Congenital Knee Flashcards
congential knee dislocation congential patella dislocation popliteal cyst bipartitie patella
1
Q
What is this?
A
- 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
2
Q
What does congential dislocation of the knee occur in?
A
- Myelomenigocele
- Arthrogryposis
- Larsen’s syndrome
3
Q
What are the associated conditions of congenital knee dislocation?
A
- Often associated with
- DDH
- Clubfoot
- metatarsal adductus
- 50% pts with congential knee dislocation will have hip dysplasia affect one or both hips
4
Q
Hos does congenital knee dislocation present?
A
- Hyperextened knee at birth
5
Q
How is congenital dislocated knee tx?
A
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 30o of flexion after 3 months of casting
- goal of surgery = obtain 90o 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
6
Q
What is the classificaiton system of congential knee dislocation?
A
- **Tarek CKD **
- Grade 1 - range of passive flexion >90o, xray simple recurvatum- serial casting 4 wks
- Grade 2- range of passive flexion 30-90o, xray- subluxation/dislocation- in noenates <4wks serial casting, if 90o achieved continue if not percutaneous quadriceps recession
- Grade 3- range of passive flexion <30o , xray = dislocation= VY Quadricepsplasty- roy crwaford technique
7
Q
what is the epidemiology of Congenital patella dislocation?
A
- 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
8
Q
What is seen on examination of congential patella dislocation?
A
- Genu Valgum
- flexion contracture of knee often present
- smiley face appearance of knee caps
9
Q
What is the tx of congential patella dislocation?
A
- 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
10
Q
What is the epidemiology of popliteal cysts in children?
A
- Most common soft tissue mass in children
-
most often not associated with menisceal tears
- unlike adult population
11
Q
What is the pathoanatomy of popliteal cysts?
A
- Popliteal cysts usually located between _semimembranosus _and medial head of gastronemius
- from herniated posterior knee joint capsule synovium
12
Q
describe the anatomy of semimembranosus?
A
- 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
13
Q
Describe the anatomy of gastronemius?
A
- 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
14
Q
What are the signs and symtpoms of popliteal cysts in children?
A
- Usually asymptomatic
Signs
- Located in popliteal fossa
- usualy located medial and distal to knee crease
- most prounced when knee extended
- mass will transilluminate
15
Q
What imaging is useful in popliteal cyst dx?
A
- Xray- normal
- USS- consistent with cystic lesion
- MRI- fluid in lesion
17
Q
what is a bipartite patella?
A
- Normal patella variant representing a failure of fusion
- often confused with patella fx
18
Q
What is the epidemiology of bipartite patella?
A
- Incidence= 2-8% population
- Male: female 9:1 ratio
- most often found superolateral region- type 3
- bilateral in 50%
19
Q
What is the pathophysiology of bipartite patella?
A
- 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
22
Q
Describe the blood supply to the patella?
A
- 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
23
Q
What is the classification of bipartite patella?
A
- Saupe
- Type 1- 5% inferior ole
- TYpe 2- 20% lateral margin
- Type 3- 75% superolateral pole
25
Q
What imaging is useful in bipartite patella?
A
- 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
-
squatting position -WB
- MRI
- Oedema around fragment
- Bone scan
- Increased uptake along superolateral aspect
