How Knee Pain Is Assessed: Examination, X-rays, MRI and Other Tests

Short answer: Most knee-pain assessments begin with a detailed history and a physical examination. A scan is not automatically the first or most useful step. The doctor considers how the pain began, where it is felt, whether the knee swelled, locks or gives way, and how the symptoms affect walking, work, sleep and sport. Examination then looks at movement, swelling, tenderness, strength, stability and function. X-rays, MRI scans and other tests are selected only when their result is reasonably likely to clarify the diagnosis or change management.

This matters because a scan finding is not the same as the cause of pain. Age-related changes, cartilage wear or meniscal abnormalities can appear on imaging even when they are not the main problem. Conversely, a normal X-ray does not show every ligament, meniscal, tendon or cartilage condition. A useful assessment brings the patient’s story, examination and any necessary test results together.

When knee pain needs urgent assessment

Most knee pain is not a medical emergency. Seek urgent medical care, however, if the knee is hot, very swollen and intensely painful, particularly with fever, chills, confusion or feeling seriously unwell. Infection inside a joint can damage cartilage and requires prompt investigation. A severe injury with obvious deformity, an open wound, inability to bear weight, rapidly increasing swelling, or a foot that becomes cold, pale, blue, numb or weak also needs urgent assessment.

Calf swelling or pain after injury, surgery, immobilisation or travel may require assessment for a blood clot. Sudden breathlessness, chest pain, fainting or coughing blood is an emergency. In Singapore, call SCDF 995 for a life-threatening emergency.^[1]

1. The history: what the doctor may ask

The consultation often starts before anyone touches the knee. The sequence of events can narrow the possibilities and guide a safe examination.

How did the pain start?

• A twist, pivot or sudden change of direction can raise concern about a ligament or meniscal injury.
• A direct blow or fall makes fracture, kneecap injury and soft-tissue trauma more relevant.
• A gradual onset may fit osteoarthritis, tendon overload, patellofemoral pain or another non-traumatic condition.
• A sudden painful, swollen knee without injury may require consideration of gout, another inflammatory arthritis or infection.

The doctor may ask whether there was a pop, whether activity could continue, and when swelling appeared. Rapid swelling after substantial trauma can suggest bleeding into the joint, although it does not identify one structure with certainty. Swelling that develops later can have several causes.

Where is the pain?

Pain at the front of the knee may involve the kneecap joint, patellar tendon, quadriceps tendon or nearby soft tissues. Pain along the inner or outer joint line can occur with meniscal or compartment-related problems. Pain behind the knee may arise from the joint, hamstring or calf structures, or a fluid-filled popliteal cyst. Location helps organise the examination, but it rarely establishes the diagnosis by itself.

What does “locking” or “giving way” mean?

Patients use these terms differently. True mechanical locking means the knee becomes physically stuck and cannot fully bend or straighten. This is different from temporary stiffness after sitting or reluctance to move because of pain. “Giving way” may reflect ligament instability, but it can also occur when pain inhibits the thigh muscles. The clinician will ask the patient to describe exactly what happens.

What matters in daily life?

An assessment should include the patient’s priorities. One person may need to climb stairs at an MRT station; another may need to squat or kneel at work; another may wish to return to running or court sport. The doctor may ask about walking distance, sleep, caregiving, upcoming travel, previous treatment, medicines, medical conditions and the time available for recovery. These details help define what a useful treatment outcome would look like.

2. What a clinical knee examination may include

The exact examination depends on the history and the patient’s comfort. It usually compares both legs and progresses from observation to more specific manoeuvres. Pain, swelling and guarding can reduce the reliability of tests soon after an injury, so reassessment may sometimes be useful.

Observation, walking and alignment

The clinician may observe standing alignment, muscle bulk, bruising, redness and swelling. Walking can reveal a limp, reduced knee bend, reduced confidence loading one side or difficulty controlling the hip and knee. Functional tasks such as a sit-to-stand, step-down or partial squat may be used when safe and relevant.

Swelling and palpation

Gentle examination can distinguish general soft-tissue swelling from fluid within the joint. The clinician may feel the kneecap, joint lines, tendons, bony landmarks, bursae and the back of the knee. Tenderness identifies a region that deserves attention; it does not necessarily identify the complete cause.

Movement, strength and function

Active and passive bending and straightening are compared. The doctor may assess whether the knee reaches full extension, whether movement is painful or blocked, and whether the kneecap moves comfortably. Thigh, hamstring, hip and calf strength may be checked. An inability to perform a straight-leg raise after injury can raise concern about the extensor mechanism and warrants prompt evaluation.

3. Ligament tests: Lachman, drawer and stress tests

Ligament tests apply controlled movement to assess whether the knee has more translation or opening than expected. These are clinician-performed tests; repeatedly trying them on an acutely injured knee at home may increase pain and does not provide a dependable self-diagnosis.

• Lachman and anterior drawer tests: commonly used when an anterior cruciate ligament injury is suspected.
• Pivot-shift test: assesses rotational instability associated with the anterior cruciate ligament, but pain and guarding can make it difficult in an awake, recently injured patient.
• Posterior drawer and posterior sag: used when a posterior cruciate ligament injury is possible.
• Valgus and varus stress tests: assess the medial and lateral collateral structures at selected knee positions.

A positive manoeuvre does not stand alone. The doctor considers the injury mechanism, swelling, comparison with the other knee and the quality of the endpoint. No single test is perfectly accurate in every setting, and diagnostic studies show that test performance varies with technique, injury timing and the population examined.^[2]

4. Meniscal tests: joint-line tenderness, McMurray and Thessaly

Menisci are fibrocartilage structures that help distribute load within the knee. When a meniscal problem is suspected, the clinician may use joint-line palpation, a McMurray manoeuvre or a weight-bearing Thessaly manoeuvre if it is safe. Pain, clicking or restricted movement may contribute to the assessment.

These tests are not definitive. Research has found variable diagnostic accuracy, especially when a test is used in isolation.^[3] A degenerative meniscal change on MRI may also coexist with osteoarthritis and may not be the principal pain generator. The practical question is not merely “Is there a tear?” but whether the whole clinical pattern suggests a lesion that changes rehabilitation, activity advice or a surgical discussion.

5. Patellofemoral, tendon and referred-pain assessment

For pain around the kneecap, assessment may include kneecap tracking, tenderness, movement under load and hip or thigh control. Patellar and quadriceps tendons are examined when pain relates to jumping, running, stairs or resisted knee extension. Bursae and superficial soft tissues are considered when pain and swelling are very localised.

The knee should not always be examined in isolation. Hip problems can present as knee pain, and nerve or lower-back conditions can produce pain, numbness or weakness that is felt around the knee. Pulses, sensation, strength or reflexes may be checked when the history suggests a neurological or circulation issue.

6. When an X-ray may be considered

An X-ray shows bone alignment, fractures, joint-space changes, bone spurs and some other bony abnormalities. It does not directly show the menisci and most ligaments. For chronic knee pain, the American College of Radiology rates knee radiography as usually appropriate initial imaging; MRI is generally not the initial scan before plain radiographs in this setting.^[4]

For suspected knee osteoarthritis, imaging may not always be necessary. NICE recommends a clinical diagnosis without imaging in people aged 45 or over who have activity-related joint pain and either no morning stiffness or stiffness lasting no more than 30 minutes, unless atypical features suggest another or additional diagnosis.^[5]

An X-ray may be considered sooner after significant trauma, particularly when fracture is possible. Clinicians may use validated decision rules, such as the Ottawa Knee Rule, alongside judgement to decide whether acute-injury radiographs are needed. These rules were designed for defined clinical settings and are not a substitute for self-assessing a serious injury.^[6]

Depending on the question, X-rays may be taken standing so that joint spaces are assessed under load, and additional views may examine the kneecap or a particular bone. The requested views should match the clinical concern.

7. When an MRI may be considered

MRI provides detailed images of ligaments, menisci, cartilage, bone marrow, tendons and other soft tissues without ionising radiation. It may be considered when:

• the history and examination suggest a clinically important ligament, meniscal, cartilage or occult bone injury;
• the knee is truly locked or there are persistent mechanical symptoms;
• significant symptoms remain unexplained after an appropriate initial assessment and, often, X-rays;
• the result could alter a rehabilitation plan, procedure or surgical decision; or
• there is concern about a less common condition not adequately assessed by X-ray.

For chronic knee pain with a negative initial radiograph or a radiograph showing joint fluid, the ACR rates MRI without contrast as usually appropriate next imaging, while the recommendation changes for other X-ray findings.^[4] This illustrates why “Do I need an MRI?” cannot be answered from pain severity alone.

MRI may be less useful when the likely diagnosis is already clear, the result would not change care, or appropriate initial management has not yet been tried. It can also reveal incidental abnormalities that create worry without explaining symptoms. Contrast is not routinely required for many common knee-pain questions; it is reserved for particular clinical indications.

8. Ultrasound, CT and other imaging

Ultrasound

Ultrasound can assess joint fluid, a popliteal cyst, superficial tendons, bursae and some dynamic soft-tissue findings. It may also guide an aspiration or injection when clinically appropriate. It is operator-dependent and does not provide the same comprehensive view of deep internal knee structures as MRI.

CT scan

CT gives detailed images of bone and uses ionising radiation. It may be selected for a complex fracture, detailed bony anatomy or pre-operative planning. It is not the routine first test for uncomplicated chronic knee pain.

Bone scan and other tests

Nuclear-medicine studies and specialised imaging are reserved for narrower questions. The doctor should be able to explain what the test is intended to confirm or exclude and how the result could affect the next step.

9. When blood tests or joint-fluid analysis matter

Blood tests are not routinely needed for every painful knee. They may help when infection, gout, inflammatory arthritis or a systemic illness is suspected. Results are interpreted with the symptoms and examination because no single routine blood test can reliably confirm or exclude infection within a native joint.^[7]

If the knee is acutely hot and swollen, aspiration may be urgent. A licensed medical doctor uses a sterile technique to remove joint fluid, which can be analysed for bacteria, white blood cells and crystals. The SANJO guideline recommends aspiration as quickly as possible when septic arthritis is suspected and prioritises bacterial identification, cell count and crystal analysis.^[7] Finding crystals can support gout or calcium-pyrophosphate disease, but infection still has to be considered when the overall presentation is concerning.

10. Patient-specific assessment scenarios

“I twisted my knee, heard a pop and it swelled quickly”

A prompt clinical assessment can check fracture risk, the extensor mechanism, ligament stability, circulation and nerve function. X-rays may come first if fracture criteria are present. MRI may follow if internal injury is suspected and the result would guide management.

“My knee has hurt gradually for years”

History, function and examination may strongly suggest osteoarthritis. An X-ray can be useful when symptoms are atypical, the diagnosis is uncertain or an intervention is being planned, but routine MRI is often unnecessary. Treatment decisions should reflect pain and function, not an image alone.

“My X-ray is normal but I still have pain”

A normal X-ray reduces the likelihood of certain bony findings but does not evaluate every soft-tissue structure. The next step might be targeted rehabilitation, reassessment, MRI or another test depending on the clinical pattern. “Normal X-ray” does not mean the symptoms are imaginary.

“I already tried physiotherapy and I am not improving”

The useful question is what was treated, for how long, how the exercises were progressed, and whether the original working diagnosis still fits. A reassessment may identify a missed contributor, a load that exceeds current capacity, or a reason to obtain imaging. It may also show that the programme needs modification rather than abandonment.

“I need to return to work next week”

Tell the doctor the exact work demands and deadline. Assessment may support a staged return, temporary restrictions, symptom-control measures or workplace modifications. No test can guarantee rapid recovery, and rushing to MRI does not itself shorten healing time. The aim is to identify immediate risk, preserve safe activity and make a realistic plan.

11. Preparing for a knee-pain appointment

• Note when symptoms started and any injury mechanism.
• Describe swelling, locking, giving way, clicking, fever, numbness or weakness precisely.
• Bring previous reports and, where possible, the actual scan images.
• List medicines, allergies and relevant medical conditions.
• Explain previous treatment and what did or did not help.
• State your priorities: work, sleep, walking, caregiving, travel or sport.

Questions worth asking include: “What is the leading diagnosis?”, “What serious possibilities have been considered?”, “What would this test change?”, “What can I do while waiting?” and “When should I seek reassessment?”

12. Coordinated doctor and physiotherapy assessment

Many knee conditions benefit from a combined view of diagnosis, symptom control and movement. The Pain Relief Clinic has in-house physiotherapists for integrated management with the licensed medical doctor. Where physiotherapy is clinically appropriate, this can make it easier to align examination findings, rehabilitation goals, progress reviews and decisions about whether further testing is warranted. Physiotherapists in Singapore are regulated by the Allied Health Professions Council, which maintains a public register.^[8]

The clinic can also assist with clinically appropriate referrals and supporting paperwork for insurance claims. Insurance coverage, required documentation, pre-authorisation and reimbursement depend on the patient’s policy and insurer. A referral, medical report or completed form does not guarantee approval or payment.

Frequently asked questions

Can a doctor diagnose knee pain without an MRI?

Often, yes. Many conditions can be assessed initially from the history, examination and, when needed, an X-ray. MRI is most valuable when it answers a remaining question that is likely to change care.

Does clicking mean I have a torn meniscus?

No. Clicking can occur for several reasons and may be painless. A meniscal problem becomes more relevant when clicking occurs with joint-line pain, swelling, restricted movement or a compatible injury, but assessment is still needed.

What is the difference between stiffness and a locked knee?

Stiffness usually eases gradually with movement. A truly locked knee has a persistent physical block to bending or straightening. New true locking, especially after injury, should be assessed promptly.

Should both knees be X-rayed?

Not automatically. The views and side requested depend on the clinical question. Comparison or weight-bearing views may sometimes help, but unnecessary radiation should be avoided.

Can ultrasound replace MRI?

Not for every question. Ultrasound is useful for fluid, cysts and selected superficial structures, while MRI offers a broader view of ligaments, menisci, cartilage and bone marrow.

Can treatment begin before a scan?

Frequently. If urgent causes have been considered and the clinical diagnosis is sufficiently clear, advice, activity modification and appropriate rehabilitation may begin without waiting for imaging. The plan should include a review point if progress differs from expectations.

Key points

• A good knee assessment starts with the patient’s story, function and priorities.
• Clinical manoeuvres contribute evidence but rarely provide certainty by themselves.
• X-rays are useful for bone, alignment and osteoarthritis-related changes; they do not show every soft-tissue problem.
• MRI is most useful when a defined unanswered question could change treatment.
• A hot, very swollen knee with systemic illness requires urgent assessment and may need joint aspiration.
• Imaging findings must be matched to symptoms and examination findings.

Arrange an assessment in Singapore

If knee pain is persistent, limits work or walking, follows an injury, or has not improved as expected, a structured assessment can help clarify the next step. The Pain Relief Clinic can provide doctor-led evaluation and coordinate in-house physiotherapy when clinically appropriate.

The Pain Relief Clinic
350 Orchard Road, #10-00 Shaw House, Singapore 238868
Call or WhatsApp: +65 9068 9605

Not every investigation or treatment mentioned on this page is required, offered or recommended by the clinic. Availability and permissible use of tests, devices and treatments in Singapore may change with evolving Ministry of Health, Health Sciences Authority and Singapore Medical Council requirements. Decisions require an individual clinical assessment and should follow current Singapore regulations and professional guidance.

References

1. Singapore Civil Defence Force. Emergency Medical Services.
2. Sokal PA, Norris R, Maddox TW, et al. The diagnostic accuracy of clinical tests for anterior cruciate ligament tears: a systematic review and meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy. 2022.
3. Konan S, Rayan F, Haddad FS. Do physical diagnostic tests accurately detect meniscal tears? Knee Surgery, Sports Traumatology, Arthroscopy. 2009.
4. American College of Radiology. ACR Appropriateness Criteria: Chronic Knee Pain.
5. National Institute for Health and Care Excellence. Osteoarthritis in over 16s: diagnosis and management (NG226).
6. Stiell IG, Greenberg GH, Wells GA, et al. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. 1996.
7. Ravn C, Neyt J, Benito N, et al. Guideline for management of septic arthritis in native joints (SANJO). Journal of Bone and Joint Infection. 2023.
8. Allied Health Professions Council Singapore. Registers of Allied Health Professionals.

Disclaimer: This information is provided for general reference only and should be used in consultation with your licensed medical doctor. It is not a diagnosis or a substitute for personalised medical advice. Seek urgent care for severe, rapidly worsening or warning-feature symptoms.

Reviewed by Dr Terence Tan — 12 September 2026