“My shoulder is making a lot of painful grinding noises”
Friction – sometimes a good thing. It keeps a tire on the road. My dog likes a good scratch behind her ear. A cold camper can start a fire with it. Structures that move in relation to each other present an opportunity for friction. Shoulders have many parts that move in relation to each other – as such, loss of normally smooth surfaces will create roughness, noise, clicking, irritation, and pain. Friction has no place in normal shoulder function. Smoothness is a very important aspect of normal shoulder comfort and function. (see Matsen, et al. “Practical Evaluation and Management of the Shoulder”). Articular cartilage and bursa normally provide this glide. Loss of smoothness creates some of the most common shoulder problems – many of which surgeons have good treatments to help.
Glenohumeral Joint
A smooth articulation between the ball and socket is possible because of articular cartilage that covers each surface. Articular cartilage is a wonderfully smooth, nearly friction free material. Unfortunately, all too often, the tissue degenerates and breaks down, leading to roughness (ARTHRITIS is the loss of normally smooth articular cartilage.) Pain, swelling, and stiffness all can result from this process.
Shoulder arthritis is treated like arthritis elsewhere: focus on maintaining flexibility and treat the inflammatory component of the disease with anti-inflamatory medications and occasional corticosteroid injections. PRP injection may offer some hope (link), although insurance will not cover the cost of this intervention. Orthobiologics such as stem cells (link) are unproven, expensive, and at this point in time have no role in treatment of shoulder arthritis.
Ultimately, shoulder replacement can be offered. Replacement, or “arthroplasty”, is one of the most predictable and effective interventions that can be offered patients across all disciplines in medicine. Different options are available – partial replacement, total shoulder replacement (stemmed and stemless implants), reverse shoulder replacement, and custom 3D printed implants. Indications and techniques continue to expand and evolve. Future posts will describe these devices in more detail. These technologies offer great hope to help patients who are struggling with shoulder arthritis. A polished cobalt-chromium metal ball rolling against a smooth and durable polyethylene layer offers a nearly friction free smooth surface to restore motion and relieve pain.
Humeroscapular Interface
The space between the undersurface of the acromion and the rotator cuff is a critically important area of the shoulder. Codman recognized its importance in his classic 1934 text: “The Shoulder: Rupture of the Supraspinatus Tendon and other lesions in or about the subacromial bursa”. He recognized the importance of the subacromial bursa and the coracoacromial arch in allowing for smooth movement of the rotator cuff against the roof of the shoulder. The arch is a normally curved structure made of the acromion, the coracoacromial ligament, and the coracoid process; it creates an essential joint surface for the rotator cuff to contact and glide against. Consider that the arch creates a secondary shoulder joint. Up to 4 cm of gliding motion between the rotator cuff and the overlying arch is seen in normal shoulders – increased friction here is detrimental. The subacromial bursa functions to minimize the friction between the cuff and arch. An inflamed, thickened bursa will create a painful loss of smooth motion. It might be one of the most common problems that bring patients to a shoulder specialist!
Anything that squeezes this space (shoulder IMPINGEMENT) increases friction in this area and can lead to inflammation of the bursa. Common causes include stiffness (of the posterior capsule), weakness (related to rotator cuff deconditioning or partial tearing), or repetitive overuse of the shoulder.
Historically, impingement was attributed to the shape of the acromion. Treatment included surgical removal of part of the acromion and release of the coracoacromial ligament (a procedure called a “decompression”). Recent well designed randomized clinical trials have shown that decompression has little role in the treatment of this condition. Acromial morphology is unlikely to contribute to impingment. Instead, treatment should focus on the stiffness, the weakness, and the inflammation/thickening of the bursa. Codman learned this almost 100 years ago, and states on page 13 of his classic text: “The coracoacromial ligament has an important duty and should not be thoughtlessly divided at any operation.” Much more to come on this important topic of shoulder impingement!
Acromioclavicular Joint
The small joint between the acromion and the clavicle can also develop smoothness issues related to arthritis, fracture, prior trauma. Weightlifters can find this small joint developing painful clicking and popping over time. Patients will often localize the discomfort to the small joint by pointing with the index finger of their opposite hand. Treatments range from conservative to surgical. More to come.
Scapulothoracic Joint
“Snapping scapula” can result from abnormal roughness between the scapula and the underlying chest wall/ribs. Irritation of one or more of several bursal areas under the shoulder blade can develop from loss of normal scapulo-thoracic movement. Weakness, stiffness, and prior injury can alter the normal gliding of the scapula. Conservative treatment with rehabilitation of scapular movement and strengthening of the interposed muscle tissue is helpful. Surgical efforts are available as well, although they are somewhat unpredictable in outcome. Snapping scapula is a challenging problem to treat quickly. Further discussion to come in the future.
Sternoclavicular Joint
The clavicle meets up with the sternum on its medial end. Degenerative arthritis or trauma can lead to clicking and swelling of this joint. The proximity to major neurovascular structures creates some challenges to treatment of this problem. Often, a problem here is best treated with benign neglect, which can be quite successful in the long term.
Summary
Loss of smooth joint surfaces (arthritis), and loss of a smooth humeroscapular interface (impingement) are common causes of shoulder. Restoration of smoothness is possible, and accomplishing smoothness will restore comfort and function to the shoulder. Shoulder replacement is one of the most predictable interventions in the world of orthopedic surgery (as such – it is also one of my favorite things to do! Nothing beats being able to achieve consistently good outcomes and seeing patients get back to doing the things they enjoy). Impingement is often improved without surgery. Impingement is a common problem, and deserves much more discussion. Stay tuned!
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