ARTHROSIS

A joint, known as ‘arthron’ in ancient Greek, is a complex structure composed of two bones, referred to as joint partners. These joint partners are encased in cartilage tissue, forming essential components of the joint, such as the humeral head and the glenoid cavity. Ensuring the smooth functioning of this joint, a protective capsule envelops it, preventing the leakage of synovial fluid and enabling frictionless movement between the joint partners. Regular physical activity plays a vital role in maintaining well-lubricated cartilage and ensuring the joint receives necessary nutrients.

In cases where cartilage is inadequately lubricated or subjected to excessive stress, it can develop cracks. As cartilage deteriorates over time, the bones can grind against each other without the cushioning protection it provides, often leading to an inflammatory response within the joint.

In everyday language, terms like joint wear and tear or joint degeneration are frequently used to describe osteoarthritis. Osteoarthritis is characterized by the progressive degeneration of cartilage tissue. This process can be likened to a car’s transmission system. If all the transmission components function seamlessly, gear-shifting proceeds without issues. However, when there is abrasion, such as worn-down cartilage, akin to pieces of cartilage breaking off, it disrupts smooth joint movement.

Osteoarthritis in the shoulder can manifest in various locations, including the acromioclavicular joint, the glenohumeral joint, or the sternoclavicular joint, which connects the sternum and clavicle.

Osteoarthritis is a natural progression that unfolds over years. To illustrate, consider a new tire with substantial tread at the outset. Over time, the tread wears down, becoming thinner and smaller. Ultimately, in the worst-case scenario, the tire is worn to the rims.

The body employs various protective mechanisms to counteract cartilage degeneration, including bone compaction, cyst formation (accumulation of fluid in the bone), and the development of bone outgrowths known as osteophytes. Sclerosis, which begins due to increased pressure on joint partners, causes the bone edges to compact and deform, redistributing the force over a broader area, thereby minimizing pain.

An apt analogy is a fakir walking across a bed of nails. If they stepped on a single nail, they would experience intense pain. However, when walking on a board covered with numerous nails, the weight distribution is even across a larger surface, leading to an automatic reduction in pain sensation.

The presence of osteophytes, or bone outgrowths, serves as a telltale sign of arthrosis. Healthy joints typically exhibit a visible joint space in X-ray images, attributed to cartilage tissue, which remains unseen in X-rays.

As cartilage deteriorates, this joint space diminishes, creating a narrowing gap between the socket and the head. This reduced joint space is a hallmark of osteoarthritis. As the condition progresses, both cartilaginous and bony structures can wear down, resulting in the formation of ‘free’ joint space and promoting further degeneration. The extent of wear can lead to significant shifts in the position of individual bones in the shoulder joint. The humeral head may dislocate posteriorly, causing increased wear in the rear portion of the socket. Furthermore, severe damage to the rotator cuff can disrupt the centration and support of the humeral head within the joint. This leads to an altered, unnatural position of the humeral head, imposing uneven loads on the joint. Over time, the glenoid cavity may experience asymmetric wear. When the rotator cuff can no longer provide stabilization, the humeral head tends to shift upwards towards the acromion, resulting in chronic contact between the humeral head and acromion. If the arm remains in this position for an extended period, the humeral head grinds against the acromion, a phenomenon known as acetabulization (akin to the hip socket), which often leads to significant discomfort for the individual.

Osteoarthritis is often characterized by its most prominent symptom – pain. Individuals affected by osteoarthritis frequently describe this discomfort as a persistent ache and a pulling sensation, particularly during shoulder movements. Furthermore, typical indicators of osteoarthritis encompass pain experienced at night while in a completely resting position.

After prolonged periods of rest, individuals may encounter symptoms such as stiffness and what is commonly referred to as “starting pain.” This pain intensifies as the joint bears a heavier load – the more stress placed on the joint, the more pronounced the discomfort. Additionally, heightened sensitivity to changes in weather and cold temperatures may be indicative of the presence of osteoarthritis.

Observable symptoms also include swollen and thickened joints, signs of inflammatory irritation, and unusual sounds during joint movement, like rubbing or grinding. These telltale signs may indicate the involvement of bone attachments, which can result in joint deformities, ultimately restricting mobility and diminishing the joint’s natural range of motion. Additionally, the extent of muscle strength may be compromised or reduced depending on the impact of osteoarthritis on the rotator cuff.

X-rays are an indispensable tool for the examination of bone structures. This diagnostic procedure allows for the assessment of critical aspects such as joint space narrowing and the extent of sclerosis at the bone margins. Through X-rays, healthcare professionals can gain valuable insights into the presence of cysts or typical bone formations known as osteophytes. Additionally, X-rays offer crucial information about the positioning of joint partners in relation to each other. They provide insights into whether the humerus is correctly centered within the joint, if it has shifted anteriorly or posteriorly, and whether there remains sufficient space between the acromion and the humeral head.

To assess the condition of the rotator cuff, healthcare providers may utilize an ultrasound or MRI. The results of these imaging techniques play a vital role in determining the appropriate course of therapy. For instance, in cases of severe damage to tendons like the supraspinatus or subscapularis, anatomic joint replacements may not be feasible. Instead, an inverted or inverse prosthesis is considered. Preoperative planning often involves a CT scan, which creates a precise 3D image of the shoulder joint. This technique enables a clear visualization of the position of the glenoid cavity and the humeral head. Moreover, contrast agents injected during the procedure help assess the integrity of the rotator cuff, including the evaluation of the fatty composition of the rotator cuff muscles.

Osteoarthritis, by its nature, is not a condition that can be entirely cured. However, when diagnosed in its early stages, its progression can be significantly slowed down through various treatment approaches. Active movement is crucial for maintaining the remaining cartilage’s nutrition in a painful joint. The better the muscles are conditioned, the more effectively they can support and control the joint, thereby reducing pain. The choice of treatment modalities should always be tailored to the specific stage of osteoarthritis.

Physiotherapy and physical interventions are instrumental in improving function and reducing pain, which may involve methods such as the application of hot and cold packs, ultrasound therapy, and more. In the initial stages of osteoarthritis, exercises to strengthen muscles and protect the joint often offer relief from symptoms.

In some cases, pain-relieving and anti-inflammatory medications are prescribed. The suitability of cortisone injections into the joint is determined by the physician. There are also alternative treatment options, like injections of hyaluronic acid preparations (which serve as a ‘replacement’ for synovial fluid) or the PRP (Platelet Rich Plasma) method, which involves the injection of ‘autologous blood’ or the patient’s own blood plasma into the affected joint. These interventions can be effective in alleviating discomfort. However, it’s important to recognize that they do not address the underlying issue. Once cartilage is worn down, it cannot be regenerated by the body or by the addition of medications.

Advances in medical research have enabled the cultivation of cartilage cells and the use of cartilage transplants in specific cases to partially replace damaged cartilage, particularly in the knee area. For more advanced osteoarthritis, joint replacement surgery (endoprosthetics) is often the recommended solution. In this procedure, an artificial joint is used to replace the surfaces of both the glenoid cavity and the humeral head.

It’s important to note that there are two main types of artificial joints used in these surgeries: the ‘anatomic’ or ‘regular’ prosthesis and the ‘reverse’ or ‘inverse’ prosthesis. The choice between these options is made based on the patient’s specific condition and requirements.