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 pr
Trang 1The 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 Harris1(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
Lewis E Zionts, MD
Trang 2warranted 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 al3found 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 mainob-tain 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
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.)
Trang 3bances 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 al4
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 deceleration4and growth
stimulation5can 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 Harris1(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
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.)
Trang 4valgus 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 tibilater-al 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
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 classification1 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
Trang 5ration 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-face13(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-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.
Trang 6lized using pins or AO cannulated
screws across the metaphyseal
por-tion of the fracture Open reducpor-tion
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
mishaps10that 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-Jones14 classified
frac-tures of the tibial tubercle into
three types Ogden et al15modified
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 ossificajunc-tion 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
Type IA
Type IIA
Type IIIA
Figure 7 The Watson-Jones14 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
Trang 7Osseous fixation may be achieved
with pins or screws Cancellous
screws placed horizontally through
the tubercle into the metaphysis
afford stable fixation Wiss et al16
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 al17permitted
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 McKeever19 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
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.)
Trang 8ideal 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 assisted21,22or through an
anteromedial arthrotomy, is
indicat-ed for irrindicat-educible 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 al26 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 Ackroyd29
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 al30observed 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
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.)
Trang 9sleeve 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 Bobechko34described 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 al35
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 Paletta36reported 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 Paletta36
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 MRI37may 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
Trang 10non–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 al39
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 al42
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 al43followed 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