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27-01-2005, 08:06 PM
Legg-Calvé-Perthes Disease. Part I: Classification of Radiographs With Use of the Modified Lateral Pillar and Stulberg Classifications
Herring JA, Kim HT, Browne R
Journal of Bone and Joint Surgery - American Volume. 2004;86-A(10):2103-2120
Legg-Calvé-Perthes Disease. Part II: Prospective Multicenter Study of the Effect of Treatment on Outcome
Herring JA, Kim HT, Browne R
Journal of Bone and Joint Surgery - American Volume. 2004;86-A(10):2121-2134
These 2 studies are the anxiously awaited product of a carefully designed prospective multicenter study that began 20 years ago. The completion of this study is a credit to the authors and to the support that they received from their institution. The study design was so powerful, in fact, that we have been hopeful that it would answer our questions and resolve our many uncertainties about Perthes disease.
It has been obvious that much of our difficulty in studying Perthes disease derives from the lack of a suitable classification of children who present with this condition, and a suitable proxy outcome assessment that can be used at skeletal maturity as a harbinger of the long-term course. Catterall and Salter/Thompson have provided classification systems for children at presentation but they are both, to some extent, staging systems and not grading systems.[1-3] We want to know how severe the disease is but they only tell us where the child is at the moment. Herring's Lateral Pillar classification has been useful but is difficult to use and is also largely a staging system.[4] For example, all children whose lateral pillar height is less than 50% at one time had a lateral pillar height that was normal. Herring has solved the difficulty in its use by adding a B/C border group which includes those children who are difficult to classify. Although this provides an escape hatch for the user, it blunts the usefulness of the classification. Nevertheless, this study does display excellent intraobserver error and shows that the classification does usefully discriminate and is useful in this condition.
The proxy outcome system used by most has been the Stulberg classification.[5] Herring has resolved the terminology problem by specifying objective criteria to aid in the classification, and has found that this classification also has excellent intraobserver error and is a useful proxy outcome in Legg-Perthes disease. It is worth pointing out, however, that a technique can have excellent intraobserver error and still not be useful.
The second study, Part II, reports on the treatment results of 451 hips in children between 6 and 12 years of age treated according to 1 of 4 protocols: bracing, range of motion, femoral osteotomy, and innominate osteotomy. A fifth group received no treatment. A total of 345 hips were available for follow-up at skeletal maturity.
There was no difference detected among the nonoperative treatments, no difference between the pelvic and femoral osteotomy groups, and no difference between the treated and untreated groups in patients under the age of 8 years (6 skeletal years). The outcomes of patients in lateral pillar B and B/C groups over that age showed significantly better results with surgery than with nonoperative treatment.
Perhaps it is not surprising that these findings are fairly consistent with our consensus that has developed over the years. We have always said that very young children don't benefit from surgery because they have so much remodeling ahead of them, and now, although we might be surprised that the age threshold is as old as 8 years, we find that understanding to be confirmed. We have always considered containment to be a prophylactic concept, and, as such, ineffective in heads already severely deformed. This study confirms that severely deformed heads (lateral pillar C) do not benefit from treatment at any age. It is also not surprising that the lateral pillar classification should prove effective because it reflects the ideas of Sommerville published over 30 years ago.[6]
This prospective cohort study presents a high level of evidence, and its findings should guide our treatment of this condition. The failure of this study to differentiate further among these groups suggests that we should continue to search for better tools for assessment of disease severity and outcome.
References
1. Catterall A, ed. Legg-Calvé-Perthes Disease. London: Churchill Livingstone; 1982.
2. Salter R. Legg-Perthes disease: The scientific basis for the methods of treatment and their indications. Clin Orth Rel Res. 1980;150:8-11.
3. Salter R, Thompson G. Legg Calvé Perthes disease. The prognostic significance of the subchondral fracture and a two group classification of the femoral head involvement. J Bone Joint Surg Am. 1984;66A:479.
4. Ritterbush J, Shantharam S, Gelinas C. Comparison of lateral pillar classification and Catterall classification of Legg Calvé Perthes disease. J Pediatr Orthop. 1993;13:200-202.
5. Stulberg S, Cooperman D, Wallensten R. The natural history of Legg-Calvé-Perthes disease. J Bone Joint Surg Am. 1981;63-A:1095-1108.
6. Sommerville E. Perthes disease of the hip. J Bone Joint Surg Am. 1971;53-B:639-649.
Herring JA, Kim HT, Browne R
Journal of Bone and Joint Surgery - American Volume. 2004;86-A(10):2103-2120
Legg-Calvé-Perthes Disease. Part II: Prospective Multicenter Study of the Effect of Treatment on Outcome
Herring JA, Kim HT, Browne R
Journal of Bone and Joint Surgery - American Volume. 2004;86-A(10):2121-2134
These 2 studies are the anxiously awaited product of a carefully designed prospective multicenter study that began 20 years ago. The completion of this study is a credit to the authors and to the support that they received from their institution. The study design was so powerful, in fact, that we have been hopeful that it would answer our questions and resolve our many uncertainties about Perthes disease.
It has been obvious that much of our difficulty in studying Perthes disease derives from the lack of a suitable classification of children who present with this condition, and a suitable proxy outcome assessment that can be used at skeletal maturity as a harbinger of the long-term course. Catterall and Salter/Thompson have provided classification systems for children at presentation but they are both, to some extent, staging systems and not grading systems.[1-3] We want to know how severe the disease is but they only tell us where the child is at the moment. Herring's Lateral Pillar classification has been useful but is difficult to use and is also largely a staging system.[4] For example, all children whose lateral pillar height is less than 50% at one time had a lateral pillar height that was normal. Herring has solved the difficulty in its use by adding a B/C border group which includes those children who are difficult to classify. Although this provides an escape hatch for the user, it blunts the usefulness of the classification. Nevertheless, this study does display excellent intraobserver error and shows that the classification does usefully discriminate and is useful in this condition.
The proxy outcome system used by most has been the Stulberg classification.[5] Herring has resolved the terminology problem by specifying objective criteria to aid in the classification, and has found that this classification also has excellent intraobserver error and is a useful proxy outcome in Legg-Perthes disease. It is worth pointing out, however, that a technique can have excellent intraobserver error and still not be useful.
The second study, Part II, reports on the treatment results of 451 hips in children between 6 and 12 years of age treated according to 1 of 4 protocols: bracing, range of motion, femoral osteotomy, and innominate osteotomy. A fifth group received no treatment. A total of 345 hips were available for follow-up at skeletal maturity.
There was no difference detected among the nonoperative treatments, no difference between the pelvic and femoral osteotomy groups, and no difference between the treated and untreated groups in patients under the age of 8 years (6 skeletal years). The outcomes of patients in lateral pillar B and B/C groups over that age showed significantly better results with surgery than with nonoperative treatment.
Perhaps it is not surprising that these findings are fairly consistent with our consensus that has developed over the years. We have always said that very young children don't benefit from surgery because they have so much remodeling ahead of them, and now, although we might be surprised that the age threshold is as old as 8 years, we find that understanding to be confirmed. We have always considered containment to be a prophylactic concept, and, as such, ineffective in heads already severely deformed. This study confirms that severely deformed heads (lateral pillar C) do not benefit from treatment at any age. It is also not surprising that the lateral pillar classification should prove effective because it reflects the ideas of Sommerville published over 30 years ago.[6]
This prospective cohort study presents a high level of evidence, and its findings should guide our treatment of this condition. The failure of this study to differentiate further among these groups suggests that we should continue to search for better tools for assessment of disease severity and outcome.
References
1. Catterall A, ed. Legg-Calvé-Perthes Disease. London: Churchill Livingstone; 1982.
2. Salter R. Legg-Perthes disease: The scientific basis for the methods of treatment and their indications. Clin Orth Rel Res. 1980;150:8-11.
3. Salter R, Thompson G. Legg Calvé Perthes disease. The prognostic significance of the subchondral fracture and a two group classification of the femoral head involvement. J Bone Joint Surg Am. 1984;66A:479.
4. Ritterbush J, Shantharam S, Gelinas C. Comparison of lateral pillar classification and Catterall classification of Legg Calvé Perthes disease. J Pediatr Orthop. 1993;13:200-202.
5. Stulberg S, Cooperman D, Wallensten R. The natural history of Legg-Calvé-Perthes disease. J Bone Joint Surg Am. 1981;63-A:1095-1108.
6. Sommerville E. Perthes disease of the hip. J Bone Joint Surg Am. 1971;53-B:639-649.