3. CAUSES:
Mechanical overload of the patellofemoral
joint.
a) Malcongruence - patellofemoral surfaces
b) Malalignment – extensor mechanism
- weakness of vastus medialis
Single injury – damage to articular surface
4. PATHOLOGY
Degeneration of articular cartilage-Precipitant
Changes in articular cartilage + subchondral bone
1.Cartilage N appearance with only biochemical changes but bone
shows reactive vascular congestion
OR
2.Cartilage softening/fibrillation with or without subarticular
intraosseous hypertension
Fibrillation usually on undersurface of the patella at the jn. of medial
and odd patellar facet /median ridge confined to superficial zones
and heals spontaneously.
NOT A PRECURSOR OF OA!
8. Lateral Articular surface involvement-usually
congenital tightness of lateral quadriceps
expansion
„Ficat’s hyperpression zone syndrome’
Or
Excessive Lateral Pressure Syndrome
Predisposes to OA
Lateral Release for prophylaxis
10. CLINICAL FEATURES
• Introspective teenage girl or athletic young adult
• Flat foot / Knock kneed athletes
• Spontaneous Pain in front of knee/ beneath the knee
cap
• Maybe h/o recurrent displacements/injury
• Aggravated by activity/climbing down
stairs/standing after prolonged sitting with knees
flexed
• Both knees
• Swelling-give way-catching(not true locking)
• Grating/grinding sensation when knee is extended
11. Signs
Appears N knee
Malalignment/tilting of patella
Quadriceps wasting
Effusion
Crepitus on moving the knee
Tenderness under the edge of the patella
Small high patella
In severe cases a/w Patella Alta
“Theatre sign”
12. Press patella against femur to elicit pain and asking patient
to contract the quadriceps first with central pressure then
compressing the medial facet and then the lateral facet
Apprehension test + implies previous
subluxation/dislocation.
Patellar tracking with pt seated at edge of the couch, flexing
and extending knee against resistance
Patellar alignment gauged by Q angle-angle subtended by
the line of quadriceps pull and the line of patellar ligament.
Should not exceed 20 degrees
Structures around knee and hip examined r/o referred pain
13. STAGES
I: swelling and softening of the cartilage
II: fissuring within the softened areas
III: fasciculation of articular cartilage almost to
level of subchondral bone;
IV: destruction of cartilage with subchondral bone
exposed
14. Grading (Bentley 1992)
• Grade I: area <0.5 cm diameter
• Grade II: Area 0.5 – 1.0 cm diameter
• Grade III: area 1.0 – 2.0 cm diameter
• Grade IV: area >2 cm diameter
a: softening, swelling/fibrillation of cartilage
b: Full thickness cartilage loss to bone
15. IMAGING
• X Rays- skyline view
lateral view with knee half flexed
Tangential views at 30, 60 and 90 degrees of
flexion
Best seen on slightly overexposed lateral X ray
Axillary radiograph determines which facet is involved
Most accurate to measure malpositon CT/MRI with knee in
full extension and varying degrees of flexion.
16. • Diagnosis made only on Arthroscopy or surgery
• Arthroscopy is useful to r/o other causes of anterior
knee pain. Also to know presence and extent of the
lesion and probing of patella with soft probe
• Gauge patellofemoral congruence, tracking and
alignment
26. Preventive Measures
Short-arc extensions
Done sitting up or lying down.
Rolled-up towel to support the thigh
keep leg and foot in the air for 5 seconds.
Lower foot as knee is bent slowly.
Repeat 10 times for each leg, twice a day.
27. Straight-leg raises
Done lying down.
Lift whole lower limb at the hip with the knee extended
keep it up in the air for 5 seconds. Then lower slowly.
Repeat 10 times for each leg, twice a day.
28. Quadriceps isometric exercises
Done sitting up, with legs extended in front
Tighten quadriceps muscles by pushing the knees
down onto the floor.
Hold for 5 seconds.
Repeat 10 times each leg, twice a day.
29. Stationary bicycling
low tension setting improves exercise
tolerance without stressing the knee.
Seat should be high enough so that the leg is
straight on the down stroke.
Start with 15 minutes a day and work up to 30
minutes a day.