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Investigation performed at Wilhelmina Children’s Hospital, Utrecht, the Netherlands
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Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.
Disclosures of Potential Conflicts of Interest
Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/G297).
Authors
Author
Eline L. van der Veer, MD1
For correspondence: e.l.vanderveer93@gmail.com
Author
Author
Author
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Peter M. van Hasselt, MD, PhD1
Author
Ralph J.B. Sakkers, MD, PhD1
1Departments of Orthopedic Surgery (E.L.v.d.V., H.W., and R.J.B.S.), Radiology (E.J.B.), and Pediatrics (P.M.v.H.), University Medical Center Utrecht, Utrecht, the Netherlands
2Department of Biomechanical Engineering, Technical University Delft, Delft, the Netherlands
Quantifying the Effects of Hip Surgery on the Sphericity of the Femoral Head in Patients with Mucopolysaccharidosis Type I
Abstract
Background: The introduction of stem cell transplantation has improved life expectancy and cognitive outcome in patients with mucopolysaccharidosis I, but this condition remains associated with substantial residual disease in several parts of the body. Many patients have hip dysplasia with progressive medial flattening of the femoral head. Quantitative evidence on the effect of surgery on remodeling to sphericity of flattened femoral heads is lacking. In the present study, we used statistical shape modeling to quantify the effect of hip surgery on the sphericity of the femoral head in patients with mucopolysaccharidosis I.
Methods: We performed a retrospective case control study involving a series of 23 patients with hip dysplasia due to mucopolysaccharidosis I. Surgery was not offered to the first 11 children (control group). Following a change in treatment protocol, the next 12 children underwent bilateral proximal femoral varus derotation osteotomy and Pemberton osteotomy for the treatment of acetabular dysplasia with progressive femoral head flattening (surgery group). The surgery and control groups were compared with a reference group of patients with normal hips. Statistical shape modeling was used to quantify the shape of the femoral head (i.e., flattening and/or roundness of the epiphysis).
Results: The mean age at the time of stem cell transplantation in the surgery and control groups was comparable (1.2 years). The mean age at the time of surgical intervention was 5.5 years, and mean duration of postoperative follow-up was 3.3 years. Statistical shape modeling showed variations within the total group in terms of medial indentation, width, height, and sphericity of the femoral heads. In contrast to the progressive femoral head flattening in the control group, the surgery group showed improvement of the sphericity of the femoral head after surgery. The overall shape characteristics of the femoral head in the surgery group were similar to those of the reference group of patients with normal hips.
Conclusions: To our knowledge, this is the first study in patients with mucopolysaccharidosis I that has shown quantitative remodeling of the dysplastic, flattened femoral head to normal sphericity after increasing containment of the femoral head.
Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.