Case 6 Patellar Instability
Case
6
Patellar
Instability
What happened ? Age
at first dislocation ? Any
Trauma ?
Other joint involved ?
Exposure - Patient standing with exposure upto
umbilicus wearing undewear
Look
Alignment of lower Extremity
– Both patella facing forward ?
-At same level ?
-Any Genu Valgum ?
Walking
Squatting
Skin normal
Quadriceps muscles wasting
Feel
Temperature
Palpation
-
Sost
tissue
-
Deep
Trochlear Groove –
tenderness
Patellar Surface
Knee ROM
Special Tests
Apprehension test at 30
degree flexion
Patellar Tilt > 20
degree abnormal
Patellar Glide > 2
1/2quadrant abnormal
Patellar Grind +
Meaurement – Quadriceps muscle wasting and
Q-angle
Hip - ROM –
External rotation (ER) is more than Internal rotaion (IR) . In case of excess
Femoral Anteversion , IR > ER
Thigh foot axis – just check it with eye balling
Discussion
X-ray –
1)AP and Lateral
View Knee
Osteochondral fragments
Patella Baja (Insall Salvati Ration
< 0.8 )
Patella Alta
((Insall Salvati Ration > 1.2 )
(Insall Salvati Ratio – diagonal patellar length /
patellar tendon length )
Bluemansat Line
– at 30 degrees knee flexion in X-ray lateral film of knee , an imaginary line
passing through roof of intercondylar notch . Patella lying above this line is
also a Patella Alta.
2) Mechant’s
View
Patellar Tilt < 10 degrees
Congruence angle -16 to -10
Trochlear Dysplasia
2) MRI Knee – to
see Articular lesion , stat of Medial Patellofemoral Ligament
3) CT Knee – to
assess TT-TG distance
Pictures
Xray Knee
Lateral View
To see Patellar
Tilt Angle
Suculus Angle
Congruence Angle
Page 12
CT – TT – TG
distance
Types of
Patellar Instabilities
Etiological
Factors
1)Bony –
Increased Q Angle, Trochlear Dysplasia
2) Malalignment
– Excess femoral Anteversion , Tibial Extortion ,Genu Valgum
3)Soft tissue
–Weak Vastus Medialis Obliqus , Tight lateral Retinaculum
4)Medial
Patellofemoral Ligament Rupture
5)Ligamentous
Laxity
Treatment
Depends on Age ,
Q
– Angle ,
TT-TG (Tibia Tuberosity – Trochlear
Groove ) distance
Conservative
1)Cylindrical
Cast
2)Soft tissue
Procedures
a) Above Patella
Lateral Retinacular Release
VMO Advancement
b)Below Patella
Roux-Goldthwait
(medialization of lateral one third of patellar tendon )
Galeazi (rerouting
Semi-tendinosis)
3)Bony
a)Elmslie-Trillat – Medialization TT
b)Fulkerson – Medialization and
Anteriorization of TT
c)Hauser – medialization , distal
and posterior positioning of TT .
(Shortcoming – increases
patellofemoral joint reaction force and not done anymore )
d)Macquet – Anterior transfer –TT
High incidence of skin
necrosis , compartment syndrome , no effect on Q
angle
How this is Different from Habitual Dislocation of
Patella ?
Patella Doesnot
dislocate every time knee is flexed.
Cause of
Habitual dislocation of Patella
Quadriceps
Contracture , Hypoplasia of Patella ,Iliotibial band (ITB) contracture ,
femoral dysplasia
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