Evaluating the Relationship Between the Second Metacarpal Cortical Percentage and Loss of Reduction in Non-Operative Distal Radius Fracture Treatment
Jason Ghodasra, MD, MSCI1, Imran S. Yousaf, DO1, Tamara D. Rozental, MD2, Kenneth R. Means, Jr., MD1 and Aviram M Giladi, MD, MS1, (1)The Curtis National Hand Center, Baltimore, MD, (2)Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
Our goal was to evaluate the effect of low bone mineral density on loss of reduction for distal radius fractures(DRF) treated with closed reduction and immobilization. Utilizing the second metacarpal cortical percentage(2MCP) as an indicator of bone mineral density, we hypothesized that 2MCP correlates with change in radiographic measurements and loss of reduction.
Patients in two health systems with DRF treated with immobilization over a 5-year period were reviewed. Patients under 18 years of age or who did not have follow-up radiographs at a minimum of 6 weeks were excluded. AO-classification, 2MCP(<50% indicating osteoporosis), and fracture stability based on LaFontaines criteria were determined from pre-reduction radiographs. Radial inclination, radial height, volar tilt, ulnar variance, and intra-articular step-off were measured on immediate post-reduction and final follow-up radiographs and compared with paired-sample t-tests. Bivariate analysis was used to evaluate the association between 2MCP and change in radiographic parameters. Measurements found to be significant in bivariate analyses were evaluated with multivariable models adjusted for age, sex, immediate post-reduction radiographic parameters, and AO-fracture type.
A total of 305 patients were included. Mean age was 60.1(SD 18.3, range 18-96) years, with 238 females(78%). 127 patients(42%) had AO type C fractures. From post-reduction to final radiographs, radial inclination decreased by 1.16 degrees(p<0.01), radial height decreased by 0.93mm(p<0.01), volar tilt decreased by 1.24 degrees(p=0.03), and ulnar variance increased by 1.44mm(p<0.01). Bivariate analysis showed that both lower 2MCP and unstable fractures per LaFontaines criteria were significantly associated with an increase in ulnar variance(p<0.01). In adjusted multivariable models, fracture instabilitiy remained associated with an increase in ulnar variance (p<0.01). Having both 2MCP<50% and an unstable fracture was associated with an additional 1.15mm increase in ulnar variance(p<0.05).
2MCP in the osteoporosis range and unstable fractures by LaFontaines criteria were associated with a significant increase in ulnar variance on final follow-up radiographs. Patients with unstable fractures and an MCP<50% are likely to have an increase of 1mm or more in ulnar variance compared to patients with otherwise similar injuries. Identifying factors in initial DRF radiographs associated with loss of reduction over the course of non-surgical treatment may identify patients for whom closed treatment is not appropriate.
Figure 1. Lower 2MCP was associated with an increase in ulnar variance.
1. Schreiber JJ, Kamal RN, Yao J. Simple Assessment of Global Bone Density and Osteoporosis Screening Using Standard Radiographs of the Hand. J Hand Surg Am. 2017 Apr; 42(4):244-249.
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