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subjects 1-congenital dislocation of knee joint 2-congenital dislocation of the patella 3-bipartate patella
1-Congenital Dislocation of the Knee described by Chatelaine in 1822 Spectrum of disease including
positional contractures rigid dislocation
Structural components include quadricep tendon contracture anterior subluxation of hamstring tendon absent suprapatellar pouch tight collateral ligament
Often occurs in children with myelomeningocele arthrogryposis Larsen's syndrome and in (1947)macfarlan described a family in
which a mother and her 3 childrens by three different fathers all had congenital dislocation of the knee.
Associated conditions in 60% of the cases often associated with developmental dysplasia of the hip, clubfoot, and
metatarsus adductus 50% of patients with congenital knee dislocations will have hip dysplasia
affect one or both hips
Etiology-Both intrinsic and extrinsic causes have been suggested. ; the extrinsic causes are mechanical factors. While intrinsic are genetic
PresentationPresents with hyperextened knee at birth
X ray findings anterior displaced tibia and hypoplastic fibula and rounded posterior tibial condyles
Classification :the Kneegrade 1, congenital hyperextension; grade 2, congenital hyperextension with anterior subluxation of the tibia on the femur; and grade 3, congenital hyperextension with anterior dislocation of the tibia on the femur
Treatment
•Nonoperative treatment • reduction with manual manipulation and casting
• indications • most cases can be treated nonoperatively
Mayer (1913) reviewed sixty-eight patients and found that a cure had been achievedin 8 1 per cent of those who were treated before three months of age ; a cure rate of only 33 per cent was achieved in those treated after three months of age.
• if both knee and hip dislocated, then treat knee first
• cant get Pavlik harness on hip if knee dislocated
• technique • long leg casting on weekly basis• Roach and Richards proposed two criteria for
successful nonoperative treatment of congenital knee dislocation: radiographic evidence of reduction and knee flexion to 90 degrees or more
• Operative treatment • surgical soft tissue release
• indications • if failure to gain 30 degrees of flexion after 3 months of casting
• goal of surgery is to obtain 90 degrees of flexion with • quadriceps tendon lengthening (V-Y quadricepsplasty or Z
lengthening) • anterior joint capsule release• hamstring tendon posterior transposition• collateral ligaments mobilization
• postoperative • cast in 45 to 60 degrees of flexion for 3 to 4 weeks
• In a child with congenital dislocation of the knee and congenital dislocation of the hip, surgical correction of the knee first is advisable
2-Congenital Dislocation of Patella A congenital, irreducible, lateral dislocation
of the patella Epidemiology
incidence rare
demographics usually dislocated at birth
often missed or misdiagnosed can be reduced at birth with subluxation and
later fixed dislocation in childhood
Pathophysiology pathoanatomy
osseous abnormalities small or absent patella hypoplastic trochlea external tibial torsion
soft tissues abnormalities thickened, tight lateral structures including
iliotibial band retinaculum
tight quadriceps causing superiorly subluxed patella
Associated conditions Larson syndrome arthrogryposis diastrophic dysplasia nail-patella syndrome Down syndrome Ellis-van Creveld syndrome
Physical exam inspection
genu valgum knee flexion contractures "smiley face" appearance of knee caps femoral condyles abnormally prominent small patella which is difficult to palpate laterally
motion
limited active flexion
as genu valgum worsens, patella subluxes posteriorly causing quadriceps to act as knee flexor
Anatomical changes 1-vastus lateralis may be absent or severely contracted, 2-the patella may be dislocated laterally and attached to
the anterior aspect of the iliotibial band. Often the patella is small and misshapen and in an abnormal location in the quadriceps mechanism.
3-Genu valgum and external rotation of the tibia on the femur commonly develop.
4- The capsule on the medial side of the knee is stretched,
5-the lateral femoral condyle is flattened, or the insertion of the patellar tendon is located more laterally than normally
Radiographs recommended views
not helpful in children younger than 3 years old because patella is not ossified
in children > 3 years of age AP lateral and sunrise
findings dislocated patella hypoplastic trochlea
Ultrasound or MRI indications
children <3 years of age can help diagnose non-ossified, dislocated patella
Nonoperative observation
indications for most part not recommended as the condition impairs long
term function if left untreated Operative
surgical reduction (Andrish technique) indications
perform early to allow for trochlear intervention requires surgical reconstruction that involves
“medializing” the entire extensor mechanism. This is accomplished with extensive lateral release and advancement of the VMO distally and medially. In more severe cases, the IT band may need to be divided transversely and the quadriceps may be lengthened by either V-Y plasty or femoral shortening.
Andrish technique) soft tissue reduction steps
divide and lengthen lateral retinaculum between oblique and transverse layers
dissect vastus lateralis from intermuscular septum and advance proximally on quadriceps tendon
release distal patellomeniscal ligaments lengthen quadriceps tendon, shorten patellar tendon to
correct patellar alta tighten medial structures via medial patellofemoral
reconstruction reroute semitendinosus through medial collateral ligament and
attach to patella osseous realignment
distal realignment usually not needed with adequate release if needed, realignment limited due to tibial tubercle
apophysis Roux-Goldthwait is preferred
3-bipartate patella (patella zebra) Normal patellar variant representing a failure of
fusion often confused with patellar fractures
Epidemiology incidence
2-8% of the population demographics
male:female ratio = 9:1 location
most often found in the superolateral region (Type III) bilateral in 50%
Pathophysiology painful bipartite patella following injury
direct or indirect injury results in disruption in fibrocartilaginous zone between main patella and accessory fragment
fibrocartilaginous zone cannot heal by bony union, resulting in persistent pain
vastus lateralis contributes to traction force in fragment separation and nonunion
Associated conditions nail-patella syndrome patella fracture
compared with patellar fractures, bipartite patellas
are located superolaterally have rounded borders may have similar findings on a contralateral knee radiograph
classifications
Saupe ClassificationType Incidence Location Image
Type I 5% Inferior pole
Type II 20% Lateral margin
Type III 75% Superolateral pole
Imaging
•Radiographs • recommended views
• AP knee radiograph • best view to visualize bipartite patella
• skyline view • prone position (non-weightbearing) • squatting position (weightbearing)
• radiograph of contralateral knee• findings
• smooth edges (differentiate from fracture)• weightbearing skyline (squatting) demonstrates increased separation of fragments
compared with non-weightbearing skyline (prone)• 50% have bilateral bipartite patella
•MRI • indications
• assessment of painful bipartite patella to determine if pain is attributable to the bipartite patella
• findings • edema around the fragment
•Bone scan • indications
• equivocal radiographs with high suspicion for bipartite patella• findings
• increased uptake along superolateral aspect
Nonoperative rest, immobilization, NSAIDS, and physical
therapy indications
nonoperative symptomatic management indicated for bipartite patella for at least 6 months
modalities rest and restriction of sports activities NSAIDS isometric strengthening exercises of the quadriceps muscle in
extension immobilization with the knee braced in 30° of flexion local corticosteroid injection
Operative open excision of the accessory fragment
indications failed nonoperative treatment >6mths irregular articular surface of accessory fragment (on radiographs)
most common treatment technique
lateral retinacular release indications
superolateral fragment (to remove traction force of vastus lateralis on the fragment)
vastus lateralis release indications
superolateral fragment to avoid long lateral retinacular release
ORIF indications
for large fragments
references 1-tachdjians pediatric orthopedics 2-campbells operative orthopedics
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