Knee Fractures & Dislocations in Pediatric Patients: Anatomy, Growth & Treatment, Slides of Orthopedics

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Fractures and Dislocations about the

Knee in Pediatric Patients

Anatomy

• Distal femoral physis- large, undulating- irregular
• Proximal tibial physis- contiguous with tibial tubercle apophysis
• Ligament and muscular attachments may lead to avulsion injuries, fracture angulation

Anatomy- Neurologic and Vascular

Structures

• Popliteal artery tethered above and below knee
• Common peroneal nerve vulnerable at fibular neck/head

Growth about the Knee

• 70% of lower extremity length
• Distal femur- average 10mm/year
• Proximal tibia- average 6mm/year
• Tibial tubercle apophysis- premature growth arrest can lead to recurvatum
• Proximal fibular physis- important for fibular growth relative to tibia and ankle alignment

Fractures of the Distal Femoral and the

Proximal Tibial Physis

• Account for only a small percentage of the total number of physeal fractures
• Are responsible for the majority of complications due to partial physeal arrest
• High incidence of growth arrest based on anatomy, energy of injuries
• Specific treatment recommendations to minimize the incidence of growth arrest

Peterson, et.al. JOP ‘94 “Olmstead

County Study”

• Experience of the Mayo clinic 1979 - 1988
• 951 physeal fractures
• 2.2% involved the physis of the distal femur or the proximal tibia
• Fractures of the distal femoral and proximal tibial physis account for 51% of partial growth plate arrest

Anatomy Predisposing

to Growth Arrest

• Peterson ‘94 noted that the distal femoral and proximal tibial physes are large and multiplanar (irregular in contour) and account for 70 and 60% of the growth of their respective bones

Anatomy, continued

• Ogden, JOP ‘82 - “undulations of the physis, which may include small mammillary processes extending into the metaphysis, or larger curves such as the quadrinodal contour of the distal femoral physis, may cause propagation of the fracture into regions of the germinal and resting zones of the physis”

Anatomy, continued

• Ogden JPO, ‘82 - distal femur develops binodal curves in coronal and sagital planes with central conical region - susceptible to damage during varus/valgus injury
• Peripheral growth arrest related to damage to zone of Ranvier stripping it away from physis and periosteum

Distal Femoral Physeal Fractures

• direct blow mechanism
• Salter I or II common
• check neurologic / vascular status

Treatment Recommendations

• Anatomic reduction is key
• Propensity for losing reduction
• Hold reduction with pins and casting

Thompson et.al. JPO ‘

• 30 consecutive fractures of the distal femoral epiphysis
• No displacement of fx treated with anatomic reduction and pin fixation
• Three of seven patients treated closed lost reduction
• proved maintenance of reduction, but not prevention of growth disturbances

Graham & Gross, CORR ‘

• Ten patients with distal femoral physeal fractures retrospectively reviewed
• All treated from ‘77 - ‘87 with closed reduction and casting or skeletal traction
• Most SHII
• Resulted in seven losing reduction and nine eventually developing deformities

Graham & Gross cont.

• Angular deformity and LLD related to the amount of initial deformity and the quality of reduction
• Recommended rigid internal fixation

Riseborough, et.al., JBJS ‘

• Retrospective study of 66 distal femoral physeal fracture-separations
• Only 16 seen primarily, others referred at different stages of treatment/complications
• Noted improved results with anatomic reduction and internal fixation in types II,III and IV, and early detection and mgmnt of growth arrest

Lombardo & Harvey, JBJS ‘’

• 34 distal femoral physeal fx. Followed avg. four years

• 2cm LLD in 36%

• Varus/valgus deformity in 33%
• Osteotomy, epiphyseodesis or both in 20%
• Development of deformity related to amount of initial displacement and anatomic reduction rather than fracture type

Distal Femoral Physeal Fractures

• closed reduction and pinning for displaced fractures
• long leg cast

Distal Femoral Physeal Fractures

• high rate of premature growth arrest rare < 2 yo 80% 2 - 11 yo 50% > 11 yo
• angular deformity
• leg length discrepancy

Patellar Sleeve Fracture

• 8-12 year old
• Inferior pole sleeve of cartilage may displace
• May have small ossified portion
• <2mm displaced, intact extensor mechanism- treat non-operatively

Patella Fractures

• much less common than adults
• avulsion mechanism
• patellar sleeve fracture
• management same as adults
• Restore articular surface and knee extensor mechanism

Osteochondral Fractures

• Usually secondary to patellar dislocation
• Off medial patella or lateral femoral condyle
• Size often under appreciated on plain films
• Arthroscopic excision vs. open repair if large

Acute Hemarthrosis in Children-without

Obvious Fracture

• Anterior Cruciate Tear
• Meniscal tear
• Patellar dislocation +/- osteochondral fracture

Knee Injuries

Acute Hemarthrosis

• ACL 50%

• Meniscal tear 40%
• Fracture 10%

Tibial Eminence Fractures

• Usually 8-14 year old children
• Mechanism- hypertension or direct blow to flexed knee
• Frequently mechanism is fall from bicycle

Myers- McKeever Classification

• Type I- nondisplaced
• Type II- hinged with posterior attachment
• Type III- complete, displaced