To The Editor:
I enjoyed seeing "Factors Associated with Bone Regrowth Following
Diabetes-Related Partial Amputation of the Foot" (81-A: 1561-1565, Nov.
1999), by Armstrong et al., as these common procedures deserve more
attention within the orthopaedic community. More information would
help me to better utilize the information in this article, however.
The extensive statistical analysis would be more meaningful with
clarification of the amputation sites, patient selection, and postoperative
measures.
I wonder if the authors have information regarding which metatarsals
were amputated. Did amputations of the second or third metatarsal
fare worse than those of the fourth or fifth metatarsal? How did
these authors perform "an isolated partial amputation of a ray"?
Did all patients have a plantar ulcer before surgery? Did all patients
have excision of the plantar skin with primary closure, or did some
have simple dǢridement of the infected bone and skin without closure
of the plantar wound? If all procedures were not identical, how
did the different treatment methods affect reulceration rates? How
many feet developed further infection or failed to rapidly heal?
Did different infectious pathogens have different reinfection or
reulceration rates?
Retrospective studies can often lead to very uncertain conclusions.
How did the authors decide upon a diaphyseal amputation level versus
a surgical neck level? What issues led these podiatric surgeons
to decide to use a saw versus a bone-cutter? The selection of patients
included in the study appears open to selective bias. When did the
surgeons decide to perform an isolated ray amputation instead of
multiple-ray or transmetatarsal amputation? Did the authors have
a minimum level of distal perfusion (that is, an ankle brachial
index above 0.50) for inclusion in the study? Did results differ
depending upon the surgeon?
I apologize for asking so many questions, but the study suggests
that partial amputations of a ray in the foot are more prone to
osseous regrowth and thus reulceration when performed more distally,
when done on men, or when performed with a bone-cutter rather than
with a saw. Clinically, I feel that these issues are probably more complicated
than they appear according to the results of analysis of the selective
data in this study.
Stuart D. Miller, M.D.
Department of Orthopaedic Surgery
The Johnston Professional Building
The Union Memorial Hospital
3333 North Calvert Street, Suite 400
Baltimore, Maryland 21218
D. G. Armstrong, S. A. Hadi, H. C. Nguyen, and L. B.
Harkless reply:
We greatly appreciate the thoughtful commentary regarding our
recent article in The Journal. Indeed, all patients
received open partial ray resection for eradication of infection
of that digit or metatarsophalangeal joint. The ray resection level
and the equipment utilized were determined by the surgeon at the
time of dǢridement. Thirty-four of the ninety-two amputations were
performed on the first ray; forty-one, on the central rays; and
seventeen, on the fifth ray. With the numbers available, we could
not detect any significant difference in the prevalence of regrowth
in those groups. Additionally, as the central question of this study
was focused on determining the factors associated with osseous regrowth,
we did not evaluate the microbiology of the wounds in question.
Specific pathogens' role in determining the outcome following infection is
an important issue and should be addressed in further works in this
milieu.
The question of potential selection bias is a compelling one.
We selected patients receiving isolated ray resection (instead of
multiple-ray or transmetatarsal amputation) to facilitate analysis.
Clearly, however, the issue of osseous regrowth at other foot-level
amputations may be even more significant.
Again, we are grateful to Dr. Miller for his insightful queries
and to The Journal for affording us the opportunity
to discuss this issue. We agree wholeheartedly with Dr. Miller that
there may indeed be numerous other clinical factors that play a
role in osseous regrowth. We also believe strongly that many of
these questions would be impossible to adequately and forthrightly
address in a retrospective analysis. We would therefore be disappointed
if the discussion of this topic ended here, and we look forward
to discourse in the future.
David G. Armstrong, D.P.M.
Suhad A. Hadi, D.P.M.
Hienvu C. Nguyen, D.P.M.
Lawrence B. Harkless, D.P.M.
Corresponding author: David G. Armstrong, D.P.M.
Department of Surgery
Veterans Affairs Medical Center
3601 South 6th Avenue
Tucson, Arizona 85723
E-mail address for D. G. Armstrong: armstrong@usa.net