Effects of Ageing on Bone

Original Editor Oyemi Sillo

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Introduction

Osteoporotic posture

As a result of the ageing process, bone deteriorates in composition, structure and function, which predisposes to osteoporosis. Bone is a dynamic organ that serves mechanical and homeostatic functions. It undergoes a continual self-regeneration process called remodelling i.e. removing old bone and replacing it with new bone. Bone formation and bone resorption is coupled tightly in a balance to maintain bone mass and strength. With ageing this balance moves in a negative direction, resulting in greater bone resorption than bone formation. This combination of bone mass deficiency and reduction in strength ultimately results in osteoporosis and insufficiency fractures.

Ageing Bone Dynamics

Bone cells

As people age the rate of bone resorption by osteoclast cells (multi-nucleated cells which contain mitochondria and lysosomes that is responsible for bone resorption) exceeds the rate of bone formation so bone weaken. The reasons for this are multi factorial, including:.

Non-Modifiable Risk Factor

• Genetics eg family history of osteoporosis
• Peak bone mass accrual in youth
• Alterations in cellular components
• Older than 50 years of age
• Comorbid medical conditions eg Hyperthyroidism, Hyperparathyroidism
• Premature birth
• Hormonal, biochemical and vasculature status e.g. low levels of estrogen
• Sarcopenia
• Seizure disorder

Modifiable Risk Factor

• Nutrition eg Calcium intake of less than 1200 mg/day, Insufficient protein intake, Inadequate Vitamin D intake, BMI <18.5,
• Physical activity,
• Addictions like drugs, excessive intake of alcohol, cigarette smoking .

Adverse Effects

Osteoporosis of the Spine

The effects of bone structure changes may bring about:

• Osteoporosis: a major cause of hip fractures in the elderly, a type of insufficiency fracture.
• Spinal Compression Fracture: Most occur at the thoracolumbar junction. 40% of the women over 80 years have received at least one compression fracture. See also Osteoporotic Vertebral Fractures.
• Reduced bone density of the vertebrae: Combined with the loss of fluid in intervertebral discs, result in a curved and shortened spine and possible poor posture, leads to pain, reduced mobility, and other musculoskeletal problems.

Prevention

Ladies gym

For more see the informative on prevention, management and physiotherapy for see Osteoporosis.

1. Exercise: (See also Age and Exercise) Ageing is associated with reduced physical activity and mechanical loading. Decreased mechanical loading exerts a decreased effect upon osteoblasts. Functional loading has been shown to improve bone mass in humans. However exercise training programs can prevent or reverse almost 1% of bone loss per year in both lumbar spine (LS) and femoral neck (FN) for both premenopausal and postmenopausal women. It is important exercise to preserve bone density, however care must be taken to avoid high-impact exercises and exercises that present the risk of falling. Functional loading exercises include: Weight-bearing exercises e.g. walking; Strengthening exercises using free weights, elastic bands, dumbbells etc.; Balance exercises e.g. tai chi.
2. Diet: A healthy diet, including adequate dosage of Vitamin D and Calcium, is also useful for preserving bone mass. And it is important to limit coffee, alcohol and tobacco consumption as they may have deleterious effect on bone mineral density.