Bone and Joint Seminar - From Babies to Baby Boomers: Models of Bone Mechanoadaptation Across the Lifespan

Dr Alex Ireland, Research Associate, Manchester Metropolitan University

Alex will be presenting at 2pm on Thursday 3rd March in the IDS lecture theatre, level A.

A free LUNCH is available from 12.30 in the seminar room opposite

Abstract

Bone strength as assessed by densitometry is predictive of fracture risk, with a standard deviation decrease in bone mineral density (BMD) associated with a doubling of fracture incidence. Therefore it is important to understand factors influencing bone strength.

Bone is highly responsive to changes in habitual loading. Increased loading leads to increases in bone strength in order to prevent fracture, such that athletes have up to 30% more bone mass in the tibia than less active peers. Conversely, reduced loading following spinal cord injury leads to loss of up to 60% bone mass, presumably in an attempt to minimise the metabolic cost of maintaining bone. This mechanoadaptive capability offers opportunities in the form of interventions aimed at increasing loading and hence bone strength, whilst presenting challenges in preventing bone loss during space flight, bed rest or chronic conditions causing disuse.

In order to understand in more detail how loading affects human bone, we have examined a number of models. Tennis players offer an opportunity to examine factors influencing effects of long-term exercise on bone strength in the racquet arm, by comparison with the ‘sedentary’ non-racquet arm. Study of skeletal development in children around the age at which independent walking is achieved permits examination of the influence of these early locomotory loads on ‘loading-naïve’ bones. The effects of exercise and disuse on tibial bone strength have been widely reported. However, little is known about mechanoadaptation of the neighbouring fibula which carries only a small proportion of shank load via an extensible interosseous membrane and ligaments, and which does not articulate directly at the ankle joint.

I will present findings obtained from study of these and other models of human loading and disuse by our group. These include information on how the earliest exposures to postnatal loading have pronounced and enduring effects on bone, how response to loading is affected by loading modality, sex, age and skeletal maturity, and how fibular mechanoadaptation supports new roles for bone.

Biography

Dr Alex Ireland is a Research Associate within the School of Healthcare Science at Manchester Metropolitan University. His main research interest is in bone mechanoadaptation, and the influence of muscular action on bone throughout the lifespan. This work has involved examination of a number of different populations from spinal cord injury patients to elite tennis players, and from toddlers to nonagenerian pole vaulters. Alex is currently employed on an MRC-funded project investigating neural contributions to the loss of muscle mass and strength in older age.