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SUThe Pivot Shift Test: Understanding Dynamic Knee Instability
The Pivot Shift Test is one of the most reliable clinical exams for detecting ACL insufficiency, particularly because it reproduces the dynamic instability patients experience during activity. But what’s really happening biomechanically?
🔬 Mechanism:
• With the knee extended, the tibia is subluxed anteriorly due to the lack of ACL restraint.
• As the knee is gradually flexed while applying valgus and internal rotation force, the iliotibial band (ITB) shifts from an extensor to a flexor - beautifully appreciated in this patient.
• Around 30–40° of flexion, the tibia suddenly reduces back into place, creating the characteristic “pivot shift.”
🎯 Why It Matters:
• A positive pivot shift indicates functional instability, which is a major factor in deciding surgical intervention.
• Unlike the Lachman test (which assesses pure translation), the pivot shift replicates the rotational instability seen in cutting and pivoting sports.
• The test is only valid if the MCL is intact since medial instability can mask the shift.
🦵 Clinical Tip:
A subtle pivot shift can sometimes be hard to appreciate. Using a relaxed patient under anesthesia often reveals a more pronounced shift.
#Orthopedics #SportsMedicine #knee #ACLInjury #KneeInstability #PivotShiftTest
#knee #ACL #pivotshift #meded
@surgeon_aujla
