The Slocum Test is a modified anterior drawer-style test used to assess anterolateral or anteromedial rotatory knee instability by changing tibial rotation. A positive result may suggest rotational laxity or increased anterior translation compared with the other side, but it does not confirm a specific ligament injury on its own.
Rotatory knee instability can involve several structures, including the cruciate ligaments, collateral ligaments, capsule, menisci, anterolateral structures, posteromedial structures and bony alignment.
The Slocum Test attempts to add rotational bias to anterior drawer-style testing. By changing the position of tibial rotation, the examiner may explore different patterns of anterior and rotational knee laxity.
It is commonly used alongside:
Lachman Test
Anterior Drawer Test
Pivot Shift Test
valgus stress testing
varus stress testing
meniscal assessment
knee swelling assessment
functional instability testing
imaging where clinically appropriate
Clinical descriptions identify the Slocum Test as a modification of the Anterior Drawer Test used to assess anteromedial rotary instability and anterolateral rotary instability.
Test name: Slocum Test
Also known as: Slocum’s test, Slocum rotary instability test
Body region: Knee
Purpose: Assess anteromedial or anterolateral rotatory knee instability
Commonly associated presentation: ACL-related laxity with possible capsular, collateral or rotational involvement
Positive finding: Increased anterior translation or rotational asymmetry compared with the other side
Negative finding: No meaningful side-to-side difference in anterior translation or rotational laxity
Best used with: Lachman Test, Anterior Drawer Test, Pivot Shift Test, varus/valgus stress tests and functional assessment
Key limitation: Published diagnostic accuracy values for the exact Slocum Test appear limited
The Slocum Test is a modified anterior drawer test.
It assesses anterior tibial translation while the tibia is rotated to bias different rotatory instability patterns.
The test may be used to assess:
anterolateral rotary instability
anteromedial rotary instability
anterior tibial translation with rotational bias
side-to-side difference
endpoint quality
instability response
In clinical descriptions:
internal tibial rotation is commonly used to assess anterolateral rotary instability
external tibial rotation is commonly used to assess anteromedial rotary instability
The test is not a stand-alone diagnostic tool.
The Slocum Test may help support assessment reasoning when rotational knee instability is suspected.
It may help professionals:
assess anterior translation with tibial rotation
compare involved and uninvolved knees
explore anterolateral versus anteromedial laxity patterns
identify whether rotational positioning changes instability response
document side-to-side differences
guide further ligament or functional testing
support referral or imaging discussion where appropriate
It should be used as part of a broader knee assessment rather than as a single decision-making test.
The Slocum Test assesses anterior tibial movement with rotational bias.
It may provide information about:
anterior tibial translation
rotational laxity
anterolateral rotary instability
anteromedial rotary instability
endpoint quality
side-to-side difference
client apprehension or guarding
It does not directly identify:
exact ligament torn
ACL fibre continuity
partial versus complete ligament injury
meniscal pathology
cartilage injury
bony injury
return-to-sport readiness
This test may be useful for:
experienced rehabilitation professionals
exercise professionals working within scope
strength and conditioning professionals working with allied health teams
movement assessment professionals
students learning knee special tests
professionals using Measurz or MAT for structured assessment recording
It may be relevant for clients who report:
knee giving way
pivoting injury
rotational instability
instability during cutting
instability during landing
recurrent knee shift
previous ACL injury
possible combined ligament injury
Use the Slocum Test when the history suggests possible rotational knee instability and the client can tolerate controlled drawer-style testing.
It may be useful when the client reports:
giving way
twisting or pivoting injury
instability with direction change
instability during sport
instability during uneven-ground movement
previous ACL injury or reconstruction
symptoms that suggest more than simple pain provocation
The test is more meaningful when it shows clear side-to-side differences in translation, rotation or endpoint quality.
Use caution with:
acute traumatic knee injury
large effusion or suspected haemarthrosis
suspected fracture
suspected multi-ligament injury
severe pain
high irritability
recent knee surgery
marked guarding
limited knee flexion
inability to relax the hamstrings
Stop testing if:
pain escalates
the client feels unsafe
guarding prevents accurate testing
symptoms feel unstable or threatening
the client asks to stop
there are red flags requiring medical review
Treatment table or plinth
Pain scale
Symptom and confidence recording
Measurz recording workflow
Optional comparison-side notes
Optional referral or further assessment notes where appropriate
Position the client lying supine.
Explain that the test assesses knee movement with the shin rotated in different positions.
The client should understand that the test will be controlled and stopped if symptoms become unsafe or uncomfortable.
Client lies on their back
Hip is flexed
Knee is flexed to approximately 90 degrees
Foot is placed on the table
Hamstrings should be relaxed
Compare both sides where appropriate
Sit lightly on or stabilise the client’s foot
Face the tested knee
Place both hands around the proximal tibia
Keep thumbs near the joint line or tibial tuberosity for reference
Observe the tibial position before applying force
Both hands hold the proximal tibia
Fingers wrap around the upper calf
Thumbs rest near the anterior tibia
Contact should be firm but not painful
Stabilise the foot and maintain the selected tibial rotation.
Monitor for:
hamstring contraction
quadriceps guarding
hip rotation
pelvis movement
foot movement
pain or apprehension
Testing is less reliable if the client cannot relax.
Perform anterior tibial translation with the tibia rotated.
Common variations include:
Internal tibial rotation: used to bias anterolateral rotary instability assessment
External tibial rotation: used to bias anteromedial rotary instability assessment
Apply a controlled anterior force to the proximal tibia.
Assess:
amount of anterior translation
rotational movement
endpoint quality
side-to-side difference
pain or apprehension
symptom familiarity
Ask the client to:
relax the thigh muscles
keep the foot relaxed
report pain, instability or apprehension
say whether the feeling is familiar
tell you immediately if they want the test stopped
Example instruction:
“I’m going to hold your shin in a rotated position and gently pull it forward to assess knee stability. Stay relaxed and tell me if you feel pain, instability or a familiar giving-way sensation.”
A positive Slocum Test may include:
increased anterior translation compared with the other side
increased rotational movement
soft or absent endpoint
clear asymmetry between internal and external rotation positions
familiar instability or giving-way sensation
apprehension linked to instability rather than pain alone
A negative finding involves:
firm endpoint
no meaningful side-to-side translation difference
no clear rotational asymmetry
no familiar instability response
no meaningful difference between rotation positions
Stop if:
pain increases sharply
guarding prevents movement
the client becomes highly apprehensive
the knee cannot be positioned safely
symptoms feel unsafe
the client asks to stop
Use controlled force only
Avoid aggressive pulling
Do not force tibial rotation
Compare sides where appropriate
Record whether laxity, pain or instability was the main finding
A positive Slocum Test may increase suspicion of rotational knee instability when anterior translation or rotational movement is greater than the comparison side.
A positive result is more meaningful when it matches:
pivoting injury mechanism
giving-way episodes
positive Lachman Test
positive Anterior Drawer Test
positive Pivot Shift Test
collateral ligament findings
meniscal or capsular findings
functional instability during sport or daily tasks
A positive result does not confirm ACL injury or a specific capsuloligamentous injury on its own.
Other factors may influence the result, including:
hamstring guarding
pain
swelling
examiner force
generalised joint laxity
previous knee injury
meniscal involvement
combined ligament injury
inconsistent tibial rotation
poor foot stabilisation
A negative Slocum Test may reduce suspicion when:
the test is performed well
the client is relaxed
no side-to-side difference is present
related ligament tests are also negative
the history is not strongly suggestive of instability
However, a negative result does not fully exclude ACL injury or rotational instability.
Some clients may only show instability during:
pivoting
cutting
landing
fatigue
sport-specific movement
higher-speed tasks
Interpretation is stronger when combined with history, swelling, Lachman Test, Anterior Drawer Test, Pivot Shift Test, collateral ligament tests, functional assessment and imaging where clinically appropriate.
High-quality diagnostic accuracy evidence reporting sensitivity, specificity or likelihood ratios for the exact Slocum Test appears limited.
At the time of writing:
Sensitivity: no high-quality published value found for this exact test and population
Specificity: no high-quality published value found for this exact test and population
Positive likelihood ratio: not established
Negative likelihood ratio: not established
Reference standard: not consistently established for this test
Clinical descriptions present the Slocum Test as a modified Anterior Drawer Test for anteromedial and anterolateral rotary instability, but exact diagnostic values are not well established in the sources found.
For broader ACL physical examination, recent reviews show that commonly used ACL tests such as Lachman, Anterior Drawer, Pivot Shift and Lever Sign vary in accuracy by setting, timing and study design. These values should not be directly assigned to the Slocum Test.
Practical interpretation:
A positive Slocum Test may increase suspicion when it shows clear asymmetry and matches the client’s history.
A negative Slocum Test does not exclude ACL injury or rotatory instability.
The test should be interpreted as a rotational drawer-style assessment, not a stand-alone diagnostic procedure.
Stronger interpretation comes from clusters of findings rather than one test result.
Specific reliability values for the Slocum Test appear limited.
Reliability may be influenced by:
knee flexion angle
degree of tibial rotation
anterior force magnitude
hand placement
foot stabilisation
client relaxation
hamstring guarding
pain and swelling
examiner experience
whether a binary or graded result is used
Validity is stronger when:
the test reproduces familiar instability
clear side-to-side difference is present
results match Lachman, Anterior Drawer or Pivot Shift findings
history suggests rotational instability
functional tasks reproduce similar instability
imaging findings, where available, support the broader presentation
Validity is weaker when:
pain is the only response
the client guards strongly
swelling limits motion
tibial rotation is inconsistent
no comparison side is available
symptoms occur only during sport-specific tasks
Rotatory knee instability is complex and can involve multiple structures, including cruciate ligaments, collateral structures, capsule, menisci and alignment factors. This supports the need to interpret the Slocum Test as one part of a broader assessment rather than as an isolated finding.
Common errors include:
not stabilising the foot
allowing hamstring contraction
inconsistent tibial rotation
pulling too aggressively
not comparing both sides
interpreting pain alone as a positive test
failing to assess endpoint quality
confusing anterior translation with rotational instability
using the test as a stand-alone ACL diagnosis
not recording whether internal or external rotation was used
Limitations include:
limited diagnostic accuracy evidence
limited published reliability data
examiner-dependent technique
difficulty standardising tibial rotation
reduced usefulness in acute painful knees
guarding can mask laxity
does not identify exact injured structure
may not reproduce dynamic sport instability
The Slocum Test may help professionals:
assess anterior tibial translation with rotational bias
explore anteromedial and anterolateral instability patterns
compare involved and uninvolved knees
document baseline rotational laxity response
guide further ligament testing
support referral or imaging discussion where appropriate
communicate assessment findings with allied health or sports medicine teams
For athletes, it may contribute to broader return-to-training reasoning when combined with:
strength testing
hop testing
landing assessment
change-of-direction assessment
confidence measures
sport-specific movement assessment
For general population clients, it may help explore giving-way symptoms during twisting, pivoting or uneven-ground movement.
For Measurz users, the main value is structured recording of test variation, side, translation, endpoint, rotational position and related findings.
Record:
test name: Slocum Test
side tested: left, right or both
result: positive, negative, unclear or unable to test
variation used: internal tibial rotation or external tibial rotation
suspected pattern: anterolateral or anteromedial rotary instability
client position
knee flexion angle
foot stabilisation method
force direction: anterior tibial translation
amount of anterior translation if estimated
endpoint quality: firm, soft or absent
rotational laxity observed
pain score from 0–10
symptom location
symptom quality
whether symptoms were familiar
guarding or hamstring contraction
comparison side
irritability level
reason for stopping if stopped early
related findings, such as Lachman, Anterior Drawer, Pivot Shift, varus/valgus stress or swelling
interpretation notes
planned retest date if monitoring change
Record whether the main response was:
increased anterior translation
increased rotational laxity
soft endpoint
familiar instability
pain only
guarding
unclear response
unable to test safely
This improves:
repeatability
communication
client education
assessment reasoning
team consistency
progress monitoring
reporting quality
Lachman Test
Anterior Drawer Test
Pivot Shift Test
Posterior Drawer Test
Varus Stress Test
Valgus Stress Test
Sweep Test
Knee Range of Motion Tests
It assesses anterior tibial translation with tibial rotation to explore anteromedial or anterolateral rotatory knee instability.
A positive result may include increased anterior translation, increased rotational laxity, soft endpoint or a clear side-to-side difference.
No. A positive result may increase suspicion of rotational knee instability or ACL-related laxity, but it does not confirm a specific injury on its own.
No. A negative result does not fully exclude ACL injury or rotational instability, especially if symptoms only occur during faster or sport-specific movement.
The Anterior Drawer Test assesses anterior tibial translation with the knee flexed. The Slocum Test adds tibial rotation to bias different rotational instability patterns.
High-quality published sensitivity, specificity and likelihood ratio values for the exact Slocum Test appear limited. It should be interpreted alongside other knee findings.
It is best used with history, Lachman Test, Anterior Drawer Test, Pivot Shift Test, collateral ligament testing, swelling assessment and functional movement testing.
The Slocum Test is a modified anterior drawer-style test.
It uses tibial rotation to assess anteromedial or anterolateral rotatory instability.
A positive result may include increased anterior translation, rotational laxity or a soft endpoint.
The test does not confirm ACL injury or a specific ligament injury on its own.
Published diagnostic accuracy evidence for the exact Slocum Test appears limited.
Interpretation is stronger when combined with history, Lachman, Anterior Drawer, Pivot Shift, collateral tests, functional assessment and imaging where relevant.
Measurz should record side, rotation variation, result, translation, endpoint quality, symptoms, guarding, comparison side and related findings.
Hughes, J. D., Rauer, T., Gibbs, C. M., & Musahl, V. (2019). Diagnosis and treatment of rotatory knee instability. Journal of Experimental Orthopaedics, 6, 48. https://doi.org/10.1186/s40634-019-0217-1
KneeGuru. (2024). Slocum test. https://www.kneeguru.co.uk/knee-a-to-z/slocum-test/
Physiopedia. (n.d.). Slocum’s test. https://www.physio-pedia.com/Slocum%27s_Test
Tanaka, M. J., et al. (2022). Diagnostic accuracy of physical examination tests for suspected acute anterior cruciate ligament injury: A systematic review and meta-analysis. International Journal of Sports Physical Therapy, 17(4), 606–615. https://ijspt.scholasticahq.com/article/36434-diagnostic-accuracy-of-physical-examination-tests-for-suspected-acute-anterior-cruciate-ligament-injury-a-systematic-review-and-meta-analysis
van Eck, C. F., van den Bekerom, M. P. J., Fu, F. H., Poolman, R. W., & Kerkhoffs, G. M. M. J. (2022). The diagnostic accuracy of clinical tests for anterior cruciate ligament injury. Knee Surgery, Sports Traumatology, Arthroscopy, 30, 3283–3292. https://doi.org/10.1007/s00167-022-06898-4
