1、Patellofemoral joint disease,Patellar Instability,the incidence of patellofemoral dislocation is approximately forty three per 100,000 individuals, with a peak incidence at the age of fifteen years particularly high in females from ten to seventeen years old,symptom,Giving-way Pain 15% redislocation

2、(20-44%) 33% report pain and weakness,Objective patellar instability OPI history Potential patellar instability PPI Painful patellar syndrome,Pathoanatomy,Increased Q angle Femoral deformity or hyper-anteversion External tibial torsion Genu valgum Ligamentous laxity Patella alta Trochlear dysplasia,

3、Out of Knee,Four major anatomic factors,Trochlear dysplasia: The shape of the trochlea is abnormal, and the osseous constraint to patellar tracking is lost Excessive TT-TG distance: This represents abnormal alignment of the extensor mechanism and a consequent valgus-displacing vector acting on the p

4、atella. Patellar tilt: This is due to insufficient medial restraints, but trochlear dysplasia also plays an important role in its genesis. Patella alta: The patella engages the femoral trochlea late in flexion, and this predisposes to instability .,Physical Examination,Mediolateral Tilt Intra-examin

5、er k= .57 Inter-examiner k= .18,Physical Examination,Assessing Patellar Orientation Intra-examiner k= .40 Inter-examiner k=.03,Physical Examination,Assessing Patellar Rotation Intra-examiner k= .41 Inter-examiner k= .03,Glide test,0 and 30 degrees Less 1 quadrant More 3 quadrants,Special Test Appreh

6、ension test,With patient supine with ankle off examination table and knee fully extended, examiner then flexes the knee to 90 and back to extension while holding the patella in lateral translation. The procedure is then repeated with medial translation. Positive if patient exhibits apprehension and/

7、or quadriceps contraction during lateral glide and no apprehension during medial glide,Measurement TT-TG Sagittal plane: hight Horizontal plane:patellar title,Frontal plane,Q-angle,Inter-examiner ICC k=.70 (.46, .85),Q-angle,In males, the Q angle should be 8 to 10 degrees; In females, the normal ang

8、le is 15 degrees 5 Insalls recommendation of 20 as an upper limit for a normal Q,A-angle,TT-TG,The TT-TG distance expresses the lateral deviation of the TibialTubercle in relation to the Trochlear Groove,TT_TG,56% of the cases of patellar instability are associated with an increased TT-TG distance 2

9、0 mm The TT-TG distance is always seen as an absolute value without any regard to the individual knee size!,The sulcus angle,The sulcus angle is formed by drawing lines outward from the deepest portion of the trochlear sulcus to the tops of the femoral condyles. The angle normally measures 138 degre

10、es (6 degrees).20 A shallow sulcus greater than 144 degrees is associated with recurrent patellar dislocation.,TT-TG,Sagittal plane,Insall-Salvati ratio,Lateral radiography; Length of patella tendon/ length of the patella 1.0 1.2 patella alta 50% of the medial restraint to the patella. Once the pate

11、lla is engaged in the trochlear groove, the slope of the lateral facet provides the primary resistance to lateral translation.,Themedial patellofemoral ligament is most taut in full knee extension with the quadriceps muscle contracted. the medial patellofemoral ligament origin is very near the physi

12、s;,MPFL reconstrucion,Tibial Tuberosity Surgery,Normal TT-TG Abnormality is excessive femoral anteversion Abnormality is excessive tibial external torsion,Tibial Tubercle Medialization TTM,AnteroMedialiZation (AMZ),AnteroMedialiZation (AMZ),Trochlear deeper,MRI evaluation for osseous contusion,These include pivot shift injury, dashboard injury, hyperextension injury, clip injury, and lateral patellar dislocation. MRI evaluation for osseous contusion is facilitated by the use of T2 fat-s