Knee exam: A systematic guide for clinicians

Key Takeaways

The knee exam follows four sequential phases: inspection, palpation, range of motion assessment, and special tests for ligament and meniscal integrity.

The Lachman test detects ACL tears with about 85% sensitivity, versus about 55% for the anterior drawer test. The difference comes from less hamstring interference at 30 degrees of flexion.

Combining multiple special tests, rather than relying on any single maneuver, significantly improves diagnostic accuracy for meniscal and ligamentous pathology.

Pabau’s digital clinical notes and structured SOAP templates help physiotherapy and orthopedic practices document knee exam findings consistently. That keeps records in line with HIPAA and CMS documentation standards.

Knee exam: A systematic four-phase clinical framework

A knee exam done without structure leaves too much to chance. A missed joint effusion or an overlooked positive Lachman can slip through when the examiner jumps straight to special tests. So can a patellofemoral sign that only shows under load. Building from inspection first catches what a rushed exam misses.

For physiotherapists, orthopedic clinicians, and primary care providers managing knee pain, a repeatable framework is the foundation of defensible clinical decision-making.

The physical therapy EMR a practice uses to document findings matters as much as the exam itself. Inconsistent notes create billing and compliance risk. This guide covers the complete knee exam sequence: anatomy, inspection, palpation, range of motion, and special tests. It also covers how to document findings and when to escalate to imaging.

Knee anatomy: Structures you must know before the exam

Mapping your hands to the right structures starts before the patient gets on the plinth. Clinicians who can visualize the anatomy in three dimensions run a faster, more accurate knee exam.

• Anterior cruciate ligament (ACL): runs from the posteromedial aspect of the lateral femoral condyle to the anterior tibial plateau; primary restraint to anterior tibial translation
• Posterior cruciate ligament (PCL): originates at the anterolateral surface of the medial femoral condyle; resists posterior tibial displacement
• Medial collateral ligament (MCL): broad ligament along the medial joint line; resists valgus stress
• Lateral collateral ligament (LCL): cord-like structure on the lateral side; resists varus stress
• Medial and lateral menisci: fibrocartilaginous C-shaped discs providing load distribution, shock absorption, and joint stability
• Patellofemoral joint: the articulation of the patella within the trochlear groove; vulnerable to malalignment and chondromalacia
• Tibial tuberosity: bony prominence on the anterior tibia; insertion of the patellar tendon and reference point for palpation

When taking a patient’s history before the knee exam, the location of their pain should immediately suggest which structures to prioritize. It also points to which special tests to include during palpation.

Taking a focused history before the knee physical exam

The history narrows your differential before a hand touches the joint.

• A twisting mechanism with a pop suggests ACL involvement.
• Medial joint pain that worsens with squatting points to the meniscus.
• Gradual anterior knee pain in a young, active patient often implicates the patellofemoral joint.

A structured musculoskeletal intake form captures these details consistently without relying on memory.

• Mechanism of injury: contact vs non-contact, direction of force, position of knee at time of injury
• Onset and duration: acute vs chronic; gradual onset suggests overuse or degenerative pathology
• Location of pain: medial, lateral, anterior, posterior, diffuse
• Aggravating and relieving factors: stairs, squatting, pivoting, rest, ice
• Locking, giving way, clicking: locking suggests a displaced meniscal tear; giving way points to ligamentous instability
• Red flag symptoms: significant swelling within two hours of injury, inability to weight-bear, neurovascular symptoms, fever with a hot joint

Inspection: What to look for in a knee physical exam

Begin with the patient standing if possible. A knee physical exam of gait and lower limb alignment reveals information no amount of supine testing can replicate. Look for antalgic gait, valgus or varus deformity, and quadriceps wasting.

• Standing: frontal plane alignment (valgus/varus), patella position (squinting or grasshopper patellae), Trendelenburg sign
• Supine: swelling (generalised vs focal), erythema, bruising, skin changes, surgical scars
• Effusion: loss of the normal medial and lateral dimples around the patella is a reliable visual sign of significant joint effusion
• Muscle wasting: compare quadriceps bulk bilaterally; measurable asymmetry of more than 2 cm at a fixed point suggests significant disuse atrophy
• Flexion contracture: observe the popliteal space with the patient supine; inability to fully extend at rest indicates posterior capsule tightness or posterior pathology

Palpation: Bony landmarks and soft tissue structures

Palpation is most informative when performed in a consistent sequence. Start lateral, move medial, then address the anterior structures. This approach avoids the common mistake of fixating on the painful area immediately and missing adjacent pathology.

• Joint line: medial then lateral, with the knee flexed to 90 degrees; point tenderness suggests meniscal pathology or collateral ligament involvement
• Tibial tuberosity: focal tenderness here in an adolescent is Osgood-Schlatter disease until proven otherwise
• Patella: superior and inferior poles, medial and lateral facets; patellar facet tenderness suggests chondromalacia patellae
• Popliteal fossa: assess for Baker’s cyst (fluctuant posterior mass, best felt with the knee in slight flexion)
• Soft tissue structures: iliotibial band at Gerdy’s tubercle, pes anserine bursa, patellar tendon

Detecting knee effusion: Bulge sign and ballottement

Effusion detection is a critical palpation skill. Two clinical tests apply depending on the volume of fluid present.

Bulge sign (for small effusions): milk fluid from the medial compartment by stroking upward along the medial side of the patella. Then stroke downward on the lateral side. A fluid bulge appearing on the medial side is a positive result. This test works best with effusions of 4-8 ml.

Patellar ballottement (for larger effusions): with the knee extended, compress the suprapatellar pouch with one hand to push fluid into the joint. Use two fingers of the other hand to sharply tap the patella. A palpable bounce, the patella rising off the trochlea and returning, confirms a ballotable effusion. Combining the bulge sign with ballottement improves detection across the full range of effusion volumes. Each test is more sensitive at a different fluid level.

Range of motion assessment in the knee exam

Normal knee range of motion runs from 0 degrees of extension to approximately 135 degrees of flexion. Clinical references suggest a variation of plus or minus 10 degrees, depending on age, build, and conditioning. Assess active movement first, then passive, then apply overpressure to determine end-feel.

Document active and passive ranges separately. A significant discrepancy between active and passive ROM, where passive substantially exceeds active, suggests quadriceps inhibition from pain or swelling. It is not a true mechanical block.

Ligament testing in the knee exam: ACL, PCL, MCL, and LCL

Ligament tests in the knee exam assess joint stability by applying controlled stress across specific structures. Each test has a defined patient position, examiner technique, and positive finding. Performing them in isolation, without correlating with history and inspection, risks over-diagnosing instability in hypermobile patients or under-diagnosing it in athletes with strong muscle guarding.

Lachman test vs anterior drawer test: Key differences

According to Solomon et al.’s JAMA review, the Lachman test’s superior sensitivity makes it the first-line ACL test in acute presentations. Valgus and varus stress tests assess MCL and LCL integrity respectively, applied at 0 and 30 degrees of flexion. Laxity at 0 degrees implicates cruciate involvement in addition to collateral ligament disruption.

Meniscal tests in the knee exam: McMurray, Apley, and Thessaly

No single meniscal test gives a reliable standalone diagnosis. Joint line tenderness on palpation combined with a positive McMurray or Apley test significantly raises the probability of a meniscal tear. The knee exam meniscus assessment is strengthened by testing with multiple provocation maneuvers and correlating with the history.

How to perform the McMurray test

The McMurray test is the most widely taught meniscal provocation test. It appears across the AAFP’s clinical evaluation guidelines for knee pain.

1. Position the patient supine with the hip flexed to 45 degrees
2. Flex the knee to maximum flexion while holding the heel with one hand and placing the other on the lateral joint line
3. To test the medial meniscus: externally rotate the tibia and gradually extend the knee while applying a valgus force
4. To test the lateral meniscus: internally rotate the tibia and gradually extend while applying a varus force
5. A positive result is a palpable or audible click or clunk at the joint line, combined with reproduction of the patient’s pain

Pain alone without a click is less specific. The McMurray test’s sensitivity for meniscal tears ranges from 53 to 89%, depending on the population studied. Sensitivity rises further when the test is combined with clinical joint line tenderness.

Note on the Thessaly test: early studies reported sensitivity above 90%, but independent replication has produced more modest results. Clinicians using sports medicine software to track clinical findings over time may find the Thessaly test adds value as part of a battery. It works best in patients whose symptoms are aggravated by weight-bearing activity rather than passive end-range movement.

Patellofemoral exam: Patellar grind, glide, and apprehension

Patellofemoral knee examination maneuvers assess tracking, articular surface integrity, and instability risk. They are often deferred in favor of ligament and meniscal tests. That skips a significant source of anterior knee pain, particularly in younger active patients and runners.

• Patellar grind test (Clarke’s sign): apply downward pressure on the patella and ask the patient to contract the quadriceps. Pain and apprehension with this maneuver suggest chondromalacia patellae. Note: high false-positive rate in asymptomatic individuals.
• Patellar glide: assess medial and lateral displacement of the patella with the knee slightly flexed. Less than one quadrant of lateral glide suggests lateral retinacular tightness.
• Patellar apprehension test: slowly displace the patella laterally while the patient is relaxed. Apprehension or attempted knee flexion to reduce the patella indicates patellofemoral instability or a history of dislocation.

When to order imaging after a knee physical exam

Most competitors’ knee exam guides stop at special tests. This section addresses what happens when the clinical picture is incomplete. Applying the Ottawa Knee Rules, an evidence-based decision tool validated across emergency and primary care settings, reduces unnecessary radiography without missing clinically significant fractures.

Refer for plain X-ray if the patient meets any of the following Ottawa Knee Rule criteria:

• Age 55 years or older
• Isolated tenderness of the patella (with no other bony tenderness)
• Tenderness at the fibular head
• Inability to flex the knee to 90 degrees
• Inability to weight-bear (four steps) both immediately after injury and in the clinical setting

MRI is warranted in two situations. First, order it when exam findings suggest internal derangement, such as a positive Lachman, positive McMurray, or locked knee. The diagnosis then needs confirmation before surgical or procedural intervention. Second, order it when symptoms persist beyond 6-8 weeks of conservative management despite a clinically negative exam. Notably, return-to-running assessment protocols for athletes recovering from knee injury should incorporate both clinical exam thresholds and imaging findings before clearance.

The original Ottawa Knee Rules validation study, published by Stiell et al. in JAMA in 1996, found 100% sensitivity for clinically significant fractures. It also reported a 28% relative reduction in radiography rates. Applying them consistently within a documented knee exam workflow reduces unnecessary imaging costs and patient radiation exposure without compromising diagnostic safety.

Documenting the knee exam in clinical practice

A thorough knee exam is only as useful as its documentation. Poorly structured notes create problems at every stage: billing, medicolegal review, handover between clinicians, and outcome tracking. This guide to writing effective clinical notes covers how to capture both objective findings and the clinical reasoning that connects a musculoskeletal assessment.

A well-structured SOAP note for a knee exam contains these elements:

• Subjective: mechanism, onset, location, aggravating/relieving factors, functional impact
• Objective: inspection and palpation findings with anatomical reference, active and passive ROM in degrees, and special test results (name, technique, positive or negative, symptom reproduction)
• Assessment: working diagnosis or differential, clinical reasoning
• Plan: imaging referral (with Ottawa Knee Rule rationale if applicable), treatment approach, follow-up timeline

Standardizing this structure across a practice reduces documentation time and improves audit readiness. Safer clinical documentation practices for physical assessment focus on precision in recording special test results. A note that says “special tests positive” without naming the test or the positive finding is clinically meaningless and creates medicolegal exposure. Practices managing physiotherapy compliance requirements under CMS documentation standards need each test named, the patient position described, and the positive or negative result stated explicitly.

Pabau’s digital intake forms and structured clinical templates help physiotherapy and orthopedic practices build knee exam documentation workflows. Findings land in a consistent, codeable format. The AI-assisted clinical notes tool further reduces the time clinicians spend on note-writing after complex musculoskeletal assessments. That leaves more of the appointment for the patient instead of the keyboard. Clinicians setting up a new physiotherapy practice benefit from embedding these templates into the new-patient workflow before the first appointment is booked. That beats retrofitting documentation after a compliance review. For teams looking at structured patient records, Pabau links each clinical note to the patient’s longitudinal record. ROM improvements, test results, and imaging reports then sit in one accessible place across the episode of care.

Standardize your knee exam documentation

Pabau gives physiotherapy and orthopedic practices structured SOAP templates, digital intake forms, and AI-assisted note generation. Every knee exam gets documented consistently, compliantly, and in less time.

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Conclusion

Missed knee pathology almost always traces back to a rushed history, an unstructured exam, or documentation that skips what was tested. The four-phase framework, anatomy through inspection, palpation, ROM, and special tests, exists to catch what a rushed exam would otherwise miss.

Pabau’s structured clinical templates help musculoskeletal practices turn exam documentation into a repeatable workflow that holds up under audit. If your practice is still documenting knee exams in free text, it is worth seeing what a structured system looks like. Book a demo to see how Pabau supports orthopedic and physiotherapy practices.

Continue your research

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