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 ASSESSING ADULT KNEE PROBLEMS


History

The common presenting symptoms from knee problems are pain, swelling, giving away and locking. A provisional diagnosis could be formulated in many cases just by a careful history!

Pain:

Onset: Was it following an injury (even if it is minor)?  Trauma – mechanism and the force of the injury will give some clue. Was the patient able to walk after the injury and able to continue the game (if so it is unlikely to be a serious injury). If the injury was significant and the patient was unable to walk because of the pain, it suggests possible significant injury.

Was there swelling after the injury? If so, did it occur immediately (within an hour or so) or overnight? If within a an hour or so – likely to be haemarthrosis and this may be due to ACL rupture, peripheral meniscal tear or osteochondral fracture – needs  A&E/specialist  assessment.

Pain location: Often I find a good starting point is to ask the patient to point to the area of pain. If the patients put their hand over the front of the knee – the most likely problem is in the patellofemoral compartment. It is quite a common problem in middle aged patients (particularly women) and often no obvious abnormality is found and the main line of treatment is physiotherapy. It could be also due to patellofemoral arthritis and it would be appropriate to get x rays including skyline view.

If the patient points with a finger to the medial or lateral joint line, the most likely problem is a meniscal tear or medial or lateral compartment arthritis. The patient may also put their hand over the outer or inner aspect of the knee (It is not unusual in my practice to see patients being referred as possible meniscal tear when often the pathology is anterior knee pain and I then refer them to physiotherapy.)

If the patient places the hand all around the knee, it could suggest a more generalised problem including osteoarthritis. Swelling could be present in both osteoarthritis and inflammatory arthritis.

Exacerbating factors: What increases the pain? In patella-femoral problems, the pain increases particularly in activities which involve bending/high flexion of the knee including sitting for long periods, getting up from sitting posture (often the patient feels a painful catching sensation), climbing stairs – particularly down stairs, walking in slopes – particularly downhill, kneeling etc.,

In arthritis affecting the medial or lateral compartment, while the pain can increase with the above activities, the pain often increases even with level walking.

Rest pain can be present when the arthritis gets worse and also in any inflammatory condition. Very rarely a sinister pathology may need to be ruled out.  Rest pain uncontrolled by conservative measures would often be considered by the surgeons as a possible indication for surgical treatment like a knee arthroplasty in appropriate cases (although not necessarily essential).

Swelling:

Majority of the swellings in the knee is due to an effusion. This could be due to a number of reasons including osteoarthritis, inflammatory arthritis as well as intra-articular problems like a meniscal tear. Generalised swelling can also occur following a minor or major injury. If the swelling gradually occurs over a period of time (eg example overnight following an injury), it is unlikely to be due to a haemarthrosis. However, if the knee swells in a matter of couple of hours, it is likely to be due to haemarthrosis and the likely causes include ACL rupture, peripheral meniscal tear or osteochondral fracture which may be associated with a patellar dislocation.

Localised swelling could be due to a number of reasons including meniscal cyst, bursa, ganglia, etc., They can vary in size which may depend on the activity level. Rapidly enlarging localised swelling should be evaluated to make sure there are no sinister causes. Localised swelling which increase in size rapidly

Locking:

Although locking is classically taught as being associated with a meniscal tear or a loose body, majority of the locking episodes are not true locking. With true locking (which is due to a mechanical block like a meniscal tear), the patient is not able to do terminal extension (20 degrees or so) but will still have reasonable flexion. In psuedo-locking (which is the more common presentation), the locking is associated with significant pain and the knee is locked solidly. Usually this is due to anterior knee pain secondary to patellofemoral problems like maltracking although it can also occur with patellofemoral arthritis. If enquired, the patients often report a bent knee activity (like coming down stairs) which caused the locking. Gradually as the pain improves the knee movement also gradually returns.

Giving away:

This is a common symptom in ACL rupture.  The patients feel a sensation of instability particularly during pivoting activities while running in a straight line may not cause any instability symptoms. A history of a significant injury with immediate swelling (hemarthrosis) should alert such a diagnosis. However, a significant number of patients without an ACL rupture also complain of giving away or a buckling sensation of the knee particularly while climbing stairs. This is usually due to a patello-femoral problem including arthritic changes. Rarely, other ligamentous injuries could also give symptoms of instability.

Clinical Examination:

I check the gait first – particularly to see if there is any antalgic gait or deformity. At the same time the back of the knee could also be inspected  (popliteal fossa).

If appropriate I check the back (upper lumbar problem can present as pain radiating to the knee). I also assess the hip movements particularly rotation and flexion. Log rolling is a particularly good test as it does not produce any force in the knee joint.  Hip examination is very important important. I am sure many of you would probably heard anecdotal stories of hip problems presenting as knee pain and was missed initially because the hip examination was not done!

The knee joint is checked for any swelling, effusion, warmth, quadriceps wasting (can occurs in a very short period) . Moderate effusion could be tested by balloting the patella. Minor effusion can be checked with a “wipe test”. When there is generalised swelling but no effusion, it suggests possible synovial hypertrophy.

 Wipe Test


Wipe Test:   This test is used to diagnose subtle effusion (when there is not enough fluid to do patellar tap test). The effusion is wiped in from the medial aspect and then wiped out from the lateral aspect. If there is fluid, a fluid bulge will be visible over the medial aspect). Wipe test is negative in the patient.

The presence of tenderness is elicited in a systematic way particularly assessing along the medial joint line and lateral joint line.  The range of movement is assessed to see if there is any limitation. Patellar tracking is also assessed during active flexion and extension.

 Then the stability of the knee is assessed (medial and lateral as well asanteroposterior instability). The medial and lateral stability is assessed by valgus and varus tests in both 30 degree knee flexion and full extension. The anterior instability is assessed with Lachmann test and anterior drawer test. The Lachmann test is easier to perform and is a better test for assessing anterior instability compared to anterior drawer test. Posterior instability is assessed by posterior drawer test (suggestive of a PCL injury).

 Lachman Test Method 1


Lachman test (method 1): This is a better test to check for anterior instability (suggesting ACL injury)  than the anterior drawer test.  With the knee in about 30 degrees of flexion, the examiner  lifts the tibia anteriorly with one hand, while supporting the thigh with the other hand. If the anterior cruciate is ruptured, there is more anterior translation of the tibia when  compared to the opposite knee and there is no firm end point. Sometimes it is a difficult test to perform particularly if the patient is apprehensive or the patient is very muscular. In those instances, method 2 may be easier.

Lachman Test Method 2


Lachman test (method 2): This  may be easier to perform particularly if the patient is apprehensive or muscular. The  patient’s knee is supported by the examiner’s bent knee on the couch. This supports the patient’s knee thus relaxing the patient. The examiner stabilises the thigh with one and uses the other hand to pull the tibia  anteriorly. If the anterior cruciate is ruptured, there is more anterior translation of the tibia when  compared to the opposite knee and there is no firm end point.

While McMurray’s test is a clinical test taught as being specific for a meniscal tear and I perform it as a part of clinical examination, I find the test often non-specific. Often patients with arthritis (including patellofemoral arthritis) complain of pain during McMurray’s test.

McMurray’s Test For Medial Meniscus


McMurray’s test (for medial meniscus):   This test is used to diagnose medial meniscal tear. The examiner feels the medial joint line with one hand. The knee is fully flexed and gradually extended while at the same time exerting a valgus force and external rotation to the knee. A painful clicking contributes a positive McMurray’s test suggesting a lateral meniscal tear. However, there may only be pain in many cases and it is not a very sensitive test. It may also be difficult to perform when there is an acute injury.

McMurray’s Test For Lateral Meniscus


McMurray’s test (for lateral meniscus):   This test is used to diagnose lateral meniscal tear. The examiner feels the lateral joint line with one hand. The knee is fully flexed and gradually extended while at the same time exerting a varus force and internal rotation of the knee. A painful clicking contributes a positive McMurray’s test suggesting lateral meniscal tear. However, there may only be pain in many cases and it is not a very sensitive test. It may also be difficult to perform when there is an acute injury.

Assessment of the patellofemoral compartment is quite an important part of the knee examination. Tenderness could be elicited along the border and also underneath the patella. I use the Clarke’s test to assess pain from the patellofemoral compartment. I generally do this test last as sometimes the pain reproduced may make further examination difficult.  

Clarke’s Test


Clarke’s Test:   This test is used to diagnose pain from the patello-femoral compartment (anterior knee pain which is quite a common condition). The examiner places his/her hand underneath the patient’s knee and the patient is asked to actively contract the quadriceps against the examiner’s hand. This is repeated with the examiner exerting pressure on the superior pole of the patella trying to prevent the proximal movement of the patella with the quadriceps contraction. While it can produce some discomfort even in normal people, the reproduction of the symptoms suggest pain from patello-femoral origin. I tend to do this as the last test in knee examination as sometimes the patients may feel as sharp pain.

The posterior part of the knee is also examined to check for swelling, tenderness etc., There are a number of other special tests. But it is probably not essential to do every test during a knee examination and generally the above simple tests would be sufficient in a busy outpatient setting and the tests could be tailored depending on the history.

Once a provisional diagnosis is made, further management would depend on the severity and duration of the symptoms and the provisional diagnosis. 

Radiological Investigations:

If a patient with a knee problem is referred to me by the general practitioner, generally I would like to have the following x-rays.

1. In young patients in whom arthritis is not suspected – AP standing and lateral and skyline views .

2. In patients in whom arthritis is suspected – AP standing with calibration, lateral with calibration and skyline views.

MRI scan may be required in some cases to aid the diagnosis.

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