What is frozen shoulder?

The definition and correct term for frozen shoulder as of 2015

Lewis (2015)[30] claimed that the most appropriate term for frozen shoulder is Frozen Shoulder Contracture Syndrome or FSCS. This term better captures the signs and symptoms of the condition.

Zuckerman (2011)[61] defined Frozen Shoulder to be the following:

“Frozen shoulder is a condition characterized by functional restriction of both active and passive shoulder motion for which radiographs of the glenohumeral joint are essentially unremarkable except for the possible presence of osteopenia or calcific tendonitis.”

Furthermore, they classified the condition into the following categories:

1 – Primary.

2 – Secondary.

2.1 – Intrinsic.

2.2 – Extrinsic.

2.3 – Systemic.

These classifications are further described below.

Generally, clinical presentation of the condition is split in three overlapping phases[8]:

Phase 1 – Freezing

Phase 2 – Adhesive

Phase 3 – Resolution

These phases are further described below.

Evolution of frozen shoulder definitions

Frozen shoulder has seen numerous changes and improvements in its definition since it was first discovered and defined.

1896

The combination of pain and reduced range of motion of the shoulder was first defined to be peri-arthrite scapula-humerale due to inflammation of the subacromial bursa by Duplay in 1896[11].

1934

Codman was the first to use the term “Frozen Shoulder” in 1934 after many years of studying and researching the condition[7]. He defined it to be: “slow onset, pain near the insertion of deltoid, inability to sleep on the affected side, painful and incomplete shoulder elevation and external rotation, and, with the exception of possible bone atrophy, normal shoulder radiographs.”

1945

Neviaser[41] first suggested that the condition is referred to as “adhesive capsulitis”. This is commonly interchanged with the term frozen shoulder today. According to Lewis, Neviaser found that the adherence was with the axillary fold or the capsule with the humeral head[30].

1969

Lundberg[35] expanded the definition of frozen shoulder syndrome by classifying it into two categories:

1 – Primary; idiopathic onset of the condition. The underlying cause or associated condition is either unknown or does not exists.

2 – Secondary; Frozen shoulder is developed following trauma injury or inactivity of the shoulder following a trauma related injury.

This classification was further improved upon in 2011 by Zuckerman[61].

1991

Wiley[56] debunked the term “adhesive capsulitis” as they found that the condition had no adherences between the humeral head and surrounding tissues. In fact, they found that frozen shoulder was due to thickening and contraction of the glenohumeral joint capsule.

2005

Dias[8] published a review of the condition in 2005 and concluded that a frozen shoulder clinically progresses through 3 overlapping stages:

Phase 1 – Painful Freezing Phase; Lasts between 2-9 months. This is predominantly a painful phase. Pain is felt around the shoulder and is the worst at night. In addition, the shoulder starts to become stiff. In the case of a primary frozen shoulder, there will be no history or injury of the shoulder prior to the onset of pain and stiffness. There will also be little to no response to non-steroidal anti-inflammatory drugs.

Phase 2 – Adhesive Phase; Lasts between 4-12 months. This is predominantly a stiffening or “freezing” phase. There is significant decrease in the range of motion of the shoulder and pain gradually begins to subside with pain felt at the restricted ranges of motion.

Phase 3 – Resolution Phase; Lasts between 12-42 months. There is spontaneous improvement in the range of motion. This is also known as the “thawing” phase. However, this phase does not necessarily mean that people with a frozen shoulder will find that their symptoms resolve over time[20,32,46]. In some instances, symptoms can remain for 20 years.

2011

Zuckerman[61] refined the evolved definition further and is used as the current definition mentioned earlier. They further improved Lundberg’s[35] classification system by improving upon the definition of secondary frozen shoulder and dividing the secondary category into a further three sub-categories:

Primary; this defines all frozen shoulder diagnosis where the underlying cause or associated condition cannot be identified or doesn’t exist.

Secondary; frozen shoulder; this defines all cases of frozen shoulder diagnosis where the underlying aetiology or associated condition can be identified. This is further divided into 3 categories.

Intrinsic; this is when the condition is associated with rotator cuff disorders included but not limited to rotator cuff tears, calcific tendonitis or bicep tendonitis.

Extrinsic; this is when the underlying condition is not at the shoulder. E.g. chest wall tumour or cervical radiculopathy. Conditions can include those that are near the shoulder. E.g. Humeral shaft fracture, scapulothoracic abnormalities.

Systemic; this is when the underlying condition is a systemic disorder. E.g. Diabetes, hyper and hypo-thyroidism.

Zuckerman[61] surveyed 211 clinicians of which 82% of clinicians agreed with the overall definition and 13% disagreed. 66% of clinicians agreed with their suggested classification breakdown and 19% remained neutral with only 15% disagreeing.

Frozen shoulder signs and symptoms

Frozen shoulder has been a poorly understood condition over the years, and it probably still is a poorly understood condition. Clinicians and scientists alike have thus tried to unify the signs and symptoms that constitute to a frozen shoulder[15]. The following signs and symptoms are from the British Elbow and Shoulder Society survey-definition of frozen shoulder.

Frozen shoulder signs

The following are the signs that BESS consider to constitute to a frozen shoulder:

• Motion of the shoulder is physically restricted and painful
• The passive (humerothoracic) elevation of the arm is less than 100° (although Rundquist[43] found that their subjects who were diagnosed to have a frozen shoulder had passive elevation angles above 110°).
• Passive external rotation less than 30°.
• Passive internal rotation less than 5°.
• Plain radiographs such as X-Rays show normal results and no signs of other conditions which could cause the above signs.
• Exploratory arthroscopy shows vascular granulation tissue in the rotator interval.

Frozen shoulder symptoms

The following are the symptoms that BESS consider to constitute to a frozen shoulder:

• The deltoid insertion is painful.
• Pain is felt at nights when the condition is onset and patient may find that they are unable to sleep on the affected shoulder.

Who suffers from frozen shoulder contracture syndrome?

Published data shows that 2%-5%[40] of the general population suffer from a frozen shoulder with a cumulative incidence of 11.2 per 1000 person-years[57]. It typically occurs in patients who are between the ages of 50-70 years. It is very rare for anyone below the age of 40 or above the age of 70 to develop a frozen shoulder[15,30].

Frozen shoulder causes

The root causes of frozen shoulder are currently unknown and poorly understood. This may change in the future with more robust scientific and clinical studies. However, multiple research studies have found certain risk factors and biological occurrences than could either increase chances of developing frozen shoulder or explains a potential cause of the condition.

Risk factors

A few risk factors have been identified that could lead to developing the condition include the following:

• Diabetes – It has been reported that up to 71.5% of diabetics also have a frozen shoulder. They are 2-4 times more at risk with a 10%-20% lifetime chance that they will develop the condition compared to the general population[1,8,14,15,35].
• Family history – Smith (2012)[48] found that people with a sibling who suffers from frozen shoulder has an increased risk in developing the condition themselves.
• Genetic predisposition – Multiple studies cited by Lewis (2015)[30] suggested that a person’s genetic makeup could make them more susceptible to developing the condition.

Aetiology

The root cause and mechanism that leads to a frozen shoulder is still largely, poorly understood. Many histological studies have found various cytokines, proteins and other biological molecules that precede and may result inflammation and fibrosis within the capsule and glenohumeral joint[16,17,18,19,21,25,31,34,51,58]. They all suggest that it is these chemicals and molecules that play a role in developing the different macroscopic signs of frozen shoulder. However, there is no evidence or consensus on what leads to an increase in these molecules in the first instance.

Current frozen shoulder treatments

The current treatment methods for frozen shoulder contracture syndrome typically fall into two categories:

• Conservative or non-invasive intervention.
• Surgical or invasive intervention.

Prior to each treatment method, it is highly recommended that the patients are educated about their condition and told about their various options[37]. This is meant to be provided with no bias, but it is inevitable that the speciality and background of the clinician will play some role in providing both information and treatment recommendations. Clinicians usually advise patients to undergo some form of conservative therapy before advising them to undergo a more invasive treatment.

Conservative frozen shoulder treatments

Wait and do nothing

This method is based on the idea that a frozen shoulder will ‘thaw’ and the condition will resolve itself[61,8] over a period of time. However, this is something that patients will not prefer as even treatment with very light exercises has shown that it can take up to 2 years to recover by a good amount of range of motion and strength, and more for a fuller recovery[9].

Physiotherapy

This is probably the most common treatment method prescribed by clinicians today. Physiotherapy can include intensive or light exercise programs, with and without stretching. It is usually referred to as a joint mobilisation and exercise therapy. There is no gold standard of exercise regimens that are prescribed. Exact exercise motions, the intensity, frequency, rest times and other motion parameters are not always defined and are not always the same between one patient to another. Despite the lack of real consistency in prescribed motions, reviews have found that the most common prescription length is usually between 6-12 weeks[15].

Multiple studies have shown that physiotherapy can improve outcomes[23,24,36,54,60]. However, these studies along with others investigating frozen shoulder treatments are not scientifically sound and thus are not considered to be very strong evidences[15,30].

Massage

Various massage techniques are performed on patients by both physiotherapists and by private massage therapists. The Niels-Asher technique[62] (NAT – a type of trigger point massage), has been studied and evidence from it shows that there is some short-term benefit in improving the range of motion of the shoulder[55]. However, this study lacked in subject numbers reducing its statistical power and therefore further studies are needed.

Acupuncture

Acupuncture is a common alternative treatment method for musculoskeletal problems that is mentioned on many occasions. Although it is a controversial method with some but weak supporting evidences[30], there is some evidence to suggest that it helps in combination with exercises for frozen shoulders[47,50]. The exact method of treatment varies from one therapist to another and from one institution to another.

Injections

There are a few different injections that can be given to patients. The most commonly administered injection is corticosteroid (CS). The purpose of the CS injection is to reduce inflammation and provide some analgesia. Studies investigating CS injections have been criticised as they have been given in combination with other treatment methods[15].

Other alternative injections can be administered as well. These include:

• High-molecular-weight sodium hyaluronate (HA) injections[52], and;
• Botulinum toxin (BTX) injections[4].

The effect of the injections, whether alone or in combination with other treatments also depends on the site of the administration. Injections have been administered in at least the following three sites:

• Glenohumeral joint. Also, referred to as the intra-articular injection.
• Subacromial space.
• Combined intra-articular and subacromial site. In this case, injections are given at both sites.

Cho (2016)[6] showed that those patients who had intra-articular and combined intra-articular and subacromial space injections had significantly better outcomes at the end of a 12 week period than those who only had an injection in the subacromial space.

Other

There are a vast number of alternative treatments other than the ones mentioned above. Some of these include but are not limited to:

• Oral steroid therapy. This is not a recommended treatment plan or commonly prescribed in the UK[15].
• Supra-scapular nerve block[15].
• Chiropractic therapy[38].

The next section describes the common invasive treatment methods, which are usually turned to when conservative treatments do not produce satisfactory results.

Invasive frozen shoulder treatments

Invasive treatments are those that involve cutting of the skin and/or requires general anaesthesia. More commonly known as surgery. The evidence base supporting these invasive treatments is more limited in terms of high quality scientific data, in comparison to conservative treatments[15].

The following are the most common surgical treatment methods for frozen shoulder contracture syndrome.

Distension arthrography, hydrodistension and hydrodilation

This intervention does not require general anaesthesia and is usually performed by a trained radiologist. The procedure is performed under ultrasound (USS) or fluoroscopic guidance.

The patient is first injected with a local anaesthetic into the glenohumeral joint. Thereafter sterile water is injected into the joint. The aim is to fill the joint with water to increase the pressure inside of the joint. This would then result in the joint capsule stretching. Radiologists believe that this stretching can lead to the same capsular ruptures that surgery would achieve.

There is some evidence to suggest that this technique works well in comparison to more conservative treatment methods[3,13,53]. However, a review referenced by Guyver (2014)[15] stated that studies regarding distension arthrography were at a high risk of being affected by bias except one. This one study reported no significant differences between the distension with steroid injection group and the placebo group at both 6 weeks and 12 weeks post treatment[3].

Manipulation under anaesthesia (MUA)

This intervention is performed under general anaesthesia. The method involves intentional tearing of the glenohumeral joint capsule by manipulating the arm through various movement patterns.

Due to risks of bone fracture, this procedure is avoided in the elderly and those who suffer from osteoporosis (brittle bone disease)[15].

Multiple studies have investigated the efficacy of MUA, whether it was MUA alone or in combination with other treatment methods[10,12,22,27,28,33,39,44,45,49]. These studies are split with some supporting the treatment and others recommending against it. The reason for these differences are multifactorial with the largest factor being the lack of scientific rigor. A review[15] found that only one of these studies provides sufficiently strong evidence. And this evidence suggests that there is no significant difference between MUA with home exercises and home exercises alone at 6 weeks, 3, 6 and 12 months post treatment[28].

Arthroscopic capsular release

This is a keyhole surgery and is becoming more and more popular choice of intervention for frozen shoulder. The surgery begins with general anaesthesia followed by multiple divisions of the rotator interval i.e. the coracohumeral ligament, anterior and superior portion of the joint capsule and the middle glenohumeral ligaments. The anterior band of the inferior glenohumeral ligament is also released. A full 360 degree capsular release has also been recommended, although not as frequently practiced[29].

There are many studies that recommend or advocate performing this intervention as they have found it to work in their investigations[2,5,26,59]. However some have found it be either counterproductive or not beneficial in comparison to other treatment methods[12,32].

This treatment method is especially recommended by some for those who have undergone manipulation under anaesthesia but have not benefitted from it as they should have[42].

A randomised controlled trial or a strong comparative study has yet to be published[15].

The MUJO Frozen Shoulder Treatment

Our treatment plan for frozen shoulder patients has been designed to be the best conservative treatment option. Patients are treated with data-driven exercise plans with our patented smart technology at the core of MUJO’s enhanced treatment method.

Patients are put in the driving seat and are in control of their treatment and progression.

While each plan is tailored to the individual, treatments typically involve an initial period exercising on the Internal Shoulder Device, performing assisted stretching movements within a defined ‘safe training envelope’ which helps to turn off the pain-restricting messages from the brain and regain range of motion before moving on to include work on the External Shoulder Device to increase strength and motor control.

Conclusion

Frozen shoulder contracture syndrome is a complex ailment of the glenohumeral joint. Despite research dating back to over a century, it is still a poorly understood condition. Various treatment methods ranging from very light exercises, to surgical interventions have been both recommended and advised against. It is clear that rigorous scientific research and medical studies are still needed to provide better guidelines, Our treatment method with the core technology at its very centre has been designed to be both better than and complimentary to most other treatment methods.

References

7.        Codman EA. The Shoulder; Rupture of the Suprasupinatus Tendon and Other Lesions in Or about the Subacromial Bursa. 1934.

11.       Duplay S. De la periarthrite scapulo-humerale. Rev Frat d trav med. 1896;53(226):b1.

41.      Neviaser J. adhesive capsulitis of the shoulder. A study of the pathological findings in periathritis of the shoulder. J. Bone Jt. Surg. 1945;27:211–222.