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How Much Varus Is Optimal with Proximal Femoral Osteotomy to Preserve the Femoral Head in Legg-Calvé-Perthes Disease?
Harry K.W. Kim, MD, MSc, FRCSC1; Ana Munhoz da Cunha, MD2; Richard Browne, PhD1; Hui Taek Kim, MD3; J. Anthony Herring, MD1
1 Center for Excellence in Hip Disorders, Texas Scottish Rite Hospital for Children Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center, 2222 Welborn Street, Dallas, TX 75219. E-mail address for H.K.W. Kim: harry.kim@tsrh.org
2 Hospital Pequeno Príncipe, Avenue Silva Jardim, 1632-Rebouças, Curitiba-PR 80250-200, Brazil
3 Pusan National University Hospital, 1-10 Ami-dong, Seo-gu Pusan, 602-739 Republic of Korea
View Disclosures and Other Information
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

Investigation performed at Texas Scottish Rite Hospital for Children, Dallas, Texas
A commentary by Paul D. Sponseller, MD, is available at www.jbjs.org/commentary and is linked to the online version of this article.

Copyright © 2011 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2011 Feb 16;93(4):341-347. doi: 10.2106/JBJS.J.00830
A commentary by Paul D. Sponseller, MD, is available here
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Abstract

Background: 

Although proximal femoral varus osteotomy is an established operative treatment for Legg-Calvé-Perthes disease, there is a lack of data on how much varus at the osteotomy is optimal for preserving the spherical shape of the femoral head. The purpose of this study was to determine if there is a correlation between the amount of varus used and the Stulberg radiographic outcome at maturity and to determine if the varus angulation improved over time.

Methods: 

The database and the radiographs of fifty-two patients treated with proximal femoral varus osteotomy from a multicenter prospective study were analyzed. The neck-shaft angles were measured before the operation, after the operation, and at the time of final follow-up, and the amount of varus placed was correlated with the Stulberg outcome at skeletal maturity. Spearman correlations and logistic regression were used for statistical analysis.

Results: 

All patients were six years of age or older at the time of diagnosis (mean 8.0 ± 1.4 years), and all were skeletally mature at the time of follow-up (mean age [and standard deviation] at the time of follow-up, 16.5 ± 2.0 years). The mean neck-shaft angle was 138° ± 7° preoperatively and 115° ± 11° postoperatively with a mean varus change of 23° ± 10°. No significant correlation was observed between the postoperative neck-shaft angle at maturity and the Stulberg outcome (r = -0.15, p = 0.17) and between the amount of varus placed and the Stulberg outcome (r = 0.14, p = 0.36). However, when the lateral pillar groups were analyzed separately with use of logistic regression, a significant relationship was observed for the lateral pillar group B (p = 0.025), with a higher postoperative neck-shaft angle having a greater probability of being associated with a Stulberg class-I or II outcome. At maturity, the mean neck-shaft angle had improved from 115° ± 11° following the initial surgery to 124° ± 8°. However, nineteen (37%) of the fifty-two patients showed no improvement (defined as a change of >5°) and fifteen (29%) of the fifty-two patients had an overriding greater trochanter.

Conclusions: 

Contrary to the conventional belief, greater varus angulation does not necessarily produce better preservation of the femoral head following proximal femoral varus osteotomy. Given the results, our recommendation is to achieve 10° to 15° of varus correction when performing proximal femoral varus osteotomy on hips that are in the early stages of Legg-Calvé-Perthes disease.

Level of Evidence: 

Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

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    References

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    Narendranadh Akkina, MS, Bhavuk Garg, MS
    Posted on October 02, 2011
    Concerns regarding study design
    Department of Orthopaedics, PGIMER, Sector 12, Chandigarh, India

    We read the article “How Much Varus Is Optimal with Proximal Femoral Osteotomy to Preserve the Femoral Head in Legg-Calvé-Perthes Disease?” by Kim et al with great interest. We had some concerns regarding the study design. To determine lateral pillar class, authors used post proximal femoral osteotomy radiographs as 44 of osteotomies were done before fragmentation stage. But in the paper published by Joseph et al 1 34 percent of Perthes disease patients who underwent femoral osteotomy in the stage of avascular necrosis bypassed the stage of fragmentation (lateral pillar collapse). In contrast in this study all patients passed through fragmentation stage (lateral pillar collapse) and the main outcome was measured between this lateral pillar group and head sphericity at maturity. One more concern is that the profile of the lateral pillar may change after osteotomy, hence it is difficult to accurately grade the degree of collapse. REFERENCES: 1. Joseph B, Rao N, Mulpuri K, Varghese G, Nair S. How does a femoral varus osteotomy alter the natural evolution of Perthes' disease? J Pediatr Orthop B; 2005:14:10-15

    Harry K.W. Kim, MD, MSc, FRCSC
    Posted on April 22, 2011
    Drs. Kim and Herring respond to Dr. Kamegaya and colleagues
    Pediatric Orthopaedic Surgeon, Texas Scottish Rite Hospital for Children and UT Southwestern Medical Center, Dallas, Texas

    Dr. Kamegaya raises an important question regarding the indications for femoral varus osteotomy (FVO) in our study patients. Our study patients came from a prospective multicenter study by Herring et al. (1) where the participating surgeons were allowed to select one treatment out of five treatments at the beginning of the study. Subsequently, all of his or her patients who met the entry criteria (age 6 to 12 at the onset of the disease, no prior treatment, and initial stages of disease at enrollment) had to be treated using the selected method. The study was designed to eliminate selection bias and to have uniformity, thus, almost all FVO were performed during the early stages of the disease when radiographic classifications, such as the lateral pillar or the Catterall classification, could not be applied. This brings up a controversial issue in the management of LCPD which partly stems from having the prognostic classification systems that cannot be applied in the early stages of the disease. There is clearly a need to develop an earlier prognostic indicator that can be applied before the deformity develops to guide treatment from the early stages of the disease.

    Meantime, how should we manage the patients presenting before these classifications can be applied? One treatment approach has been to wait and observe until the patient can be classified. As argued by Dr. Kamegaya, this “wait-to-classify” approach may prevent operating on patients who would not have needed a surgery. Others, however, argue that if the main goal of treatment is to prevent deformity and to obtain a spherical femoral head at skeletal maturity then the idea of “wait-to-classify” is suboptimal as the femoral head is deforming during this observational period and may not remodel even with a surgical intervention. The results from a multicenter prospective study from Norway showed that when FVO was performed at the mid fragmentation stage when these classifications can be applied (i.e. taking the “wait-to-classify” approach), only 43% of the patients aged greater than 6 at the time of diagnosis had a spherical femoral head at the 5-year follow up (2). This is in contrast to the prospective study by Herring et al. where 68% of the patients with disease onset between the ages of 6 and 8 and 62% of the patients with the disease onset between 8 and 12 had a spherical femoral head at skeletal maturity (1). A large retrospective study of 640 patients by Joseph et al. also suggests that earlier intervention is associated with better results (3).

    With regards to the amount of varus angulation, we found no significant correlation between the amount of varus angulation and the radiographic outcome even when we analyzed the poor prognostic, older age group of patients separately (age 8-12 at the disease onset). We do agree with Dr. Kamegaya that if a FVO is performed at the mid-fragmentational stage, a greater varus angulation will be required to obtain containment. However, when FVO was performed in the early stages of LCPD, we found no benefit to placing high degrees of varus angulation. In our view, placing a high degree of varus angulation produces unnecessary morbidity and the need for further surgeries.

    References

    1. Herring JA, Kim HT, Browne R. Legg-Calve-Perthes disease. Part II: prospective multicenter study of the effect of treatment on outcome. J Bone Joint Surg Am. 2004;86:2121-34.

    2. Wiig O, Terjesen T, Svenningsen S. Prognostic factors and outcome of treatment in Perthes' disease: a prospective study of 368 patients with five-year follow-up. J Bone Joint Surg Br. 2008;90:1364-71.

    3. Joseph B, Rao N, Mulpuri K, Varghese G, Nair S. How does a femoral varus osteotomy alter the natural evolution of Perthes' disease? J Pediatr Orthop B. 2005;14:10-5.

    Makoto Kamegaya
    Posted on April 22, 2011
    How Much Varus is Optimal?
    Orthopaedic Surgeon, Chiba Children's & Adult Orthopaedic Clinic

    To the Editor:

    I enjoyed the article concerning femoral varus osteotomy for the treatment of LCPD. However, we found some points in the manuscript which were quite different from what we have summarized in our past investigations.

    1. The authors mentioned that the majority of the patients underwent a femoral varus osteotomy (FVO) at an early stage of the disease, when the Herring's classification or other predictors for the prognosis was of no use. We wonder if those surgeries were performed based on definite indications for an FVO. There was no indication found in the text. This means that the patient selection possibly included patients with mild or moderate severity in which good results could have been expected even with conservative treatment. In fact, about a half of the patients in this study would be 8 or less years of age at the onset due to the mean age of 8.0 +/- 1.4 at the onset. In those patients, the surgical result would naturally be good, in spite of very mild (10 or 15 degrees) varus placed at surgery. A 10 or 15 degrees of varus will not be enough to obtain sufficient containment for creating a more spherical femoral head in severe conditions. According to our previous studies, we have been able to differentiate patients who need surgical treatment from those who could be treated conservatively to some extent (1), and in a paired study between surgical and conservative treatment groups, confirmed that an FVO (35-40 degrees varus) produced a better result in the Stulberg classification, compared with conservative treatment (2). Therefore, it is difficult for us to accept the authors' conclusion.

    2. The greater trochanter overriding necessarily occurs in an FVO. However, the main purpose of an FVO is to produce a more spherical femoral head, and it should be accomplished only at the active stage. Lecuire reported that the more spherical the femoral head, the better the long term result (3). Such overriding or leg length discrepancy could be recovered with subsequent surgical intervention. It does not indicate any reason for hesitating to perform an FVO (35-40 degrees varus) in the severely involved patient.

    References

    1. Kamegaya M, Saisu T, Miura Y, Moriya H. Proposed prognostic formula for Perthes' disease. Clin Orthop. 2005;440:205-8.

    2. Kamegaya M, Saisu T, Ochiai N, Hisamitsu J, Moriya H. A paired study of Perthes' disease comparing conservative and surgical treatment. J Bone Joint Surg Br. 2004;86:1176-81.

    3. Lecuire F. The long-term outcome of primary osteochondritis of the hip (Legg-Calve-Perthes disease). J Bone Joint Surg Br. 2002;84:636-40.

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