Assessment of Bone Mineral Density in the Distal Tibia Using Quantitative Hounsfield Samples From Computer Tomography

The distal tibia bone quality is of paramount importance for ankle fractures, total ankle implants, ankle fusions, and osteotomy procedures. Despite this fact relatively little is known regarding the overall bone quality for this section of the tibia. Previous literature suggest that there is a statistically significant decrease in bone mineral density within the distal 5% to 10% segment of the tibia medullary canal. This segment of medullary bone is considerable in size and thus valuable for fixation constructs as it is oftentimes utilized for medial malleolar fractures, distal tibia fractures, total ankle replacements, ankle fusions, and other procedures. This study assessed bone attenuation between the distal 5% and 10% mark of the tibia in 1% slices via Hounsfield unit measurements on CT scans based on previously established correlation between Hounsfield units and bone mineral density found on DEXA scans. One hundred five distal tibia segments were assessed with an average interval in percentile slices of 3.8 mm. As expected there was a gradual decrease in bone attenuation noted with each proximal percentile segment. There exists a statistically significant difference in bone attenuation among males versus females as well as those older than 60 years versus younger than 60 years. The findings suggest fixation constructs in the tibia medullary canal may find limited benefit proximal from 7% segment in females ≥60, or 26.1 mm from tibial plafond. Fixation constructs in tibia medullary canal may find limited benefit proximal from 8% segment in males <60, or 32.3 mm from tibial plafond.