Effect of a cast on short-term reproducibility and bone parameters obtained from HR-pQCT measurements at the distal end of the radius

J.J.A. de Jong, J.J. Arts, U. Meyer, P.C. Willems, P.P. Geusens, J.P.W. van den Bergh, B. van Rietbergen

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BACKGROUND: High-resolution peripheral quantitative computed tomography (HR-pQCT) is a promising tool to assess the fracture-healing process at the microscale in vivo. Since casts are often used during fracture treatment, they might affect the assessment of bone density, microarchitectural, and biomechanical parameters and the short-term reproducibility of those parameters, e.g., as a result of beam-hardening. The aim of this study was to assess the effect of a plaster-of-Paris and/or fiberglass cast on bone parameters and on the short-term reproducibility of the HR-pQCT measurements of those parameters.

METHODS: The effects of a cast on HR-pQCT-derived bone parameters were evaluated by comparing HR-pQCT scans of fifteen human cadaveric distal radial specimens from one male and fourteen female donors (median age, eighty-four years [range, sixty-two to ninety years] at the time of death) in three conditions: with a plaster-of-Paris cast, with a fiberglass cast, or without a cast. Short-term reproducibility was assessed using duplicate scans of the distal end of the radius in sixteen healthy volunteers without a fracture (nine men and seven women with a median age of twenty-six years; range, twenty-two to thirty-nine years) while wearing and not wearing a fiberglass cast.

RESULTS: Compared with measurements made with no cast, the plaster-of-Paris cast introduced a systematic error in the bone parameters ranging from -2.6% in trabecular separation to -9.8% in cortical thickness. Bone parameters were affected only marginally by fiberglass, with errors between -0.6% and -1.6% in trabecular separation and cortical thickness, respectively. Short-term reproducibility with a fiberglass cast was similar to that with no cast: approximately 1% for bone density parameters, 4% to 5% for microarchitectural parameters, and 3% to 4% for biomechanical parameters.

CONCLUSIONS: A plaster-of-Paris cast has a considerable effect on HR-pQCT measurements. A fiberglass cast only marginally affects the bone parameters, and the short-term reproducibility of HR-pQCT measurements in patients with a fiberglass cast is comparable with that in patients without a cast. In studies on fracture-healing using HR-pQCT, a fiberglass cast is desirable if immobilization is indicated. The use of a plaster-of-Paris cast should be avoided if possible; however, if not avoidable, corrections after the scan are desirable to adjust for the error introduced in the bone parameters.

Original languageEnglish
Pages (from-to)356-362
Number of pages7
JournalJournal of Bone and Joint Surgery. American Volume
Issue number5
Publication statusPublished - 2 Mar 2016


  • Adult
  • Aged
  • Aged, 80 and over
  • Bone Density
  • Casts, Surgical
  • Female
  • Fracture Fixation
  • Fracture Healing
  • Healthy Volunteers
  • Humans
  • Male
  • Middle Aged
  • Radius
  • Radius Fractures
  • Reproducibility of Results
  • Tomography, X-Ray Computed
  • Journal Article


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