Surgery for Anterior Cruciate Ligament Deficiency in Children and Young Adults.
Edited By: Gregory A. Schmale, M.D.
Last updated Wednesday, January 12, 2005
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Review of the condition
Characteristics of anterior cruciate ligament deficiency
A knee without an anterior cruciate ligament (ACL) is a potentially
unstable knee. The ACL is a primary resistor to anterior translation of
the tibia on the femur (it is a tether to limit forward slipping of the
tibia at the knee). The action of the ACL is typically noticed during
running and cutting activities (running with sudden changes of
direction), while descending stairs, and often during simple activities
of daily living.
Individuals with ACL deficient knees may have the feeling of
giving-way (buckling or collapsing from pain or weakness) or
instability during sports or activities of daily living. These episodes
may be painful and may produce or exacerbate other injuries in the
knee, such as meniscal tears (rips or rents in the "C"-shaped cartilage
bumper between the femur and the tibia). Swelling is commonly noted
after such giving way episodes. Lateral joint line pain and tenderness
are often seen in the ACL deficient knee.
Types
ACL deficiency may arise from intra-substance tears (partial tears or
stretching injuries), seen more often in adolescents approaching
skeletal maturity or adults, or from bony avulsion off of the femur or
the tibia. Tibial eminence fracture (fracture of the bony bump on the
central tibial plateau) is the most common cause of ACL deficiency in
children 8-12 years of age. Falls from a bicycle or twisting falls
during play are the most common cause of this injury. These fractures
of the tibial eminence may be non-displaced (still in their natural
position), minimally displaced (slightly moved from their natural
position) with a posteriorly intact hinge of bone, or fully displaced
(completely moved from their natural position) and even rotated. Often,
intra-substance injury or partial ACL tear accompanies these fractures.Similar conditions
ACL deficiency in children and adolescents must be distinguished
from patellar instability, meniscal injury (injury to the "C"-shaped
cartilage bumper between the femur and the tibia), posterior cruciate
ligament injury, injury to the posterolateral corner, and medial and
lateral collateral ligament injury. Each of these conditions may
produce sudden painful giving way of the knee (buckling or collapse
from pain or weakness), though the site of the pain, the position of
the knee during the incident, and whether the pain precedes or follows
initiation of the giving-way helps distinguish the cause.
Physical exam can also distinguish the cause of painful giving-way
of the knee. Patellar instability is typically accompanied by medial
knee pain and apprehension with attempted lateral dislocation of the
patella in mild knee flexion. Meniscal injury is accompanied most often
by joint line tenderness, and pain may be provoked by rotation and
flexion/extension of the knee. These provocative tests are less likely
to be positive in children and adolescents with meniscal tears. Other
ligamentous injuries of the knee usually produce abnormal motions of
the knee with stress during physical exam.
Incidence and risk factors
In children with traumatic knee injuries producing hemarthrosis (an
acutely swollen knee), between 10-65% have sustained and ACL disruption
via either ligament tear or tibial eminence fracture (fracture of the
bony bump on the central tibial plateau). (Stanitski, JPO 1993, Matelic
AJSM, 1995, Eiskjaer, Acta O, 1987) In the under 12 years age group,
acute anterior instability of the knee is most commonly a result of
tibial eminence fracture, whereas in those over 12 years of age,
intra-substance anterior cruciate ligament disruption is the most
common cause of anterior instability. (Kellenberger, 1990).
In the US, between one and four percent of all ACL reconstructions
performed at three sports practices were in skeletally immature
patients. (Nottage and Matsuura, 1994) The incidence of ACL disruption
in adults is estimated to be approximately one in 1750 persons under
age 45 in the US, (Griffin, JAAOS, 2000) suggesting that the incidence
of disruptions in children going to surgery lies between approximately
one in 50,000 and one in 200,000. The actual incidence of injury would
thus be considerably higher.
Recent studies suggest that young woman playing basketball may be up
to eight times more likely to sustain an ACL rupture than a similar
group of young men.
Diagnosis
A physician diagnoses ACL deficiency in children and adolescents by
reviewing the patient's history, performing a thorough physical exam,
and by taking radiographs of the knee. The examination of an ACL
deficient knee reveals asymmetric anterior motion of the tibia relative
to the femur, often with a soft end-point at the extreme of anterior
translation (increased forward slipping of the tibia at the knee when
compared with the other side).
It is essential that the surgeon establish the diagnosis prior to
initiating ACL reconstruction. Surgery may be proposed, however, as a
means to assist in making the diagnosis for a swollen, unstable knee.
Stress radiographs under local or general anesthesia would help
distinguish a fracture through the growth plate of the femur or tibia
as the cause of gross swelling.
In the face of acute knee swelling or hemarthrosis, diagnostic
arthroscopy may reveal ligament disruptions or bony avulsions of
ligaments (ACL/PCL/medial patellofemoral ligament), meniscal tears
(rips or rents in the "C"-shaped cartilage bumper between the femur and
tibia), or osteochondral fractures (breaks in the bone at the joint
surface with a slender piece of bone covered by cartilage made loose in
the joint). Diagnostic arthroscopy revealed previously missed
osteochondral fracture in five of 21 knees with acute hemarthrosis
reported recently. If a locked knee is encountered on physical exam,
incarcerated fracture fragments or meniscus may be presumed and
arthroscopy may be therapeutic as well.
Medications
Medications can help decrease the pain accompanying giving-way
episodes (buckling or collapse from pain or weakness). Masking the
symptoms of giving-way, however, may result in worse injury to the knee
with activity, such as meniscal tear (rip or rent in the "C"-shaped
cartilage bumper between the femur and the tibia) or osteochondral
fracture (break in the bone at the joint surface with a slender piece
of bone covered by cartilage made loose in the joint).
Exercises
Exercises, especially conditioning of the hamstrings (which are
important secondary stabilizers to the ACL deficient knee), are a key
element to management of this condition. Many children and adolescents
may have only mild instability clinically. With hamstring strengthening
and proprioceptive training of the knee (training to learn where the
limb is in space), ACL reconstruction may not be necessary.
Strengthening the hamstrings prior to an ACL reconstruction and
during post-operative rehabilitation is essential to success of the
procedure. In most cases the exercises can be performed daily in a
patient's home with minimal equipment.
Possible benefits of anterior cruciate ligament deficiency surgery
When combined with a good rehabilitation effort, ACL reconstruction in
children and adolescents may restore prior knee function and allow
return to prior activity levels without pain or risk of further injury
to the knee. Though the knee may take a number of years before it feels
as reliable as the uninjured knee, return to cutting (running with
sudden changes of direction) and jumping sports after a year of a
scheduled rehabilitation program can be expected.Surgery for Anterior Cruciate Ligament Deficiency at the University of Washington, Department of Orthopaedics and Sports Medicine, Seattle, Washington
If you are interested in making an appointment to discuss this procedure in Seattle, you can request an appointment using our online referrals website. To request a referral online, please click here. You can also call 206-987-3700 to make an appointment. Our clinical center is located in Seattle Washington, USA
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