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Letters to the Editor to:

Scientific Articles:
Ilkka Helenius, Ville Remes, Timo Yrjönen, Mauno Ylikoski, Dietrich Schlenzka, Miia Helenius, and Mikko Poussa
Harrington and Cotrel-Dubousset Instrumentation in Adolescent Idiopathic Scoliosis. Long-Term Functional and Radiographic Outcomes
J Bone Joint Surg Am 2003; 85: 2303-2309 [Abstract] [Full text] [PDF]
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[Read Letter to the Editor] Dr. Helenius and colleague respond
Ilkka Helenius, MD, PhD, Mikko Poussa, MD, PhD   (30 December 2003)
[Read Letter to the Editor] A Comparison of Harrington and Cotrel-Dubousset Instrumentation
Charles T. Price, M.D.   (30 December 2003)

Dr. Helenius and colleague respond 30 December 2003
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Ilkka Helenius, MD, PhD,
Research Fellow
ORTON, Orthopaedic Hospital, Helsinki, Finland,
Mikko Poussa, MD, PhD

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Re: Dr. Helenius and colleague respond

ilkka.helenius{at}helsinki.fi Ilkka Helenius, MD, PhD, et al.

We thank Dr Price for his interest in our retrospective comparative study between Harrington and Cotrel-Dubousset instrumentation in adolescent idiopathic scoliosis (JBJS Am 2003;85-A:2303-2309). Due to the historical nature of the study design, the studied groups were somewhat different, as the number of patients with King type I curves was three times (9/78 vs 2/57) more common in Harrington than in Cotrel-Dubousset instrumentation group. It is true that anterior instrumentation (Zielke) alone or along with Cotrel-Dubousset instrumentation was used for thoracolumbar or lumbar curves during the study period (between 1987 and 1990). However, those patients treated with anterior instrumentation were not included in the present study, which may have produced a small selection bias to this study. In the original manuscript we stated: "If patients with King type I curves were excluded from both groups, the number of patients with abnormal lumbar extension (30% vs. 15%) and trunk side bending (56% vs. 36%) was significantly higher in the Harrington rod instrumentation group (p = 0.039 and p = 0.026, respectively) (than in Cotrel-Dubousset instrumentation group). No correlations were observed between the magnitudes of the thoracic or lumbar curves and the spinal mobility measurements."

The large and significant difference in the radiographic correction does not disappear, if patients with King type I curves are excluded from both groups (Table 1), but instead becomes even more stronger.

Thus, based on our article and additional data represented here, we do not believe that improvements seen in this study would be due to patient selection or improvements in anteriorsurgery. Instead, we can conclude that Cotrel-Dubousset instrumentation yielded better long-term functional and radiographic outcomes in patients with adolescent idiopathic scoliosis than did Harrington instrumentation, even if patients with lumbar curves were excluded.

Ilkka Helenius, MD, PhD, Research Fellow
Mikko Poussa, MD, PhD, Chief Orthopedic Surgeon
ORTON, Orthopaedic Hospital, Helsinki, Finland

Table 1. Radiographic correction in coronal plane deformities if patients with King type I curve are excluded.

  Harrington Instrumentation (n=69) Cotrel-Dubousset Instrumentation (n=55) P value
Thoracic curve      
   Preoperative 54±10° 55±10° N. S.
   Two-year follow-up 39±101° 25±12° < 0.0001
   Correction 27±178% 55±15% < 0.0001
   Final follow-up 45±12° 33±11° < 0.0001
   Final correction 15±26% 40±19% < 0.0001
Lumbar curve      
   Preoperative 35±11° 33±11° N. S.
   Two-year follow-up 26±11° 19±15° 0.0001
   Correction 29±26% 50±39% < 0.0001
   Final follow-up 29±13° 23±13° 0.001
   Final correction 15±32% 35±32% 0.0001
A Comparison of Harrington and Cotrel-Dubousset Instrumentation 30 December 2003
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Charles T. Price, M.D.,
Pediatric Orthopedic Surgeon
Nemours Children's Clinic, 83 W. Columbia Ave., Orlando, FL 32806.

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Re: A Comparison of Harrington and Cotrel-Dubousset Instrumentation

cprice{at}nemours.org Charles T. Price, M.D.

To the Editor:

The article by Helenius, et.al., "Harrington and Cotrel-Dubousset Instrumentation in Adolescent Idiopathic Scoliosis" (JBJS 85A:2303-9) is an excellent attempt to compare an older method to a newer method. Changes in techniques are often made for theoretical reasons without proven benefit. Then it becomes difficult to perform randomized contemporaneous studies of efficacy. The authors have indicated some of the limitations of this historical method of comparison.

However, it should be noted that there are more than four times the number of lumbar curves (King I) in the Harrington group than in the Cotrel-Dubousset group. Did this represent a change in selection of lumbar curves for anterior instrumentation during the time when Cotrel-Dubousset instrumentation was available? If so, the Harrington group may contain a disproportionate number of lumbar curves that underwent two-stage distraction with posterior instrumentation rather than anterior instrumentation. This small selection bias could affect the comparison due to elimination of patients from the Cotrel-Dubousset group who would no longer be candidates for posterior surgery. Thus the improvements seen in this study may reflect changes in patient selection and improvements in anterior surgery rather than a change in posterior instrumentation.

Charles T. Price, M. D. Chief of Pediatric Orthopedics Surgeon in Chief Nemours Children's Clinic 83 W. Columbia Ave. Orlando, FL 32806