Bone density correlates with clinical outcomes after ankle fracture fixation

Osteoporosis and decreased bone density are known to increase fracture incidence and severity. Although much is known regarding the effects of bone density on fracture risk and the treatment options for prevention of fragility fractures, whether bone quality alters clinical outcomes after fracture fixation is unknown. The purpose of this study was to determine whether bone quality correlates with clinical outcomes after fracture fixation.

A prospective database of all operatively treated ankle fractures by a single surgeon from 2003 to 2013 was used to identify patients. All patients included in the study had preoperative computed tomography (CT) imaging of the injured ankle and postoperative CT imaging of the contralateral ankle. Hounsfield unit (HU) measurement values were determined by placing an elliptical region of interest confined to the cancellous metaphyseal region of the distal tibia and fibula. The primary and secondary clinical outcomes included Foot and Ankle Outcome Scores (FAOS) and ankle range of motion (ROM). Included patients had at least 12 months of clinical outcome data.

Sixty-four patients met the inclusion criteria. Comparison of HU values from the injured and contralateral side demonstrated almost perfect agreement (ICC(2,1) = 0.938), suggesting that HU values can be accurately measured in the setting of a fracture. Increased HU values of the injured distal tibia and fibula significantly correlated with improved outcomes in four of five FAOS domains, including pain, activities of daily living, sports, and quality of life (beta = 0.285-0.344; P ≤ 0.05 for all). Range of motion outcomes did not significantly correlate with HU values.

Our results suggest that decreased bone quality, as measured using preoperative CT, significantly correlates with inferior short-term clinical outcomes. These results have significant implications for integrating bone quality into treatment algorithms for fracture patients.