To The Editor:
The article entitled "Excision for the Treatment of Periarticular
Ossification of the Knee in Patients Who Have a Traumatic Brain
Injury" (81-A: 783-789, 1999), by Ippolito et al., is indeed timely.
Knee heterotopic ossification is uncommon following traumatic brain
injury but is common, second only to hip ossification, following
spinal cord injury1,10. The site is usually at the distal part of
the femur inferomedially, but the ossification may occur in any
plane. True osseous ankylosis of the knee is extremely rare, which
differentiates this location from the hip and elbow.
Resection of this heterotopic ossification has also become commonplace
at our institution. This is due to less orthoapedic influence in
our own rehabilitation programs and to early discharges required
by health maintenance organizations in the private arena. Knee heterotopic ossification
usually responds to physical therapy techniques. Manipulation under
anesthesia is beneficial in the case of the agitated traumatic brain
injury patient, although this should not be performed following
a spinal cord injury due to early osteoporosis and potential fracture2,5.
Timing for the operation is dictated by neurological recovery,
with a longer wait necessary for patients with neurological residua.
A subvastus approach gives excellent exposure of the heterotopic
ossification mass6. Since there is no true osseous ankylosis, freeing
the vastus mobilizes the pathology - that is, the fibrous adhesions between
the vastus and the heterotopic ossification. At times, resection
may not be necessary. This is best predicted by the radiographic
sunrise view. Putting the knee through a range of motion may produce
a snapping of the vastus medialis or tibial collateral ligament
over the heterotopic ossification mass. Resection is definitely
indicated in this situation. Careful dissection is necessary inferomedially
as the superficial and deep portions of the tibial collateral ligament
may be resected, rendering the knee and meniscus unstable. This
dilemma is similar to that seen in resection of heterotopic ossification
at the elbow4.
Hamstring release is usually not necessary if rehabilitation
is available and if neurological sequelae are minimal. Scientifically,
dynamic electromyograms are helpful but often are not practical.
The semimembranosus has a large cross-sectional diameter while the
semitendinosus has a better mechanical advantage at knee flexion,
which argues for their release. If the flexion contracture is not
great, these two tendons are released, leaving the sartorius and
gracilis muscles to balance the biceps. If the patient has a severe
contracture or has severe neurological damage, a complete medial
and lateral release is performed. The joint capsule is not pathological
in neurological myostatic contractures, and its release is not necessary.
Neurological recovery dictates recurrence after resection3. Indomethacin
and radiation may prevent recurrence, but this combination has not been
evaluated in the neurologically compromised patient9. Likewise,
continuous passive motion may assist in the maintenance of joint motion,
but it cannot be concluded that continuous passive motion is associated
with decreased recurrence. Finally, most heterotopic ossification
resection principles were developed from the more complicated hip
procedures. The hip heterotopic ossification principles may be less stringently
applied to the knee and even the elbow, but knee principles may
not be applicable to the hip.
Douglas E. Garland, M.D.
2760 Atlantic Avenue
Long Beach, California 90806
E. Ippolito, R. Formisano, P. Farsetti, R. Caterini,
and F. Penta reply:
We feel honored that our article has stimulated the interest
of Dr. Garland, whose pioneering studies on periarticular heterotopic
ossification in patients who have sustained an injury to the central
nervous system represent a landmark for every orthopaedic surgeon
who is concerned with the surgical treatment of that pathological condition.
On the basis of our own experience, we fully agree with Dr. Garland's
epidemiological considerations on the prevalence of knee periarticular
heterotopic ossification as well as on the likelihood of the resolution
of joint stiffness in many cases of knee periarticular heterotopic
ossification with physical therapy only. However, we saw that agitated
postcomatose patients who have periarticular heterotopic ossification
develop knee stiffness less frequently, probably because of the
continuous uncontrolled movements of their limbs. On the other hand,
as Dr. Garland certainly knows, many neurologists and rehabilitation
therapists have recently suggested that periarticular heterotopic
ossification should be operatively removed as soon as the general
condition of the postcomatose patient starts to get better because
the recovery of articular movements may also improve other neurological
sequelae.
It has often been very hard for us to dissect the periarticular
heterotopic ossification from the medial part of the capsule of
the knee joint as well as from the medial part of the collateral
ligament. However, resection of both the medial capsule and the
medial collateral ligament never produced knee instability in our
patients, probably because they were not able to perform certain
strenuous activities like running or practicing a sport owing to
their residual neuromuscular problems.
Regarding postoperative treatment, we did not say that continuous
passive motion always decreases the recurrence of knee periarticular
heterotopic ossification after its operative excision. We only said
that our series had a lower recurrence rate compared with those
of the only two previously reported series on operative excision of
knee periarticular heterotopic ossification, in which continuous
passive motion was not used. For this reason, we think that continuous
passive motion might have played an important role, but we fully
agree with Dr. Garland when he says that the recurrence rate after
periarticular heterotopic ossification excision is strictly dependent on
both the mental and the neurological recovery of postcomatose patients.
We also agree with Dr. Garland's concluding remarks on the peculiar
features of periarticular heterotopic ossification in different
articulations. Of course, the principles of operative and postoperative
treatment of periarticular heterotopic ossification at the knee
do not fully apply to periarticular heterotopic ossification at
the hip and only partially apply to periarticular heterotopic ossification
at the elbow. We have reported our personal experience on elbow
and hip periarticular heterotopic ossification surgical excision
in two papers that have recently been published7,8.
Ernesto Ippolito, M.D.
Rita Formisano, M.D.
Pasquale Farsetti, M.D.
Roberto Caterini, M.D.
Francesca Penta, Ph.D.
Corresponding author: E. Ippolito, M.D.
Via V. Tiberio, 24
00191 Rome, Italy
E-mail address: ippolito@med.uniroma2.it