Technical Information about ACL Injuries in Children.
Last updated Thursday, January 13, 2005
Considerations in treating childrenConsiderations in treating ACL injuries in childre All of the reported studies on ACL reconstruction in skeletally
immature patients are complicated by the wide range of ages of the
study subjects. Most studies deal with patients who are post pubertal
and near skeletal maturity. This is clearly a different group when
compared to the patient near skeletal maturity.
The important considerations for treatment in this age group include:
- determining biological age,
- appropriate classification of injury type,
- accurately quantifying laxity,
- the effect of transphyseal drill holes on subsequent growth,
- special considerations in graft selection in the skeletally immature, and
- complications.
Age The determination of biologic age is necessary when comparing
methods of treatment and when devising a treatment plan. The Tanner
Staging of biologic age is an appropriate way to classify skeletally
immature patients (30). A simplification of this system would be to
combine groups I and II into a prepubescent category and groups III and
IV into a pubescent category.
Those in the pubescent group have developed secondary sexual
characteristics and are near full growth. Patients in this group can be
generally treated as adults and make up the bulk of most published
studies. Prepubescent patients ( groups I and II) constitute the group
of most concern since they have considerable growth remaining. Most
recommendations of this chapter pertain to the treatment of
prepubescent patients. Injury The type of ACL injury is important in formulating a treatment plan and predicting outcome. Injuries can be classified as:
- bony avulsions,
- interstitial tears, or
- bony avulsions with associated interstitial tears.
It is generally agreed that bony avulsions have a better prognosis
than interstitial tears. The determination of injury type may require
arthroscopic inspection. Although, the use of magnetic resonance
imaging has greatly improved the ability to determine the region and
extent of injury. With true isolated bony avulsions, a good result can
be expected with anatomic replacement of the avulsed fragment.
Laxity The level of laxity following ACL injury in children is important in
treatment decisions. Children in general have more normal laxity than
adults and a comparison with the opposite knee is vital. Absolute
laxity is also important since functional disability is closely related
to absolute laxity. The pivot shift phenomenon usually occurs with
anterior laxity of greater than 10 mm. Laxity less than this amount
(negative pivot shift or pivot glide) should generally be treated
nonoperatively particularly in the prepubescent population. When
anterior laxity becomes greater than 15 mm not only are sporting
activities dangerous, but everyday activities may become impaired
making surgical intervention more necessary.Tunnels A review of available literature reveals incomplete knowledge as to
the effect of drill holes upon the physis. Most data on physeal
closures have been extrapolated from traumatic injuries (31). It is
felt that a carefully placed drill hole is far traumatic to the growth
plate than are the injuries that are included in most growth arrest
studies. Care should be taken to minimize the trauma to the physis when
creating drill holes. Several general principles regarding surgery near
the physis can be made:
- Drill holes should be as small as possible.
- Centrally placed tunnels, if growth is affected, are less likely to cause an angular deformity.
- Only soft tissue grafts should traverse the physis. Bone blocks or
fixation devices that traverse the physis are more likely to cause
growth arrest.
- Extraarticular procedures that require extensive dissection or
fixation devices near the physis may be more damaging than transphyseal
tunnels.
Graft Soft tissue grafts only should be considered when transphyseal drill
holes are used for ACL reconstruction. Bone blocks traversing the
physis have an increased risk for increasing the likelihood for
premature physeal closure at that location. Harvesting of an autogenous
bone-patellar tendon-bone graft also runs the risk of damaging the
tibial tubercle apophysis. The use of allograft or synthetics in this
age group has little indication. The most ideal graft for traversing
the physis is one of autogenous hamstring tendons.Complications Since the potential exists for growth interference following ACL
reconstruction through an open physis, there is understandable
increased anxiety patient and their family. If a growth disturbance is
recognized, a definitive treatment plan should be set in place to
minimize the morbidity of this complication; appropriate consultation
with a pediatric orthopaedic is helpful to determine the timing and
most appropriate intervention. Rehabilitation may also need to be
modified to make it more fun to entice cooperation and participation.
Should stiffness (arthrofibrosis) develop in this age group,
arthroscopy and release of adhesions is preferred over manipulation
alone since less than gentle manipulation may potentially endanger the
physis.
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