Shoulder Pain – Complexity to Simplicity A Regional Approach to Shoulder Pain The best way to approach a problem of shoulder pain is to look at the pain from a regional point of view. This allows for easy identification of specific pathological problems that occur at each region. In this talk, we look at the patterns of pain that occur with the different regions around the shoulder. From this, we will focus on the pathological problems that can be expected in each region and then look at specific physical examination findings that can be used to confirm a diagnosis or help further clarify the problem. Although this talk is focused on the diagnosis of causes of shoulder pain, we also take a look at some updates and salient features of treatment. In general, pain in the region of the shoulder can be grouped into 4 main types. These relate to specific patterns of pain that allow history taking to help us focus on the likely cause(s) before moving on to examination. A fairly clear-cut diagnosis is almost always achievable without the need to resort to special tests to help make the diagnosis. Of course, this does not include all possible causes of pain. The uncommon problem will still need a thorough and complete approach to determining cause, often with the requirement for special investigations. Remember that this is a good guide. Don't neglect other causes of referred pain that may cause pain in and around the shoulder. Included here is cardiac pain, diaphragmatic pain, apical lung disease and malignant bone pain. Acromio-Clavicular joint pain distribution The Acromio-Clavicular joint is a special case when it comes to shoulder pain. This joint is the final articulation between the torso and the upper limb. Almost all arm movements will cause movement at this joint. Therefore, pain coming from this joint will tend to occur with almost all upper limb movements. The key to making the correct diagnosis lies in the pain distribution. The AC joint has a very particular pattern of pain. Whilst pain may be well localised to the AC joint, it usually causes a wide area of referred pain. This is very similar to the C4 nerve root dermatome. Classically, the pain extends from the tip of the acromion all the way to the occiput on the same side. It forms a rough diamond shape that drapes over the top of the shoulder as far back as the scapular spine and as far forward as the clavicle. Dr Gavan White 2017 The pain is aggravated by most arm movements, so it may be confused with painful arc/subacromial impingement unless the distribution of pain is taken into account. The pain is often worsened more with movements that compress the joint, such as adduction and elevation above shoulder height. Subacromial pain distribution Pain originating from the subacromial space is the most common type of pain encountered with shoulder pain. Given that most of the pain is initiated by compression of painful structures in the subacromial space, movements that induce the pain are typically into abduction – the so called painful arc syndrome. Again, it has a typical pain distribution pattern that often confuses the source of the pain. The pain distribution is similar to the area of innervation of the Axillary nerve, or even the C5 nerve root dermatome. Typically, the person describes a pain over the deltoid and often points to the lower part of the deltoid as it inserts into the humerus. Sometimes, the pain will extend down the lateral arm as far as the elbow. Gleno-humeral joint pain distribution Typically, gleno-humeral joint pain is felt as a deep pain in the anterior shoulder region as well as in the posterior shoulder region. By its nature, the pain is aggravated by shoulder movements. Unlike ACJ and subacromial pain, this may also include pain with internal and external rotation with the shoulder in the neutral position. Otherwise, the pain will occur with all movements, especially at end range of all movements. Gleno-humeral arthritis may produce limitation of movement because of pain and some weakness. Adhesive capsulitis classically causes pain at end range, with reduction of motion in all directions. The difference being that passive movement is also reduced with adhesive capsulitis. One particular type of gleno-humeral pain is that of subluxation or instability. The pain, here, is often intermittent and aggravated by getting the arm into external rotation in the abducted arm. On top of this, there is a typical symptom of the 'dead arm', where the person moves the arm, feels pain and a pins and needles type of pain and is unable to move the arm for a few seconds. Cervical referred pain The typical referred pain of cervicogenic cause relates to the cervical level that is causing the pain. It may simulate ACJ pain as well as subacromial pain. Typically, this pain is aggravated by neck posture and movement, but arm movement may aggravate it if there is a radicular component. Typically, pain of C4 distribution is felt over the base of the neck, on top of the shoulder and out to the acromion. C5 pain extends from the deltoid region, down the arm to the lateral side of the elbow. Dr Gavan White 2017 A hallmark of cervical referred pain is that it is a deep pain that is poorly defined and poorly localised. It is often described as a deep toothache and being shown over the general distribution as described. Radicular pain may have a burning quality and may be associated with some sensory symptoms in the dermatome affected. Common Causes of Pain in Each Region Having determined that the bulk of presentations of shoulder pain can be reasonably easily put into one of these four groups, the next step of the process is to consider what the causes of pain are in each group. This should be done before examination, so that specific examination techniques can be used to confirm or refute the likely diagnoses. By doing this, it also reduces a big list of causes of shoulder pain into a manageable group for each region. Again, these causes are not exhaustive. The whole aim of this approach is to simplify, but not to ignore the less common. If the pain doesn't fit with this approach, then don't make it fit, it is time to stand back and reconsider the whole problem. Acromio-Clavicular joint Dislocation, subluxation, sprain Obviously, this group come in as a traumatic event. Sometimes, though, the person may present some time down the track after an injury with ongoing pain. Osteoarthritis Degenerative arthritis of the ACJ is the most common cause of pain from the joint, when we look at insidious onset of pain without discreet trauma. Most commonly this will develop some years following a dislocation, subluxation or sprain. Osteolysis The ACJ is a joint, similar to the Pubic Symphysis, where the joint is made up of a strong capsule with an internal fibrocartilaginous disc. In a similar way to Osteitis Pubis, the ACJ can develop a form Osteitis following injury, that progresses to dissolution of bone and pain. Rheumatoid arthritis It is important to remember that Rheumatoid arthritis has a few favourite joints that it attacks, and this may be a presenting complaint. The 'odd' joints that may be involved include the ACJ, the crico-aretenoid joint as well as the joint between the Dens and the body of C1. In a person who presents with typical ACJ arthritis, especially bilateral, it is wise to check for RA. Subacromial Space The most common cause of shoulder pain is subacromial pathology. In essence, anything that causes subacromial impingement or is painful to use (tendinopathy or tear) will cause this classic pain. Dr Gavan White 2017 Subacromial bursitis Thickening and an effusion of the bursa is a classic cause of subacromial pain. In general, it will cause typical impingement signs. It classically causes pain at night. A good rule of thumb is that if the impingement signs are positive but there is no pain or weakness with resisted rotator cuff strength testing, then subacromial bursitis is the most likely cause. Rotator cuff tendinopathy As with most forms of tendinopathy, the tendons of the rotator cuff may become painful with overuse, overloading or recurrent impingement. In general, the Supraspinatus is the most commonly affected, followed by subscapularis. The Infraspinatus is an uncommon cause in isolation. Typically, there will be positive impingement signs, pain on resisted strength testing of the involved tendon, but there should not be true weakness. Pain inhibited weakness is reasonably common, though. Rotator cuff tear As with tendinopathy, tears tend to occur most commonly in the Supraspinatus tendon, followed by Subscapularis. Infraspinatus rarely tear in isolation but may be involved in a massive cuff tear. Again, there should be positive impingement signs, pain with resisted strength testing of the affected tendon, but there is usually some associated weakness. As with bursitis, a cuff tear will frequently cause significant night pain. Calcific tendinitis Acute calcific tendinitis is a complication of degenerative tendinopathy. It comes on rapidly and causes severe pain. Unlike most other conditions in this group, the presentation is an acute one. There may be severe pain, heat and very limited movement, mimicking septic arthritis. More commonly, though, is chronic calcific tendinopathy, where a less dramatic presentation with pain and positive impingement signs occurs. It is difficult to differentiate this from tendinopathy or a tear clinically. X-ray or ultrasound will confirm the diagnosis. Fractured Greater Tuberosity In this situation, there should be an acute presentation following a fall.