Knee Pain During Stress Testing (Push and Pull Maneuvers)
When your knee exam hurts during push and pull testing (anterior/posterior drawer, Lachman, or varus/valgus stress tests), you most likely have ligamentous injury (ACL, PCL, or collateral ligaments), meniscal pathology, or joint instability that requires specific clinical correlation and imaging to guide management.
What the Pain Indicates
Pain during stress testing suggests:
- Ligamentous injury: ACL tears (anterior drawer/Lachman positive), PCL tears (posterior drawer positive), or collateral ligament injuries (MCL/LCL with varus/valgus stress)
- Meniscal tears: Joint line tenderness with pain during McMurray testing (83% sensitivity, 83% specificity) 1
- Joint instability: Chronic ligamentous laxity or post-traumatic changes
- Referred pain: Consider hip pathology if knee radiographs are unremarkable 2
Diagnostic Approach
Initial Imaging
Start with plain radiographs including anteroposterior, lateral, and tangential patellar views 2. This is the appropriate first imaging study even though 20% of patients inappropriately receive MRI without recent radiographs 2.
When Radiographs Are Normal or Show Only Effusion
Proceed to MRI without contrast 2. MRI is more sensitive than radiography and accurately depicts:
- Ligamentous tears (ACL, PCL, collateral ligaments)
- Meniscal abnormalities (though note: most people over 70 have asymptomatic meniscal tears) 2
- Joint effusion extent and synovitis
- Bone marrow lesions associated with increased pain 2
Important caveat: In patients 45-55 years old, meniscal tears are equally common in painful and asymptomatic knees, so correlation with clinical findings is essential 2.
Management Algorithm
Conservative Management First-Line
For most ligamentous and meniscal injuries without severe instability:
- Exercise therapy (knee and hip strengthening) - this is the foundation 3, 4, 1
- Education and self-management programs (strong recommendation) 4
- Oral NSAIDs when not contraindicated (strong recommendation for pain and function) 4
- Acetaminophen as initial oral analgesic if NSAIDs contraindicated 5, 4
Specific Injury Management
Medial collateral ligament injuries: Usually managed conservatively with physiotherapy 6
Meniscal tears:
- Degenerative tears: Exercise therapy for 4-6 weeks is first-line; surgery is NOT indicated even with mechanical symptoms 1
- Severe traumatic tears (bucket-handle with displaced tissue): Surgery likely required 1
ACL/LCL injuries: Most require surgical management 6
When to Refer for Surgery
- Severe traumatic meniscal tears with displacement
- ACL or LCL complete tears in active patients
- Failed conservative management after 4-6 weeks
- Persistent instability affecting function
Key Clinical Pitfalls
- Don't order MRI prematurely: 20% of chronic knee pain patients get MRI without recent radiographs, which is inappropriate 2
- Don't assume meniscal tears need surgery: In patients over 40, meniscal tears are often degenerative and respond to exercise therapy 1
- Don't miss referred pain: Always consider hip and lumbar spine pathology if knee imaging is unremarkable 2
- Examination timing matters: Acute knee exams can be difficult; repeat examination 3+ days after injury if initial assessment is limited 6