate clinical test for ACL injury 3
• MRI is the gold standard for diagnosis with 96% sensitivity and 97% specificity on 3T equipment and should be ordered to confirm the diagnosis and identify concomitant injuries (meniscal tears, collateral ligament injuries, bone contusions) 2, 3
• However, do not delay orthopedic referral waiting for MRI results 4

Critical Time-Sensitive Counseling

The 3-Month Window

Strongly emphasize to patients that early ACL reconstruction within 3 months significantly reduces the risk of additional cartilage and meniscal injury - this is a strong recommendation from the American Academy of Orthopaedic Surgeons 1, 2

• After 3 months, the risk of secondary injuries to menisci and cartilage increases substantially 2
• This timeframe is particularly critical for younger, active patients who want to return to pivoting sports 2

Treatment Pathway Discussion

• Younger patients (<30 years) with vigorous physical activity should be counseled toward early ACL reconstruction to provide knee stability and protect menisci 2
• Active patients of any age should consider reconstruction to lower future meniscus pathology risk and improve long-term pain and function 1, 2
• Conservative management (rehabilitation alone) is an option, but 39-51% of patients ultimately require delayed surgery due to persistent instability 5

Urgent Referral and Follow-Up

Orthopedic Consultation Timing

• Arrange orthopedic follow-up within 1-2 weeks for definitive treatment planning 4
• Earlier consultation is warranted if there are concerns for:
  • Locked knee (suggesting displaced meniscal tear requiring urgent arthroscopy)
  • Vascular compromise (rare but emergent)
  • Multi-ligamentous injury patterns 3

Pre-Surgical Rehabilitation Consideration

• If surgery is likely, early physical therapy referral for "prehabilitation" can improve postoperative outcomes including quadriceps strength, knee range of motion, and potentially decrease time to return to sport 6
• At minimum, one preoperative visit should ensure adequate voluntary muscle activation and absence of flexion contracture 6

Common Pitfalls to Avoid

• Do not dismiss the injury as "just a sprain" - ACL rupture has significant long-term consequences including up to 90% risk of knee osteoarthritis 3
• Do not delay orthopedic referral beyond 2 weeks - the 3-month surgical window is critical and patients need time for informed decision-making and pre-operative optimization 1, 2
• Do not recommend prophylactic knee bracing as definitive treatment - this is not effective for preventing ACL injury or managing established tears 1
• Do not miss concomitant MCL tears - these can be managed non-surgically alongside ACL reconstruction with good outcomes 1, 2