What is the approach to managing a knee injury?

Approach to Knee Injury

Begin with a thorough history focusing on mechanism of injury (direct blow, fall, or twisting), immediate ability to bear weight, and presence of audible pops or immediate swelling, followed by selective radiography using validated clinical decision rules to avoid unnecessary imaging. 1

Initial Clinical Assessment

History - Key Elements

• Mechanism of injury determines injury pattern: twisting injuries suggest ligamentous or meniscal damage, direct blows suggest fractures or contusions, and hyperextension suggests cruciate ligament injury 2, 3
• Immediate weight-bearing ability after injury is critical—inability to bear weight immediately or take four steps suggests need for imaging 1
• Timing of swelling: immediate swelling (within 2 hours) suggests hemarthrosis from ACL tear or fracture, while delayed swelling suggests meniscal injury 4, 5
• Audible pop or snap at time of injury strongly suggests ACL rupture 5

Physical Examination - Specific Findings

• Palpate the fibular head for tenderness (Ottawa rule criterion) 1
• Assess isolated patellar tenderness without other bony tenderness 1
• Test knee flexion to 90 degrees—inability suggests significant injury requiring imaging 1
• Evaluate for joint effusion as a sign of intra-articular pathology 6
• Assess quadriceps and hamstring strength systematically 7

Note: Examination may be difficult acutely due to pain and swelling; repeat examination 3-5 days post-injury if initial assessment is limited 4

Imaging Decision Rules

Apply Ottawa Knee Rule (Age ≥18 years)

Order knee radiographs if ANY of the following: 1

• Age ≥55 years
• Tenderness at fibular head
• Isolated patellar tenderness
• Cannot flex knee to 90°
• Cannot bear weight immediately after injury
• Cannot take 4 steps in emergency department

This approach reduces radiographic studies by 23-35% while maintaining 100% sensitivity for fractures 1

Pittsburgh Decision Rule (Alternative)

Order radiographs if: 1

• Age <12 years OR >50 years
• Cannot take four weight-bearing steps in emergency department

Standard Radiographic Views

When imaging is indicated, obtain: 6

• Frontal projection (AP or PA)
• Lateral view
• Tangential patellar view (sunrise/skyline)

Acute Management (First 24-72 Hours)

RICE Protocol

• Rest: Avoid weight-bearing activities that provoke pain 2, 3
• Ice: Apply for 15-20 minutes every 2-3 hours 2, 3
• Compression: Use elastic bandage to minimize swelling 3
• Elevation: Keep knee elevated above heart level 2, 3

Pharmacological Management

• Start with paracetamol/acetaminophen as first-line oral analgesic 1, 6
• Add NSAIDs at lowest effective dose if paracetamol inadequate 1, 6
• Consider topical NSAIDs or capsaicin as safe alternatives with clinical efficacy 1, 7

Injury-Specific Non-Operative Management

Medial Collateral Ligament (MCL) Injuries

Most MCL injuries, including grade III tears without concurrent injuries, can be managed non-operatively 2, 5

• Allow weight-bearing as tolerated 2
• Hinged knee brace for comfort and protection during healing 4, 5
• Progressive physiotherapy focusing on range of motion and quadriceps strengthening 4, 5

Meniscal Tears

Acute traumatic meniscal tears in patients <40 years can be successfully treated non-operatively with outcomes equal to surgery at 1 year 2

• Small peripheral tears respond well to conservative management 4, 5
• Physiotherapy-led rehabilitation program 5
• Reserve arthroscopy for mechanical symptoms (locking, catching) or failed conservative treatment 4

Patellar Dislocation

Initial treatment consists of short period of knee bracing in extension with progression to weight-bearing as tolerated 2

• Immobilization for 1-2 weeks in extension 2
• Progressive quadriceps strengthening, particularly VMO (vastus medialis obliquus) 4
• Consider patellar taping for symptom relief during rehabilitation 6

Posterior Cruciate Ligament (PCL) and Lateral Collateral Ligament (LCL)

Isolated PCL and LCL injuries can usually be managed conservatively 4, 5

• Protected weight-bearing with crutches initially 5
• Emphasis on quadriceps strengthening to compensate for posterior instability 4

Referral Indications

Refer to Orthopedics When:

• Grade III ACL tears in patients desiring return to pivoting sports 2, 5
• Meniscal tears with mechanical symptoms (locking, catching) 4, 5
• Extensor mechanism disruptions (patellar or quadriceps tendon rupture) 5
• Multi-ligament injuries or combined ACL with meniscal tears 2
• Persistent symptoms despite 3 months of appropriate conservative management 8

Refer to Physical Therapy:

• All acute knee injuries benefit from structured rehabilitation 4, 5
• Focus on quadriceps activation, range of motion, and functional strengthening 7, 4

Common Pitfalls to Avoid

• Do not order MRI without recent radiographs first—this occurs inappropriately in 20% of chronic knee pain cases 6
• Do not assume all ACL tears require surgery—grade I and II tears without instability can be managed conservatively 2
• Do not delay re-examination—if initial exam is limited by pain/swelling, reassess at 3-5 days 4
• Do not overlook referred pain—if knee radiographs are normal but symptoms persist, evaluate hip and lumbar spine 6

Expected Recovery Timeline

Most patients report clinically relevant recovery, with pain decreasing most significantly in the first 3 months 8

• At 12 months follow-up, approximately 25% report full recovery and 50% report major improvement 8
• No clear difference in outcomes between patients with meniscal/ligament lesions versus those without structural damage on imaging 8