How much flexion of the knee is recommended for the lateral projection of the patella?

NORMAL ANATOMY

Osteology

Attachments

Muscle
Ligament/tendon

RADIOGRAPHIC VIEWS

AP/PA View

Positioning
- patient
- beam
  - aim 1.5cm distal to apex of patella
Indications
- fracture
- joint alignment
- OA
  - PA view preferred over AP view
  - weightbearing view preferred over non-weightbearing view
Critique
- symmetrical femoral + tibial condyles
- fibular head should be bisected by the tibia
- visualization of intercondylar eminence in intercondylar fossa

Weightbearing AP/PA (Rosenberg) view

Full-length weightbearing AP (PCA) view

Lateral View

Positioning
- patient
- beam
  - aim 2.5cm distal to medial epicondyle
  - tilt 5-7° cephalad (if rolled lateral)
Indications
- fracture
- OA
- patella fracture = horizontal ray view to avoid displacement
- patella alta/baja = requires knee in 30° flexion
- trochlear dysplasia
- joint effusion
Critique
- visualization of suprapatellar fat pad = via knee flexion < 30°
- appropriate IR/ER
  - superimposition of posterior aspect of femoral condyles
  - superimposition of fibular head + tibia
  - open patellofemoral joint
  - no visualization of adductor tubercle
- appropriate cephalad angulation = open tibiofemoral joint

Oblique View

Positioning
- patient
- beam
  - aim 1.5cm distal to apex of patella
Indications
- fracture = femoral condyle, patella
- OA
- intercondylar fossa pathology = loose bodies
- OCD lesions
Critique
- superimposition of patella + ipsilateral femoral condyle
- asymmetrical tibiofemoral joint spaces

Tangential View

Positioning

METHOD Inhaltsverzeichnis Show How much flexion of the knee is best for the lateral projection of the patella? How much flexion of the knee is recommended for the lateral projection of the patella quizlet? How much knee flexion is required for the sunrise or Settegast method to demonstrate the patella? What Cr angle should be used for a lateral projection of the knee on an average patient?	PATIENT	BEAM
Sunrise/Settegast	supine vs. prone	knee flexed 90°	inf-sup	10-20° cephalad
Hughston	prone	knee flexed 50-60°	inf-sup	45° cephalad
Merchant	supine	knee flexed 40°	sup-inf	30° caudad
Laurine	semi-recumbent	knee flexed 30°	inf-sup	30° cephalad

Indications
- patellar malalignment or tilt
- trochlear groove depth
- OA
- vertical patella fracture
Critique
- visualization of femoral condyles + trochlear groove
- no superimposition of patella + femur
- open patellofemoral joint

Intercondylar View

Positioning

METHOD	PATIENT	BEAM
Beclere	supine	knee flexed 40°	AP	40° cephalad
Camp Coventry/Tunnel	prone	knee flexed 40°	PA	40° caudad
Holmblad	erect vs. kneeling	knee flexed 70°	PA	0°

Indications
- OCD = displaced cartilage
- congenital slipped patella = flattening/underdevelopment of lateral femoral condyle
- hemophilia = intercondylar widening
- intercondylar fossa pathology = loose bodies
Critique
- superimposition of patella + ipsilateral femoral condyle
- asymmetrical tibiofemoral joint spaces

NORMAL FINDINGS

Normal variants

CLINICAL PEARLS

Knee OA

Classification = Kellgren & Lawrence
Recommended views
- weightbearing AP
- weightbearing lateral
- semi-flexed 45° PA
  - most sensitive for early joint space narrowing (JSN)
- tangential
Findings
- joint space narrowing (JSN)
- osteophytes
- eburnation of bone
- subchondral sclerosis/cysts

TKA templating

AP/PA view

Lateral view
Sunrise/Tangetial view

TKA periprosthetic fracture

Classification

distal femur
- Lewis & Rorabeck
- Su

proximal tibia = Felix
patella = Goldberg

Goldberg Classification

Type I Fracture not involving implant/cement interface or quadriceps mechanism
Type II Fracture involving implant/cement interface and/or quadriceps mechanism
Type III Type A: inferior pole fracture with patellar ligament rupture
Type B: inferior pole fracture without patellar ligament rupture
Type IV All types with fracture dislocations

Recommended views
- AP
- lateral
- consider CT scan for better delineation of fracture pattern and proximity to implant
Treatment criteria
- distal femur
  - nonoperative treatment acceptable if nondisplaced fractures with stable prosthesis
  - retrograde IMN if
    - intact/stable prosthesis with open-box design to accommodate nail
    - fracture proximal to femoral component (Su Type I)
    - fracture that originates at the proximal femoral component and extends proximally (Su Type II)
  - ORIF with fixed angle device if
    - intact/stable prosthesis
    - Lewis-Rorabeck II or Su Types I or II (described above) unable to accommodate intramedullary device
    - fracture distal to flange of anterior femoral component (Su Type III)
  - revision to long stem prosthesis if
    - loose femoral component
    - Lewis-Rorabeck III or Su Type III (described above) with poor bone stock
  - distal femoral replacement if elderly patients with loose (Su type III) or malpositioned components and poor bone stock
- proximal tibia
- patella
  - nonoperative treatment acceptable if
    - stable implants with intact extensor mechanism
    - non-displaced fractures
  - ORIF vs. revision arthroplasty vs. patellectomy if

TKA aseptic loosening

TKA instability

Classification
- extension = varus/valgus instability
- flexion = AP, occurs when the flexion gap exceeds the extension gap
- mid-flexion = malrotation when the knee is flexed between 45 and 90 degrees
- global = laxity of both flexion and extension gaps, as well as varus/valgus instability
- genu recurvatum = fixed valgus deformity and iliotibial band contracture
Recommended views
- weightbearing AP
  - used to assess joint line symmetry
- full-length AP
  - used to assess overall mechanical alignment
- lateral
  - used to assess femoral component sizing (assess posterior condylar offset compared to native), tibial slope, tibial subluxation, recurvatum
  - flexion lateral can often see paradoxical rollback in PCL incompetent CR knees
Findings
- extension instability
  - excessive distal femoral resection
  - oversized femoral component
  - reverse tibial slope
- flexion instability
  - overresection of posterior femoral condyles
  - undersized femoral component
  - increased tibial slope
- mid-flexion instability
  - anterior or proximal placement of femoral component (look at the joint line to fibular head distance for evidence of joint line elevation)
- genu recurvatum

TKA patellar maltracking

Recommended views
- AP
  - used to assess placement of femoral component and Q angle
- lateral
  - used to assess femoral component anterior offset (overstuffing)
- tangential
  - used to assess subluxation of patella, placement of patellar component, angle of patellar resection, and patellar tilt
Findings
- laterally subluxed patella
- increased Q angle
- anterior placement of femoral component
- asymmetric patellar resection
- lateral placement of patellar component
- lateral osteophyte on patella

TKA patellar prosthesis loosening

Recommended views
- lateral
- tangential
Findings
- loss of radiolucent space in patellofemoral joint with contact between patella bone and femoral component
  - seen on lateral view
- dissociated patellar component
  - patellar component adjacent/superficial to patella
  - seen on lateral and tangential views
- thinning of polyethylene
  - seen on tangential view

TKA heterotopic ossification

Classification = Furia & Pelligrini
- class I = island of bone localized to suprapatellar soft tissues
- class II = bone organized into areas of ossification contiguous with the anterior distal femur
- grade A = ≤ 5 cm
- grade B = > 5 cm
Recommended views
- AP
- lateral
Findings
- ossification along anterior distal aspect of femur and within quadriceps mechanism
  - typically visible 3-4 weeks post-operatively and matures within 1-2 years
Treatment criteria
- nonoperative treatment acceptable in most cases
- excision if
  - quadriceps muscle snapping
  - patellofemoral tracking difficulties
  - patellofemoral instability

How much flexion of the knee is best for the lateral projection of the patella?

The patella is perpendicular to the plane of the IR. For new or unhealed patellar fractures, the knee should not be flexed more than 10 degrees (check with your medical director). Knee flexion of 20 to 30 degrees is otherwise preferred – this position relaxes the muscles and shows maximum volume of the joint cavity.

How much flexion of the knee is recommended for the lateral projection of the patella quizlet?

Instructor Explanation: 5-10° knee flexion is required for a lateral projection of the patella.

How much knee flexion is required for the sunrise or Settegast method to demonstrate the patella?

In the prone position the IR is placed under the knee and the knee is flexed 115 degrees from the horizontal axis. Patella sunrise view with 115 degrees knee flexion.

What Cr angle should be used for a lateral projection of the knee on an average patient?

For a lateral view, the patient is positioned on the affected side, with the knee flexed 20-30 degrees. One method to obtain the tunnel view is to have the knee flexed 40-50 degrees with the patient prone and support placed under the tibia-fibula.

How much flexion of the knee is recommended for the lateral projection of the patella?

How much flexion of the knee is best for the lateral projection of the patella?

How much flexion of the knee is recommended for the lateral projection of the patella quizlet?

How much knee flexion is required for the sunrise or Settegast method to demonstrate the patella?

What Cr angle should be used for a lateral projection of the knee on an average patient?

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