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The PDF of the article you requested follows this cover page.

This is an enhanced PDF from The Journal of Bone and Joint Surgery

2007;89:2550-2551.J Bone Joint Surg Am.Jan Paul M. Frlke

with Wrist Fractures?Can Vitamin C Prevent Complex Regional Pain Syndrome in Patients

This information is current as of November 6, 2007

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Letters to The Editor

Calcaneal Osteomyelitis Caused

by Exophiala jeanselmei

in an Immunocompetent Child

To The Editor:

In reference to our case report entitled Cal-

caneal Osteomyelitis Caused by Exophiala

jeanselmeiin an Immunocompetent Child.

A Case Report (2007;89:859-62), my coau-

thors and I would like to bring to the notice

of the readers of The Journalthat the same

case report has been published by one of us

in the Indian Journal of Medical Microbiology

as an article entitled Eumycetoma Pedis

Due to Exophiala jeanselmei.1

The publication in the Indian Journal

of Medical Microbiologywas meant to high-

light the microbiological aspects of the dis-

ease as the said fungus is extremely rare. The

authors regret any confusion this might have

caused to the readers of both articles.

Shah A. Khan, MS, MRCS(Ed)

Department of Orthopaedics, All IndiaInstitute of Medical Sciences, AnsariNagar, New Delhi 110 029, India, e-mail:[email protected]

This letter originally appeared, in slightly different form, onjbjs.org. It is still available on the web site in conjunctionwith the article to which it referred.

Reference

1. Capoor MR, Khanna G, Nair D, Hasan A, Rajni,

Deb M, Aggarwal P. Eumycetoma pedis due to

Exophiala jeanselmei.Indian J Med Microbiol.

2007;25:155-7.

Navigated Total Knee Replacement

To The Editor:

We read with interest and concern the arti-

cle, Navigated Total Knee Replacement.

A Meta-Analysis (2007;89:261-9) by Bau-

wens et al. We submitted a similar meta-

analysis to The Journal of Bone and Joint Sur-

geryover one year ago, which was appropri-

ately rejected for publication because of the

inclusion of data from abstracts and uncon-

trolled case series. The reviewers and edi-

tors also expressed concern that our finding

of an advantage for navigated total knee ar-

throplasty compared with conventional total

knee arthroplasty based on radiographic

alignment end points needed to be balanced

against the lack of evidence with regard to

differences in cost-effectiveness, complica-

tion rates, and long-term outcomes be-

tween the two procedures.

We were in the process of updating

our meta-analysis in light of more recent

publications (excluding data from abstracts

and uncontrolled case series) when the

study by Bauwens et al. was published.

Having reviewed essentially the same data-

base, we were perplexed by the authors

conclusion that navigated knee replace-

ment provides few advantages over conven-

tional surgery on the basis of radiographic

end points, as our own meta-analysis re-

vealed a significant improvement in radio-

graphic end points with computer-assisted

navigation.

Our concerns about the discrepancies

between our findings and those of Bauwens

et al. prompted us to investigate their source

data. We contacted them, and they gra-

ciously provided us with the raw data for

all studies included in their meta-analysis.

On further review, we discovered multipleinaccuracies of data extraction and/or data

entry in their analysis.

In four of the studies1-4reviewed in

the article by Bauwens et al., the data for

conventional techniques were entered into

the data set for navigated replacement for

analysis while the data for the navigated re-

placements were entered into the data set for

conventional techniques. We were also able

to determine errors of data extraction, data

entry, patient count, or patient group as-

signment from four additional studies5-8.

One paper9was included and counted as

reporting mechanical axis data when thesedata were not reported in the study. A kin-

ship study10(i.e., a study sharing overlapping

data with an already included study) was in-

cluded when it should have been excluded.

There were two additional studies11,12in

which the numbers that we extracted were

slightly different from those in the report by

Bauwens et al.; we note these only as dis-

crepancies (not errors) in extraction.

Our further review of their paper also

suggested that their labeling and descrip-

tion of results were misleading. Specifically,

they describe their meta-analyses as those

of relative risk of malalignment and label

their figures accordingly. In the Discussion,

they state that the available data suggest

that navigation reduces the relative risk of 3

of malalignment by 25%. This statement

is in error because their meta-analysis was

not of the relative risk of malalignment, but

rather the relative risk of alignment (i.e., the

chance that a patient has alignment after the

procedure). It would, therefore, have been

accurate for them to state that conventional

total knee arthroplasty decreases the relative

chance of alignment by 25%. When misfit,

instead of fit, is the outcome of choice, the

results are quite different from those re-

ported by Bauwens et al. Correctly stated,the risk of malalignment with conventional

replacement is appropriately three times

that with computer-assisted surgery.

In conclusion, our findings of data

extraction and entry errors cause us to chal-

lenge the conclusions in the article regarding

the meta-analysis of radiographic end

points following conventional compared

with navigated knee replacement surgery.

A correct data analysis demonstrates over-

whelming evidence of a much lower error

rate with navigation. Reversal of some of the

extracted data and misreporting of relative

risks for fit as risks of malalignment are par-tially responsible for the muted difference

that Bauwens et al. described between navi-

J Bone Joint Surg Am.2007;89:2547-55

LETTERSTOTHEEDITORMUSTBESUBMITTEDELECTRONICALLY;

INSTRUCTIONSAREATWWW.JBJS.ORG/LETTERS

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T H E J O U R N A L OF B ON E & JOINT S U R G E R Y J B J S .OR G

VOLUME 89-A NU M B E R 11 NOVEMBER2007

LE T T E R ST O T H E E DITOR

gated and conventional total knee arthro-

plasty. These errors, however, do not obviate

their other discussion points regarding the

methodological limits of the available trials,

including a dearth of evidence on long-term

outcomes, quality of life, and costs.While we recognize and understand

the challenges inherent in performing meta-

analyses, our intent is to bring these errors

to the attention of the readers of The Journal

to correct any erroneous impression that

this work may have left with the readership.

J. Bohannon Mason, MD

Thomas Fehring, MD

Kyle Fahrbach, PhD

Corresponding author: J. Bohannon Mason,MD, OrthoCarolina Hip and Knee Center,1915 Randolph Road, Charlotte, NC 28207,e-mail: [email protected]

Disclosure:In support of their research for orpreparation of this work, one or more of theauthors received, in any one year, outsidefunding or grants in excess of $10,000 fromDePuy, and Johnson and Johnson, Warsaw, In-diana. Neither they nor a member of their im-mediate families received payments or otherbenefits or a commitment or agreement toprovide such benefits from a commercial en-tity. No commercial entity paid or directed, oragreed to pay or direct, any benefits to any re-search fund, foundation, division, center, clini-cal practice, or other charitable or nonprofitorganization with which the authors, or a

member of their immediate families, are affili-ated or associated.

D. Stengel, K. Bauwens, G. Matthes,

M. Wich, F. Gebhard, B. Hanson,

and A. Ekkernkamp reply:

We read with great interest the letter from

Dr. Mason and colleagues. Since they raised

substantial concerns about the validity of

our findings, we carefully reviewed the data

set that formed the basis for all analyses and

figures presented in The Journal.

We reviewed the references cited by

Mason et al.1-4and found no data shift betweenthe conventional and navigated-surgery

groups. Such a shift was unlikely since the

forest plots consistently showed an advan-

tage for the navigated-surgery cohort.

Mason et al. also claimed that they

found additional errors of data extraction

from four other studies that we reviewed5-8,

but unless they are more specific in their

criticisms, we cannot respond properly.

We would refer Mason et al. to the

Materials and Methods section of our pa-

per, where we stressed that the numbers of

patients were extracted from histograms

whenever possible. This may explain most

of the differences that they noted between

their and our data sets. Additional differ-ences might be related to different handling

of the unit of interestthat is, the patient or

the knee. Bolognesi and Hofmann9did in-

deed report the alignment of the femoral

and the tibial component rather than the

mechanical axis. However, if navigation im-

proves both femoral and tibial component

alignment, it is very likely that the resulting

mechanical axis will be optimized as well.

Since the observed effects were consistent

with others, we decided to include that

study in our analysis. We definitely identi-

fied and excluded some kinship studies, but

we could not retrieve a dual publication byMielke et al.10.

When posing a null hypothesis, it is

important to define the accepted standard of

care. Risk ratios and other relative measures

are asymmetric. This was the reason why we

also provided risk differences, which can be

used for calculating the number needed to

treat. Currently, navigation is an experimen-

tal add-on and may either decrease the risk

of malalignment or increase the chance of

alignment. It is, however, not justified to ar-

gue that conventional surgery would in-

crease the relative risk of malalignment over

that associated with navigated componentplacement. With regard to health-policy de-

cisions, this is a dangerous statement since it

would imply that all patients who are not

operated on with computer assistance but

undergo conventional total knee arthro-

plasty by an experienced surgeon are at a

higher risk of having malalignment when

compared with those who undergo total

knee arthroplasty with navigated compo-

nent placement.

Importantly, our analyses and plots

showed a significant advantage of navigated

over conventional knee replacement in

terms of radiographic surrogates, so we arein complete agreement with Mason et al.

Yet, unless these advantages are consistent

with improved outcomes, we think that our

conclusion Navigated knee replacement

provides few advantages over conventional

surgery on the basis of radiographic end

points is valid.

Finally, we regret that Mason et al.,

after receiving our data set (the sending of

which shows our openness and willingness

to engage in scientific debate), did not con-

tact us again to compare both data sets and

to discuss, explore, and resolve any possible

differences jointly before submitting a Letter

to the Editor challenging our scientific repu-

tation. We are sorry that Dr. Masons groupcould not publish their paper, but we are

deeply disappointed in their behavior.

Dirk Stengel, MD, PhD, MSc

Kai Bauwens, MD

Gerrit Matthes, MD

Michael Wich, MD

Florian Gebhard, MD, PhD

Beate Hanson, MD, MPH

Axel Ekkernkamp, MD, PhD

Corresponding author: Dirk Stengel, MD,PhD, MSc, Department of Trauma and Or-thopedic Surgery, Center for Clinical Re-search, Unfallkrankenhaus Berlin, Warener

Strasse 7, 12683 Berlin, Germany, e-mail:[email protected]

J.N. Katz and E. Losina

comment on the above letters:

In their meta-analysis of the effectiveness of

navigated total knee replacement, Bauwens

et al. found that navigation was associated

with favorable results in terms of several ra-

diographic parameters. The data were insuf-

ficient to evaluate effects on complication

rates or functional outcomes. The article

stimulated the above letter from Mason et

al. and a letter from Gregori and Holt13,which prompted additional letters of clarifi-

cation from Bauwens et al.

Caught in the crossfire, readers might

well ask why a meta-analysis led to such edi-

torial dueling. Of note, controversy over

meta-analysis is long-standing14. The de-

bates stem in part from the methodological

complexity of meta-analysis, a powerful but

challenging analytic technique that permits

pooling of estimates across studies. We will

discuss a few of the many methodological

complexities of meta-analysis to put the cor-

respondence about navigated total knee re-

placement in perspective.

Why Pool? Meta-Analysis Compared

with Traditional Literature Review

If pooling raises so many questions, why

bother to pool estimates quantitatively

across studies? In many reviews, the authors

simply array the findings of separate studies

in evidence tables without attempting to

synthesize them quantitatively into single

estimates of effect. A key rationale for pool-

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ing is that the available evidence may consist

of small studies that show positive (or nega-

tive) effects but lack power to establish the

associations with significance. Pooling these

smaller studies may avoid false-negative re-

sults due to Type-II error.A useful example of this application

of meta-analysis was provided by Felson and

Anderson in a meta-analysis of the effect of

cytotoxic therapy and corticosteroids com-

pared with that of corticosteroids alone for

patients with lupus nephritis15. Prior small

studies had suggested a beneficial effect of

cytotoxic therapy. The meta-analysis over-

came the small sample sizes of the compo-

nent studies and illustrated the beneficial

effect of cytotoxic therapy across studies.

Pooling also permits the investigator

to examine whether particular study charac-

teristics are associated with the principaloutcome. This technique is termed metare-

gression.The investigator develops a regres-

sion model in which each study serves as a

single observation, contributing a single es-

timate of outcome and of each covariate.

The investigator can weight studies differen-

tially in order to give greater importance in

the regression to those that have larger sam-

ple sizes or that are of higher methodologi-

cal quality. Metaregression can yield insights

about sources of variability in outcome

measures across studies. For example, it may

be that trial designs are associated with

larger effects and nonrandomized designs,with smaller effects, or vice versa.

Why Not Pool?

Pooling the results of separate studies into

single estimates of effect involves several as-

sumptions that frequently are not satisfied

by the literature under review. Clearly, the

outcome variable must be consistent across

studies. This constraint poses no problem

when the outcome is unambiguously de-

fined, such as thirty-day all-cause mortality

following hip replacement. However, when

studies measure satisfaction, pain relief,

functional status, and other such complexoutcome variables, the task becomes more

complicated. These domains are often mea-

sured with different tools in different stud-

ies, or different cutoffs are used to define

success. For example, the authors of some

studies of the outcome of total knee replace-

ment might use the WOMAC (Western

Ontario and McMaster Universities Os-

teoarthritis Index) as the principal outcome

measure whereas others might use the SF-36

(Short Form-36) or the Knee Society Scale.

Attempting to synthesize results in these

circumstances involves essentially com-

bining apples and oranges and is not

advisable. Standardization of outcome

assessment and reporting in specific fieldswould assist investigators who wish to per-

form meta-analysis.

In addition, the underlying statistical

methodology of meta-analysis assumes that

each of the studies to be synthesized repre-

sents one observation from a single distribu-

tion of studies. This assumption is validated

with tests of homogeneity of the odds ratios

(or other effect estimates) across studies. If

the group of studies to be synthesized ap-

pears to emanate from a single distribution,

the homogeneity criterion is met and the

studies may be synthesized in a meta-analysis.

If, on the other hand, the assumption ofhomogeneity is not met, and the studies ap-

pear to be heterogeneous, then the investi-

gators should be cautious about pooling.

The investigators could simply choose not to

pool the studies quantitatively. Alternatively,

the investigators might wish to perform a

metaregression to identify sources of hetero-

geneity. For example, it may be that higher-

quality studies or a particular study design

(e.g., trials) are associated with higher effect

estimates.

What to Pool?

A meta-analysis is essentially an observa-tional study of individual studies16. As with

all observational studies, the results are in-

fluenced by the selection criteria that dic-

tate which studies are included in the meta-

analysis and which are excluded. An issue

that arises frequently, and was a major focus

of contention about the paper by Bauwens

et al., is whether to include unpublished

studies. Excluding unpublished studies risks

publication bias, a form of selection bias in

meta-analyses that arises because positive

studies are, on the average, more likely to

be published than negative studies. How-

ever, including unpublished studies thathave not passed peer review risks the in-

clusion of studies with results that may not

be credible.

Another important decision is

whether to restrict the analysis to random-

ized controlled trials or to include observa-

tional designs. The advantage of restricting

the analysis to randomized controlled trials

is that randomization greatly reduces the

risk of selection bias in each component

study of the meta-analysis. Including obser-

vational studies permits the meta-analysis to

simply propagate the biases inherent in the

component studies. The disadvantage of

restricting the sample to randomized

controlled trials is that for many clinicalproblems, including navigated total knee

replacement, there are few randomized

controlled trials and most of the relevant

literature includes observational designs.

Returning to Navigated

Total Knee Replacement

Bauwens et al. handled most of the above-

mentioned issues with sophistication. They

decided to pool because they were concerned

that multiple underpowered studies would

fail to establish an effect that might become

apparent in a pooled analysis. They included

nonrandomized trials because they were notcomfortable restricting the analysis to ran-

domized controlled trials. (An alternative ap-

proach would be to use metaregression to

examine whether the magnitude of effect dif-

fered between randomized and observational

studies; if it did, the meta-analysis could be

done in subgroups.) The authors weighted the

studies according to sample size and quality.

They used appropriate analytic techniques to

look for publication bias and, finding no evi-

dence of such a bias, they restricted the analy-

sis to published studies. In addition to stating

the results of these analyses of publication bias,

displaying the graphical evidence would havebeen helpful to readers.

Bauwens et al. concluded that the

studies that they wished to synthesize were

heterogeneous. Having established heteroge-

neity, the authors could have simply decided

not to pool the studies at all. Alternatively,

they could have developed a metaregression

model, which would have been useful in

identifying and ultimately controlling for

sources of heterogeneity. They could have

stratified according to such characteristics

and tested whether the stratified meta-

analysis would have yielded less heteroge-

neity. The authors did indeed perform ametaregression, but they did not use it to

identify strata in which studies were more

homogeneous, as discussed here. By docu-

menting heterogeneity and not doing any-

thing about it, the authors in a sense made a

diagnosis without offering a remedy.

Data Sharing

Synthesizing the results of various studies is

ultimately a collaborative activity. The in-

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vestigator will often wish to contact other

scientists who have access to original trial

data or who themselves have attempted a

data synthesis. These collaborations can

help move the field forward. In fact, the Na-

tional Institutes of Health (NIH) and otherresearch sponsors have developed specific

provisions for facilitating data sharing in or-

der to best leverage the precious data gar-

nered in NIH-funded studies. In this regard,

we were particularly impressed by the will-

ingness of Bauwens et al. to share their data

and we were disappointed that Mason et al.

chose to communicate their observations in

a letter to The Journalwithout discussing the

findings with the original authors. Readers,

and ultimately patients, were not served well

by this failure to behave collaboratively.

Concluding RemarksThe meta-analysis by Bauwens et al.

prompted questions about selection of stud-

ies, choice of common outcome measures

across studies, assessment and management

of heterogeneity, interpretation of results,

and approaches to collaboration. The les-

sons learned from these studies of navigated

total knee replacement are that investigators

should make individual studies as definitive

as possible by using the most rigorous de-

signs feasible, powering studies adequately,

and using standardized measures of out-

come. Pooling is a powerful method for ag-

gregating information across studies, but itis ultimately a collaborative effort. Leaders

in the field should designate standard mea-

sures of outcome to facilitate pooling, and

investigators should work collaboratively

with one another so that data syntheses

move the field forward, bringing quality and

value to patients.

Jeffrey N. Katz, MD, MSc

Elena Losina, PhD

Corresponding author: Jeffrey N. Katz, MD,MSc, Orthopaedic and Arthritis Center forOutcomes Research, Brigham and WomensHospital, 75 Francis Street, PBB-B3, Boston,MA 02115, e-mail: [email protected]

Disclosure: The authors did not receive anyoutside funding or grants in support of theirresearch for or preparation of this work. Nei-ther they nor a member of their immediatefamilies received payments or other benefits ora commitment or agreement to provide suchbenefits from a commercial entity. No com-mercial entity paid or directed, or agreed topay or direct, any benefits to any research fund,

foundation, division, center, clinical practice,or other charitable or nonprofit organizationwith which the authors, or a member of theirimmediate families, are affiliated or associated.

These letters originally appeared, in slightly different form,on jbjs.org. They are still available on the web site in conjunc-tion with the article to which they refer.

References

1. Bthis H, Perlick L, Tingart M, Lring C, Zura-kowski D, Grifka J. Alignment in total knee ar thro-

plasty. A comparison of computer-assisted surgery

with the conventional technique. J Bone Joint Surg Br.2004;86:682-7.

2. Perlick L, Bthis H, Lerch K, Lring C, Tingart M,

Grifka J. [Navigated implantation of total knee en-

doprostheses in secondary knee osteoarthritis of

rheumatoid arthritis patients as compared with con-ventional technique]. Z Rheumatol. 2004;63:140-6.

German.

3. Saragaglia D, Picard F, Chaussard C, Montbarbon

E, Leitner F, Cinquin P. [Computer-assisted knee

arthroplasty: comparison with a conventional proce-

dure. Results of 50 cases in a prospective random-

ized study]. Rev Chir Orthop Reparatrice Appar Mot.

2001;87:18-28. French.

4. Sparmann M, Wolke B, Czupalla H, Banzer D, Zink

A. Positioning of total knee arthroplasty with and with-

out navigation support. A prospective, randomised

study. J Bone Joint Surg Br. 2003;85:830-5.

5. Chauhan SK, Scott RG, Breidahl W, Beaver RJ.

Computer-assisted knee ar throplasty versus a

conventional jig-based technique. A randomised,

prospective trial. J Bone Joint Surg Br. 2004;86:

372-7.

6. Confalonieri N, Manzotti A, Pullen C, Ragone V.

Computer-assisted technique versus intramedullary

and extramedullary alignment systems in total knee

replacement: a radiological comparison. Acta Orthop

Belg. 2005;71:703-9.

7. Kim SJ, MacDonald M, Hernandez J, Wixson RL.Computer assisted navigation in total knee arthro-

plasty: improved coronal alignment. J Arthroplasty.

2005;20(7 Suppl 3):123-31.

8. Perlick L, Bthis H, Tingart M, Perlick C, Grifka J.

Navigation in total-knee arthroplasty: CT based im-

plantation compared with the conventional technique.

Acta Orthop Scand. 2004;75:464-70.

9. Bolognesi M, Hofmann A. Computer navigation

versus standard instrumentation for TKA: a single-

surgeon experience. Clin Orthop Relat Res. 2005;

440:162-9.

10. Mielke RK, Clemens U, Jens JH, Kershally S.

[Navigation in knee endoprosthesis implantation

preliminary experiences and prospective compara-

tive study with conventional implantation technique].

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11. Anderson KC, Buehler KC, Markel DC. Computerassisted navigation in total knee arthroplasty: com-parison with conventional methods. J Arthroplasty.

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12. Haaker RG, Stockheim M, Kamp M, Proff G,Breitenfelder J, Ottersbach A. Computer-assisted nav-

igation increases precision of component placementin total knee ar throplasty. Clin Or thop Relat Res.

2005;433:152-9.

13. Gregori A, Holt G. Letter regarding Navigated

total knee arthroplasty. A meta-analysis. (2007;89:261-269). J Bone Joint Surg Am. epub 2007

Mar 27. http://www.ejbjs.org/cgi/eletters/89/2/

261#31862.

14. Goodman SN. Have you ever meta-analysis you

didn't like? Ann Intern Med. 1991;114:244-6.

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Can Vitamin C Prevent Complex

Regional Pain Syndrome in

Patients with Wrist Fractures?

To The Editor:

In the article Can Vitamin C Prevent Com-

plex Regional Pain Syndrome in Patients

with Wrist Fractures? A Randomized, Con-

trolled, Multicenter Dose-Response Study

(2007;89:1424-31), Zollinger et al. studiedthe prophylactic effect of vitamin C on the

prevalence of complex regional pain syn-

drome in 416 patients with a wrist fracture.

They concluded that vitamin C is indeed ef-

fective, and they recommended giving 500

mg of vitamin C daily for fifty days to each

patient with a wrist fracture to prevent com-

plex regional pain syndrome.

Some limitations of this study men-

tioned in the article include a large selection

bias (416 of 2137 eligible patients were en-

rolled) and a low event rate due to an unex-

pected low prevalence of complex regional

pain syndrome (4.2% compared with 22%in the authors previous study1). This means

that only eighteen patients (eight of the

328 in the treatment group and ten of the

ninety-nine in the placebo group) fulfilled

the criteria for complex regional pain syn-

drome. In one patient with fractures of both

wrists, complex regional pain syndrome de-

veloped on one side, where the fracture

turned out to be badly reduced, and the

other side healed without complications.

This example reveals dramatically how this

study demonstrates a strong confounder: al-

though the number of fractures needing re-

duction was equal in both groups, thequality of the reduction was not mentioned.

Open reduction and internal fixation

of wrist fractures generally achieves a better

reduction than closed reduction with appli-

cation of a cast. Retrospective studies of sur-

gically treated wrist fractures have therefore

demonstrated a lower incidence rate of

complex regional pain syndrome, of around

3.5%2. To my knowledge, no prospective

study has ever demonstrated an association

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between the incidence of complex regional

pain syndrome and the quality of reduc-

tion, but pain syndromes in general occur

more frequently when fractures are not ade-

quately reduced.

Much scientific effort has been putin attempts to achieve prophylaxis and

treatment for complex regional pain syn-

drome with pharmacological means, but

these efforts did not result in any clinical

recommendations3. Conservative physical

therapy has provided some benefit for pa-

tients with complex regional pain syn-

drome4. Since the introduction of functional

and time-contingent pain-exposure phy-

sical therapy in children with complex re-

gional pain syndrome by Sherry et al. in

19995, more reports on this approach are

to be expected for adult patients as well.

A difference is therefore to be ex-pected between patients with complex re-

gional pain syndrome who are treated by

a physical therapist and those who are not.

The use of any form of physical therapy is

not mentioned in this paper, introducing

another possible confounder. This paper

therefore does not provide support for the

effectiveness of vitamin C in preventing

complex regional pain syndrome.

Jan Paul M. Frlke, MD, PhD

University Medical Center St. Radboud, P.O.Box 9101, 6900 HB Nijmegen, The Nether-lands, e-mail: [email protected]

Disclosure: The author did not receive anyoutside funding or grants in support of his re-search for or preparation of this work. Neitherhe nor a member of his immediate family re-ceived payments or other benefits or a com-mitment or agreement to provide such benefitsfrom a commercial entity. No commercial en-tity paid or directed, or agreed to pay or direct,any benefits to any research fund, foundation,division, center, clinical practice, or othercharitable or nonprofit organization withwhich the author, or a member of his immedi-ate family, is affiliated or associated.

P.E. Zollinger, W.E. Tuinebreijer,

R.S. Breederveld, and R.W. Kreis reply:

We read the letter of our colleague, Dr.

Frlke, with great interest. First, on the ba-

sis of our study, we believe that vitamin C

does prevent complex regional pain syn-

drome. Unfortunately, most of Dr. Frlkes

comments do not apply to our study.

The number of enrolled patients in

our study in relation to the number of eligi-

ble patients was mentioned in the Discus-

sion of our article. The quality of reduction

was studied in this paper and in our paper in

Lancet1as well. In both studies, there was no

relationship between the occurrence of

complex regional pain syndrome and theneed to undergo fracture reduction. More-

over, the quality of reduction did not influ-

ence the chance of complex regional pain

syndrome developing. We performed the

current study because, to our knowledge,

there have been no published studies since

19991that either confirm or refute our origi-

nal findings.

To our knowledge, no prospective

study has ever demonstrated an association

between the prevalence of complex regional

pain syndrome and the quality of reduc-

tion. Retrospective studies do not have the

level of evidence that is needed. Dr. Frlkemakes a misjudgment by citing the article by

Arora et al.2. Arora et al. found that, of 114

patients followed for one year, five had type-

I complex regional pain syndrome and three

had type-II complex regional pain syn-

drome. Thus, the prevalence of type-I com-

plex regional pain syndrome in their study is

4.39% (not 3.5% as stated in Dr. Frlkes let-

ter) and is higher than our overall preva-

lence of 4.2%; it stands in contrast with the

2.4% for all of our patients treated with vita-

min C. The difference is even more striking

when the 4.39% rate is compared with the

prevalence of only 1.8% in our group receiv-ing 500 mg of vitamin C and 1.7% in the

group receiving 1500 mg.

Why the articles by Rowbotham3, Oer-

lemans et al.4, and Sherry et al.5are cited is

unclear to us. Our study is about the possible

prevention of complex regional pain syn-

drome after a wrist fracture in adults treated

with a prophylactic dose of vitamin C and

not about the therapy for complex regional

pain syndrome itself. The end point of our

study was defined as the presence of complex

regional pain syndrome at any time within

one year after the fracture (see the Study De-

sign section). The article by Rowbotham3deals with pharmacotherapy in patients with

complex regional pain syndrome.

The article by Oerlemans et al.4is a

very well-respected trial comparing adjuvant

physical therapy with occupational therapy

for patients with complex regional pain syn-

drome. Here lies the difference with our frac-

ture patients. If we had treated our patients

with physical therapy as well, we would have

created our own confounding factor. Skep-

tics would have challenged our conclusions

and pointed to the positive effect of the physi-

cal therapy rather than to the effect of vita-

min C, as Dr. Frlke does now.

When complex regional pain syn-

drome develops in patients who have sus-tained a wrist fracture, it is of course treated

with physical therapy and medication, if

necessary6. The article by Sherry et al.5deals

with the outcome in children with complex

regional pain syndrome after exercise ther-

apy. However, we believe that complex re-

gional pain syndrome in children is a

completely different entity than complex

regional pain syndrome in adults, and so

is the approach to its treatment. This was

confirmed by Wilder et al.7, who reminded

us that, in children, complex regional pain

syndrome most often involves the lower ex-

tremity (87% [sixty-one] of seventy cases),which is in contrast to the situation in

adults, who have more upper-extremity

complex regional pain syndromes. The

therapie used by Sherry et al.5consisted of

aerobic functionally directed exercises, hy-

drotherapy, and desensitization. Which

therapy achieved the desired outcome? Can

it get more confounding than this?

Paul E. Zollinger, MD

W.E. Tuinebreijer, MD, PhD, MSc, MA

R.S. Breederveld, MD, PhD

R.W. Kreis, MD, PhD

Corresponding author: Paul E. Zollinger, MD,Department of Orthopaedic Surgery, Zieken-huis Rivierenland, President Kennedylaan 1,4002 WP Tiel, The Netherlands, e-mail:[email protected]


References

1. Zollinger PE, Tuinebreijer WE, Kreis RW, Breeder-

veld RS. Effect of vitamin C on frequency of reflex

sympathetic dystrophy in wrist fractures: a random-

ized trial. Lancet. 1999;354:2025-8.

2. Arora R, Lutz M, Hennerbichler A, Krappinger D, Es-

pen D, Gabl M. Complications following internal fixa-

tion of unstable distal radius fracture with a palmar

locking-plate. J Orthop Trauma. 2007;21:316-22.3. Rowbotham MC. Pharmacologic management ofcomplex regional pain syndrome. Clin J Pain.

2006;22:425-9.

4. Oerlemans HM, Oostendorp RA, de Boo T, Goris

RJ. Pain and reduced mobility in complex regional

pain syndrome I: outcome of a prospective ran-

domised controlled clinical trial of adjuvant physical

therapy versus occupational therapy. Pain.

1999;83:77-83.

5. Sherry DD, Wallace CA, Kelley C, Kidder M, Sapp

L. Short- and long-term outcomes of children with

complex regional pain syndrome type I treated with

exercise therapy. Clin J Pain. 1999;15:218-23.

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6. The Netherlands Society of Rehabilitation Special-

ists. Guidelines: Complex regional pain syndrome

type I. 2006. http://www.posttraumatischedystro-

fie.nl/pdf/CRPS_I_Guidelines.pdf.

7. Wilder RT, Berde CB, Wolohan M, Vieyra MA,Masek BJ, Micheli LJ. Reflex sympathetic dystrophy

in children. Clinical characteristics and follow-up

of seventy patients. J Bone Joint Surg Am. 1992;

74:910-9.

Exposure to Direct and Scatter

Radiation with Use of

Mini-C-Arm Fluoroscopy

To The Editor:

We commend Giordano et al. on their excel-

lent work in quantifying the risk of radia-

tion when using a mini-C-arm fluoroscopy

unit, as reported in their study entitled

Exposure to Direct and Scatter Radiation

with Use of Mini-C-Arm Fluoroscopy(2007;89:948-52). Their methodology, how-

ever, does not accommodate for the mea-

surement of increased radiation exposure

when the C-arm is used in the conventional

method, with the image intensifier verti-

cally above the radiation source1. Nor does it

estimate what the exposure dose would be

immediately level to the receiver. Their data,

however, remain of value to advance the

overall safety of fluoroscopy in theater.

In our as yet unpublished survey of

more than seventy-five orthopaedic trainees

and theater staff in the United Kingdom, we

found that the majority had poor workingknowledge of conventional image intensi-

fier usage and surprisingly little insight into

ionizing radiation protection issues. Al-

though most orthopaedic trainees in the

United Kingdom do not push the button,

they do guide the radiographer and super-

vise the surgical assistant and theater staff.

Therefore, the patient, surgical teams, and

theater staff may be at risk of exposure. With

appropriate training of surgeons, the mini-

C-arm may be adopted more widely in the

National Health Service, thereby releasing

overburdened radiographers from theater

while increasing throughput and safety intheater, as alluded to by White2. However, we

believe that this can only occur once the re-

cently disbanded ionizing radiation protec-

tion course has been reinstigated.

Narlaka Jayasekera, MRCS

Richard Roach, FRCS(Orth)

Corresponding author: Narlaka Jayasekera,Department of Orthopaedics, Princess RoyalHospital, Telford, Shropshire TF1 6TF, UnitedKingdom, e-mail: [email protected]

Disclosures:The authors did not receive anyoutside funding or grants in support of theirresearch for or preparation of this work. Nei-ther they nor a member of their immediatefamilies received payments or other benefits ora commitment or agreement to provide suchbenefits from a commercial entity. No com-mercial entity paid or directed, or agreed topay or direct, any benefits to any research fund,foundation, division, center, clinical practice,or other charitable or nonprofit organizationwith which the authors, or a member of theirimmediate families, are affiliated or associated.

J.F. Baumhauer and

B.D. Giordano reply:

We appreciate the comments of Mr. Jayasek-

era and Mr. Roach and acknowledge that

our methodology does not reflect a number

of conventional techniques that have beenemployed in the past during the routine use

of mobile C-arm fluoroscopy.

In our paper, we make note of several

dose-reducing measures that have been

studied over the years and have enabled

mobile C-arm operators to produce high-

quality images while optimizing the overall

safety to the patient and operating room

staff. These measures include minimizing

exposure time, reducing exposure factors,

manipulating the x-ray beam with collima-

tion, maximizing distance from the beam,

using protective shielding, and imaging with

the C-arm in an inverted orientation relativeto the specimen.

Positioning the phantom limb di-

rectly on the platform of the image intensi-

fier increases the distance from the radiation

source to the specimen, subsequently reduc-

ing the amount of scatter produced. Al-

though many of these measures have been

studied with use of a standard large C-arm

unit, the literature regarding similar param-

eters with the mini C-arm unit is limited. In

our experimental design, we attempted to

create a best-case scenario by utilizing

known dose-reducing techniques to quan-

tify radiation exposure just as a surgeonwould likely strive to achieve in a true op-

erating room setting.

With regard to the second portion

of the correspondents comments, we point

out that at positions of 15 and 25 cm from a

focal point on the phantom hand, we found

minimal radiation exposure (1 to 2 mrem) as

measured with our dosimeters. These mea-

surements were made in the plane of the im-

age intensifier. In contrast, when the radiation

dosimeter was placed directly in the phantom

hand, substantial exposure levels (181 to 272

mrem) were recorded. We did not collect data

points between these two locations.

We concur with Jayasekera and Roach

that many orthopaedic trainees and, for thatmatter, a great number of mini or large C-

arm operators, have a poor understanding of

the science behind image intensifier usage.

This may lead them to grossly underestimate

the potential for high-dose radiation expo-

sure if these mobile fluoroscopy units are not

used judiciously and with proper intent.

A common error made by novice

trainees is the use of the mini C-arm to im-

age larger body parts such as the tibia, fe-

mur, humerus, elbow, or shoulder. As the

tissue density and cross sectional area of the

imaging subject increase, technique factors

automatically adjust, in the normal mode,to produce an image with optimal penetra-

tion and visual quality. To accommodate for

the increased tissue density of a larger body

part, technique factors increase by a sub-

stantial margin, leading to a much higher

radiation exposure rate than may have been

encountered when using a large C-arm.

We appreciate the interest in our pa-

per and strive to advance science safety with

the commonly used fluoroscopy units.

Judith F. Baumhauer, MD

Brian D. Giordano, MD

Corresponding author: Judith F. Baumhauer,MD, Division of Foot and Ankle Surgery, Uni-versity of Rochester Medical Center, 601 Elm-wood Avenue, Box 665, Rochester, NY 14642,e-mail: [email protected]


References

1. Tremains MR, Georgiadis GM, Dennis MJ. Radia-

tion exposure with use of the inverted-C-arm tech-

nique in upper-extremity surgery. J Bone Joint Surg

Am. 2001;83:674-8.

2. White SP. Effect of introduction of mini-C-arm imageintensifier in orthopaedic theatre. Ann R Coll Surg

Engl. 2005;87:53-4.

Integrity of the Lateral Femoral

Wall in Intertrochanteric Hip

Fractures: An Important

Predictor of a Reoperation

To The Editor:

The article Integrity of the Lateral Femoral

Wall in Intertrochanteric Hip Fractures: An

Important Predictor of a Reoperation,

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(2007;89:470-5), by Palm et al., is particu-

larly important because it confirms previous

reports on the critical role played by the

lateral wall in the reconstruction of pertro-

chanteric hip fractures1-3. While devices such

as the dynamic hip screw and sliding hipscrew have been considered the gold stan-

dard in the treatment of pertrochanteric hip

fractures for fifty years, this type of iatro-

genic complication has been reported only

recently1; thus, I would like to offer some

observations.

The lateral wallexists in conjunction

with a pertrochanteric hip fracture; it does

not exist, as an anatomical structure, in a

normal intact femur. It is important to dis-

tinguish between those fractures where the

lateral wall does not exist preoperatively and

those where it does exist preoperatively and

is fractured either intraoperatively or post-operatively. The former have already been

defined in the Fracture and Dislocation

Compendium, where, in fact, the term lat-

eral wallis not used4. This classification sys-

tem does distinguish types 31-A1 and 31-A2

fractures, which are defined as pertrochan-

teric fractures, from a type 31-A3, which is

defined as an intertrochanteric fracture. It is

unfortunate that the authors do not use

both terms. Rather, they use only the term

intertrochanteric fracture, which may lead to

misunderstanding and confusion. On the

other hand, the iatrogenically fractured lat-

eral wall, occurring during or following asurgical procedure, converts a pertrochan-

teric A1 or A2 fracture into an intertrochan-

teric A3 fracture and is certainly different

and deserves special attention. The clear dis-

tinction between the two did not emerge

from the paper.

Because of the nature of this compli-

cation, it has been considered to be a dis-

tinct entity: the pantrochanteric fracture5.

Once a fracture of the lateral wall is

recognized as an iatrogenic complication,

and the events leading to the fracture are

understood, a reevaluation of the situation

is indicated. First, new definitions are neces-sary. It is important to distinguish between

fracture collapse, the outcome of fracturing

the lateral wall (an adverse postoperative

event), and controlled fracture impaction

(a desirable postoperative event). This has

previously been defined together with other

relevant definitions1and could have been re-

ferred to by the authors.

Careful definition will not only

contribute to better understanding of the

postoperative radiograph, and hence the

patient's condition, but will also facilitate

decision-making in the postoperative reha-

bilitation period, e.g., the type of weight-

bearing to be instituted.

In addition, when it is possible to at-tribute the collapse to certain procedures

and/or devices, this should enable us to set

new surgical standards designed specifically

to avoid this kind of complication.

Yechiel Gotfried, MD, MS

Bnai Zion Medical Center, 47 GolombStreet, P.O.B. 4940, Haifa 31048, Israel.E-mail: [email protected]

Disclosure: The author did not receive anyoutside funding or grants in support of his re-search for or preparation of this work. Theauthor, or a member of his immediate family,

received, in any one year, payments or otherbenefits in excess of $10,000 or a commit-ment or agreement to provide such benefitsfrom a commercial entity (Orthofix, Inc.). Nocommercial entity paid or directed, or agreedto pay or direct, any benefits to any researchfund, foundation, division, center, clinicalpractice, or other charitable or nonprofit or-ganization with which the author, or a mem-ber of his immediate family, is affiliated orassociated.

H. Palm, S. Jacobsen, S. Sonne-Holm,

and P. Gebuhr reply:

We appreciate the interest by Dr. Gotfried inour recent article and are delighted that he

finds our study to be particularly important.

In a large number of patients, our study

does, in fact, confirm previous reports of the

importance of the integrity of the lateral

femoral wall, including the fact that a frac-

ture of the lateral femoral wall is most often

an iatrogenic complication.

Dr. Gotfried raises good questions

regarding the nomenclature used in the ar-

ticle. The general nomenclature for these

fractures is quite confusing. As the terms

trochanteric, pertrochanteric, pantrochan-

teric, and intertrochanteric, etc., are oftenmixed up, we also find it highly relevant to

achieve international consensus on this

matter. In our article, we simply used the

term intertrochantericfor all type 31-A

fractures, in part, because we found that

Dr. Gotfried also previously did this1, al-

though not in a later article2referred to in

our study. We now agree that using the

termspertrochantericfor the type 31-A1

and 31-A2 fractures and intertrochanteric

only for the type 31-A3 fractures would

have been more precise. On the other hand,

we still find that we enable the reader to

distinguish between the fracture types by

using the AO/OTA classification numbers,

including the very important subtypes inthe text and tables, and by showing an il-

lustrating diagram.

We agree that new definitions of bio-

mechanical complications are necessary

and that the knowledge that the lateral

femoral wall is an iatrogenic complication

could contribute to a better understanding

of the treatment of these fractures. We cur-

rently treat type 31-A1 and 31-A2.1 frac-

tures with a sliding hip screw fixed to a

lateral plate and type 31-A3 fractures with

a sliding hip screw fixed to an intramedul-

lary nail.

As a third of the 31-A2.2 and 31-A2.3 fractures in our study were converted

to 31-A3 fractures, we now also treat these

fractures using the sliding hip screw fixed

to an intramedullary nail. In the future,

perhaps other systems designed specifi-

cally to avoid a perioperative fracture of the

lateral femoral wall1might prove to be su-

perior to treat these specific fracture sub-

groups. To date, it has not been feasible to

categorize fractures into all of the AO/OTA

subgroups as this demands very large

groups of patients.

Henrik Palm, MD

Steffen Jacobsen, MDStig Sonne-Holm, MD, DMSc

Peter Gebuhr, MD

Corresponding author: Henrik Palm, MD,Department of Orthopaedic Surgery, Copen-hagen University Hospital of Hvidovre, Kette-gaard Alle 30, DK-2650 Hvidovre, Denmark,e-mail: [email protected]


References

1. Gotfried Y. Percutaneous compression plating of

intertrochanteric hip fractures. J Orthop Trauma.

2000;14:490-5.

2. Gotfried Y. The lateral trochanteric wall: a key

element in the reconstruction of unstable pertro-

chanteric hip fractures. Clin Orthop Relat Res.

2004;425:82-6.

3. Im GI, Shin YW, Song YJ. Potentially unstable inter-

trochanteric fractures. J Orthop Trauma. 2005;19:5-9.

4. Fracture and dislocation compendium. Ortho-

paedic Trauma Association Committee for Codingand Classification. J Orthop Trauma. 1996;10 Suppl

1: v-ix, 1-154.

5. Gotfried Y. Pantrochanteric hip fracture: an entity.

J Bone Joint Surg Br. (Suppl III) 2000;82:235.

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Comparison of the Vastus-Splitting

and Median Parapatellar Approaches

for Primary Total Knee Arthroplasty:

A Prospective, Randomized Study.

Surgical Technique

To The Editor:The otherwise excellent article, Compari-

son of the Vastus-Splitting and Median

Parapatellar Approaches for Primary Total

Knee Arthroplasty: A Prospective, Random-

ized Study. Surgical Technique (2007;89

Suppl 2 Part 1:80-92), by Kelly et al., was

marred by an error in the legend to Figure

1. The axial radiograph of the knee was

mislabeled as a Merchant radiograph of

the patella.

The shape and appearance of the

dista part of the femur on the radiograph

demonstrates that it is really a Settegast

view. This technique requires the knee to beacutely flexed well beyond 90, drawing the

patella, which might otherwise be severely

subluxated laterally at the trochlear level,

into the intercondylar space to articulate

with the distal, or weight-bearing, surface

of the femoral condyles.

Conversely, the Merchant axial

view radiograph is exposed with both

knees flexed no more than 45, showing

the patellas true relationship to the

trochlea1,2.

This may seem to be a minor point,

but if the surgeon is not aware that the

patella is subluxated laterally prior to sur-gery, he or she may not take sufficient mea-

sures to correct that subluxation during

surgery. Many postoperative patellofemo-

ral complications can be avoided if the sur-

geon is aware of this problem before

surgery.

Alan C. Merchant, MD

Stanford University, 124 Marvin Avenue,Los Altos, CA 94022, e-mail: [email protected]

Disclosure: The author did not receive anyoutside funding or grants in support of his

research for or preparation of this work.Neither he nor a member of his immediatefamily received payments or other benefits ora commitment or agreement to provide suchbenefits from a commercial entity. No com-mercial entity paid or directed, or agreed topay or direct, any benefits to any researchfund, foundation, division, center, clinicalpractice, or other charitable or nonprofit or-ganization with which the author, or a mem-ber of his immediate family, is aff iliated orassociated.

V.D. Pellegrini Jr., M.J. Kelly,

M.N. Rumi, M. Kothari, K.J. Bailey,

W.M. Parrish, and M.A. Parentis reply:

We thank Dr. Merchant for correctly identi-

fying our error as it relates to patellofemoral

imaging of the knee. We concur with hiscomments and, indeed, customarily per-

form patellofemoral imaging with the knee

in 30 of flexion to more sensitively identify

lateral subluxation of the patella. The patel-

lar view presented in our paper does not re-

flect our usual practice.

We appreciate Dr. Merchants efforts

in bringing this inadvertent misrepresenta-

tion to our attention as well as that of the

readership of The Journal.

Vincent D. Pellegrini Jr., MD

Matthew J. Kelly, MD

Mustasim N. Rumi, MD

Milind Kothari, DOKatrina J. Bailey, PT

William M. Parrish, MD

Michael A. Parentis, MD

Corresponding author: Vincent D. PellegriniJr., MD, Department of Orthopaedics, Univer-sity of Maryland School of Medicine, 22 SouthGreene Street, Suite S 11 B, Baltimore, MD21201, e-mail: [email protected]


References

1. Merchant AC, Mercer RL, Jacobsen RH, Cool CR.

Roentgenographic analysis of patellofemoral congru-ence. J Bone Joint Surg Am. 1974;56:13916.

2. Merchant AC. Patellofemoral imaging. Clin Orthop

Relat Res. 2001;389:1521.

Cost-Effectiveness of Extended-

Duration Antithrombotic Prophylaxis

After Total Hip Arthroplasty

To The Editor:

We read with interest the recent paper The

Cost-Effectiveness of Extended-Duration

Antithrombotic Prophylaxis After Total Hip

Arthroplasty (2007;89:819-28), by Skedgel

et al., regarding economic decision-making,with reference to extended thrombopro-

phylaxis after total hip arthroplasty. The

authors refer to a study by Lapidus et al.1,

who stated that 38.4% of patients receiving

low-molecular-weight heparin required a

community nurse for administration. For

cost-effectiveness, the number requiring a

community nurse must be

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heparin could meet a threshold of $50,000

per quality-adjusted life year gained with

home care rates of

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