1. Patello femoral instability
Case presentation
Dr. Moahammadreza Piri
Orthopaedic surgeon, Isfahan university of medical
sciences, Iran
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2. Case number 1
History:
40 year-old female
History of falling down and left
patellar dislocation ten years ago with
recurrent dislocation of patella
Complaining of knee pain and patellar
instability
Arthroscopic surgery ten years ago
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3. Physical exam
Positive J sign
Positive glide test
Positive grind test
Positive apprehension test
Positive patellar tilt
Q angle:27
Positive active tracking
test
3
9. Case number two
history:
33 year-old female with past history of falling down and
patellar instability
Many unsuccessful periods of non operative treatment
including rehabilitation
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14. Anatomy and biomechanics
Extensor mechanism:
Vastus lat.: 7-10degree
Vastus med longus: 15-18degree
Vastus med obligus: 55 degree
VMO is the main dynamic stabilizer
of patella
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39. 39
PF instability
The key to successful surgical interaction is
correctly identifying and treating the pathologic
anatomy producing the instability
Factors in patella instability:
• Trochlear dysplasia
• Patella tilt
• Patella alta
• Excessive TT-TG distance
Surgical treatment
52. Proposed treatment for case number one:
MPFL reconstruction by STT + lateral release
Proposed treatment for case number two:
MPFL reconstruction by STT + lateral release + antromedialization of
tibial tuberosity
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