Effects of Ageing on Joints

Original Editor - Wendy Walker

Top Contributors - Lucinda hampton, Wendy Walker, WikiSysop, Lauren Lopez, Tony Lowe and Laura Ritchie

Introduction

No matter how healthy an individual is, as they age their joints will show some changes in mobility, due in part to changes in the connective tissues. As joint range of movement has a direct effect on posture and movement, this can result in marked alteration of function.

Age-related Changes in Connective Tissue

Cellular Changes: The below factors predispose the elderly to altered connective tissue biology and a decrease in effective maintenance of tissue homeostasis.

1. Alterations in circulating humoral factors (hormones, cytokines, growth factors)
2. Built in cellular senescence (loss of a cell's power of division and growth)
3. Slower turnover of many connective tissue cell populations
4. Age-associated alterations in matrix molecule cross-linking
5. An increase in pigments and fatty substances inside the cell (lipids). Many cells lose their ability to function, or they begin to function abnormally. As aging continues, waste products build up in tissue. A fatty brown pigment called lipofuscin collects in many tissues, as do other fatty substances.
6. Altered control of apoptosis (programmed cell death) .

Gross Changes: Increased stiffness; Decreased strength; Reduction in water content

Age-related Changes in Bone

Bony changes have a direct effect on joint mobility, influencing the joint surfaces to alter joint mechanics. See Effects of Ageing on Bone. Subchondral bone (the layer directly below the articular cartilage) undergoes reduction in thickness and density with increased age.

Age-related Changes in Cartilage

With ageing, joint movements becomes stiffer and less flexible because the amount of synovial fluid inside the synovial joints decreases and the cartilage becomes thinner. Ligaments also tend to shorten and lose some flexibility, making joints feel stiff.

Age in the cartilage is likely due to ageing changes in cells and tissues that make the joint more susceptible to damage and less able to maintain homeostasis ie an imbalance exists between catabolic and anabolic activity driven by local production of inflammatory mediators in the cartilage and surrounding joint tissues. There is a close relationship between chondrocyte activity and local articular environment changes due to cell senescence, followed by secretion of inflammatory mediators. The senescent secretory phenotype likely contributes to this imbalance through the increased production of cytokines and MMPs (matrix metalloproteinases) and a reduced response to growth factors. Oxidative stress appears also to play an important role in the degradation of cartilage seen in ageing with excessive ROS (reactive oxygen species ) affecting cell function.

Age-related Changes in Synovial Fluid

Synovial fluid lubricates joints for smooth movement. Healthy joints contains high amounts of high molar mass hyaluronic acid (HA) molecules in the synovial fluid giving it the required viscosity for its function as lubricant solution, which naturally cushion joints and other tissues. With age, the size of the hyaluronic acid molecules in joints decreases inhibiting its ability to work as effectively in support cushioning and lubrication.

The video below gives an insight of the role HA plays in the joints health. Due to cellular senescence HA degrades.

Age-related Changes in Collagen

Collagen is part of connective tissue, and is found in cartilage, ligaments, tendons and bones as well as skin. Collagen fibers keep your skeletal system flexible, but collagen levels in the body start to decline after about age 25. These declines can cause ligaments tendons bones and cartilage to become less flexible and more brittle over time.

Age-related changes in collagen (including senescence-related secretory phenotypes, chondrocytes' low reactivity to growth factors, mitochondrial dysfunction and oxidative stress, and abnormal accumulation of advanced glycation end products) all lead to this altered structure and decreased functional ability in collagen (Image Collagen triple helix).

Range of Movement

Joint range of movement (ROM) decreases with increasing age. Passive and active ROM both decrease however often the active ROM reduces more than the passive ROM. This reduction in ROM is not uniform, and different joints show different degrees of restricted movement, as well as different patterns of directional limitations. The reduction in joint movement maybe related to different patterns of daily living usage.

Specific Joint ROM Changes

1. Cervical spine - extension and side flexion show the greatest reduction in ROM.
2. Thoracic and lumbar spine - extension is the most limited movement in older adults and rotation shows little or no age-dependent decline.
3. Hip - extension ROM has been shown to reduce by 20% when comparing 25 to 39 year olds to 60 to 74 year olds.
4. Ankle - dorsiflexion ROM is reduced with age.
5. Upper limb: there is less influence of age on joint ROM (compared to spine and lower limb).
6. The shoulder complex shows the greatest changes in the upper limb, whereas no age-associated decline in ROM of the elbow or wrist have been noted (in the absence of disease).

Physiotherapy

Exercise can prevent many age-related changes to muscles, bones and joints – and reverse these changes as well. It’s never too late to start living an active lifestyle and enjoying the benefits.

1. Exercise can help slow the rate of bone loss and make bones stronger.
2. Older people can increase muscle mass and strength through muscle-strengthening activities.
3. Balance and coordination exercises, such as tai chi, can help reduce the risk of falls.
4. Physical activity in later life may delay the progression of osteoporosis as it slows down the rate at which bone mineral density is reduced.
5. Weight-bearing exercise, such as walking (with walking poles increases arm bone density) or weight training, is the best type of exercise for maintenance of bone mass. There is a suggestion that twisting or rotational movements, where the muscle attachments pull on the bone, are also beneficial.
6. Older people who participate in hydrotherapy (which is not weight bearing) still experience increases in bone and muscle mass compared to sedentary older people.
7. Stretching also is excellent to help maintain joint flexibility.