Copyright © 2007 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Ernesto Ippolito, MD*,
University of Rome Tor Vergata, Rome, Italy
Posted June 2007
Two studies have shown that, during infancy, the position of
the tarsal bones is difficult to estimate on radiographs because the centers of
ossification are small and eccentrically positioned within the
osteocartilaginous anlagen1,2. Moreover, the navicular bone, one of
the most displaced bones in clubfoot deformity, does not ossify until the age
of three or four years.
Since Dr. Ponseti3 recommends initiation of his
treatment protocol shortly after birth, babies are usually two-months old when
manipulative treatment ends. At that time, the clubfoot correction should be
assessed, and the option to perform subcutaneous Achilles tenotomy should be
evaluated. Dr. Ponseti emphasizes the "palpation" assessment as the best way to
check clubfoot correction by direct identification of the skeletal components
of the deformity. I personally can attest that during my two years of
attendance at the Ponseti clubfoot clinic (1977-1978), I never saw Dr. Ponseti
make even one radiograph of a foot during treatment. However, less experienced
orthopaedic surgeons who start to apply the Ponseti method would be helped with
a more objective method to evaluate the efficacy of the manipulative treatment
before undertaking subcutaneous Achilles tenotomy. Indeed, due to the abundance
of fat in the heel pad of some clubfeet, it can be difficult to identify by
palpation the alignment of the os calcis in relation with the other skeletal
components of the foot. In those instances, a surgeon who wishes to avoid
causing a rocker-bottom deformity of the foot might be uncertain about whether or
not to perform a subcutaneous Achilles tenotomy.
As shown by Pirani et al.4, only magnetic
resonance imaging may clearly show the real position of the chondro-osseus components
in congenital clubfoot. However, for obvious reasons, such an imaging
investigation cannot be routinely proposed to assess the efficacy of the
Ponseti technique in babies with congenital clubfoot.
I agree with Dr. Radler and coworkers that the lateral
tibiocalcaneal angle is the best radiographic parameter to detect false
correction of clubfoot in the lateral plane. However we should always think
about the first principle of the Ponseti manipulative technique—that is, to
manipulate "gently." Stretching of the plantar ligaments of the midtarsal
joints when the Achilles tendon is tight and unyielding causes the surgeon to
apply too much force in attempting foot dorsiflexion and thus causes rocker-bottom
deformity. Forceful maneuvers should never be done, and the equinus should be
corrected very gently, with the correction starting by the time of application
of the second plaster cast. In almost 15% to 20% of cases, the triceps
surae-Achilles tendon unit may be gradually stretched to allow a true
dorsiflexion of the foot. Nevertheless, in most cases, the equinus position is
maintained by a tight Achilles tendon that can be easily palpated throughout
the skin, and a subcutaneous lengthening might be performed before application
of the fifth plaster cast.
In conclusion, I believe that we must agree with Dr. Radler
and coworkers that the standard use of radiographs during treatment of clubfeet
should be discouraged. Nevertheless, when the orthopaedic surgeon is not yet
fully familiar with the clinical evaluation of the foot correction, knowing the
tibiocalcaneal angle can be helpful in particular cases, either to determine the
right indication for an Achilles tenotomy or to detect pseudocorrection
(iatrogenic rocker-bottom deformity). On the basis of my personal experience5,
I believe that no prognostic value should be given to either the anteroposterior
or lateral talocalcaneal angles in the feet of babies or adults who are being
managed for congenital clubfoot, because those angles do not correlate with the
final clinical and functional results.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.
References
1. Howard CB, Benson MK. The ossific nuclei and the cartilage anlage of the talus and calcaneum. J Bone Joint Surg Br. 1992;74:620-3.
2. Cummings RJ, Hay RM, McCluskey WP, Mazur JM, Lovell WW. Can clubfeet be evaluated accurately and reproducibly? In: Simons GW, editor. The clubfoot: the present and a view of the future. New York: Springer; 1994. p 104-13.
3. Ponseti IV. Congenital clubfoot. Fundamentals of treatment. New York: Oxford University Press; 1996.
4. Pirani S, Zeznik L, Hodges D. Magnetic resonance imaging study of the congenital clubfoot treated with the Ponseti method. J Pediatr Orthop. 2001;21:719-26.
5. Ippolito E, Fraracci L, Caterini R, Di Mario M, Farsetti P. A radiographic comparative study of two series of skeletally mature clubfeet treated by two different protocols. Skeletal Radiol. 2003;32:446-53.
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