JBJS -- Letters to the Editor for Herring et al., 86 (10) 2121-2134

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Letters to the Editor to:

Scientific Articles:
John A. Herring, Hui Taek Kim, and Richard Browne
Legg-Calvé-Perthes Disease. Part II: Prospective Multicenter Study of the Effect of Treatment on Outcome
J Bone Joint Surg Am 2004; 86: 2121-2134 [Abstract] [Full text] [PDF]

Letters to the Editor: Submit a response to this article

Electronic letters published:

Dr. Herring responds to Dr Charalambous: John A. Herring, M.D. (2 December 2004)

Can we conclude that the lateral pillar classification is related to outcome in Legg-Calve-Perthes ?: Charalambos P Charalambous, Paul Marshall, Consultant in Paediatric Orthopaedics (2 December 2004)

Dr. Herring responds to Dr. Little: John A. Herring (2 December 2004)

Bracing vs. Surgery in Children with LCP Disease: David G Little (2 December 2004)

Dr. Herring responds to Dr Charalambous 2 December 2004

John A. Herring, M.D.
Texas Scottish Rite Hospital for Children, Dallas, TX 75129
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Re: Dr. Herring responds to Dr Charalambous

tony.herring{at}tsrh.org John A. Herring, M.D.

To the Editor:
Dr. Charalambous notes that a number of hips may have been treated surgically prior to classification, and this was the case. The investigators in the surgical groups usually performed their procedures in the earliest stage of disease, before classification was possible, with the hope that surgery would be helpful for all hips. Only after completion of the study did the efficacy of surgery in the different subgroups become evident.
This then raises the question of the effect of surgery on the lateral pillar classification. Is it possible that surgical treatment might change the physiology which produces the radiographic signs we use for classification? While many hips were observed to develop more severe lateral pillar collapse after early surgical intervention, some surgical influence remains a possibility. One approach to the answer is to compare the distribution of lateral pillar groups among the various treatment groups. If surgery improves the classification, there should be fewer severe hips in those groups. We found similar distributions of pillar classifications between treatment groups with one exception--there were fewer lateral pillar C hips in the innominate osteotomy group. This neither proves nor refutes the question. We have long assumed that severity was intrinsic to an affected hip, and prognosis could be determined by radiographic studies. If severity is shown to be modified by treatment, we will have to find new ways to study the efficacy of treatment. If it were true that surgery moved some C hips into a B, or B/C border classification, we would have further support for the usefulness of the surgery. Further studies will be necessary to answer this question.

Can we conclude that the lateral pillar classification is related to outcome in Legg-Calve-Perthes ? 2 December 2004

Charalambos P Charalambous,
Resident in Orthopaedics
Dept of Orthopaedics, Lancaster Royal Infirmary, F.204, 159 Hathersage Road, Manchester, M13 0HX, UK,
Paul Marshall, Consultant in Paediatric Orthopaedics
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Re: Can we conclude that the lateral pillar classification is related to outcome in Legg-Calve-Perthes ?

bcharalambos{at}hotmail.com Charalambos P Charalambous, et al.

To the Editor:
We are writing with regards the methodology reported in the recent study by Herring, et al.(1) In it, the authors recommend that the lateral pillar classification is based on radiographs in the early fragmentation stage of Legg-Calve-Perthes disease with classification prior to early fragmentation being unreliable. The authors conclude that the lateral pillar classification group is related to the outcome of operative treatment as compared to non- operative treatment, with groups B and B/C favoured by surgery, and group C doing poorly despite the mode of treatment. Nevertheless, in 93 of 120 hips treated operatively in this study, surgery was performed in the increased density stage prior to fragmentation.
Was the lateral pillar classification in these hips determined in the fragmentation stage and thus post surgery? Isn�t it possible that surgery in the pre- fragmentation stage could have influenced the lateral pillar height during fragmentation and thus the observed relationship of the lateral pillar group to final outcome, in particular, the failure to show any benefit of surgery for group C hips?
1. Herring JA, Kim HT, Browne R. Legg-Calve-Perthes Disease. Part I: Classification of radiographs with use of the modified Lateral pillar and Stulberg Classifications. JBJS (Am) 2004;86: 2103-2120.

Dr. Herring responds to Dr. Little 2 December 2004

John A. Herring,
MD
Texas Scottish Rite Hospital for Children
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Re: Dr. Herring responds to Dr. Little

tony.herring{at}tsrh.org John A. Herring

To the Editor:
Dr. Little's letter raises some interesting and necessary points. He has noted that when all hips are analyzed there is not a significant difference in outcome between hips treated surgically and those treated in a brace. As Dr. Little notes, we found the most powerful prognostic indicators to be lateral pillar classification and age at onset. With this in mind, in a non-random study, one cannot rely on overall comparisons of treatment groups without segregating for the classification and age factors. Our analysis of outcome between the surgical and braced hips showed the following:
1. No difference in outcome in patients 8 years of age or less at onset.
2. In lateral pillar B hips over age 8 years, the braced hips had 15 Stulberg I-II (45%),14 Stulberg III (42%) and 4 Stulberg IV (12%) results, compared to 24 Stulberg I-II (73%), 7 Stulberg III (21%) and 2 Stulberg IV (6%) results in the surgically treated group, p=.079.
3. In the B/C border group over age 8 the results were for braced hips, 2 Stulberg I-II , 2 Stulberg III, and 4 Stulberg IV outcomes vs. 0 Stulberg I-II, 8 Stulberg III, and 3 Stulberg IV for the surgical group, p=0.067. These analyses do not quite reach significance at the p=0.05 level due to the small sample sizes, but the qualitative difference are notable. From this comparison we conclude that bracing is not as effective as surgical treatment in these two lateral pillar groups with older children. (There were no differences in outcome in lateral pillar C hips between braced and surgically treated hips.)
4. Comparisons between brace treatment and the combined range of motion and no treatment groups for the over 8 year onset and lateral pillar B, B/C, and C categories showed no notable differences between the groups with p values of 0.84, 0.35, and 0.59 respectively. We conclude from this analysis that outcome in the brace treatment group is not significantly different from that in the combined range of motion treatment and no treatment groups in older children.
Dr. Little's "number needed to treat" analysis compared outcome between bracing and surgery for all hips, and noted that one of six patients would be improved. It is my hope that this study will begin to alter this sort of global thinking about treatment for Legg Perthes patients. Our study clearly identifies groups of patients, based on age of onset and severity classification, who are destined for a good outcome without treatment. These patients should be analyzed separately from those who have a greater likelihood of a poor outcome. We show significant advantages for the surgically treated hips of older patients with lateral pillar B and B/C border severity, and no advantage for the lateral pillar C hips. The evidence we have presented does not support universal bracing as efficacious for Legg Perthes, nor does it support any specific treatment for 65% of the hips in this study. We present evidence which supports surgical treatment for a specific group of children.
Dr. Little's final question regarding classification after treatment brings up a familiar dilemma. While the early surgical treatment was a planned part of the study, the finding of efficacy in specific groups was an outcome determined after completion of the study. Thus we recommended a waiting period before advising surgery which was not used in the study. This is fine, but what is the surgeon to do? Should one wait for classification or should the surgery be offered at presentation to any child who is over 8 years old at onset? Based on the distribution of cases in this study, if the surgeon operated on all children over age 8, 84% would benefit, and 16% would not. While it is possible that some of the efficacy of surgery may be lost by waiting six or more months to determine the classification, we have no specific evidence to that effect.With our current state of knowledge, this issue becomes the surgeon's and patient's choice.

Bracing vs. Surgery in Children with LCP Disease 2 December 2004

David G Little,
Orthopaedic Surgeon
The Children's Hospital at Westmead, Sydney Australia
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Re: Bracing vs. Surgery in Children with LCP Disease

davidl3{at}chw.edu.au David G Little

To the Editor:
The paper by Herring et al in the October Journal on Legg Calve Perthes (LCP) disease is a landmark in paediatric orthopaedics. Dr Herring and the LCP study group are to be congratulated on accumulating so much data in a prospective long-term study.
The authors have performed an expansive analysis. Sample size constraints led the authors to combine groups and conclude that operative was better than non-operative. However, if we combine bracing and surgical (containment) versus ROM and no treatment (non-containment), this is highly significant by chi square (p<0.01) in favour of containment. When the operative and bracing groups are compared there is no significant difference , though the sample sizes are roughly equivalent (129 brace, 119 surgery). The authors appear to have been selective in their comparisons. By logistic regression and Wald chi square values the most important factors were classification and age, not treatment.
Another way to look at the effect of surgery is to examine the number needed to treat (NNT) to move a patient from one Stulberg class to another. If we compare bracing and surgery in percentage terms and accept the "best case" that surgery was superior, 7% of patients were moved from IV-V to III, and 9% from III to I-II. Thus 16% of patients moved a Stulberg grade with surgery. This gives an NNT of 6.25 - we need to operate on >6 patients to move one patient one Stulberg grade. Using this data, families should be informed when consenting for surgery that there is a 1 in 6 chance the surgery will improve their prognosis over bracing.
The one other problem in the methodology is that most of the surgical patients were operated on before classification. We are then told to use classification and age to determine need for surgery. Is this valid?
This is a landmark study on LCP disease but the data and conclusions remain open to interpretation and debate.