Initial Management of Acute Right Knee Pain
Apply the Ottawa Knee Rule to determine if radiographs are needed, then initiate RICE protocol and anti-inflammatory medication while ruling out urgent pathology requiring immediate referral. 1, 2
Immediate Assessment for Urgent Referral
Refer urgently if any of the following are present:
- Severe pain with inability to bear weight for 4 steps combined with acute trauma 3
- Signs of joint infection: fever, swelling, erythema, and severely limited range of motion 3
- Inability to actively extend the knee or perform straight-leg raise (suggests extensor mechanism disruption from patellar fracture) 1
- Immediate joint effusion after trauma with inability to bear weight (suggests tibial plateau or other fracture) 1
Imaging Decision: Ottawa Knee Rule
Obtain anteroposterior and lateral knee radiographs if ANY of these criteria are met: 1, 2
- Age > 55 years
- Isolated patellar tenderness on examination
- Tenderness at the fibular head
- Inability to flex the knee to 90 degrees
- Inability to bear weight for 4 steps immediately after injury and in the emergency department
Special consideration: In patients unable to provide reliable history (intoxication, altered mental status, polytrauma), obtain radiographs regardless of decision-rule criteria 1
Initial Treatment Protocol
For patients without urgent referral criteria, begin immediate conservative management:
RICE protocol for first 24-72 hours: 4
- Rest from weight-bearing activities
- Ice application
- Compression
- Elevation
Anti-inflammatory medication to reduce pain and swelling 4
Next Steps Based on Initial Radiographs
If radiographs are negative but clinical suspicion for internal derangement remains (meniscal tear, ligament injury):
- Proceed with MRI without intravenous contrast as the next imaging modality 1
- MRI should be performed before any surgical planning to fully delineate ligamentous, meniscal, and bony injuries 1
Physical examination findings guide need for advanced imaging: 2
- Joint line tenderness is sensitive (75%) for meniscal tears but not specific (27%)
- McMurray test is specific (97%) for meniscal tears but not sensitive (52%)
- Lachman test is more accurate than drawer sign for anterior cruciate ligament tears
Non-Operative Management Considerations
Most acute knee injuries can be managed non-operatively: 5
- MCL tears (except grade III with concurrent injuries)
- Meniscal tears in patients under 40 years old (evidence shows equal outcomes to surgery at 1 year)
- Patellar dislocations (short period of knee bracing in extension with progression to weight-bearing as tolerated)
Grade III ACL tears are the notable exception requiring surgical consideration 5
Common Pitfalls to Avoid
- Do not skip radiographs in patients meeting Ottawa Knee Rule criteria – the rule is highly sensitive for fractures 2
- Do not order MRI as first-line imaging – plain films must be obtained first unless contraindicated 6
- Do not assume inability to bear weight rules out soft tissue injury – ligamentous and meniscal injuries can present with similar severity 3