Osteosarcopenia

This article or area is currently under construction and may only be partially complete. Please come back soon to see the finished work! (22/04/2023)

Original Editor - Saliu Balogun

Top Contributors - Saliu Balogun  

Introduction

Osteosarcopenia, sometimes called sarco-osteopenia, is a geriatric syndrome that refers to the presence of both low bone mass (osteopenia/osteoporosis) and low muscle mass/function (sarcopenia) within the same individual. Sarcopenia and osteopenia are independent risk factors for several conditions, including fractures and falls. Hence, the presence of these conditions within the same person (i.e., osteosarcopenia) further exacerbates the risk of poorer health outcomes. For example, compared to those with sarcopenia or osteopenia alone, individuals with osteosarcopenia have an elevated risk of impaired physical performance, falls(ref), fracture(ref), poor mobility, impaired quality of life and mortality(ref).

Prevalence

Unlike osteopenia/osteoporosis, several clinical definitions of sarcopenia have been proposed (see sarcopenia). Hence, the prevalence of osteosarcopenia varies depending on the definitions of sarcopenia considered. Generally, the prevalence of osteosarcopenia is estimated to range from 5 to 37% among community-dwelling older people. With the global population ageing, the proportion of individuals with osteosarcopenia is projected to increase, irrespective of the definition of sarcopenia considered.

Pathophysiology: Bone muscle interaction

Bone and muscle are anatomically and functionally interconnected. The bone-muscle interaction was traditionally provided by the mechanostat theory, which suggests that bone strength is responsive to the mechanical load exerted by the skeletal muscle. Hence, bone modelling and remodelling are biomechanically influenced by the muscle. However, more recent evidence suggests that the relationship between bones and muscles is beyond biomechanical forces and that there are biochemical and molecular pathways through which bone and muscles communicate and influence each other’s function. The video provides a further discussion on the pathophysiology of osteosarcopenia.

Risk factors

Osteosarcopenia has shared risk factors with other chronic diseases, including physical inactivity and high adiposity. High adiposity increases fat infiltration within and around the skeletal muscle, compromising muscle and bone quality. Osteosarcopenia increases with age, and it is more prevalent among women compared to men. Interestingly, increasing years of schooling was related to a lower prevalence of osteosarcopenia, although the pathway explaining this relationship is unclear. The presence of chronic diseases, including diabetes, also increases the risk of osteosarcopenia.

Clinical assessment

The assessment of osteosarcopenia includes detailed history (including previous medical records), risk factors assessment, physical examination and assessment of muscle and bone quality using DEXA. Osteoporosis can be ascertained using bone mineral density measured via DEXA, and sarcopenic status can be evaluated using DEXA-assessed appendicular lean muscle mass.

Rapid assessment of osteosarcopenia may be challenging in clinical practice because DEXA is required to measure bone and muscle mass. Rapid screening tools such as the SARC-F questionnaire may be used to identify probable sarcopenia, and FRAX© may be used in the absence of BMD. Potential osteosarcopenia identified using SARC-F and FRAX tools should be followed by a formal diagnosis using DEXA.

Physiotherapy management

Individuals with osteosarcopenia may have other comorbidities; hence, physiotherapy management may be individualised. Generally, physiotherapy management will include resistive and high/low weight-bearing exercises combined with medications to manage osteoporosis. Progressive resistance exercise will help improve muscle strength and bone microarchitecture by stimulating osteoblastogenesis and muscle protein synthesis. Other physiotherapy management may include exercises to improve balance and functional capacity.