Correspondence

Winter, Robert B. M.D.; Lonstein, John E. M.D.; Noonan, Kenneth J. M.D.; Weinstein, Stuart L. M.D.; Jacobson, William C. M.D.; Dolan, Lori A. M.S.

Journal of Bone & Joint Surgery - American Volume:
Correspondence

    TO THE EDITOR:

    We read “Use of the Milwaukee Brace for Progressive Idiopathic Scoliosis” (78-A: 557–567, April 1996), by Noonan et al., with considerable interest. We were particularly struck by the difference between their analysis of results and ours5.

    As the details in both articles are reviewed, the reason for the difference becomes clear. First, Noonan et al. reviewed the results for 102 patients, although those for only eighty-eight were analyzed statistically since they, unlike us, eliminated patients who had curves of more than 45 degrees. A statistically valid comparison of this small group of eighty-eight patients with the 1020 patients in our study is difficult, especially when the results have to be subdivided according to age, curve, magnitude, and compliance.

    Second, the duration of treatment with the brace in their study (one year and eight months) was much shorter than that in ours (three years and eight months).

    Third, in the study by Noonan et al., the best correction in the brace for the group for which treatment failed was 8 per cent and that for the group for which treatment was successful was 20 per cent. In our study, the over-all average best correction in the brace was 30 per cent.

    Another criticism that we have is the inadequate bibliography concerning the results of bracing for idiopathic scoliosis. Noonan et al. did not cite the superb study of Milwaukee bracing by Salanova9, which is also available as a monograph3, Salanova9 and Durand3 found that, of the curves associated with the highest risk for progression (thoracic curves in premenarchal girls who had a Risser sign of 0 or 1), only 21 per cent worsened, in contrast to the expected 68 per cent rate of worsening for untreated curves. These results were recorded five years after removal of the brace.

    In their discussion, Noonan et al. stated: “We are not aware of any randomized prospective studies of bracing with long-term follow-up.” We wonder why they did not cite the randomized prospective international multicenter study of bracing by Nachemson et al.8, which showed that bracing significantly altered the natural history of idiopathic scoliosis (p < 0.0001).

    We also wonder why they did not cite the study by Fernandez-Feliberti et al.4, who compared equivalent groups of patients with idiopathic scoliosis, one of which was managed with a brace and one of which was not. Those authors found that the control group had a 300 per cent greater chance of having an operation or progression of a curve to 40 degrees or more.

    We believe that Noonan et al. should have concluded that the use of a Milwaukee brace providing minimum correction and worn for only twenty months did not demonstrate substantial benefit to the patients. Also, in consideration of the excellent results with bracing that have been recently published, their method of treatment was inadequate and should be altered.

    Robert B. Winter, M.D.; John E. Lonstein, M.D.: Minnesota Spine Center, 606 24th Avenue South, Suite 606, Minneapolis, Minnesota 55454

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    Dr. Noonan, Dr. Weinstein, Dr. Jacobson, and Ms. Dolan reply:

    We are pleased to compare and contrast our experience with the Milwaukee brace with that of Lonstein and Winter, whose conclusions5 differed from ours. After their examination of our paper, Dr. Winter and Dr. Lonstein concluded that our “method of treatment was inadequate and should be altered.” We disagree and believe that this statement stems from inadequate analysis of our paper. Furthermore, we believe that careful review of the paper by Lonstein and Winter5 yields conclusions that are not too dissimilar from our own.

    It is certainly true that the study population from Minneapolis5 was larger than ours. We included only patients who would meet contemporary indications for bracing; patients who had a curve of more than 45 degrees were excluded as they are not routinely managed with a brace. However, it should be noted that a large number of patients were excluded in the study by Lonstein and Winter5 as well. Most (909) of the 1020 patients had no documented progression of the curve and had an initial curve of 15 degrees or more and were managed immediately with a brace. For comparisons with natural history, Lonstein and Winter excluded 496 patients who did not have one of four major curve patterns or who had a curve of less than 20 or more than 39 degrees. We do not know why they excluded patients who had other curve patterns from the natural history comparisons. These patients had a slightly higher rate of operative intervention (23 to 29 per cent).

    Perhaps Lonstein and Winter should have excluded even more patients from their study5. We do not know why they did not exclude the 150 patients for whom an initial Risser sign could not be determined while eighty-four other patients were excluded because their records were incomplete. The authors also implied that most of the patients were fully compliant and wore the brace until “it was discontinued by the treating physician.” This is difficult to assess, however, as only 28 per cent (283) of their patients completed the questionnaire.

    Winter and Lonstein incorrectly state that the average duration of bracing in our report was one year and eight months; in fact, it was two years and eleven months for all of the patients and three years and eight months for those who were not managed operatively. This latter number is similar to the duration of three years and ten months for patients who did not have an operation in their report5. In addition, the average Risser sign at the time of weaning from the brace was 3.9 for all of our patients. This is similar to the parameters for weaning described by Lonstein and Winter5. We disagree with their conclusion that bracing was performed improperly.

    Winter and Lonstein are correct in that the patients in our study in whom the curve did not progress 5 degrees at the cessation of bracing or who did not meet the indications for an operation had an average maximum correction of the curve in the brace of 20 per cent and those who had a failure had an average maximum correction in the brace of 8 per cent. They reported5 better correction of 30 per cent; however, these discrepancies can be accounted for. For instance, errors (of 5 to 8 degrees1,7) inherent to the measurement of the Cobb angle must be considered; if a curve of 35 ± 5 degrees corrects to 20 ± 5 degrees in the brace, the percentage of correction could range from 63 per cent (1 - 15/40) to 17 per cent (1 - 25/30). Although we have shown that maximum correction of the curve in the brace is significant, it may be difficult to apply this finding clinically and such figures derived from both studies should be viewed in light of potential measurement error. It should also be noted that all of the radiographs in our study were remeasured to determine the best correction, whereas, in the study by Lonstein and Winter, only the radiograph that had the best correction on the basis of retrospective review was remeasured. Clearly, increased error is possible if not all of the radiographs are remeasured.

    We did not cite the study by Salanova9 as we did not have access to the original doctoral thesis3. In addition, our paper was accepted for publication before the studies by Nachemson et al.8 and Fernandez-Feliberti et al.4 were published. However, as both of those papers concerned the results of bracing with a thoracolumbosacral orthosis, we would not have included them in our study. We do, however, stand by our statement that “we are not aware of any randomized prospective studies of bracing with long-term follow-up.” It should be noted that the multicenter study from the Scoliosis Research Society8 revealed that the brace had a significant effect on progression of the curve at maturity, and we believe that these patients need to be followed to determine the true effectiveness of bracing with a thoracolumbosacral orthosis. After careful analysis of the study by Fernandez-Feliberti et al.4, we believe that it contains statistical problems and that their conclusions may not be well supported.

    Perhaps Dr. Winter and Dr. Lonstein took exception with our study because of perceived differences in the results. We believe that, in some respects, our results are similar to theirs and that the differences can be explained.

    In their analysis of failure, Lonstein and Winter5 included patients who had an operation for indications that were not completely dependent on progression of the curve and, in many cases, were not even recorded. Also, they did not include any patients who were not managed operatively but who would meet contemporary indications for an arthrodesis on the basis of the magnitude of the curve. In our study, 42 per cent of patients at high risk for progression who had an initial curve magnitude of as much as 45 degrees had a failure as determined by an operation or a curve of more than 50 degrees at the time of follow-up (an indication for an operation). Lonstein and Winter noted a 29 per cent rate of operative intervention in patients who had documented progression of a 30 to 39-degree curve. A 30 per cent rate of operative intervention was noted in patients who had a Risser sign of 1 or less and an initial curve of 30 to 39 degrees. Furthermore, we documented no additional treatment in 110 of 111 patients. Lonstein and Winter obtained follow-up contact with 283 (28 per cent) of 1020 patients and could not be sure that the remaining patients had not received additional treatment elsewhere. It is likely that with better follow-up and the inclusion of curves that were more than 50 degrees at the time of follow-up, the rate of operative intervention in immature patients who had an initial curve of 30 to 39 degrees or documented progression would be similar to that reported in our study.

    We found at least 5 degrees of progression of the curve at the end of bracing in 48 per cent of our patients. Lonstein and Winter5 reported a 40 per cent rate for curves of 20 to 29 degrees (with a Risser sign of 0 or 1), which was significantly different (p = 0.0001) from the 68 per cent rate for natural history. It is interesting that they did not document any significant difference between the natural history and the result with bracing for curves that were more than 30 degrees, which is in agreement with our findings. The higher rate in our study is probably due to the greater curve magnitudes (an average of 3 to 6 degrees more) at initial bracing and the inclusion of curves that were at high risk for progression. When Lonstein and Winter examined the minority of patients who had documented progression, they documented an average increase in magnitude of the curve at cessation of bracing of 3 to 4 degrees. The patients who had no documented progression had an improvement of 4 to 5 degrees. The poorer results for the progressive curves are masked if the results for these two groups are averaged together. Lonstein and Winter also reported continued progression of curves after cessation of bracing, at which time there was no longer a significant difference in rates of failure between the treated patients and the natural history predictions. This corroborates our suggestion that bracing may function to maintain selected curves until bracing is stopped, after which the curve progresses to a level predetermined by unknown factors and is eventually unaffected by fairly crude orthotic treatment.

    Historical review of the literature demonstrates that many patients who had relatively minor curves that were at low risk for progression were treated with a brace needlessly and would have had a good result without bracing. As the indications for bracing have become restricted to curves with a higher risk for progression, the number of good results has diminished. This has led orthopaedists to question the ability of a brace to affect the natural history or, alternatively, to return to the bracing of smaller curves that may not need such treatment. For this reason, we believe that the true effectiveness of bracing for adolescent idiopathic scoliosis is not currently known.

    Kenneth J. Noonan, M.D.: Department of Orthopaedics, Orlando Regional Medical Center, 1314 Kuhl Avenue, Orlando, Florida 32806

    Stuart L. Weinstein, M.D.; William C. Jacobson, M.D.; Lori A. Dolan, M.S.: Department of Orthopaedic Surgery, The University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa 52242-1009

    1. Carman, D. L.; Browne, R. H.; and Birch, J. G.: Measurement of scoliosis and kyphosis radiographs. Intraobserver and interobserver variation. J. Bone and Joint Surg., 72-A: 328-333, March 1990.
    2. Carr, W. A.; Moe, J. H.; Winter, R. B.; and Lonstein, J. E.: Treatment of idiopathic scoliosis in the Milwaukee brace. Long-term results. J. Bone and Joint Surg., 62-A: 599-612, June 1980.
    3. Durand, H. M.: Faut-il abandonner le traitement orthopédique de la scoliose. Doctoral thesis, University Paul Sabatier, Toulouse, France, 1988.
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    7. Morrissy, R. T.; Goldsmith, G. S.; Hall, E. C.; Kehl, D.; and Cowie, G. H.: Measurement of the Cobb angle on radiographs of patients who have scoliosis. Evaluation of intrinsic error. J. Bone and Joint Surg., 72-A: 320-327, March 1990.
    8. Nachemson, A. L.; Peterson, L.-E.; and Members of the Brace Study Group of the Scoliosis Research Society: Effectiveness of treatment with a brace in girls who have adolescent idiopathic scoliosis. A prospective, controlled study based on data from the brace study of the Scoliosis Research Society. J. Bone and Joint Surg., 77-A: 815-822, June 1995.
    9. Salanova, C.: Late results of Milwaukee brace. Orthop. Trans., 10: 2, 1986.
    Copyright 1997 by The Journal of Bone and Joint Surgery, Incorporated