In their article, they claim for a 91% success rate in eradicating
the initial infection. However, according to the above
statement, eradicating the initial infection is only a part of
the complete treatment plan. If I understand properly, the data
provided the following:
• 99 cases entered the study;
• 16 cases were not reimplanted and, consequently, cannot
be considered as having a “functional, stable and painless
knee joint”;
• 7 cases experienced a recurrence of the initial infection;
• 13 cases experienced a new infection (or a recurrence of
the previous one?) and, consequently, cannot be consid-
ered as having an “eliminated infection” after the 2-stage
exchange.
That means that 36 cases did not fulfill the primary treatment
plan, leaving 63 success cases for an actual success rate of 64%,
which is far from the 91% claimed.
I would appreciate to get any comment from the authors
about my understanding of their article.
Jean-Yves Jenny, MD
Hôpitaux Universitaires de Strasbourg
Centre de Chirurgie Orthopédique et de la Main, France
© 2011 Elsevier Inc. All rights reserved.
doi: 10.1016/j.arth.2011.03.010
In Reply:
Thank you for your careful review of the data in our article
entitled Modern Treatment of Infected Total Knee Arthroplasty
with a 2-Stage Reimplantation Protocol (J Arthroplasty 2010;25:
1015-1021). In our article, we explicitly claim a 91% success
rate in eradicating the initial infection in patients who
completed the 2-stage reimplantation protocol. Our data
support this claim as follows:
•
95 patients (99 knees) with infected total knee arthro-
plasties treated at our institution during the study period
•
7 patients died before the 2-year follow-up and were not
included in analysis
•
16 patients never underwent 2-stage reimplantation proto-
coland,therefore,werenotincludedintheanalysis
•
This left 72 patients (75 knees) who underwent 2-stage
reimplantation and had 2-year minimum follow-up
available for analysis
•
7 of these cases experienced recurrence of initial infection
•
Therefore, 68 of 75 knees remained free of the initial
infection, yielding a success rate of 91%.
Although you claim 36 cases did not fulfill the primary
treatment plan, the purpose of our study was to evaluate the
success rate specifically among patients who did complete the 2-
stage reimplantation protocol, which is why patients who did
not undergo the protocol were excluded. In addition, we chose
to exclude patients without 2-year follow-up to gain a more
accurate success rate at midterm follow-up. Therefore, it is
unjustified to consider the size of our eligible cohort as 95
patients because only 72 patients were truly qualified for
inclusion. Furthermore, total knee arthroplasties in which the
initial infection was eradicated but subsequently developed an
infection with a different strain were counted as successes
because the development of an infection with a different type of
bacteria is unrelated to the initial bacterial infection. This is the
same format we used in a previous peer-reviewed manuscript
from our institution in which the same infectious disease
consultant is a coauthor and has extensively reviewed the data.
Once again, thank you for your careful review of our article,
and we hope this clarifies your understanding of our data.
Sincerely,
Geoffrey H. Westrich, MD
Associate Professor of Orthopedic Surgery
Hospital for Special Surgery, New York, New York
© 2011 Elsevier Inc. All rights reserved.
doi: 10.1016/j.arth.2011.03.012
To the Editor:
With great interest, I read the article by Larson et al
(J Arthroplasty. 2010;25(7):). Patients with inheritance of
abnormal renal tubular phosphate wasting show bony
deformities mostly in the lower extremities [1]. Because of
rotational and angular deformities, it is still a challenge for
an orthopedic surgeon to correct those deformities to dece-
lerate the development of osteoarthritis. We also reported
about a 43-year-old woman with inherited vitamin D–
resistant rickets that developed because of multiple deformi-
ties and osteoarthritis of the hip and knee joint [2]. She
firstly was treated with bilateral total knee arthroplasty (PFC
post-stab; DePuy Johnson&Johnson Orthopaedic Inc, War-
saw, Ind). The immediate postoperative outcome was good
but showed deterioration at the 12-month follow-up with
decrease of range of motion. Total knee arthroplasty in
hypophosphatemic rickets remains a challenge for the
orthopedic surgeon but can be recommended in severe
knee pain; however, preoperative interventions should be
considered to prevent postoperative complications.
Joern W.-P. Michael, MD, PhD
Department of Orthopaedic and Trauma Surgery
University of Cologne, Cologne, Germany
References
1. Matsubara H, Tsuchiya H, Kabata T, et al. Deformity corrections for
vitamin D–resistant hypophosphatemic rickets of adults. Arch
Orthop Trauma Surg 2008;128:1137.
2. Michael JWP, Sobottke R, Springorum HP, et al. Hypophosphatemic
diabetes and knee pain: does treatment with total knee arthroplasty
promise success? Z Rheumatol 2009;68:491.
© 2011 Elsevier Inc. All rights reserved.
doi: 10.1016/j.arth.2011.02.002
In Reply:
We would like to thank Dr Michael for his comments
regarding our article “Hip and Knee Arthroplasty in Hypopho-
sphatemic Rickets” (J Arthroplasty. 2010;25). We agree with
Dr Michael's comments regarding the difficulties in addressing
bone deformities present in patients with this condition. As
pointed out in our study, the main challenges when
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The Journal of Arthroplasty Vol. 26 No. 5 August 2011