What should be evaluated in a patient with knee pain and how are the meniscal examination maneuvers (McMurray test, Apley grind test, Thessaly test) performed?

Evaluation of Knee Pain and Meniscal Examination Techniques

Initial Assessment Framework

Begin with plain radiographs (anteroposterior and lateral views at minimum) for any patient presenting with knee pain, as this is the foundation of evaluation regardless of suspected pathology. 1

History Elements to Obtain

• Age of patient - critical for differential diagnosis, as osteoarthritis is most likely in patients ≥45 years with activity-related pain and <30 minutes of morning stiffness (95% sensitivity, 69% specificity), while patellofemoral pain typically affects those <40 years 2, 3

• Mechanism of injury - acute twisting trauma suggests meniscal tear in younger patients, while degenerative tears occur in patients ≥40 years with osteoarthritis 3

• Location and quality of pain - anterior knee pain during squatting is 91% sensitive and 50% specific for patellofemoral pain 3

• Mechanical symptoms - locking, catching, or giving way (though these do NOT indicate need for surgery in degenerative meniscal tears) 3

• Ability to bear weight - inability to bear weight for 4 steps or flex knee to 90 degrees mandates immediate radiography per Ottawa knee rules 1, 4

• Presence of effusion or swelling - joint effusion visible on lateral radiograph at 25-30 degrees flexion suggests intra-articular pathology 1

Physical Examination Sequence

Always examine the uninjured knee first for comparison. 5

Inspection and Palpation

• Joint line tenderness - 83% sensitive and 83% specific for meniscal tears, though when used alone it is only 27% specific 4, 3, 6

• Focal bony tenderness - at patella or fibular head requires immediate radiography per Ottawa rules 1, 4

• Effusion assessment - palpate for fluid wave or ballottement 5

• Range of motion testing - both passive and active, documenting any limitations 5

Meniscal Examination Maneuvers

McMurray Test (Most Specific)

The McMurray test is 97% specific but only 52% sensitive for meniscal tears, making it excellent for ruling IN a tear when positive but poor for ruling OUT when negative. 4, 6

Technique:

• Patient supine with knee fully flexed
• Examiner holds heel with one hand and palpates joint line with other hand
• For medial meniscus: externally rotate the tibia while extending the knee from full flexion
• For lateral meniscus: internally rotate the tibia while extending the knee from full flexion
• Positive test: palpable or audible click/pop at joint line during the maneuver, often with pain 5, 6

Clinical interpretation: When combined with joint line tenderness (61% sensitivity, 84% specificity), diagnostic accuracy improves significantly 3, 6

Apley Grind Test

Technique:

• Patient prone with knee flexed to 90 degrees
• Examiner applies downward compression force through the heel while rotating the tibia internally and externally
• Positive test: pain with compression and rotation suggests meniscal pathology 5

Note: This test has less validation in the literature compared to McMurray, but remains clinically useful when combined with other findings 5, 6

Thessaly Test

Technique:

• Patient stands flat-footed on affected leg while holding examiner's hands for balance
• Patient rotates knee and body internally and externally three times at 5 degrees of knee flexion, then repeats at 20 degrees of flexion
• Positive test: medial or lateral joint line discomfort or a sense of locking/catching 6

Clinical pearl: The 20-degree flexion position is more sensitive for meniscal pathology 6

Bounce Test

Technique:

• Patient supine with knee extended
• Examiner places one hand on anterior thigh and uses other hand to bounce the heel, attempting full passive extension
• Positive test: springy block to full extension suggests displaced meniscal tear or loose body 5

Ligamentous Examination

Anterior Cruciate Ligament

The Lachman test is more sensitive and specific than the anterior drawer test and should be the primary ACL assessment. 4, 6

Lachman Test Technique:

• Patient supine with knee flexed 20-30 degrees
• Examiner stabilizes distal femur with one hand and applies anterior force to proximal tibia with other hand
• Positive test: increased anterior translation compared to contralateral knee with soft or absent endpoint 5, 6
• Accuracy: 74% sensitive, 95% specific for ACL tears 4

Posterior Cruciate Ligament

Posterior Drawer and Tibial Sag Tests:

• Tibial sag test: Patient supine with hips and knees flexed 90 degrees; observe for posterior displacement of tibia relative to femur
• Posterior drawer test: From same position, apply posterior force to proximal tibia
• Accuracy: 81% sensitive, 95% specific for PCL tears 4

Collateral Ligaments

Valgus and Varus Stress Testing:

• Valgus stress (medial collateral ligament): Apply lateral-to-medial force at knee with slight flexion
• Varus stress (lateral collateral ligament): Apply medial-to-lateral force at knee with slight flexion
• Test at both 0 degrees (full extension) and 30 degrees flexion 5

Imaging Algorithm

When to Order Plain Radiographs (Ottawa Knee Rules)

Obtain radiographs immediately if ANY of the following are present: 1, 4

• Age >55 years with acute trauma
• Tenderness at head of fibula
• Isolated patellar tenderness
• Inability to bear weight for 4 steps
• Inability to flex knee to 90 degrees

When to Advance to MRI

If radiographs are normal or show only effusion but pain persists, MRI without IV contrast is the next appropriate study. 1

MRI is indicated for: 1

• Suspected meniscal tears requiring surgical evaluation
• Suspected ligamentous injuries
• Evaluation of bone marrow edema or occult fractures
• Assessment of articular cartilage damage
• Persistent pain despite conservative management

Critical caveat: In patients 45-55 years old, meniscal tears are equally common in painful and asymptomatic knees, and in those >70 years, the majority have asymptomatic meniscal tears 1. Therefore, finding a meniscal tear on MRI does NOT automatically indicate it is the pain source or requires surgery. 3

Common Pitfalls to Avoid

• Never assume normal radiographs exclude significant pathology - MRI may be needed for occult fractures, osteochondritis dissecans, or early cartilage injury 1

• Do not order MRI without recent radiographs first - approximately 20% of patients inappropriately receive MRI without plain films 1

• Consider referred pain sources - obtain hip radiographs if knee films are unremarkable, especially in adolescents where hip pathology commonly refers to the knee 1

• Joint line tenderness alone is insufficient - it has good sensitivity (75-83%) but poor specificity (27%) for meniscal tears and must be combined with other findings 4, 3, 6

• Mechanical symptoms do NOT mandate surgery for degenerative meniscal tears - exercise therapy is first-line treatment even with locking or catching 3

• Do not delay aspiration if infection is suspected - septic arthritis requires urgent intervention regardless of imaging findings 1