Association between Bone Mineral Density and Fracture Characteristics in the 5th Metatarsal Bone Base Fracture in Elderly for Prediction of Osteoporotic Fracture

SLR - March 2022 - Justin Muser

Reference: Chun D, Min T, Cho J, Won S, Shon J, Yi Y.  Association between Bone Mineral Density and Fracture Characteristics in the 5th Metatarsal Bone Base Fracture in Elderly for Prediction of Osteoporotic Fracture. J Bone Metab 2021;28(3):231-237.

Level of Evidence: IV

Scientific Literature Review

Reviewed By: Justin Muser, DPM
Residency Program: Our Lady of Lourdes Memorial Hospital – Binghamton, NY

Podiatric Relevance: Low-energy traumatic fractures in the tarsal and metatarsal areas have often been associated with osteoporosis. There have been prior studies that have determined links between patients with metatarsal fractures and osteoporosis of the spine, while others have concluded that fractures of the foot are largely independent of bone mineral density. This study attempts to analyze a correlation between bone mineral density and the type of fifth metatarsal fracture, while also attempting to determine a correlation between the radiologic parameters that may be linked to the type of fifth metatarsal fracture. 

Methods: The study retrospectively divided eighty-seven patients with fifth metatarsal fractures into three groups, Zone 1 avulsion fractures of the proximal tubercle (n=36), Zone 2 fractures of the metaphyseal-diaphyseal junction (n=33), and Zone 3 fractures of the diaphysis (n=18). The bone mineral density values from the femur and lumbar spine of the three groups were compared, and whether accompanying osteoporosis drugs were administered. Radiological parameters including the heel alignment angle, heel moment arm, and the metatarsus adductus angle were also analyzed and compared.

Results: The mean bone mineral density values were highest in Zone 1 and lowest in Zone 3 fractures, however there was no significant statistical difference between the groups. The mean heel alignment angle was -2.2 degrees in Zone 1, 2 degrees in Zone 2 and 2.6 degrees in Zone 3 which was statistically significant. The mean heel moment arm was -8.9 millimeters in Zone 1, 3.55 millimeters in Zone 2, and 6.1 millimeters in Zone 3 which was statistically significant. The mean metatarsus adductus angle was 20.15 degrees in Zone 1, 20.1 degrees in Zone 2, and 28.85 degrees in Zone 3 which was statistically significant. Post hoc analysis revealed significant correlations with the heel alignment angle, heel moment arm, and the metatarsus adductus angle between the Zone 1 group and the Zone 3 group.

Conclusions: Fractures of the fifth metatarsal are common low-energy traumatic injuries of the foot. The results from this study suggest that bone mineral density does not have a significant role in determining the location on the fifth metatarsal for these fractures. Rather, the study suggests that biomechanical factors play a more critical role in determining the location of these types of fractures. From a clinical perspective, this study sheds light on the importance of managing the biomechanical factors including hindfoot varus and metatarsus adductus as a way to prevent these types of injuries or perhaps, to adjust for during healing to aid consolidation and after healing to reduce risk of recurrence.