Shoulder Pain

Introduction

Shoulder pain is an extremely common but vague symptom that many patients experience. It has been estimated that between 20 and 50% of people seek help for shoulder pain within their lifetimes. Because the entire area extending from the base of the neck, to the tip of the shoulder, both front and back can be considered “the shoulder”, there are often many conditions that can present with “shoulder pain”.  Generally, the cause of the pain can be localised to either a cervical spine (neck) problem or a shoulder joint problem. Cervical spine problems are beyond the scope of this article, hence while some symptoms of cervical spine problems will be discussed later on, emphasis will be placed on shoulder joint issues.  In order for one to understand what can potentially go wrong with the shoulder joint, it is necessary to know some basic anatomy of a normal shoulder joint.

Anatomy of the Shoulder Joint

Bony anatomy of the shoulder

The shoulder joint is made up of 3 bones: the shoulder blade (scapula), the humeral head and the collar-bone (clavicle).

Shoulder joint

Movements around the shoulder involve 3 separate articulations: the glenohumeral joint, the acromioclavicular joint and the scapulothoracic articulation. When the arm is raised, the majority of movement occur at the glenohumeral joint and the scapulothoracic articulation.

Shoulder with bursa

4 muscles are attached to the scapula and send their respective tendons across the glenohumeral joint and attach to the humerus just beyond the humeral head. These 4 tendons are collectively known as the rotator cuff. You can think of the muscles as motors and their tendons as pulleys. Contractions of the muscles will hence bring about movement at the joint that their tendons cross. A part of the scapula, known as the acromion, forms a roof over the humeral head and rotator cuff. To reduce friction between the acromion and the underlying rotator cuff during shoulder movements, a thin sac containing a sliver of fluid sits on the superior surface of the rotator cuff. This sac is known as the bursa.

Shoulder joint with intact labrum

The glenohumeral joint is a ball and socket joint, comprising the socket (the glenoid) and the ball (the humeral head). Both surfaces of the joint are covered with an extremely smooth and rubbery cartilage (known as articular cartilage). The smooth surfaces create a frictionless articulation when lubricated with a small amount of joint fluid. The glenohumeral joint is designed to provide a large range of movement; hence you are able to perform many tasks like reaching overhead for a high shelf or scratch your back. However, flexibility comes at the price of stability. As such, the shoulder joint (more specifically, the glenohumeral joint) is the most commonly dislocated joint in the body. The glenohumeral joint has several means to prevent dislocations:

• The cartilage on the glenoid surface is shallower at the center than at the periphery, hence deepening the socket
• Cartilaginous extensions of cartilage (the labrum) at the periphery of the glenoid aids in further deepening the socket further yet does not restrict range of movement
• Various ligaments connect the humeral head to the glenoid helping to stabilize the joint further
• The rotator cuff helps to pull the joints together further enhancing stability

What sort of pain might a patient with shoulder problems encounter?

The most common symptom that patients seek help for is pain. Characteristics of the pain can reveal a lot about the problem. Aching pain felt at the top of the shoulder (trapezius muscle area), back of the shoulder (especially between the shoulder blades) and base of the neck is more often associated with cervical spine issues and is beyond the scope of this article. Shoulder pathology often causes pain either at the front or back of the shoulder, deep within the shoulder area or frequently at the side of the arm where the deltoid muscle ends.

The pain may be sharp in nature, aggravated by certain movements like rotation of the arm and raising the arm up high; or it could be aching and gnawing in nature. Some patients find that the pain is more bothersome at night and interferes with their sleep. Often times, patients feel pain if they are side sleepers and lie on the affected side. Some patients may even have difficult lying on the unaffected side because their affected arm falls across their bodies due to gravity and that causes them pain. Others may find that turning in bed wakes them up due to pain in their shoulder.

Pain aggravated by movements is very common. Sometimes patients may be relatively pain-free at rest, but experience pain when they raise their arms overhead. Many will report having a specific arc of pain while they raise their arms, i.e. when they try to raise their arms from the side of their bodies, the movement is pain-free till their arms are about 60° from their bodies. Then they experience pain till their arms are about 120° from their bodies. After which the pain seems to abate. Occasionally, patients may tell me that they encounter difficulties at work when lifting loads because with certain movements, they feel a sudden sharp pain which makes their entire arms go numb!

Some shoulder problems may be mainly sport specific and may only occur during over movements like over tennis serves, badminton smashes, volleyball spikes or throwing a ball. Others may occur during gym work outs like bench presses or shoulder presses.

What other symptoms might a patient with shoulder pain encounter?

Stiffness

Arguably, the next most common symptom, aside from pain, is stiffness. Many patients will find that they have gradually lost movement in their shoulders. They may experience difficulty reaching their other shoulder for scratching or bathing. Ladies often complain that they are unable to do up the clasps of their bra, while men may complain that they have difficulty placing their wallets in the back pocket of their pants. Active patients will find that they are unable to, perhaps, hang from the pullup bars, do certain yoga poses, reach for certain shots during ball games etc.

Weakness

Many patients will find that their arms are not as strong as they used to be. This often manifests itself during work that requires heavy lifting, or during sports. Some patients suffer acute and severe weakness immediately after an injury and are unable to actively lift their arms. This is a condition known as pseudo-paralysis. After a period of rest, however, many patients will be able to lift their arms again albeit with some weakness and discomfort. They then mistakenly assume that their shoulder tendons are not seriously injured. Because the individual rotator cuff tendons merge into each other as they insert onto the humerus, even with a complete tear of the supraspinatus tendon, for example, patients may still be able to lift their arms as the surrounding tendons will be able to compensate.

Asymmetry

Occasionally, the observant patient may notice that in order to raise the arm, he/she shrugs up the shoulder on the affected side hence giving an asymmetrical appearance when viewed in the mirror.

What brought on the shoulder pain?

Injury

Injuries are common causes of shoulder issues in all age groups. In older patients, falls are usually the most commonly mechanism of injury, whereas in younger patients, injuries are usually sport related.

Older patients often fall after having slipped or tripped over a step. The human reflex is to break the fall with our upper limbs to prevent facial or head injuries. Many patients will experience a sudden acute pain in their shoulders, often accompanied by a snapping sensation (or noise) in the shoulder. The patient may have difficulty raising his arm after that.

Younger patients seldom sustain serious shoulder injury after a “mere” fall, unless the impact is great (e.g. falling from a height or motor vehicular accident). More often, younger patients will sustain shoulder injuries from having their arms yanked in “unnatural” positions during sports. Commonly as well, they may feel a sudden pain while using their arms with excessive force (e.g. trying to do a really hard tennis serve or throwing a ball hard during a baseball game). The games that patients get injured playing varies from place to place. In Singapore where I am based, games like baseball and American football are not popular, but rugby, soccer and racquet sports are. Hence the type of injuries that I see commonly may be slightly different from Japan, for example, where baseball is rather popular.

Mild “sprain”

Many patients will report that their shoulder problem started after they had sustained a mild injury while doing mundane things like reaching out for an object, reaching for something in the backseat of the car. The mild injury might not even have been painful initially, but the shoulder pain progressively became worse after.

What will the doctor do?

Your doctor will chat with you and ask you more about the problem in order to narrow down the list of possible problems. A careful examination of the shoulder is then carried out. Your doctor will likely have an idea of what is the problem with your shoulder, but it may be a list of 3-4 possible problems! In order to identify the problem with more accuracy, he will usually need to order some tests.

What tests can be done to confirm the diagnosis?

This section will briefly discuss the common investigations that doctors carry out to identify the problem. For a more detailed discussion regarding investigations, please go to the page on investigations.

The simplest test is a series of x-rays for the shoulder. X-rays are excellent investigations for viewing bony and joint problems but they are not so useful for soft tissue problems such as labral, cartilage or tendon problems. Most people are familiar with x-rays and are aware that they are quick, simple and non-invasive scans that take only as long as it takes to snap a photograph. X-rays, however, involve small amounts of radiation which some patients may not be so keen on.

Ultrasound scans are next in line. Ultrasounds are good and relatively simple tests which can sometimes be done in the doctor’s office. They are non-invasive and comfortable for the patient. There is no potential harm to the patient as there is no radiation at all. The drawback of ultrasounds, however, is that they are operator dependent. That means that if a sonographer is not sufficiently proficient or experienced with ultrasounds, their ability to accurately diagnose the problem will also be adversely affected. In addition, certain pathology within the glenohumeral joint cannot be visualized during the scan. Lastly, in the event that a bad rotator cuff tear is detected, ultrasound examinations may not yield enough information for the surgeon to accurately predict the chances of success of surgical repair. This may necessitate further assessment with a more detailed investigation resulting in increased cost and delay in establishing a diagnosis.

The final investigation is an MRI (magnetic resonance imaging) scan. An MRI scan is by far, the most informative scan. Although some doctors ask for an MR arthrogram (where an injection of a fluid is administered into the glenohumeral joint to enhance the appearance of some problems), I find that a plain non-invasive MRI scan is equally accurate. This eradicates the need for the injection which may be painful and unpleasant for the patient.

What are the likely problems with my shoulder?

It is often easiest to group problems according to several categories, namely: age of patient and mechanism of injury.

Young patients with sporting injuries:
• Rotator cuff sprain
• Labral tears
• Acromioclavicular joint injuries
• Shoulder instability

Older patients with no or trivial injuries:
• Rotator cuff sprain
• Rotator cuff tendinosis/ tendinitis
• Impingement or bursitis
• Frozen shoulder
• Calcific tendinitis (Acute or chronic)
• Arthritis

Older patient with significant injury:
• Rotator cuff tear
• Fractures around the shoulder

How can my shoulder pain be treated?

Treatment options can generally be classified into 2 categories: non-invasive and invasive options. I generally start patients off with non-invasive treatment modalities first, unless the pathology is such that surgery is clearly required. If non-invasive options prove to be ineffective, it may then be necessary to resort to more invasive options.

Non-invasive options:
Many shoulder problems can resolve spontaneously, given sufficient time and rest. Sprains, inflammatory conditions and even some labral tears can heal and recover. To make things more bearable, pain and anti-inflammatory medications can be taken. Physiotherapy is often useful. A good physiotherapist will be able to analyze your movements and identify problems with the dynamics of your shoulder movements. He/she can then focus on correcting those issues.

Invasive options:
Invasive options comprise injections, manipulation and surgery.

Injections: Injections are commonly administered for a variety of shoulder problems. There are also various types of injections available. Medical practices also vary from place to place; hence I will be discussing practices specific to Singapore, where I am based.  The most common injection in the shoulder is a cortisone (steroid) injection. Steroids suppress inflammation and are used in inflammatory conditions such as tendinitis, bursitis and frozen shoulder. They can be administered in the office. Some doctors use ultrasound imaging to enhance the accuracy of the injection, but that is not strictly required. Plate rich plasma (PRP) injections have recently become popular. The theory for PRP is simple. Your blood contains many chemicals that your body produces to bring about healing. A small amount of blood is taken from you and spun down in a centrifuge. The blood separates into a lower intense red layer and clear top layer. The clear layer is collected and injected into the area where healing is desired. Because this layer is rich in chemicals required for healing, theoretically, healing should occur more readily wherever it is injected. Saline injections are used sometimes specifically for frozen shoulders in a procedure known as hydrodilatation. This will be covered in greater detail in the section on frozen shoulders.

Manipulation: Manipulation is technically a non-invasive procedure by itself. However as either deep sedation or more commonly, general anaesthesia is required to perform this procedure, I classify this as an invasive procedure. It involves forceful but controlled manipulation of the shoulder in established cases of frozen shoulder. Manipulation is covered in more detail in the section on frozen shoulders.

Surgery: Surgery is often the last resort in cases that have failed to respond favorably to non-invasive options. In certain cases, non-invasive options clearly yield inferior results and surgery may be advised as the most suitable option. Most shoulder surgeries these days can be performed via minimally invasive techniques (keyhole surgery). Some patients are of the mistaken impression that keyhole surgery can be performed via only one single small incision much like literally the keyhole of a door! In reality, at least 2 such holes are required to successfully perform such procedures. To a surgeon, within reason, the number of incisions is not important. The basic principle of keyhole surgery is that this technique allows the surgery to be performed effectively while minimizing injury to surrounding structures (less “collateral damage”). For example, open surgery of the shoulder performed to repair a torn labrum used to involve dividing a large and important tendon that sits directly in front of the shoulder in order to access the glenohumeral joint. This necessitates a repair of the said tendon after the labrum has been repaired. In addition, because the glenohumeral joint is a deep, a larger incision is required for adequate visualization of the joint. This may be especially challenging in patients who are overweight or who are very muscular. With minimally invasive techniques, excellent view of the joint can be easily achieved even in such patients. The drawback of minimally invasive surgery is that the learning curve for a surgeon to be proficient in these techniques can be steep. The surgeon must have had significant experience performing them in order to attain this proficiency. Please refer to the section on keyhole surgery to learn more.

What should I do now?

Shoulder pain is extremely common and most problems are self-limiting. While this article tries to shed light on this problem, it is impossible to accurately identify the problem and find an effective solution via description in an article. If your shoulder is bothering you, do strongly consider consulting your family doctor about it. He/she will be able to handle most common shoulder issues and advise you accordingly if a referral to an orthopaedic specialist is required.

Disclaimer:

The above information is meant to be used as a guide and for patient education purposes. This article is not meant to be a used for self diagnosis or a substitute for professional medical evaluation or advice. As patients may be differing symptoms, please see your family doctor or orthopaedic specialist if you have any symptoms or worries.

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