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Soft-Tissue Abnormalities Associated with Treatment-Resistant and Treatment-Responsive Clubfoot: Findings of MRI Analysis

Moon, Daniel K. MD, MS, MBA; Gurnett, Christina A. MD, PhD; Aferol, Hyuliya BS; Siegel, Marilyn J. MD; Commean, Paul K. BEE; Dobbs, Matthew B. MD

Journal of Bone & Joint Surgery - American Volume: 6 August 2014 - Volume 96 - Issue 15 - p 1249–1256
doi: 10.2106/JBJS.M.01257
Scientific Articles
Disclosures

Background: Clubfoot treatment commonly fails and often results in impaired quality of life. An understanding of the soft-tissue abnormalities associated with both treatment-responsive and treatment-resistant clubfoot is important to improving the diagnosis of clubfoot, the prognosis for patients, and treatment.

Methods: Twenty patients with clubfoot treated with the Ponseti method were recruited for magnetic resonance imaging (MRI) of their lower extremities. Among these were seven patients (six unilateral cases) with treatment-responsive clubfoot and thirteen patients (five unilateral cases) with treatment-resistant clubfoot. Demographic information and physical examination findings were recorded. A descriptive analysis of the soft-tissue abnormalities was performed for both patient cohorts. For the patients with unilateral clubfoot, we calculated the percentage difference in cross-sectional area between the affected limb and the unaffected limb in terms of muscle, subcutaneous fat, intracompartment fat, and total area. With use of the Wilcoxon signed-rank test, we compared inter-leg differences in cross-sectional areas and the intracompartment adiposity index (IAI) between treatment-responsive and treatment-resistant groups. The IAI characterizes the cross-sectional area of fat within a muscle compartment.

Results: Extensive soft-tissue abnormalities were more present in patients with treatment-resistant clubfoot than in patients with treatment-responsive clubfoot. Treatment-resistant clubfoot abnormalities included excess epimysial fat and intramuscular fat replacement as well as unique patterns of hypoplasia in specific muscle groups that were present within a subset of patients. Among the unilateral cases, treatment-resistant clubfoot was associated with a significantly greater difference in muscle area between the affected and unaffected limb (−47.8%) compared with treatment-responsive clubfoot (−26.6%) (p = 0.02), a significantly greater difference in intracompartment fat area between the affected and unaffected limb (402.6%) compared with treatment-responsive clubfoot (9%) (p = 0.01), and a corresponding higher inter-leg IAI ratio (8.7) compared with treatment-responsive clubfoot (1.5) (p = 0.01).

Conclusions: MRI demonstrated a range of soft-tissue abnormalities in patients, including unique patterns of specific muscle-compartment aplasia/hypoplasia that were present in patients with treatment-resistant clubfoot and not present in patients with treatment-responsive clubfoot. Correlations between MRI, physical examination, and treatment responsiveness may aid in the development of a prognostic classification system for clubfoot.

Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

1Departments of Orthopaedic Surgery (D.K.M., C.A.G., H.A., and M.B.D.), Pediatrics (C.A.G.), Neurology (C.A.G.), and Radiology (M.J.S. and P.K.C.), Washington University School of Medicine, 1 Children’s Place, Suite 4S-60, St. Louis, MO 62110. E-mail address for M.B. Dobbs: dobbsm@wudosis.wustl.edu

Copyright 2014 by The Journal of Bone and Joint Surgery, Incorporated
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