Knee examination: A systematic clinical guide

Key takeaways

A knee examination runs in four stages: inspection, palpation, range of motion, and special tests.

The Lachman test detects 85 to 98% of ACL tears, against 62 to 78% for the anterior drawer test.

Specificity is high across almost every knee special test, so a positive finding is worth acting on.

The Ottawa Knee Rules decide when an acute knee injury needs an X-ray, and MRI follows a clear film.

Structured templates in Pabau keep each stage’s findings retrievable at the follow-up visit.

Knee injuries make up a large share of musculoskeletal presentations in primary care, physical therapy, and orthopedic settings. A systematic knee examination narrows the differential, guides the imaging decision, and shapes management before a single scan is ordered.

This guide walks through the sequence in clinical order, from history-taking to special tests. It also sets out the accuracy data behind each test, so you know which findings can exclude an injury and which can only confirm one.

Whether you work in a physical therapy practice, a sports medicine setting, or general practice, a reliable framework reduces missed diagnoses. The sections below cover each stage of the knee examination in clinical detail, with technique notes and diagnostic accuracy where the evidence supports it.

What is a knee examination?

A knee examination is a structured clinical assessment of the knee joint’s integrity, function, and pathology. It follows a four-stage sequence: inspection, palpation, range of motion testing, and special tests. Each stage narrows the differential before special tests confirm a working diagnosis.

The examination applies across clinical contexts, from acute sports injury to long-term osteoarthritis monitoring. Recording findings the same way at every visit is what makes them comparable, which an EMR built for rehab handles with fixed templates. A standardized approach also cuts inter-examiner variability, which matters when several practitioners assess the same patient over time.

• Inspection: visual assessment at rest and during movement
• Palpation: bony landmarks, joint lines, soft tissue structures
• Range of motion: active and passive flexion and extension
• Special tests: ligament, meniscal, and patellofemoral provocation tests

Taking a focused history first

History guides the physical examination. Without it, you end up examining every structure instead of prioritizing the likely pathology. Five questions carry most of the diagnostic yield.

• Mechanism of injury: contact vs. non-contact, direction of force, landing mechanics
• Onset: acute vs. insidious, and any recent change in activity level
• Pain location: medial, lateral, anterior, posterior, or diffuse
• Mechanical symptoms: locking (true locking vs. pseudolocking), clicking, giving way
• Swelling: immediate swelling suggests hemarthrosis, delayed swelling suggests synovitis

Instability during pivoting or deceleration points toward ACL pathology. Locking that resolves with a twisting movement suggests a bucket-handle meniscal tear. Diffuse morning stiffness lasting more than 30 minutes raises concern for inflammatory arthropathy.

These flags decide which special tests to prioritize. The same reasoning runs through a hip examination, and referred hip pain is a common reason a knee complaint produces no knee findings at all.

Inspection: What to look for

Begin inspection with the patient standing, then supine. Standing reveals alignment, deformity, and gait. Supine gives a clear view of swelling and muscle bulk.

Standing inspection

• Alignment: genu valgum (knock knees), genu varum (bow legs), or hyperextension (genu recurvatum)
• Muscle wasting: quadriceps and vastus medialis oblique (VMO) atrophy, visible medially
• Gait: antalgic gait (shortened stance phase on the affected side), Trendelenburg sign, or a stiff-legged pattern
• Scars: previous arthroscopy portals, open surgery incisions, or trauma marks

Supine inspection

• Swelling: suprapatellar fullness suggests effusion, while localized swelling may indicate bursitis
• Erythema and warmth: visible redness raises concern for septic arthritis or crystal arthropathy
• Patellar position: patella alta or baja, visible at rest

Quadriceps wasting out of proportion to the history suggests a more chronic process, or reflex inhibition from a long-standing effusion. Note it before palpation, because it shapes what you tell the patient about the recovery timeline.

Palpation: Key landmarks and findings

Palpate systematically, moving from bony landmarks to soft tissue structures. Warn the patient about possible tenderness before you begin.

Bony landmarks

• Patella: patellar facets for tenderness (patellofemoral pathology), patellar pole for insertional tendinopathy
• Tibial tuberosity: Osgood-Schlatter in adolescents, patellar tendon insertion tenderness in adults
• Femoral condyles: medial and lateral, with lateral condyle tenderness in iliotibial band syndrome
• Fibular head: LCL attachment, and the common peroneal nerve runs close by

Joint line and soft tissue

Joint line tenderness is one of the most useful palpation findings. Pooled data put its sensitivity at 63% and its specificity at 77% for meniscal tears, per a systematic review in Evidence-Based Medicine. Medial tenderness points toward the medial meniscus, and lateral tenderness toward the lateral meniscus or lateral compartment disease.

Palpate the MCL along its course, from the medial femoral epicondyle to the proximal tibia. The LCL is easiest to feel with the knee in a figure-of-four position. Check the popliteal fossa for a Baker’s cyst in any patient with a chronic effusion.

Assessing knee effusion

Three tests detect effusion, each suited to a different fluid volume.

• Bulge sign (sweep test): best for small effusions. Sweep fluid medially toward the suprapatellar pouch, then tap the lateral side and watch for a medial fluid wave
• Patellar tap (ballottement): for moderate effusions; compress the suprapatellar pouch with one hand while tapping the patella sharply, and a click indicates fluid beneath
• Cross-fluctuation: for large effusions; compress one side of the suprapatellar pouch and feel for fluctuation on the opposite side

Range of motion: Active and passive testing

Normal knee range of motion runs from 0 degrees extension to 135-140 degrees flexion. Assess active movement first. Passive movement follows, to determine whether the restriction is contractile or structural.

• Active flexion and extension: the patient moves through full range while you note pain arcs, crepitus, and end-range limitation
• Passive flexion: a soft end-feel suggests effusion, while a hard end-feel suggests a bony block or osteophytes
• Hyperextension: lift the heel with the knee extended, and recurvatum beyond 5-10 degrees may indicate posterior capsule laxity
• Extension lag: full passive extension with no active extension indicates extensor mechanism weakness or disruption

A fixed flexion deformity means the knee cannot reach 0 degrees extension even passively. It is a key indicator of significant intra-articular pathology or posterior capsule contracture. Record the exact degrees of limitation at each visit, so you can track progression or response to treatment.

Special tests for ligament and meniscal injury

Special tests isolate individual structures. No test is diagnostic on its own, so read each one against the history and the palpation findings. The table below summarizes the key tests with technique and diagnostic accuracy.

Figures are drawn from published systematic reviews. Values shift with the population and the examiner’s experience, so cite the individual study in clinical reporting.

Read down the specificity column and the tests look interchangeable. Read down the sensitivity column and they separate sharply, which is what decides whether a negative result tells you anything.

ACL: Lachman test and anterior drawer test

The Lachman test is performed with the knee at 20-30 degrees of flexion. Stabilize the distal femur with one hand while applying an anterior force to the proximal tibia with the other. A positive test shows anterior translation greater than 3 mm with a soft or absent end-feel.

The Lachman outperforms the anterior drawer test in acute settings for a mechanical reason. The drawer test needs 90 degrees of flexion, which hurts in a fresh injury. The resulting hamstring guarding masks the translation you are trying to feel.

Collateral ligaments: Valgus and varus stress tests

Perform collateral tests at both 0 degrees and 30 degrees of knee flexion. At full extension the posterior capsule and cruciate ligaments contribute to stability, so isolated collateral laxity only shows at 30 degrees. Medial joint-line opening at 30 degrees indicates MCL injury.

Grade the laxity as you go. Grade I is 0-5 mm of opening and grade II is 5-10 mm. Grade III is more than 10 mm, or no firm end-feel at all.

Meniscal tests: McMurray’s, Thessaly, and Apley

For McMurray’s test, flex the knee fully, then extend it while applying internal rotation for the lateral meniscus or external rotation for the medial meniscus. Combine that with valgus or varus stress. A palpable or audible click at the joint line is positive.

The Thessaly test is performed at 20 degrees of flexion during single-leg stance, with internal and external rotation. It loads the meniscus through body weight, which is why it often reads more sensitively than McMurray’s in weight-bearing populations.

The Apley grind test is performed prone at 90 degrees of flexion, with downward compression and rotation. Pain on compression indicates meniscal pathology. Pain that eases on distraction points to ligamentous rather than meniscal involvement.

Patellofemoral examination and Clarke’s test

Clarke’s test, or the patellar grind, is performed with the knee extended. Apply pressure to the superior pole of the patella and ask the patient to contract the quadriceps. Anterior knee pain with this movement is a positive finding.

The patellar apprehension test is more specific for lateral patellar instability. Displace the patella laterally with the knee at 20-30 degrees. Apprehension, or a quadriceps contraction to protect the joint, counts as positive.

Once the special tests are done, assess neurovascular status. Check the popliteal, posterior tibial, and dorsalis pedis pulses. Test sensation across the L3-S1 dermatomes. Motor testing of ankle dorsiflexion (L4), great toe extension (L5), and plantar flexion (S1) completes the lower limb screen.

After a knee dislocation, treat this step as urgent. Popliteal artery injury is time-sensitive, and absent distal pulses call for an immediate vascular surgery consultation.

When to order imaging after a knee examination

Not every knee presentation needs imaging. The Ottawa Knee Rules, derived by Stiell and colleagues in Annals of Emergency Medicine, guide the X-ray decision after acute injury. Their sensitivity for clinically significant fractures approaches 100%.

X-ray is indicated if any one of the following is present:

• Age 55 or older
• Isolated patella tenderness, with no other bony tenderness
• Tenderness at the head of the fibula
• Inability to flex the knee to 90 degrees
• Inability to bear weight for four steps, both at the time of injury and on assessment

The Pittsburgh knee rules are the main alternative, and they cut more unnecessary films at a slightly narrower age range. Pick one rule as your practice default rather than switching between them case by case, because mixed criteria are where fractures get missed.

When the findings suggest soft-tissue pathology and no fracture, MRI is the investigation of choice. The American Academy of Orthopaedic Surgeons recommends MRI for suspected ACL or meniscal tears where the clinical picture stays inconclusive.

MRI adds the most value when the Lachman or McMurray’s test is equivocal. It also earns its place when pain or swelling blocks an adequate examination, or when surgery is planned. The same decision-rule logic drives the Ottawa ankle rules calculator for foot and ankle injury.

Documenting the findings

Documentation matters as much as the examination. An undocumented finding cannot inform a colleague at the next visit, support a medico-legal case, or track rehabilitation progress over time.

A structured note captures alignment and gait from inspection, then the exact tenderness locations from palpation. Use anatomical landmarks rather than “tender knee”. Record range of motion in degrees for both active and passive movement, and log each special test with its grade.

Free text makes that hard to sustain under time pressure. Practice management software like Pabau lets you build a knee examination form that prompts every stage in order. No section gets skipped on a busy list.

Consistent records also support audit and quality improvement. If a practice’s notes show a pattern of missed effusion documentation, the training fix can be aimed at that stage precisely.

How Pabau keeps knee examination findings comparable across visits

Most practices still record knee findings as free text. The wording changes with the practitioner, and the range of motion figures sit buried inside a paragraph. Charting progress means rereading six notes end to end.

Pabau replaces that with a form you design once. Drawing fields mark the tender joint line, numeric fields hold flexion and extension in degrees, and single-choice fields carry each special test result. Pabau Scribe, our AI scribe, can transcribe spoken findings straight into those fields during the consultation.

The payoff shows up at the follow-up. Last visit’s numbers are already on screen, so you measure change instead of estimating it, and a covering colleague reads the same structure you wrote.

Document musculoskeletal examinations in one structured place

Pabau gives physical therapy and sports medicine practices custom examination forms, so knee findings stay consistent between practitioners and stay retrievable at every follow-up.

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Conclusion

The sequence carries the diagnosis, not any single test. Inspection and palpation build the shortlist, range of motion measures the functional cost, and special tests confirm the structure at fault.

The accuracy data is the part worth holding on to. Almost every knee test is specific, so a positive finding usually means something. Only the Lachman, posterior drawer, and valgus tests are sensitive enough that a negative result genuinely lowers your suspicion.

Write the findings down in a form the next clinician can read at a glance. Book a demo to see how Pabau structures knee examination notes, so progress stays measurable across visits.

Continue your research

Rehabilitating a knee after injury? Return-to-running protocol for physical therapy sets out the staged criteria for getting a patient back to load safely.

Tracking knee outcomes over a course of care? Knee outcome survey is a ready-to-use patient-reported measure you can score at each review.

Handing out meniscal rehab exercises? Meniscus rehab exercises handout gives patients a printable progression they can follow between visits.

Choosing software for a physical therapy practice? Physiotherapy clinic management software compares what the main platforms handle for scheduling, notes, and billing.

Frequently asked questions