Patellofemoral Disorders
Anatomy
Wiberg’s Classification of patella shape:
(Descriptive only and has no correlation to pathological conditions)
Type I |
Concave facets, symmetrical and equal in size (10%) |
Type II |
Medial facet is smaller. Lateral facet is concave (65%) |
Type III |
Medial is distinctly smaller with marked lateral predominance (25%) |
Patellofemoral kinematics
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Patella increases the moment arm of the quadriceps thus increasing quad strength by 33-50%
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The femur articulates only with a portion of the patella in each position of flexion, moving from proximal to distal with increasing flexion
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Patellofemoral joint reaction force
CLINICAL
History
Examination (Also see Torsional Profile Assessment)
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Standing examination
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Varus/ valgus alignment
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Examination of gait
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Pelvic obliquity and leg length inequality
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Q-angle
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Femoral and tibial torsion
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Miserable malalignment syndrome:
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internal torsion of the femur, external torsion of the tibia and pronated feet
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Position of subtalar joint. Pes planus.
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Sitting examination
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Supine examination
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Q angle (Normal M 10° F 15)
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Quadriceps mass (VMO atrophy)
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Hamstring tightness (popliteal angle)
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Examination for medial plica
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Tibial torsion
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Tenderness on quadriceps or patellar tendon insertion, patellar facets, retinaculum tightness hamstrings, or heel cord
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Crepitation and patellar compression
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Apprehension test (20-30°flexion)
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Clarke's Snatch test (pain on contraction of the quadriceps with the patella fixed)
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Patellar tilt (evaluates tension of the lateral restraint)
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Patellar glide test (knee flexed 20 to 30°)
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Decreased: 1 quadrant or less medial glide is indicative of tight lateral restraint
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increased: subluxable, or dislocatable patella
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Prone examination
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Hip motion - femoral neck anteversion (abnormal if IR exceeds ER by more than 30°)
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Quadriceps tightness - Ely test (especially rectus femoris)
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Leg-heel alignment (Normal 2-3° of varus)
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Hindfoot-forefoot alignment: (Normal: long axis of heel 90° perpendicular to transverse axis of forefoot)
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