What is the treatment for knee trauma?

Treatment of Knee Trauma

Begin with plain radiographs (anteroposterior and lateral views) as the initial imaging study for all patients with knee trauma who meet Ottawa knee rule criteria, followed by conservative management with NSAIDs, functional support, and early mobilization for negative radiographs, or MRI without contrast if significant effusion, inability to bear weight, or mechanical symptoms persist beyond 5-7 days. 1, 2

Initial Clinical Assessment

Apply the Ottawa Knee Rule to determine need for immediate radiographs:

• Age >55 years 1, 3
• Focal tenderness at the patella or fibular head 1, 3
• Inability to bear weight for 4 steps immediately after injury 1, 3
• Inability to flex knee to 90 degrees 1, 3

Override Ottawa criteria and obtain radiographs immediately if:

• Gross deformity present 1, 2
• Palpable mass 1, 2
• Penetrating injury 1, 2
• Altered mental status (head injury, intoxication, dementia) 1, 2
• Neuropathy (paraplegia, diabetes) 1, 2
• Prosthetic hardware present 1, 2

Assess for vascular emergency in high-energy trauma:

• Check for absent pulses, pallor, or neurological deficits requiring immediate CTA of lower extremity 1, 2
• Vascular injury occurs in approximately 30% of posterior knee dislocations and requires prompt surgical intervention 1, 2

Radiographic Imaging Protocol

Obtain minimum two views:

• Anteroposterior view 1, 2, 3
• Lateral view with knee at 25-30 degrees flexion 1, 2, 3

Add supplemental views based on clinical suspicion:

• Patellofemoral view for suspected patellar fractures or dislocation 1, 3
• Cross-table lateral view with horizontal beam to visualize lipohemarthrosis (indicates intra-articular fracture) 1, 3
• Internal and external oblique views as needed 1, 3

Management Based on Radiographic Findings

If Fracture Identified on Radiographs

Proceed to orthopedic consultation for definitive management 2

Consider CT without contrast for:

• Better fracture characterization, particularly tibial plateau fractures (CT shows 100% sensitivity vs 83% for radiographs) 1, 2, 3
• Suspected radiographically occult fractures 1, 3

If Radiographs Negative

Initiate conservative management protocol:

• NSAIDs for pain and swelling control 2
• Functional support with semirigid or lace-up braces to decrease risk of recurrent injury 2
• Range of motion exercises with focus on quadriceps activation 2
• Progressive weight-bearing as tolerated 2

Re-examine at 3-5 days post-injury as excessive swelling and pain can limit initial examination accuracy 2

Indications for MRI Without Contrast

Order MRI if any of the following persist after initial conservative management:

• Significant joint effusion 1, 2, 3
• Inability to fully bear weight after 5-7 days 1, 2, 3
• Mechanical symptoms (locking, catching) suggesting meniscal injury 1, 2, 3
• Joint instability on examination suggesting ligamentous injury 1, 2, 3

MRI is superior for evaluating:

• Meniscal tears 1, 2
• Ligamentous injuries (cruciate and collateral) 1, 2
• Bone marrow contusions and occult fractures 1, 2
• Articular cartilage damage 1, 2

High-Energy Trauma and Knee Dislocation

For significant trauma (motor vehicle accident, suspected knee dislocation):

• Obtain radiographs first regardless of clinical decision rules 1
• Perform immediate reduction and splinting if frank dislocation present 4
• Order CTA of lower extremity if vascular injury suspected (less invasive than conventional angiography with similarly high accuracy) 1
• Consider MRA simultaneously with MRI for evaluation of internal derangement and vascular injuries 1

Orthopedic Referral Criteria

Refer to orthopedics if:

• Joint instability on examination 2, 3
• Inability to bear weight persisting beyond 5-7 days 2
• Mechanical symptoms present 2
• MRI reveals significant ligamentous injury or complex meniscal tear 2
• Vascular injury identified 1, 2
• Knee dislocation (multiligament injury) 5, 4

Critical Pitfalls to Avoid

Do not assume negative radiographs rule out significant injury - occult fractures and soft tissue injuries are common 2, 3

Avoid ordering MRI with IV contrast for routine meniscal or ligamentous injuries - it provides no additional diagnostic value over non-contrast MRI 2

Do not delay vascular imaging or surgical consultation in high-energy trauma - early restoration of flow to ischemic limb prevents amputation 4

Physician judgment should supersede clinical guidelines when appropriate - the primary goal is identifying fractures requiring immediate intervention while avoiding unnecessary radiation exposure 1, 3