Special Tests

Summary 

An overall summary of the special tests for the knee would be that none are 100% accurate in detection pathology within the knee (but neither are radiological investigations) and therefore they should be used and interpreted with care and used in conjunction with subjective findings. 

Anterior Cruciate Ligament (ACL)  – Lachmans Test 

The Lachmans Test is an anterior draw of the tibia on a stabilised femur at 15-30 degrees of knee flexion, primarily looking for signs of instability.

See link for visual representation of the test: https://www.youtube.com/watch?v=dH_jnTy1rNk&index=12&list=PLAD99E958AC0F43B1

Numerous studies have examined the sensitivity and sensitivity of the Lachmans test with results ranging from 80-99% for sensitivity and a specificity of 95%. Adaptations can be made for those examiners with small hands or patients with large legs. 

Anterior Cruciate Ligament (ACL) – Pivot shirt Test 

The pivot shift test attempts to produce an anterior subluxation of the lateral tibial plateaux in relation to the femoral condyle as the knee comes into extension.  The test looks for reproduction of the instability symptoms. 

See link for visual representation of the test: https://www.youtube.com/watch?v=ZWEGB0ToXZo&index=22&list=PLAD99E958AC0F43B1

Several studies have been performed to determine the diagnostic accuracy of this test with results reporting sensitivity from 84-98% and specificity of 98% in an anesthetised patient,  however only 35% when the patient is awake.

Posterior Cruciate Ligament  (PCL)  – sag sign

A passive test looking at the position of the tibia on the femur when the patient is laying supine, knee flexed at 90 degrees, foot placed on the bed. The test looks for a posterior drop of the tibial plateaux in comparison to the femoral condyles. 

The literature reports sensitivity of the sag sign is 70-90 % and specificity 99-100%, however there is limited research.

Posterior Cruciate Ligament  (PCL) – Posterior draw test

A therapist facilitated posterior draw of the tibia on the femur. With the knee in the same position as the Sag Sign test, the tibia is first glided anteriorly relative to the femoral condyles and then posteriorly, looking for signs of instability compared to the opposite leg. 

See link for visual representation of the test: https://www.youtube.com/watch?v=rP_1cZgMEq0&index=13&list=PLAD99E958AC0F43B1

The literature suggests a sensitivity of >90% and specificity of <95% , increasing with these percentages when used in combination with the Sag Sign test. 

Collateral ligaments – medial and lateral stress tests  (MCL/LCL)

The collateral ligament tests stress the knee into a valgus/varus direction between 0-30 degrees of flexion, looking for pain and laxity. 

See link for visual representation of the test:

MCL: https://www.youtube.com/watch?v=NMi2RsAohSw&list=PLAD99E958AC0F43B1&index=14

LCL: https://www.youtube.com/watch?v=GDheZioSCs4&index=15&list=PLAD99E958AC0F43B1

Little is known regarding the accuracy of the MCL/LCL stress tests but are commonly used in clinical practice. 

Patellofemoral joint tests (PFJ) 

Special tests for the PFJ as a pain producing structure, for  position, alignment and direction of movement are poor. Often the reasons for anterior knee pain are multifactorial and require a comprehensive assessment by a physiotherapist. 

Meniscal Tests – McMurrays

The McMurrays test aims to approximate the femoral condyle with the tibial plateaux, thereby compressing and then sheering across the meniscal surface, looking for clicking sensation and pain. There have been a number of modifications of this test through the years, making direct comparison of research studies difficult. 

See link for visual representation of the test. 

https://www.youtube.com/watch?v=fkt1TOn1UfI&index=18&list=PLAD99E958AC0F43B1

There is a wide variation in the reported sensitivity (16-58%) and specificity (77-98%) of the McMurrays test for detecting meniscal tears. It is thought to still be useful when combined with other special tests and subjective finding.

Meniscal Tests – Eges

This is often called the standing McMurrays Test as is produces and compression and sheering through the meniscal surfaces similar to the McMurrays. 

See link for visual representation of the test. 

https://www.youtube.com/watch?v=FGs1WlmUdWg&index=21&list=PLAD99E958AC0F43B1

The literature reports the detection of medial meniscus tears with a sensitivity of 61% and specificity of 81%, and slightly higher with lateral meniscus tears, sensitivity 64% and specificity 90%. 

Meniscal Tests – joint line tenderness 

This test involves palpation directly over the joint line (thereby anterior portion of the meniscus) both medially and laterally in a flexed knee. 

The literature reports sensitivity of in the range of 55-85% and specificity of 29-67%. Joint line tenderness is also present in other pathologies around the knee, so used in isolation may not be that good, but when combined with other meniscal tests, increases it validity as a test for meniscal tears. 

References: 

Malanga G, Andrus S, Nadler S & McLean J (2003) Physical Examination of the knee: A review of the original test descriptions and scientific validity of common orthopaedic tests. Arch Phys Med Rehabil Vol 84, April 2003 pg 592-603

Akseki DOzcan OBoya HPinar H (2004) A new weight-bearing meniscal test and a comparison with McMurray’s test and joint line tenderness.Arthroscopy. 2004 Nov; 20(9):951-8.

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