Copyright © 2006 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Christopher P. Chiodo, MD*,
Brigham and Women's Hospital, Boston, Massachusetts
Posted August 3, 2006
In 1983, Johnson reported on what has now become the most
widely used staging system for posterior tibial tendon dysfunction1.
In this system, all patients with a flexible flatfoot deformity were classified
as having stage-II disease, regardless of the severity of the deformity.
In the more recent literature, multiple procedures have been
described for the treatment of stage-II posterior tibial tendon dysfunction. This
observation suggests that contemporary foot and ankle surgeons demonstrate
little consensus on how best to treat this disorder. One simple explanation for
this lack of consensus is that stage II encompasses a wide spectrum of disease
and includes both mild and severe deformities. It may thus be unrealistic to
expect one single operation to be uniformly successful in this setting.
In the present study, Vora and colleagues present cadaveric
data that support this position. Using a novel adult flatfoot model, they have
demonstrated that a medializing calcaneal osteotomy combined with a flexor
digitorum longus tendon transfer procedure is indeed adequate for the
correction of a mild flatfoot deformity. Not surprisingly, they further
demonstrate that these procedures are inadequate for the correction of more
severe deformities. Specifically, flexor digitorum longus tendon transfer
combined with medializing calcaneal osteotomy left the talar-first metatarsal
angle, talonavicular angle, and medial cuneiform height substantially
undercorrected in the severe flatfoot model. These findings led the authors to
suggest that it may be time to formally subcategorize flexible flatfoot
deformities to facilitate further clinical investigation.
The authors then addressed the intriguing concept of using arthroereisis
as a surgical adjuvant in the treatment of more advanced flatfoot deformity. Arthroereisis
entails the use of a sinus tarsi implant to mechanically block subtalar eversion.
This procedure has been widely embraced by the podiatric community, and there
have been recent reports in the orthopaedic literature advocating its use for
both pediatric and adult patients2-5. The data from the present
study demonstrate that, in a cadaveric flatfoot model, the addition of
arthroereisis does significantly improve the corrective power of flexor
digitorum longus transfer combined with medializing calcaneal osteotomy. It
must be noted, though, that the radiographic correction in the severe model was
still incomplete. While the talonavicular angle and medial cuneiform height
were similar to that in the intact state, the lateral talo-first metatarsal
angle was only partially corrected despite the addition of the arthroereisis
procedure.
The findings of these authors have very noteworthy clinical
implications. Many would advocate the use of selective hindfoot fusion or
lateral column lengthening for more severe yet flexible flatfoot deformities. The
ability to avoid these more involved procedures and the potential morbidity
that is associated with them would be substantial. In the hands of a competent
surgeon, arthroereisis can be performed relatively quickly. Further, the
implant is extra-articular and can be readily removed, if necessary.
Of course, further clinical testing will be necessary to
validate the biomechanical findings of these authors. Questions remain
regarding the long-term survival and implications of a sinus tarsi implant, its
precise indications, and its exact mechanism of action. Still, these authors
are the first to finally study arthroereisis in a cadaveric biomechanical model
and are to be applauded for their innovative approach to a complex and
challenging clinical disorder.
*The author did not receive grants or outside funding in
support of his research for or preparation of this manuscript. He did not
receive 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,
educational institution, or other charitable or nonprofit organization with
which the author is affiliated or associated.
References
1. Johnson KA. Tibialis posterior tendon rupture. Clin Orthop Relat Res. 1983;177:140-7.
2. Viladot R, Pons M, Alvarez F, Omana J. Subtalar arthroereisis for posterior tibial tendon dysfunction: a preliminary report. Foot Ankle Int. 2003;24:600-6.
3. Needleman RL. Current topic review: subtalar arthroereisis for the correction of flexible flatfoot. Foot Ankle Int. 2005;26:336-46.
4. Zaret DI, Myerson MS. Arthroerisis of the subtalar joint. Foot Ankle Clin. 2003;8:605-17.
5. Gutierrez PR, Lara MH. Giannini prosthesis for flatfoot. Foot Ankle Int. 2005;26:918-26.
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