Professor Deiary F KaderDepartment of Sport, Exercise, Northumbria University, Newcastle

www.oasir.co.uk

Knee Surgeon, Nuffield Hospital, Newcastle upon Tyne

PATELLOFEMORAL JOINT INSTABILITY

PostGrad Orth Deiary Kader

Postgraduate OrthopaedicsFRCS(Tr&Orth) Revision Course

Newcastle Upon Tyne 16-21 March 2015

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Professor Deiary KaderConsultant Orthopaedic & Trauma Surgeon

Knee Surgeon

Nuffield Hospital Newcastle

NGMV Charity

PLAN

Presentation

Frank dislocation

Subluxation

Symptomatic instability

Pain due to mal-tracking

PATELLAR DISLOCATION

Re-dislocation rate

First Time 17-20%

Second Time 44%-71%

High dissatisfaction following

conservative Rx

PFJ BIOMECHANICS

Patellofemoral joint reaction force

WALKING 0.5xBW

STRAIGHT LEG RAISE 0.5xBW 0 DEG

CYCLING: 1.2 × BW

RISING FROM A CHAIR w ARMS: <3 × BW

STAIRS (UP OR DOWN) 3.3xBW 60 DEG

JOGGING & SQUAT–RISE 6xBW at 140 deg

SQUAT–DESCENT 7.6x BW at 140 deg

JUMPING UP TO 12 × BW

Ff

Ft

Fj

TrigonometryFjf=Ff cos(angle/2)

PostGrad Orth Deiary Kader

PATELLAR STABILITY

DETERMINED BY

– Soft Tissue 0-300

Muscles

Ligaments MPFL (at 200-300)

– Bone morphology >300

CAUSES OF PATELLA INSTABILITY

• Soft Tissue• Global --HMS (Hyperlaxity)• Medial

• MPFL Insufficiency• VMO dysplasia/VL dominance

• Lateral -- ITB, Contracture Lat Ret • Osseous abnormalities• Patella alta/ morphology• Trochlea dysplasia

• Lower limb Malalignment (Torsion or Genu Valgum)

– Fem anteversion, Ext tibia torsion, foot pronation

– Increased Q angle or TT:TG distance• Gait (Valgus thrust, Pelvis core muscles)

WHY THE PATELLA IS UNSTABLE

Lower limb Malalignment??

– Femur, tibia or foot pronation

Osseous abnormalities??– Patella alta– Increased Q angle – Trochlea dysplasia

Soft Tissue??– HMS– MPFL Insufficiency– Muscle or ITB

Gait ??

PostGrad Orth Deiary Kader

KNEE ASSESSMENT

Leg Alignment Varus/valgus

Soft tissue imbalance

Ligament assessment (ACL,PCL, MCL, LCL)

Meniscal assessment

Medial/ Lateral compartment OA

Hip , Spine, peripheral pulses

Apprehension test

PATELLA ASSESSMENT

Beighton Score0---9

Patella Alignment (Q Angle)

Dislocation in extn (J Sign)

Quads Bulk/ ITB (Ober's test)

Hamstring Tightness

Patella height Alta/Baja

Patella Mobility (N@300=<1/2)

Parapatellar tenderness

Patella Apprehension

PFJ Crepitus

PFJ Compression (Clarke test)

Trochlea Depth Normal (1380) – Shallow ,Flat , Convex , Cliff

Many potential problems

• Crude measure

• How it is measured?– Flexion, Extension

– Standing, Sitting, Supine

– Muscle relaxed/tense

• No standard method

Q- Angle

IMAGING OF THE PATELLOFEMORAL JOINT

AP and Lateral Knee x-ray

Merchant’s view

MRI Axial view

CT Rotational Profile

Merchant’s

Trochlea dysplasia

Blumensaat's line

Normal Trochlea Depth

NORMAL

MEASURING PATELLA HEIGHT

Caton – Deschamps index =1.2

Blackburne-peel index = 1.12

PostGrad Orth Deiary Kader

MPFL injury

Patella pain

Articular Damage

MRI SCAN

ROTATIONAL PROFILE CTEVIDENCE BASED INTERVENTION

1. Femoral Anteversion N=50 -150

2. Knee rotation N=30

3. External Tibial torsion 250-300

4. TT:TG offset (N= 10-19mm)

5. Patella index

6. Patella Tilt (N=average QD&QC <200)

7. Trochlea Tilt (N>130)

8. Trochlea DepthNormal (1380+/- 60)

TRUE Q ANGLE, MEASUREMENT OF THE TIBIAL TUBEROSITY-TROCHLEAR GROOVE (TT/TG)

DISTANCE

Normally TT/TG = 2-9 mm pathologic measure is > 19 mm

PostGrad Orth Deiary Kader

HOW USEFUL IS TT:TG

• Large variation in normal value (patient size and height)

• Poor interrater reliability 3-5mm measurement error– Trochlea ?deepest point of

– Tib Tub bony landmark vs Central point of PT attachment 4mm

• What condition? – Flexion or extension

– Weight bearing 5mm

• MRI or CT measurement

TREATMENT OF PATELLA INSTABILITY

Conservative firstQuads strengthening Core stabilityMcConnell TapingInsolesGait

Med Epicondyle

Add Tubercle

Patella

MPFL

PostGrad Orth Deiary Kader

PostGrad Orth Deiary Kader

BONY TUNNEL

PostGrad Orth Deiary Kader

MX OF PATELLA INSTABILITY

Patellofemoral Instability with Malalignment

Distal Realignment

tibial tubercle transfer

Combined

MPFL Recon

FULKERSON'S TECHNIQUE OF ANTEROMEDIALIZATION

A steeper osteotomy plane will produce more anteriorization along with medialization

OTHER PATELLOFEMORAL PROBLEMS

Patella Alta

– Distal transfer (Distalization)

Trochlea Dysplasia

– Trochloplasty

PostGrad Orth Deiary Kader

1.4 cm

Patella alta

TROCHELOPLASTY

TAKE HOME MESSAGE

The approach to patellar instability should be

individualised and tailored to each patient’s

symptoms, anatomy and physical demands

PostGrad Orth Deiary Kader

24 years old female doctor had a permanents dislocation of the patellaTreated with1. Lateral release2. Tib Tub Medialisation3. Tib Tub Distalisation4. Trochleaoplasty5. MPFL Reconstruction

PostGrad Orth Deiary Kader

TREATMENT SUMMARY

MPFL Reconstruction (very popular >80%)

Tib Tub Medialisation on the decline

Tib Tub Distalisation excellent procedure

Trochleoplasty

Distal femoral Osteotomy

THANK YOU