Using HR-PQCT and Finite Element Analysis to Inform Clinical Assessment of Distal Radius Fractures

Distal radius fractures (DRFs) are commonly treated non-operatively with cast immobilization; however, there are no standardized clinical practice guidelines to direct optimal duration of immobilization following a DRF. Finite element (FE) modelling coupled with highresolution peripheral quantitative computed tomography (HR-pQCT) allows for non-invasive in vivo assessment of bone density and stiffness throughout the fracture healing process, which may inform fracture healing progression and cast removal. Many fracture assessment instruments have been developed for clinical use, but a lack of validation and standardization has led to considerable variability in the assessment of fracture healing. We hypothesized that changes in bone stiffness and bone mineral density measured using HR-pQCT can better inform the duration of casting following a DRF. We aimed to identify clinical assessment instruments that were good predictors of fracture stiffness and could inform cast removal.

Participants (n=30) with a stable DRF were followed for two week intervals from the time of fracture until two months post-fracture, then at three months and six months post-fracture. At each follow-up, participants underwent clinical, radiographic, and functional assessments, as well as had their fractured wrist scanned using HR-pQCT. Recovery of bone stiffness during fracture healing was determined from micro-FE (µFE) models generated from HR-pQCT image data.

During fracture healing, significant longitudinal changes were found in µFE-estimated stiffness, patient-reported outcomes, grip strength, range of motion (ROM), tenderness, number of cortices healed based on radiographs, and fracture line visibility (p<0.05); however, no significant change was detected in HR-pQCT based total bone mineral density. Grip strength, ROM, and patient-reported outcomes such as the Patient-Rated Wrist Evaluation (PRWE) and the Quick Disability of the Arm, Shoulder and Hand (QuickDASH) questionnaire correlated strongly with µFE-estimated stiffness (0.61≥ rm ≥0.71). Based on µFE-estimated stiffness, PRWE and QuickDASH are the best predictors of stiffness recovery (p<0.05) and may be used to guide duration of cast immobilization in the clinical setting.

Year	Entry
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Year

Entry

2003

Ahlborg HG, Johnell O, Turner CH, Rannevik G, Karlsson MK. Bone loss and bone size after menopause. NEJM. July 24, 2003;349(4):327-334.

2018

Whittier DE, Manske SL, Kiel DP, Bouxsein M, Boyd SK. Harmonizing finite element modelling for non-invasive strength estimation by high-resolution peripheral quantitative computed tomography. J Biomech. October 26, 2018;80:63-71.

2008

MacNeil JA, Boyd SK. Bone strength at the distal radius can be estimated from high-resolution peripheral quantitative computed tomography and the finite element method. Bone. June 2008;42(6):1203-1213.

2010

Burghardt AJ, Issever AS, Schwartz AV, Davis KA, Masharani U, Majumdar S, Link TM. High-resolution peripheral quantitative computed tomographic imaging of cortical and trabecular bone microarchitecture in patients with type 2 diabetes mellitus. J Clin Endocrinol Metab. 2010;95(11):5045-5055.

2010

Boskey AL, Coleman R. Aging and bone. J Dent Res. December 2010;89(2):1333-1348.