Vol 10, No 5, September/October 2002
345
The knee is a common site of in-
jury in children and adolescents,
especially those who engage in
competitive sports. The physician
who evaluates and treats fractures
in the pediatric age group must be
familiar with the types of injuries
and complications that are unique
to these patients. Fractures of the
immature knee, such as those that
involve the distal femoral and
proximal tibial epiphyses, tibial
tubercle apophysis, tibial spine,
patella, articular cartilage, and
proximal tibial metaphysis, are
particularly challenging in terms
of establishing the diagnosis and
predicting long-term sequelae. An
understanding of the classifica-
tion, clinical and radiographic
evaluation, treatment, and poten-
tial complications of each type of
injury can lead to more effective
treatment as well as to clear com-
munication with the child’s par-
ents.
Distal Femoral Epiphyseal
Fractures
Classification

The most commonly used system
to classify fractures involving the
distal femoral epiphysis is that of
Salter and Harris
1
(Fig. 1). In type I
fractures, there is a separation
through the physis with no involve-
ment of the adjacent metaphysis or
epiphysis. Type II fractures are the
most common. In these injuries, the
fracture line traverses the physis
before exiting obliquely across one
corner of the metaphysis. Displace-
ment is usually toward the side of
the metaphyseal fragment. A type
III injury consists of a fracture
through the physis that exits through
the epiphysis into the joint. A type
IV fracture consists of a vertical, intra-
articular fracture that traverses the
metaphysis, physis, and epiphysis.
Most type III and IV injuries require
accurate reduction, usually supple-
mented by internal fixation, to align
the physis and achieve a congruous
joint surface. Type V fractures are
crush injuries to the physeal cartilage.
These rare injuries are usually diag-
nosed in retrospect or by association

with the mechanism of injury.
Signs and Symptoms
The patient with a distal femoral
epiphyseal fracture usually presents
with effusion of the knee joint, local
soft-tissue swelling, and tenderness
over the physis. In displaced injuries,
deformity may be evident, and soft
or muffled crepitus with motion
often can be felt. In the anteriorly
displaced, or hyperextension, injury,
the patella becomes prominent and
the anterior skin is often dimpled.
With posterior displacement of the
epiphysis, the distal metaphyseal
fragment becomes prominent just
above the patella. Although arterial
injury is less common than with a
proximal tibial physeal injury, a care-
ful neurovascular examination is
Dr. Zionts is Professor, Department of
Orthopaedics and Pediatrics, Keck School of
Medicine, University of Southern California,
and Director, Pediatric Orthopaedics, Women’s
and Children’s Hospital, University of
Southern California Medical Center, Los
Angeles, CA.
Reprint requests: Dr. Zionts, Room 3L-31,
1240 North Mission Road, Los Angeles, CA
90033.

Copyright 2002 by the American Academy of
Orthopaedic Surgeons.
Abstract
Traumatic forces applied to the immature knee result in fracture patterns differ-
ent from those in adults. The relative abundance of cartilage in the knee of the
growing child may make the diagnosis of certain injuries more challenging. If
plain radiographs fail to reveal a fracture, a stress radiograph, computed tomog-
raphy scan, or magnetic resonance imaging study may help to establish the
diagnosis. Certain fractures, such as hyperextension injuries to the distal
femoral or proximal tibial epiphysis, or displaced tibial tuberosity fractures, may
be especially susceptible to neurovascular problems. Although the use of appro-
priate treatment techniques may minimize the occurrence of late complications
such as malunion and physeal bridging, not all problems are preventable. A
careful discussion of the injury with both patient and parents should stress the
importance of follow-up so that any problems that do occur can be promptly
addressed.
J Am Acad Orthop Surg 2002;10:345-355
Fractures Around the Knee in Children
Lewis E. Zionts, MD
warranted to rule out damage to the
popliteal vessels or peroneal nerve.
Imaging Studies
Anteroposterior and lateral radio-
graphs should routinely be obtained
to evaluate the displacement of the
fractures. Oblique radiographs may
help reveal minimally displaced
fractures. Gentle-stress radiographs
can help differentiate a physeal sep-
aration from a ligamentous injury in

a patient who has pain and appar-
ent laxity of the knee and whose
plain radiographs fail to reveal a
fracture. Adequate analgesia can
alleviate muscle spasm and protect
the physis from further damage
during the examination.
Magnetic resonance imaging
(MRI) or computed tomography
(CT) also may help to identify frac-
ture lines in nondisplaced injuries.
2,3
Naranja et al
3
found MRI useful for
diagnosing fractures when an injury
was not apparent on plain radio-
graphs, especially in children with a
preceding traumatic event, effusion
or swelling, and refusal to bear
weight on the extremity (Fig. 2).
Treatment
The goals of treatment are to ob-
tain and maintain an anatomic re-
duction and avoid further damage to
the physis. The form of treatment is
determined by both the fracture type
and the degree of displacement.
For Salter-Harris type I and II
injuries, nondisplaced fractures are

immobilized for 4 to 6 weeks in
either a long leg cast or hip spica
cast. The duration of immobiliza-
tion will vary with the age of the
patient. Short, obese children, or
patients who may be unreliable, are
better managed in a spica cast.
4
Displaced fractures should be
reduced under general anesthesia.
Longitudinal traction can be used
during the reduction maneuver to
avoid further damage to the physis.
Internal fixation makes subsequent
displacement less likely, allows the
use of a long leg cast with a greater
margin of safety, and avoids the
need to immobilize the knee in an
extreme position of flexion or exten-
sion to maintain the reduction.
4,5
Smooth transphyseal pins are used
for type I injuries and for type II
injuries with small metaphyseal
fragments. Bending and burying
the pins just beneath the skin can
minimize the risk of bacterial
contamination of the knee joint.
Type II fractures with an adequately
sized metaphyseal fragment may be

stabilized using pins or AO cannu-
lated screws across the metaphyseal
portion of the fracture fragment
(Fig. 3). Open reduction is indicated
for any type I or II fracture that is
irreducible by closed means.
For Salter-Harris type III and IV
injuries, nondisplaced and stable
fractures may be managed by cast
immobilization alone. Careful follow-
up of these patients at weekly inter-
vals is needed so that any displace-
ment may be promptly addressed.
Alternatively, these injuries may be
stabilized using percutaneous pins
or screws to minimize the risk of late
displacement. Open reduction and
internal fixation is indicated for all
displaced type III and IV fractures to
restore congruity of the joint surface
and to align the physis. Because
these are intra-articular fractures, full
weight bearing is not begun until
radiographs demonstrate adequate
fracture healing.
Outcome
At most anatomic locations, a
growth disturbance after a type I or II
injury is rarely seen. However, when
these fractures involve the distal

femoral epiphysis, problems with
shortening and angular deformity
are more common.
4,6
Presumably
this is because greater forces are
required to disrupt the distal femoral
physis, and the undulating shape of
this growth plate renders it more sus-
ceptible to damage by shearing and
compressive stresses. Growth distur-
Fractures Around the Knee in Children
Journal of the American Academy of Orthopaedic Surgeons
346
Type I Type II Type III Type IV Type V
Figure 1 The Salter-Harris classification
1
for fractures of the distal femoral epiphysis. The dashed line indicates the fracture line.
(Reproduced with permission from Edwards PH Jr, Grana WA: Physeal fractures about the knee. J Am Acad Orthop Surg 1995;3:63-69.)
bances are more likely to occur with
fractures in younger patients and
after fractures that are initially dis-
placed more than one half the diame-
ter of the shaft.
5,6
Riseborough et al
4
observed that fractures of the distal
femoral epiphysis in patients 2 to 11
years of age were caused by more

severe trauma and were more likely
to lead to growth problems than sim-
ilar fractures in adolescents.
Careful clinical evaluation is rec-
ommended at 6 months after the
injury to detect physeal irregulari-
ties that may suggest an impending
growth disturbance.
7
Comparative
radiographs of both lower extremi-
ties are helpful for detecting these
changes early. The patients should
be followed at regular intervals
until skeletal maturity because both
growth deceleration
4
and growth
stimulation
5
can occur after distal
femoral physeal injuries.
The precise amount of leg-length
discrepancy that requires treatment
remains controversial. Generally,
leg-length inequalities estimated to
be <2 cm at skeletal maturity can be
managed nonsurgically. If the esti-
mated discrepancy at maturity is 2
to 5 cm, an appropriately timed

epiphysiodesis of the contralateral
extremity may be indicated. For
inequalities estimated to be >5 cm at
maturity, leg lengthening should be
considered.
Significant angular deformity
resulting from malunion or a partial
growth arrest may be managed by
osteotomy or by hemiepiphysiode-
sis. When an osseous bridge is pres-
ent, resection may be considered in
children who have at least 2 years of
growth remaining and whose
lesions occupy <50% of the growth
plate. MRI is now the imaging
modality of choice to evaluate these
lesions. Three-dimensional model-
ing can be used to produce physeal
maps that show the site and extent
of the abnormality, which are useful
for preoperative planning.
8,9
Oste-
otomy combined with concomitant
epiphysiodesis may be indicated in
children who have larger physeal
bridges or who are approaching
skeletal maturity.
Proximal Tibial
Epiphyseal Fractures

Classification
The most commonly used classifi-
cation system for fractures of the prox-
imal epiphysis of the tibia is that of
Salter and Harris
1
(Fig. 4). It corre-
sponds to the system used for the dis-
tal femur. Type I is a separation
through the physis without involve-
ment of the adjacent metaphyseal or
epiphyseal bone. Type II traverses the
physis before exiting obliquely across
one corner of the metaphysis. These
fractures are usually the result of a
Lewis E. Zionts, MD
Vol 10, No 5, September/October 2002
347
A
D
B
C
Figure 2 A 13-year-old boy sustained an injury to his right knee. Anteroposterior (A) and
lateral (B) radiographs did not show a fracture. Sagittal T2-weighted (C) and axial fast
spin echo (D) MRIs revealed a nondisplaced Salter-Harris type IV fracture of the proximal
tibia (arrows). (Panels A–C reproduced with permission from Zionts LE: Fractures and
dislocations around the knee, in Green NE, Swiontkowski MF: Skeletal Trauma in Children,
ed 3. Philadelphia, PA: WB Saunders, in press.)
Fractures Around the Knee in Children
Journal of the American Academy of Orthopaedic Surgeons

valgus stress with the metaphyseal
fragment on the lateral side. Type III
is a fracture through the physis that
exits through the epiphysis into the
joint. Type IV is a vertical, intra-artic-
ular fracture through the metaphysis,
physis, and epiphysis. These fractures
may involve either the medial or later-
al tibial plateau.
Signs and Symptoms
The patient with a fracture of the
proximal tibial epiphysis presents
with an effusion of the knee joint,
local soft-tissue swelling, and ten-
derness over the physis. Deformity
is present in displaced injuries.
Because of its close proximity to the
proximal tibial epiphysis, the popli-
teal artery is potentially at risk in
these injuries. Posterior displace-
ment of the tibial shaft in relation to
the epiphysis, as may occur after a
hyperextension injury, can produce
a laceration or thrombosis of the
popliteal artery (Fig. 5). Because the
fracture may partially or completely
reduce before the patient is evaluated,
arterial injury must be considered in
every patient with this injury.
10

The guidelines for evaluating
children who sustain this injury are
similar to those used for adults after
a traumatic knee dislocation. A
careful neurovascular examination
must be done, documenting the
presence of the dorsalis pedis and
posterior tibial arterial pulses, the
status of the distal perfusion of the
limb, and the function of the poste-
rior tibial and peroneal nerves. In
an obviously ischemic extremity,
the displacement should be reduced
as soon as possible. If the vascular
deficit persists, an arterial explo-
348
A DB C
Figure 3 Anteroposterior (A) and lateral (B) radiographs of a Salter-Harris type II fracture (arrows) of the distal femur in a 9-year-old
boy. Anteroposterior (C) and lateral (D) posttreatment radiographs. The fracture was stabilized using two AO cannulated screws across
the metaphyseal portion of the fragment, supplemented by immobilization in a long leg cast for 4 weeks.
Figure 4 The Salter-Harris classification
1
for fractures of the proximal tibial epiphysis. (Adapted with permission from Hensinger RN [ed]:
Operative Management of Lower Extremity Fractures in Children. Park Ridge, IL: American Academy of Orthopaedic Surgeons, 1992, p 49.)
Type I
Anteroposterior view Lateral view
Type II Type III Type IV
ration should be performed imme-
diately. In the absence of an obvi-
ously ischemic limb, patients who

have a diminished or absent pulse,
or those who recover pulses and
perfusion after reduction of the frac-
ture, should undergo arteriogra-
phy.
11,12
Ongoing evaluation of the
lower extremity is important during
the first few days after the fracture
so that a developing compartment
syndrome or intimal tear with throm-
bosis may be detected promptly.
Imaging Studies
Anteroposterior and lateral radio-
graphs usually reveal the fracture.
When the plain radiographs appear
to be normal, gentle-stress radiogra-
phy or MRI may be used to detect a
nondisplaced or otherwise obscure
injury, as described for the distal
femur. When stress radiographs are
considered, hyperextension should
probably be avoided. On occasion,
CT may be used to evaluate and
classify injuries more fully, especially
in Salter-Harris type III and IV frac-
tures that involve the articular sur-
face
13
(Fig. 6).

Treatment
The goals of treatment are to
obtain and maintain an anatomic
reduction and to avoid further dam-
age to the growth plate. For Salter-
Harris type I and II injuries, nondis-
placed fractures are immobilized in
a long leg cast for 4 to 6 weeks, de-
pending on the age of the patient.
Displaced fractures are gently re-
duced under general anesthesia to
avoid further damage to the growth
plate. Because many of these frac-
tures are the result of hyperexten-
sion injuries, flexion usually
achieves reduction. Immobilization
of the knee in marked flexion may
increase the risk of vascular com-
promise and thus should be avoid-
ed. The use of internal fixation
allows the knee to be immobilized
in 20° to 30° of flexion, a position
that poses less risk to the circulation
and makes subsequent displace-
ment not as likely. Smooth, crossed
transphyseal pins are used for type I
and II fractures with small meta-
physeal fragments. Type II frac-
tures with an adequately sized me-
taphyseal fragment may be stabi-

Lewis E. Zionts, MD
Vol 10, No 5, September/October 2002
349
Figure 5 Lateral view of the knee showing
the potential for popliteal artery laceration
or thrombosis (arrow) after a hyperexten-
sion injury to the proximal tibial physis.
(Adapted with permission from Tolo VT:
Fractures and dislocations around the knee,
in Green NE, Swiontkowski MF [eds]:
Skeletal Trauma in Children. Philadelphia,
PA: WB Saunders, 1994, vol 3, pp 369-395.)
Popliteal
artery
A
D
B
C
Figure 6 Salter-Harris type IV fracture of the proximal tibia in a 12-year-old boy.
A, Anteroposterior radiograph does not demonstrate the fracture well (arrows).
B, Coronal reconstruction CT scan shows the fracture line (arrows) more clearly.
C, Axial CT view of the joint surface shows minimal displacement at the articular surface
(arrows). D, The fracture was stabilized with two AO screws inserted percutaneously.
lized using pins or AO cannulated
screws across the metaphyseal por-
tion of the fracture. Open reduction
is indicated for irreducible type I
and II fractures.
Nondisplaced Salter-Harris type
III and IV injuries may be placed in

a long leg cast for 6 weeks. Careful
follow-up of these patients at
weekly intervals is necessary to
address any displacement prompt-
ly. Alternatively, cannulated
screws may be inserted percuta-
neously to stabilize these fractures
(Fig. 6). Displaced fractures are
treated by open reduction and
internal fixation to restore con-
gruity of the joint surface and to
align the physis. After reduction,
smooth pins or screws are inserted
horizontally to avoid crossing the
physis. Because these fractures are
intra-articular, full weight bearing
should not be allowed until radio-
graphs show complete healing.
Outcome
In general, the prognosis for a
closed fracture of the proximal tibial
epiphysis is good. Shortening and
angular deformity are uncommon
because these fractures tend to occur
in older children and adolescents
and because the proximal tibial
epiphysis contributes less to the
overall growth of the limb than does
the distal femur. Open injuries to the
proximal tibial epiphysis have a much

poorer prognosis. These fractures
are often caused by lawnmower
mishaps
10
that result in damage to
the perichondral ring. Angular de-
formities, either alone or in combina-
tion with limb shortening, are com-
monly seen after these open injuries.
Tibial Tubercle Fractures
Classification
Watson-Jones
14
classified frac-
tures of the tibial tubercle into
three types. Ogden et al
15
modified
this classification to include two
subtypes, A and B, according to the
severity of displacement and com-
minution (Fig. 7). In type IA, the
fracture is distal to the normal junc-
tion of the ossification centers of
the proximal end of the tibia and
tuberosity. In type IB, the fragment
is displaced (hinged). In type IIA,
the fracture is at the junction of the
ossification centers of the proximal
end of the tibia and tuberosity. In

type IIB, the fragment is comminut-
ed and the more distal fragment is
usually proximally displaced.
Type III fractures extend into the
joint. Type IIIA is not comminut-
ed; type IIIB is.
Signs and Symptoms
Fractures of the tibial tubercle
most often occur in males between 12
and 17 years of age. These injuries
are most frequently associated with
sports activities, particularly basket-
ball and competitive jumping events.
Injury is caused by either violent con-
traction of the quadriceps muscle, as
occurs with jumping, or acute pas-
sive flexion of the knee against a con-
tracted quadriceps muscle, as occurs
when a football player is tackled.
The patient with a fracture of the
tibial tubercle presents with local
soft-tissue swelling and tenderness
directly over the tubercle. Patients
with a type I injury usually are able
to extend the knee against gravity,
whereas those with a type II or III
injury are unable to do so. Most of
the patients with type II and III
fractures have a hemarthrosis of
the knee joint.

Imaging Studies
Accurate lateral radiographs of
the tubercle are essential to evaluate
this injury. Because the tubercle is
just lateral to the midline of the
tibia, the best profile is obtained
with the leg in slight internal rota-
tion. Oblique radiographs of the
proximal end of the tibia are helpful
to visualize fully the extension of
the fracture into the knee joint.
15
Treatment
Nondisplaced type I fractures
(IA) can be treated successfully by
immobilization in a cylinder cast or
long leg cast with the knee in full
extension for 4 to 6 weeks, followed
by progressive rehabilitation of the
quadriceps muscle. Displaced type
I injuries, as well as nearly all type II
and III injuries, are best treated by
open reduction and internal fixation
through a midline vertical incision.
Any interposed soft tissue, such as a
flap of periosteum, is removed to
facilitate an accurate reduction. In
all type III injuries, the menisci
should be inspected for tears or
peripheral detachments.

Fractures Around the Knee in Children
Journal of the American Academy of Orthopaedic Surgeons
350
Type IA
Type IIA
Type IIIA
Figure 7 The Watson-Jones
14
classification
of fractures of the tibial tubercle as modi-
fied by Ogden et al.
15
(Reproduced with
permission from Edwards PH Jr, Grana
WA: Physeal fractures about the knee. J Am
Acad Orthop Surg 1995;3:63-69.)
Type IB
Type IIB
Type IIIA
Osseous fixation may be achieved
with pins or screws. Cancellous
screws placed horizontally through
the tubercle into the metaphysis
afford stable fixation. Wiss et al
16
recommended the use of 4.0-mm
cancellous screws rather than larger
implants, such as 6.5-mm screws, to
lessen the incidence of bursitis that
may develop over prominent screw

heads. Washers may be helpful to
prevent the screw head from sinking
below the cortical surface. The con-
tinuity of the patellar ligament and
avulsed periosteum is also repaired.
If severe comminution is present, a
tension-holding suture may be nec-
essary to secure the repair.
Postoperatively, the patient wears
a cylinder or long leg cast for 4 to 6
weeks, followed by progressive reha-
bilitation of the quadriceps muscle.
Return to regular activities is permit-
ted after the quadriceps has regained
normal strength and a full range of
motion of the knee joint has been
achieved. Mirbey et al
17
permitted
their patients to resume sports activi-
ties at an average of 3 months after
injury; however, after type II and III
injuries, patients may require 16 to 18
weeks after cast removal to return to
their preinjury activity levels.
15
Outcome
The prognosis for a fracture of the
tibial tubercle is very good. Compli-
cations are uncommon. The theoretic

complication of genu recurvatum has
not been reported because most of
these injuries occur when the physis
is nearing normal physiologic clo-
sure. Compartment syndrome, pre-
sumably caused by tearing of nearby
branches of the anterior tibial recur-
rent artery, has been reported after
tibial tubercle fractures.
16,18
Patients
should be carefully monitored and
those treated surgically considered
for prophylactic anterior compart-
ment fasciotomy. Bursitis over pro-
minent screw heads that necessitates
removal of the implant has been re-
ported.
16
Tibial Spine Fractures
Classification
The anterior tibial spine, or emi-
nence, is the distal site of attachment
of the anterior cruciate ligament.
Before ossification of the proximal
tibia is complete, the surface of the
spine is cartilaginous. When exces-
sive stresses are applied to the ante-
rior cruciate ligament, the incom-
pletely ossified tibial spine offers

less resistance than does the liga-
ment, resulting in a fracture through
the cancellous bone beneath the
tibial spine. Traumatic forces that
would cause a tear of the anterior
cruciate ligament in an adult com-
monly lead to a tibial spine fracture
in a child.
Meyers and McKeever
19
classi-
fied tibial spine fractures into three
main types (Fig. 8). In type I frac-
tures, the fragment is minimally dis-
placed, with only slight elevation of
the anterior margin. In type II frac-
tures, the anterior portion of the
avulsed fragment has a posterior
hinge and the anterior portion is ele-
vated. In type III fractures, the
avulsed fragment is completely dis-
placed and may be rotated.
Signs and Symptoms
Fractures of the tibial spine usu-
ally occur in children 8 to 14 years
of age and are often the result of a
fall from a bicycle. The patient with
a fracture of the tibial spine typically
presents with pain, a hemarthrosis,
and a reluctance to bear weight. The

knee may be held in a slightly flexed
position because of hamstring spasm.
Imaging Studies
Anteroposterior and lateral radio-
graphs will demonstrate a tibial
spine fracture, with the degree of
displacement best evaluated on the
lateral view. Radiographs often un-
derestimate the size of the avulsed
fragment, which is largely cartilagi-
nous. When routine radiographs
show only small flecks of bone in the
intercondylar notch, MRI may be
useful to further assess the injury.
Treatment
Type I fractures and minimally
displaced type II fractures may be
treated by closed means. If a tense
hemarthrosis is present, an aspira-
tion of the knee joint should be per-
formed under sterile conditions and
a long leg cast applied. Although the
Lewis E. Zionts, MD
Vol 10, No 5, September/October 2002
351
Figure 8 The Meyers and McKeever
19
classification for tibial spine fractures. (Adapted
with permission from Tolo VT: Fractures and dislocations around the knee, in Green NE,
Swiontkowski MF [eds]: Skeletal Trauma in Children. Philadelphia, PA: WB Saunders, 1994,

vol 3, pp 369-395.)
Type I
Type II Type III
ideal position of immobilization is
still the subject of some controversy,
10° of flexion seems to be an opti-
mal position to immobilize the knee
joint. Some authors have suggested
immobilizing the knee in greater
flexion to relax the anterior cruciate
ligament.
19,20
Hyperextension prob-
ably should be avoided so as not to
compromise the distal circulation.
Radiographs should be done to con-
firm the reduction of the tibial spine
fragment and repeated in 1 to 2
weeks to ensure that displacement
has not occurred. The cast usually
can be removed in 6 weeks and re-
habilitation of the knee initiated.
Surgical reduction, either arthro-
scopically assisted
21,22
or through an
anteromedial arthrotomy, is indicat-
ed for irreducible type II fractures
and all type III fractures. The ante-
rior horn of the medial meniscus, if

interposed, is removed from the
fracture site to facilitate an accurate
reduction. When reduction is per-
formed through an arthrotomy, the
fragment can be secured using an
absorbable suture passed through
the cartilaginous portion of the frac-
ture fragment and the anterior tibial
epiphysis. After arthroscopic reduc-
tion, either an absorbable suture or
cancellous screw can be used to fix
the fragment. In an adolescent pa-
tient with a small fragment, fixation
may be achieved by weaving a non-
absorbable pullout suture through
the anterior cruciate ligament with
the ends passed through drill holes
in the anterior tibia. Postopera-
tively, the knee is immobilized in 10°
to 20° of flexion in a long leg cast.
The cast is removed in 6 weeks and
rehabilitation is begun.
Outcome
A good outcome may be expected
for fractures of the tibial spine, at
least in the short term. Nonunion of
properly treated fractures is rare.
Several authors have documented
anterior cruciate laxity and some
loss of full knee extension despite

healing of the fracture in an anatomic
position.
23-25
This laxity has been
attributed to interstitial tearing of
the anterior cruciate ligament that
presumably occurs before the frag-
ment is avulsed. Late laxity varies
according to the severity of the ini-
tial injury. Compared with type I
injuries, greater laxity has been
noted after type II and III frac-
tures.
24
Despite the laxity, few
patients complain of pain or insta-
bility.
Few long-term studies of this
injury have been published. For an
average of 16 years, Janarv et al
26
fol-
lowed 61 children who had anterior
tibial spine fractures. Although most
of their patients had a good clinical
result at long-term follow-up, these
authors found no evidence to sug-
gest that the anterior knee laxity
resulting from the injury diminished
over time. Because of the persistent

laxity of the anterior cruciate liga-
ment, which has been documented
in several studies,
23-26
the long-term
prognosis for this injury remains
unclear, and parents of children with
this injury should be appropriately
counseled.
Patellar Fractures
Classification
Patellar fractures rarely occur in
children because the patella is largely
cartilaginous and has greater mobil-
ity than in adults. Ossification of
this sesamoid bone does not begin
until 3 to 5 years of age.
27
Most pa-
tellar fractures occur in adolescents
when ossification is nearly com-
plete.
28
Fractures of the patella are gener-
ally classified according to the loca-
tion, pattern, and degree of displace-
ment. Houghton and Ackroyd
29
described the so-called sleeve frac-
ture that occurs through the carti-

lage on the inferior pole of the patella
(Fig. 9). This fracture occurs most
commonly in children 8 to 12 years
of age. A large sleeve of cartilage is
pulled off the main body of the pa-
tella along with a small piece of
bone from the distal pole. The diag-
nosis of this injury may be missed
because the distal bony fragment is
not readily discernible on radio-
graphs. Grogan et al
30
observed that
avulsion fractures can involve any
segment of the patellar periphery.
They described four patterns of in-
jury: superior, inferior, medial (which
often accompanies an acute lateral
dislocation of the patella), and lateral
(which they attributed to chronic
stress from repetitive pull from the
vastus lateralis muscle).
Signs and Symptoms
The patient with a fracture of the
patella usually demonstrates local
tenderness, soft-tissue swelling, and
hemarthrosis of the knee joint.
Active extension of the knee is diffi-
cult, especially against resistance. A
palpable gap at the lower end of the

patella suggests the presence of a
Fractures Around the Knee in Children
Journal of the American Academy of Orthopaedic Surgeons
352
Articular
cartilage
Figure 9 Lateral view of a sleeve fracture
of the patella. (Adapted with permission
from Tolo VT: Fractures and dislocations
around the knee, in Green NE, Swiontkow-
ski MF [eds]: Skeletal Trauma in Children.
Philadelphia, PA: WB Saunders, 1994, vol
3, pp 369-395.)
sleeve fracture. A high-riding patella
implies that the extensor mechanism
has been disrupted.
With marginal fractures, local ten-
derness and swelling are present
over the medial or lateral margin of
the patella, and straight-leg raising
may still be possible. The presence
of an avulsion fracture of the medial
margin suggests an acute patellar
dislocation that may have reduced
spontaneously. When an acute pa-
tellar dislocation is suspected, other
findings, such as tenderness over the
medial retinaculum and a positive
apprehension sign, also might be
noted on physical examination.

Imaging Studies
Anteroposterior and lateral
radiographs are necessary to evalu-
ate fractures of the main body of
the patella. Transverse fractures
are best seen on the lateral view.
A lateral radiograph taken with
the knee in 30° of flexion may better
ascertain the soft-tissue stability and
true extent of displacement.
30,31
Small flecks of bone adjacent to the
inferior pole in a patient who has
sustained an acute injury may indi-
cate that a sleeve fracture is pre-
sent. MRI may be useful for diag-
nosing a sleeve fracture when the
diagnosis is not clear from the clini-
cal and plain radiographic find-
ings.
32
Marginal fractures that are
oriented longitudinally may be best
seen on a skyline-view radiograph.
Treatment
Treatment guidelines for patellar
fractures in children are generally
the same as those for adults. Closed
treatment in a cylinder cast with the
knee in extension is recommended

for nondisplaced fractures, particu-
larly if active extension of the knee
is present. Surgical treatment is
indicated for transverse fractures
that show more than 3 mm of dias-
tasis or step-off at the articular sur-
face.
31,33
Fixation may be achieved
using the AO tension band tech-
nique, a circumferential wire loop,
or interfragmentary screws. The
retinaculum should be repaired at
the time of osseous fixation. Partial
or total patellectomy should be
reserved for injuries with wide-
spread comminution. Sleeve frac-
tures should be accurately reduced
and stabilized using modified ten-
sion band wiring around two longi-
tudinally placed Kirschner wires.
Small marginal fractures are proba-
bly best excised. If a large portion
of the articular surface is involved,
screw fixation of the fragment may
be preferable to excision.
Outcome
The outcome after a fracture of
the patella is generally good. Re-
sults are poorer with fractures that

show greater displacement and
comminution.
28
If displaced frac-
tures are not accurately reduced,
complications can include patella
alta, extensor lag, and quadriceps
muscle atrophy.
31
Osteochondral Fractures
Classification
Osteochondral fractures of the
knee are most often the result of a
direct blow on a flexed knee or
shearing forces associated with an
acute dislocation of the patella.
Rorabeck and Bobechko
34
described
three fracture patterns following
acute patellar dislocations in chil-
dren: inferomedial fracture of the
patella, fracture of the lateral fem-
oral condyle, and a combination of
the two. They estimated that osteo-
chondral fractures occur in approxi-
mately 5% of all acute patellar dislo-
cations in children. Others have
demonstrated a much higher rate of
osteochondral fracture after acute

dislocation of the patella in the pedi-
atric age group. Nietosvaara et al
35
found associated osteochondral frac-
tures, either capsular avulsions or
intra-articular loose bodies, in 28 of
72 children (39%) after an acute dis-
location of the patella. Stanitski and
Paletta
36
reported arthroscopically
documented articular injuries in 34
of 48 older children and adolescents
(71%) after acute patellar dislocation.
Signs and Symptoms
The patient with an osteochon-
dral fracture of the knee presents
with a painful, swollen joint. The
patient is reluctant to bear weight,
and any attempt to flex or extend the
knee is resisted. Tenderness may be
elicited over the injured portion of
the articular surface. A sterile aspi-
ration of the knee joint is likely to
yield a hemarthrosis and fat glob-
ules, a finding that may suggest the
presence of an osteochondral frac-
ture somewhere in the knee. After
an acute patellar dislocation, the pa-
tient also may exhibit tenderness or a

palpable gap along the medial patel-
lar retinaculum and a positive appre-
hension sign.
Imaging Studies
Osteochondral fractures may be
difficult to see on plain anteroposte-
rior and lateral radiographs, espe-
cially if the ossified portion of the
fragment is small. Oblique, skyline,
and notch views should be obtained
when an osteochondral fracture is
suspected. Stanitski and Paletta
36
found that only 8 of 28 osteochondral
loose bodies retrieved at arthroscopic
examination (29%) could be identi-
fied on a complete four-view radio-
graphic series. Arthrography, CT,
and MRI
37
may better visualize frag-
ments that are largely cartilaginous.
Treatment
Most authorities recommend sur-
gical management of acute osteo-
chondral fractures of the knee.
31,34
Whether the fragment is excised or
reattached depends on its size and
origin. There is no agreement as to

the size of the fragment that man-
dates reattachment. In general, if
the fragment is small and from a
Lewis E. Zionts, MD
Vol 10, No 5, September/October 2002
353
non–weight-bearing surface, it may
be removed arthroscopically. Larger
fragments from weight-bearing
areas should be replaced. Numerous
fixation techniques have been used
with comparable results, including
small, threaded Steinmann pins in-
serted in a retrograde fashion, coun-
tersunk AO minifragment screws,
Herbert screws, fibrin sealant or
other adhesives, and biodegradable
pins. After reattachment, weight
bearing should be avoided until
radiographs confirm that healing of
the fragment is complete.
Outcome
A good result may be expected
after removal of small fragments that
do not involve the weight-bearing
surface of the joint. The outcome is
less certain for large fracture frag-
ments from a weight-bearing area.
Complications include stiffness be-
cause of adhesions and quadriceps

muscle atrophy. Patients whose
osteochondral fractures occurred as
a result of an acute patellar disloca-
tion may experience recurrent sub-
luxation or dislocation. This compli-
cation is most prevalent in patients
whose first dislocation occurred in
their early teenage years and in
those with predisposing anatomic
factors in the unaffected knee, such
as passive lateral hypermobility of
the patella, a dysplastic distal third
of the vastus medialis obliquus mus-
cle, and a high and/or lateral posi-
tion of the patella.
38
Proximal Tibial
Metaphyseal Fractures
Classification
Fractures involving the proximal
metaphysis of the tibia are unusual
injuries in children. The most com-
mon type of fracture in this region is
a minimally displaced, valgus green-
stick injury. The fracture line usually
extends two thirds of the way across
the proximal metaphysis of the tibia
although, in some instances, the frac-
ture may extend completely across.
Despite their innocuous appearance,

these fractures often develop a pro-
gressive valgus angulation during
fracture healing as well as after
union of the fracture.
Signs and Symptoms
These injuries are seen most often
in children younger than 10 years of
age and are usually the result of
low-energy trauma. The patient
with a minimally displaced fracture
of the proximal metaphysis of the
tibia presents with pain, swelling,
and tenderness at the fracture site.
Imaging Studies
Anteroposterior and lateral radio-
graphs usually reveal the fracture,
which is most apparent on the an-
teroposterior view.
Treatment
Minimally displaced fractures of
the proximal tibial metaphysis may
be treated by closed methods. Treat-
ment is directed toward correcting
the valgus angulation and closing
the medial gap at the fracture site.
The lower limb is immobilized in a
long leg cast with the knee in exten-
sion, and varus molding is applied to
the fracture site. Healing is usually
complete by 4 to 6 weeks.

Outcome
The most common problem asso-
ciated with a minimally displaced
fracture of the proximal tibial me-
taphysis is progressive valgus angu-
lation. The angulation occurs most
rapidly during the first 12 months
after the injury and continues at a
slower rate for as long as 18 to 24
months.
39,40
It is important to em-
phasize to parents the possibility of
subsequent deformity despite ade-
quate and appropriate treatment of
the fracture.
Although the exact cause of the
deformity is not known, relative
overgrowth of the medial portion of
the proximal tibial physis, presum-
ably because of fracture-induced
hyperemia, probably plays a role.
41
In a series of children with posttrau-
matic tibia valga, Ogden et al
39
found a generalized increase in lon-
gitudinal growth of the injured tibia
both proximally and distally, and an
eccentric proximal medial over-

growth in every patient.
Early corrective osteotomy gener-
ally is not indicated in the treatment
of this problem because of the high
rate of recurrence after osteotomy
and the trend toward spontaneous
improvement of the angulation as
the child grows.
40
McCarthy et al
42
compared the results of surgical ver-
sus nonsurgical treatment in a series
of children with posttraumatic tibia
valga. They found no significant
difference in lower-extremity align-
ment between the groups at the time
of injury, at maximal deformity, or
at latest follow-up. For an average
of 15 years, Tuten et al
43
followed
seven patients with posttraumatic
tibia valga and found in all patients
that spontaneous improvement of
the angulation had occurred, result-
ing in a clinically well-aligned,
asymptomatic limb in most. They
concluded that patients with this de-
formity should be followed through

skeletal maturity and that surgical
intervention should be reserved for
patients who have symptoms caused
by malalignment.
Summary
Awareness of the unique types of
fractures that occur around the knee
of the growing child will allow the
physician to make a prompt and
accurate diagnosis, apply appropri-
ate treatment techniques, and antici-
pate potential problems. An ade-
quate discussion with both patient
and parents should emphasize the
importance of follow-up care to
allow early detection and manage-
ment of any complications.
Fractures Around the Knee in Children
Journal of the American Academy of Orthopaedic Surgeons
354
Lewis E. Zionts, MD
Vol 10, No 5, September/October 2002
355
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