This post continues the series called Aging Educated. The first post is about muscle health and some common muscle pathologies as well. Check it out here. If you are new to the website feel free to check out my About Me page. Briefly, I am a physical therapist that currently works in home health. I enjoy teaching older adults about their body, health, and exercise to maintain an active lifestyle and be more educated in medical decisions.
Joints Defined
Unlike what many may think, joints are not just about bones. Yes, joints are defined as the area where two articulating surfaces come together; however, those bones require other structures to make up a working joint. There are ligaments that surround the joint and the cartilage that lines the bony surfaces to provide sliding surfaces for smooth movements and cushioning. There is also fluid in most joints called synovial fluid that provides lubrication and nutrients for the joints. We also cannot ignore the muscles attached to the bones which allow for joint movement. Joints are complex structures and learning more about what specific structures make up a joint allows us to analyze why there is dysfunction in a joint especially with conditions that occur more frequently in the aging adult.
Joint Components
As mentioned above, there are many structures that comprise a joint. Lets get into a little more detail about these structures.
Ligaments attach bones to one another. They are a special type of connective tissue that help stabilize our joints. They have limited blood supply which contributes to the slower healing time that many ligament injuries require. Ligament injuries are called sprains if there is no major tearing.
Another component of joints that support movement are bursae. We have approximately 160 bursae in our bodies. These help cushion the joint as well as providing cushioned support between some tendons. A bursa can be irritated and swollen, particularly around large joints and is called bursitis (see age related changes below).
Cartilage plays an important role in weight distribution and cushioning joints to prevent damage. Cartilage lines the articulating surfaces of the joints and can be torn or damaged through disease processes such as osteoarthritis (see common pathologies below).
Synovial fluid is in every mobile human joint. This fluid provides shock absorption, nutrient distribution, and lubrication for the joint surfaces to prevent damage. This is one of the many reasons movement is important in rehabilitation. Movement helps encourage synovial fluid motility and promotes healing by bringing nutrients to an injured region.
In addition to these structures, the muscles surrounding joints are what allow these joints to move within the available range. We talked in detail about muscle health in a previous Aging Educated post, check it out here.
Types of Joints
Our bodies have many different types of joints. Some are very mobile, such as the shoulder which can move in all 3 planes of movement. Others are fused joints such as our skull sutures which harden from cartilage after birth to form the unmoving parts of our skulls. There are also very unique joints such as the saddle joint of the thumb that allows the unique range of motion and articulating movements we can perform with our thumbs.
Different joints have different levels of complexity and structure. Some, such as the knee and elbow do not require as many individual ligaments for stabilization because of their limits in range of motion due to joint structure. Others, such as the shoulder require more complex muscle, ligament, bursa support to prevent injury and provide stable movement in all joint ranges allowed.
Successful Joint Movement
Now that we have talked about a few of the joint components and shapes which allow for unique movement we can talk about successful joint movement and the changes that lead to joint movement issues. These are specific to risks for older adults. This article is not exhaustive especially in regards to genetic conditions that lead to joint health issues.
Age Related Changes
As with all tissues, joints are effected by the aging process as well. Joint movement can become more difficult due to reduced fluid in the joints as well as ligament tightness which leads to reduced joint flexibility. Specifically in the spine, the gel cusion (disc) between each bone of the spine loses fluid and can become thinner. This is one factor that can contribute to height loss in older adults. Posture and bone changes contribute as well.
Common Pathologies
Dislocation
Dislocation is defined as an injury to the joint which results in the ends of the bones being forced from their normal positions. The shoulder joint is the most common joint that is dislocated.
20% of shoulder dislocations occur in adults over 60. Falls on an outstretched arm is the most common cause of shoulder dislocation in older adults.
Ligament Sprain or Tear
Ligaments are dense structures that support the joints and contribute to stability. These can be injured with force such as an ankle sprain or can even be torn especially with athletic activity or a fall. Ligament injuries have different severity levels and a wide range of management strategies depending on severity. Physical therapy plays a role in ligament injury often, whether it requires surgery or not. Rehabilitating a ligament injury fully is important because of how our ligaments contribute to joint stability and balance reactions, especially in older adults.
Bursitis
As mentioned above, bursae are fat pads that help support our joints. When these become inflamed it is called bursitis and can be very painful and difficult to manage. Bursitis commonly occurs in knees especially in people that kneel repetitively. Bursitis can be treated with ice, rest, therapy and some cases cortisone injections to reduce inflammation and allow improved movement.
Osteoarthritis
Osteoarthritis is very common in adults over 65. Estimates report that up to 50% of older adults have osteoarthritis. Osteoarthritis can be diagnosed by x-ray and is defined as a condition in a joint which results in the reduction in thickness of articular cartilage and thickening of the bone at these joint surfaces. Thinking about what we discussed earlier in this post, cartilage plays an important role in force distribution in a joint as well as smooth movement. People with osteoarthritis often report pain which affects daily activity and exercise participation and joint range of motion may be reduced as the disease progresses.
Interestingly, osteoarthritis is not always symptomatic (painful) even in people where x-rays show joint changes. Osteoarthritis does not have to be a lifelong painful condition or even result in the need for a joint replacement if it is managed well. Osteoarthritis has many treatments and physical therapy is a very effective one. A physical therapist can teach you pain management tools, movement strategies, exercises to improve strength, balance, and decrease weakness and pain.
Conclusion
I hope this has been a helpful article for you. Please feel free to email me directly at christine@agingwithability.com for any questions you may have. Also, check out my home safety assessment below that you can sign up for my email list and receive for free. This gives you a room by room guide to improve your safety in your home and prevent falls. As a home health physical therapist, I help people prevent falls at home and environmental risk factors such as poor lighting or cords in a pathway are easy to identify as possible risks and correct with a few simple changes. You will only receive emails from me if you sign up for my list. I do not sell your information to anyone; it is just another way to get notified of new posts or videos here on the blog. So please join me!
Also, check out the other posts in the Aging Educated Series
Muscle Health
Bone Health
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