Congenital Knee

Question 1

What is this?

Answer 1

• Congenital dislocation of the knee
• Spectrum of disease including
  
  • positional contractures
  • rigid dislocation

Structural components include

• tight quadriceps
• anterior subluxation of hamstring tendon
• Absent suprapatellar pouch
• tight collateral ligament

Question 2

What does congential dislocation of the knee occur in?

Answer 2

• Myelomenigocele
• Arthrogryposis
• Larsen’s syndrome

Question 3

What are the associated conditions of congenital knee dislocation?

Answer 3

• Often associated with
  
  • DDH
  • Clubfoot
  • metatarsal adductus
• 50% pts with congential knee dislocation will have hip dysplasia affect one or both hips

Question 4

Hos does congenital knee dislocation present?

Answer 4

• Hyperextened knee at birth

Question 5

How is congenital dislocated knee tx?

Answer 5

Non operative

• Reduction with manual manipulation and long leg casting ( weekly basis)
  
  • most cases can be tx non operatively
  • if both knees and hip dislocated then tx knee first as can’t gt Pavlik harness on hip if knee dislocated

​​Operative

• Surgical soft tissue release
• if failure to gain 30^o of flexion after 3 months of casting
• goal of surgery = obtain 90^o flexion with
  
  • quads tendon lengthening- VY quadriecepsplasty of Z lengthening
  • Anterior joint caspule release
  • hamstring tendon post transposition
  • collateral ligaments mobilisation
  • post -op = cast in 45-60 degrees of flexion for 3-4 wks

Question 6

What is the classificaiton system of congential knee dislocation?

Answer 6

• **Tarek CKD **
• Grade 1 - range of passive flexion >90^o, xray simple recurvatum- serial casting 4 wks
• Grade 2- range of passive flexion 30-90^o, xray- subluxation/dislocation- in noenates <4wks serial casting, if 90^o achieved continue if not percutaneous quadriceps recession
• Grade 3- range of passive flexion <30^o , xray = dislocation= VY Quadricepsplasty- roy crwaford technique

Question 7

what is the epidemiology of Congenital patella dislocation?

Answer 7

• Rare
• Patella is hypoplastic or absent
• Femoral trochlear is flat
• Lateral retinculum is tight
• patella completely dislocates laterally
• patella often adherent to iliotibial band- amking it irreducible
• Must be distinguished from recurrent dislocations

Question 8

What is seen on examination of congential patella dislocation?

Answer 8

• Genu Valgum
• flexion contracture of knee often present
• smiley face appearance of knee caps

Question 9

What is the tx of congential patella dislocation?

Answer 9

• Surgery
  
  • extensive lateral retinacular release - often all the way to the greater trochanter
  • hamstring tenodesis- semitendinosis tenodesis
  • medial plication
  • transfer of half of patella tendon

Question 10

What is the epidemiology of popliteal cysts in children?

Answer 10

• Most common soft tissue mass in children
• most often not associated with menisceal tears
  
  • ​unlike adult population

Question 11

What is the pathoanatomy of popliteal cysts?

Answer 11

• Popliteal cysts usually located between _semimembranosus _and medial head of gastronemius
• from herniated posterior knee joint capsule synovium

Question 12

describe the anatomy of semimembranosus?

Answer 12

• Origin- superior lateral quadrant of ischial tuberosity
• Insertion- post surface of medial tibial condyle
• action
  
  • extends the thigh, flexes the knee and rotates the tibia medially esp when knee is flexed
• nerve- tibial nerve L5,S1, S2

Question 13

Describe the anatomy of gastronemius?

Answer 13

• Origin- medial head from post nonarticular surface of medial femoral condyle. Lateral head from lateral surface of femoral lateral condyle
• Insertion- 2 heads unite to a broad aponeurosis which eventually unites on the middle 1/3rd of the posterior calcaneal sufrace
• action- powerful planar flexion ankle
• innervation- tibial nerve S1,2
• each head supplied by siral branch of popliteal artery

Question 14

What are the signs and symtpoms of popliteal cysts in children?

Answer 14

• Usually asymptomatic

Signs

• Located in popliteal fossa
• usualy located medial and distal to knee crease
• most prounced when knee extended
• mass will transilluminate

Question 15

What imaging is useful in popliteal cyst dx?

Answer 15

• Xray- normal
• USS- consistent with cystic lesion
• MRI- fluid in lesion

Question 16

What is the tx of popliteal cyst in children?

Answer 16

Non operative

• Observation
  
  • mainstay of tx
  • majority resolve spontaneously

​​Operative

• Excision
  
  • only if cyst causes discomfort or failure of spontaneous resolution

Question 17

what is a bipartite patella?

Answer 17

• Normal patella variant representing a failure of fusion
• often confused with patella fx

Question 18

What is the epidemiology of bipartite patella?

Answer 18

• Incidence= 2-8% population
• Male: female 9:1 ratio
• most often found superolateral region- type 3
• bilateral in 50%

Question 19

What is the pathophysiology of bipartite patella?

Answer 19

• Direct / indirect injury -> disruption in fibrocartilagnous zone between main patella & accessory fragment
• Fibrocartilaginous zone cannot heal by bony union -> peristent pain
• Vastus lateralis contributes to traction forces in fragment separation and nonunion

Question 20

What are the associated conditions with bipartite patella?

Answer 20

• Nail Patella syndrome
• Patella fx
  
  • cf patella fx bipartitie patella are lcoated
  • superiolaterally
  • have rounded borders
  • may have similar findings on a contralteral knee radiograph

Question 21

Describe the ostoeology of the patella?

Answer 21

• Largest sesmoid bone in the body
• ossification
  
  • males 4-5 years
  • females 3 yrs
  • accessory ossification centre appears between 8-12 years
  • separate fragment attached to patella by fibrocartilaginous tissue
• Biomechanics
  
  • falcrum for the quadriceps
  • protects knee joint
  • enhances lubrication of the knee

Question 22

Describe the blood supply to the patella?

Answer 22

• Predominantly from distal to proximal
• 6 Arteries
• superior geniculate artery
  
  • superficial femoral arterry
• Superior lateral geniculate artery
  
  • Branch popliteal a
• Superior medial geniculate a
  
  • Branch politeal a
• Inferior Lateral geniculate a
  
  • Popliteal a
• Inferior medial geniculate a
  
  • popliteal a
• Recurrent anteriot tibial a
  
  • Branch ant tibial a

Question 23

What is the classification of bipartite patella?

Answer 23

• Saupe
• Type 1- 5% inferior ole
• TYpe 2- 20% lateral margin
• Type 3- 75% superolateral pole

Question 24

What are the signs and symptoms of bipartite patella

Answer 24

• Most asymptomatic
• only 2% symptomatic
  
  • ANTERIOR knee pain from
  • direct trauma
  • indirect trauma/reptitive small injuries
  • aggravated by squatting, jumping and climbing

Signs

• local tenderness over accessory fragment
• haematoma
• quads inhibition
• usual patella prominence/palpable defect
• larger than normal patella

Question 25

What imaging is useful in bipartite patella?

Answer 25

• Xrays
  
  • Ap knee - best view to see bipartite
  • skyline view
    
    • squatting position -WB
      
      • increase separation of fragments cf nwb skyline prone
      • smooth edges cf FX
    • Prone position NWB
    • 50% bilateral bipartite patella
• MRI
  
  • Oedema around fragment
• Bone scan
  
  • Increased uptake along superolateral aspect

Question 26

What is the tx of biparitie patella?

Answer 26

• Nonoperative
• • Rest, immobilisation, nsaids, PT
    * Non op symptomatic mx indicated for bipartitie patella for at least 6 months
    * iosmetric strecthing exercises of quads muscle in extension
• Operative
  
  • open excision of accessory fragment
    
    • failed consx tx
    • irregular articular sufrace of accessory
  • Lateral retinacular release
    
    • superolateral fragment
    • to remove traction from vastus lateralis
  • vastus lateralis release
    
    • superolat fragment
    • to avoid a long lateral release
  • ORIF
    
    • large fragments