On the left-right asymmetry in hip bone mineral density: review and remarks

This comprehensive narrative review explores the left-right asymmetry in hip bone mineral density and its potential links to limb dominance, within the general population. Through an in-depth analysis of the existing literature, this study uncovers conflicting findings regarding significant bone mineral density left-right differences between regions of the proximal femora. Furthermore, the review probes into the complex interplay between the mechanical and physiological factors that influence bone adaptation and bilateral skeletal asymmetry. This complexity is further underscored by considering the impact of limb preferences, such as handedness and footedness. The inclusion criteria for this review encompassed original articles in English language (population-based observational studies, community studies, clinical trials, involving adult and elderly living individuals within the general population) that reported or not differences in left-right hip bone mineral density measured by Dual-energy X-ray Absorptiometry. This review points out methodological concerns and research gaps, emphasizing the need for more inclusive investigation and a deeper understanding of the relation between directional bilateral asymmetry and behavioral lateralization. Furthermore, the potential clinical implications associated with these variations are discussed, particularly in relation to osteoporosis, as the evaluation of the left-right or dominant/non-dominant differences in hip bone mineral density could be impactful. In conclusion, the majority of the reviewed studies focused on left-right hip BMD differences from a skeletal or bone mineralization perspective while they overlooked the consideration of limb dominance. This highlights a significant methodological concern that has a substantial impact on the results and their interpretation. Therefore, it remains inconclusive whether left-right differences are significant or not.