Unlocking the Mystery of Frozen Shoulder: Causes, Symptoms, and Treatment Options

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Frozen shoulder is a condition that affects your shoulder joint. It usually involves pain and stiffness that develops gradually, gets worse, and then finally goes away. This can take anywhere from a year to 3 years. The cause of frozen shoulder is not fully understood. However, there are groups who have a higher risk of developing frozen shoulder. These include people who have diabetes, are 40-70 years old, the majority of whom are women, people with chronic diseases, those who have been immobilized for a long period of time or had to look after a relative who has been immobilized, and people who have had trauma to the shoulder, such as surgery. It is not apparent why these groups of people are at higher risk. The shoulder is made up of three bones which are connected by ligaments to form a ball-and-socket joint. The bones in question are the upper arm bone (humerus), the shoulder blade (scapula), and the collarbone (clavicle). The end of the scapula, known as the acromion, forms the roof of the shoulder. A layer of connective tissue, the shoulder capsule, surrounds the joint. The synovial fluid inside the capsule helps to lubricate the joint, enabling the humerus to move freely. In frozen shoulder, the capsule becomes so thick and tight that movement is painful and very difficult. Collagen bands called adhesions develop, causing pain and restricting movement to the point where the shoulder can be very hard to move. This restricted movement causes the tissues around the joint to contract and form a shoulder “capsule”. In the worst cases, the doctor may have to put the patient to sleep and move the arm (manipulation) to loosen the capsule and make movement of the shoulder easier.

Definition of frozen shoulder

Frozen shoulder is a condition that leads to pain and stiffness in the shoulder. It is also known as adhesive capsulitis or shoulder contracture. The range of movement is also decreased. It is not certain why this condition develops, but there are a number of things that may increase the risk of having it. It is more common in people who have other health conditions such as diabetes or stroke. Other problems with the shoulder which cause pain and mean it is moved less are also thought to increase the risk of frozen shoulder. In comparison to other types of shoulder pain, people who experience frozen shoulder are often less likely to move their shoulder. This is because moving the shoulder leads to pain, so it becomes stiff due to lack of use. It is the prolonged lack of movement that leads to a frozen shoulder. Normally the shoulder has a very wide range of movement, with three main bones supported by a group of muscles, tendons, and ligaments. The humerus fits into the socket of the shoulder blade and movement is coordinated by the rotator cuff which keeps the ball of the humerus in the socket. The bone of the shoulder is covered by the shoulder capsule; strong connective tissue which joins the socket to the head of the humerus. The inside of the capsule is lined by synovium, which produces synovial fluid. This lubricates the shoulder and helps movement. In frozen shoulder, the capsule becomes inflamed and contracted. This leads to adhesions and bands of tissue developing and the amount of synovial fluid is reduced. Any movement of the shoulder causes pain and due to the lack of synovial fluid, the movement of the shoulder becomes grating. Finally, in the freezing stage there is very little movement of the shoulder and the pain gradually decreases, though the stiffness remains.

Causes of frozen shoulder

Just as its name suggests, the primary reason for frozen shoulder is the very fact that it is “underused”. This is a very typical scenario for people with chronic shoulder pain; due to the pain, they will move their shoulder less and less with time. This lack of movement is what allows the shoulder to “freeze”. There are other people who are more susceptible to getting a frozen shoulder, including those who have had prolonged immobility or reduced mobility of the shoulder, such as after a stroke, or individuals who have had recent surgery or trauma to the area. Diabetics, in particular, have a higher potential to develop a frozen shoulder, to the extent that diabetics have been reported as being twice as likely to develop a frozen shoulder than the general population. If you are at risk of getting a frozen shoulder, it is useful to recognize this sooner rather than later, as early intervention is actually the most effective way of preventing it from occurring in the first place. A frozen shoulder can also develop spontaneously without an obvious cause. This typically happens over a long period of time, and most people are not aware of exactly when it started, just that their shoulder gradually became more and more painful and stiff until they were unable to ignore it.

Symptoms of frozen shoulder

Stiffness of the shoulder is the hallmark of this condition. It affects active and passive range of motion of the shoulder, particularly external rotation. Patients experience pain, which is often worse at night. It can also be bad enough to affect all activities of daily living and cause a significant degree of disability. There are three phases that each last for several months to years. These are freezing, frozen, and thawing. In the freezing phase, there is the onset of pain and progressive loss of movement. It is usually the worst during the night and can be very painful to lie on the affected shoulder. This phase usually lasts 2-9 months. The frozen phase involves a slow improvement in pain, but the stiffness and loss of movement remain for 4-12 months. Finally, the thawing phase sees a gradual return to normal movement. Around 90% of people with a frozen shoulder will have significant improvement with a return to function to a level near the pre-disease status. It is, however, difficult to know how long this will take. Complete resolution is likely within 2 to 3 years; however, it may take up to 5 years.

Diagnosis and Examination

Global ROM will be considerably reduced on the affected side of frozen shoulder. A study by Shaffer et al. (1994) determined that there was an average reduction of 50% in flexion, 48% in abduction, 38% in internal rotation, 29% in external rotation, and 25% reduction in adduction. Measures taken with a goniometer have shown that these results can be even more substantial in comparison to the ranges of ROM on the unaffected shoulder.

Assessing range of motion Assessing range of motion (ROM) is considered to be the most reliable way to diagnose adhesive capsulitis when the appropriate measures are taken. Active ROM is defined as the movement of a joint with the use of a patient’s own muscle. Passive ROM is the movement of a joint provided entirely by an external force. ROM is measured best by a goniometer to identify the different movements on the affected shoulder in comparison to the unaffected shoulder. This can be used to measure the limitations of movement and can indicate the improvement being made. In the early stages of frozen shoulder, there is a global reduction in ROM, especially when measured passively. During the later stages of the condition, ROM will be reduced mostly concerning external rotation and abduction. However, it has been shown that in some late-stage cases, internal rotation has been more affected.

Adhesive capsulitis has been described as having three distinct stages. This begins with the ‘freezing’ phase, which can be the area of most pain and can typically last 2-9 months. This phase involves a gradual onset of pain with progressive loss of movement. The ‘frozen’ phase is the stage where pain eases; however, the movement remains reduced and this can last 4-12 months. Finally, the ‘thawing’ phase is when the movement begins to improve and return to normal and can last between 5-26 months.

Physical examination for frozen shoulder The physical examination for frozen shoulder is usually by observation and touch to determine the restrictions in movement and pain experienced. However, it needs to be systematic for all movements: flexion, abduction, external rotation, internal rotation, and extension.

Physical examination for frozen shoulder

Palpation is important to find the source of pain. Palpation should be systematically done on the bony structures, joints, and muscular insertions and origin. The patient’s feedback when pain is provoked should be noted. Numerous ligamentous tests may be done, particularly involving the acromioclavicular and glenohumeral joints. Due to patient guarding and protective muscle spasm, the frozen shoulder patient may not allow complete testing. Range of motion testing allows documentation of the natural history of the frozen shoulder. Both active and passive ROM should be tested on the patient. This will provide baseline data and also assist in planning therapy by identifying which stage the patient is in. ROM testing is also important in order to document any adjacent or associated pathologies. Active ROM may be normal in early adhesive capsulitis, with restrictions occurring with passive movements. This would indicate an intra-articular problem involving the glenohumeral joint. Any deficits in active ROM suggest a muscular condition. Isolated subscapularis tendon tears, which are common in patients over the age of 50, can be tested with the lift-off from the extension and external rotation positions.

The physical examination for the frozen shoulder consists of mainly three things: observation, palpation, and range of motion (ROM) testing. BYU Medical Group suggests comparing the affected shoulder with the unaffected side. Observing any abnormal or deviated posture may indicate a muscular or joint condition. Unilateral superior trapezius atrophy may indicate nerve root impingement due to disc herniation. Wasting of the deltoids and anterolateral arm may indicate axillary nerve lesions. Swelling or atrophy of the shoulder girdle muscles can occur in a variety of conditions and should be followed. Observation of any swelling, erythema, or ecchymosis should note any overt signs of inflammation or trauma. Any discoloration or scars are also important to document. Gait and posture when approaching and turning the patient from the side, front, and back views to observe for any abnormalities.

Different stages of frozen shoulder

The clinical stages of frozen shoulder were outlined by Harry and Hannafin, and are based largely on the degree of symptom severity, including pain and stiffness. Stage one is considered the “freezing” stage, which can last from 6 weeks to 9 months. Onset is gradual, with pain being the earliest and most dominant symptom in this stage. As the pain increases around the shoulder, the range of motion decreases and it becomes harder to perform activities of the upper limb, particularly those where the arm is raised away from the body. This stage ends when the shoulder has very little movement. Stage two is the “frozen” phase and can last from 4-6 months. The pain may or may not decrease in intensity, but remains the prominent symptom in the condition. The loss of motion becomes the biggest issue compared to the pain. However, the capsule and synovium inflammation in the first two phases are self-limiting and typically resolve without serious long term effects. In the final phase, “thawing”, there is a gradual return to shoulder movement. It can last anywhere from 5 months to 4 years, with significant variability of time. The primary concern in this phase is the pain that occurs when attempting to move the shoulder. This usually leads to avoidance of shoulder movement, thus perpetuating the stiffness and creating a psychological effect on the individual.

Assessing range of motion in frozen shoulder

The range of motion is vital as it is a reflection of the stage of the condition. Usually, when assessing range of motion in frozen shoulder, it can be inferred with the help of the patient’s history. The doctor will usually ask how long was the duration of pain before the stiffness sets in and the duration of stiffness until the patient notices a reduction in shoulder movement. This is rather subjective and unreliable. A more objective assessment on range of motion is done by using a goniometer. A goniometer is a tool used to measure the angle of joint movement. In frozen shoulder, reduction in both active and passive range of motion will usually occur. Usually, when the patient has reduced range of motion, particularly external rotation, against the normal unaffected shoulder, it indicates frozen shoulder. The global range of motion loss is usually documented against the normal side. An average normal range of motion of the shoulder region compared to the affected side and the normal unaffected side can be seen in Table 2.1 in a study by Rukah and Kherad (2007) on adhesive capsulitis of the shoulder. This study uses a sample of 32 patients (24 males, 8 females) that have an age between 40 to 70 years old.

Treatment and Management

A recent randomized controlled trial by Buchbinder et al. (2008) compared the effectiveness of a single steroid injection and a single steroid injection/placebo distension followed by a physiotherapy program of up to 10 sessions and home exercises. They found no notable difference in outcomes between the group having the injection only and the group having the injection/distension. However, both groups experienced improvement in pain and function over 6 weeks and continuing up to a year later. An injection to the shoulder can be more painful due to the arm being held still in a position of discomfort for the injection and for a short time after. A 2005 study by Carette et al. found that patients with diabetes had a poorer response to steroid injections and may experience a transient increase in pain for the first 2 weeks following the injection. This transient increase in pain must be considered when planning to have an injection.

Non-surgical treatment options for frozen shoulder include gentle stretching, steroid injection, and joint distension (manipulation of the shoulder under general anaesthetic). Each of these treatments aims to reduce pain and maintain movement in the shoulder to aid daily activities. There is limited evidence to suggest which of these treatments is most effective.

Non-surgical treatment options for frozen shoulder

Hydrodilatation can be used, which involves distending the shoulder joint under sterile conditions with saline solution and corticosteroids. A catheter is inserted and the solution will be injected to stretch the shoulder, which in turn will help regain movement. There is little evidence showing how effective this method is, but the results of the studies so far have been quite good. This method is relatively safe, but in some cases, it has caused the shoulder to dislocate or cause a rotator cuff injury. Less common methods include transcutaneous electrical nerve stimulation (TENS) and even Botox. Massage therapy is a safe method and can help increase the range of motion in the shoulder. However, it is advised to seek a therapist who understands the condition well so that their methods can be modified.

Non-surgical treatment options for frozen shoulder include medications like NSAIDs, corticosteroids, and strong painkillers. More often than not, people who suffer from frozen shoulder are prescribed NSAIDs because they can help reduce pain and swelling associated with the frozen shoulder. There are potential side effects associated with it, but it is usually well tolerated. Corticosteroids can be taken orally or even injected into the shoulder joint. The doctor will determine the amount of corticosteroids and the method of taking it, both of which can affect the final result. Studies show that taking corticosteroids can lead to a faster recovery, but it is unclear if the results are better in the short or long run. Corticosteroids can lead to an increase in blood glucose levels in diabetic patients. This can be dangerous for some, so the patient must monitor their blood sugar level often while using these medications.

Role of range of motion exercises in frozen shoulder

Gentle, progressive range of motion exercises are very important in the treatment of frozen shoulder. They need to be done daily, either as ‘self-stretch’ or using a pulley. Effective aggressive physiotherapy can be painful and can actually exacerbate the condition in the early painful stage. The goals of physiotherapy are pain control, maintenance and development of range of motion and finally strength. The ‘capsular pattern’ of loss of range of motion needs to be addressed using passive and then active exercises to each affected joint. Role of Manipulation Whilst manipulation of the shoulder under general anaesthetic is an effective treatment of frozen shoulder, it can be argued that this is unnecessary in many cases if appropriate physiotherapy effectively mobilises the shoulder joint. Range of motion exercises can be an aggressive approach too, if done too forcefully. Ewald described stretching and tearing the adhesions under direct vision using arthroscopy (MUA). This is a less common method but is effective for patients who do not respond to conservative treatment and do not wish to progress to arthroscopic adhesiolysis. Ewald EA The pathophysiologic basis of adhesions and a new method of treating intraarticular pathologic changes using an endoscope. Orthopade 1998;27:536-50

Surgical options for frozen shoulder

The treatment of frozen shoulder is usually conservative and only a small population of people requires surgical options. The choice of treatment depends on various factors including degree of pain and stiffness, as well as the patient’s occupation and hand dominance. If non-surgical methods fail to improve the condition, then surgical options can be considered. The primary indication for surgery is the failure of non-surgical treatment and the continuation of debilitating pain and stiffness that does not improve with time. There are various surgical options that can be considered, but all involve manipulation of the shoulder to break up the adhesions and scar tissue. This may be performed under a general anaesthetic, but in more minor cases a local anaesthetic and sedation is all that is required. The options include manipulation under anaesthetic, where the aim is to improve range of movement by releasing the adhesions. This does not involve any cuts to the skin. If manipulation is not successful, then surgical release of the shoulder (manipulation under arthroscopy) can be tried. This involves cutting the adhesions and scar tissue using keyhole surgery and is usually performed by a specialist shoulder surgeon. Although it is invasive, it aims to rapidly improve the range of movement and reduce the pain in the shoulder. Following any surgical intervention, it is important to continue conservative treatment with the aim of preventing a recurrence of the frozen shoulder.

Prevention and Outlook

The exact cause of frozen shoulder is not known. It develops when the shoulder is not used for a long time, either because it is injured or kept in a sling, or because of pain or illness. It can also happen spontaneously without any obvious cause. Anything which causes the shoulder to be painful and not used for a long time can predispose to frozen shoulder. So, one theory about prevention is that it’s important to keep moving the shoulder, using it in as full a range of movement as possible and performing activities that involve the shoulder and cause little or no pain. It’s also thought to be important to treat properly and as soon as possible any causes of shoulder pain such as rotator cuff injury. However, it is not known whether this will definitely prevent the problem. Outlook is generally good in the long term, although there may sometimes be some persistence of pain and limitation of movement particularly in older individuals. A frozen shoulder will usually get better on its own, although this may take several months to a couple of years. Often the best treatment is to just take painkillers and carry on as normal. This probably gives a better outcome than avoiding use of the shoulder. Physical therapy can help, particularly in the early phases when there is pain and signs of inflammation. Stretching and aggressive therapy are usually not very useful and can in fact make things worse by causing pain and aggravating inflammation. A recent study has shown that the most effective thing for improving pain and movement in the early phase is mobilisation techniques, and this backs up earlier evidence that stretching and exercises do not help. Surgery may be considered in severe cases, particularly if the symptoms are very troublesome and have lasted a long time. It mainly involves manipulation of the shoulder under general anaesthetic and injection of steroids. This is done in the hope of improving pain and movement in the shorter term. The long term effectiveness of surgery is not known.

Preventing frozen shoulder

Allow your shoulder to rest and avoid any activities that cause pain. Continuation of the activity that causes pain will make your injury worse. The final area that can be addressed is posture. Many people will have a tendency to guard their shoulder by leaning away from the painful shoulder, shrugging the shoulder up, or hanging the arm. People are often unaware that they are assuming these postures, but over time it can cause significant stiffness and weakness in the shoulder.

To prevent frozen shoulder after injury or surgery, it is very important to perform the full range of motion exercises for the specified time. Do the home exercise program as instructed by your therapist to prevent complications. Do not ignore pain that persists for more than a few days. Apply the RICE principle – rest, ice, compression, and elevation to a shoulder that is injured or painful.

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Sarah Taylor

Obstetrics & Gynaecology