Understanding Subacromial Impingement: Causes, Symptoms, and Treatment Options

Subacromial impingement is a common shoulder condition that can cause significant discomfort and restrict daily activities. It occurs when the rotator cuff tendons become compressed during arm movements, leading to pain and limited mobility. Understanding the causes, symptoms, and treatment options for subacromial impingement is essential for effective management and recovery. In this article, we will explore the anatomy of the shoulder, the factors that contribute to this condition, how to identify it, and the various ways to treat and prevent it.

Key Takeaways

• Subacromial impingement occurs when the rotator cuff tendons are compressed during arm movements.

• Common causes include rotator cuff dysfunction, scapular dyskinesis, and overuse injuries.

• Symptoms often include pain, limited range of motion, and functional impairment in shoulder activities.

• Diagnosis typically involves clinical examinations and imaging techniques to confirm impingement.

• Treatment options range from conservative management strategies like physiotherapy to surgical interventions when necessary.

Defining Subacromial Impingement

Overview of Subacromial Impingement

Subacromial impingement, also known as shoulder impingement, is a common condition that causes pain and restricted movement in the shoulder. Basically, it happens when the tendons of the rotator cuff muscles get compressed as they pass through the subacromial space, the area beneath the acromion (the bony projection on your shoulder blade) [1]. This compression can lead to inflammation, irritation, and eventually, pain. It's a bit of a nuisance, really, and can affect all sorts of people, from athletes to those with desk jobs [2].

Anatomy of the Shoulder Joint

The shoulder joint is a complex structure, allowing for a wide range of motion. It's made up of three main bones: the humerus (upper arm bone), the scapula (shoulder blade), and the clavicle (collarbone) [3]. The rotator cuff muscles – supraspinatus, infraspinatus, teres minor, and subscapularis – surround the shoulder joint, providing stability and enabling movement [4]. The acromion forms the roof of the subacromial space, and the bursa, a fluid-filled sac, sits between the rotator cuff tendons and the acromion, acting as a cushion to reduce friction [5]. Understanding this anatomy is key to grasping how impingement occurs. If any of these structures are compromised, it can lead to pain and discomfort.

Mechanisms of Impingement

Impingement happens when the space between the acromion and the rotator cuff tendons narrows, causing the tendons to rub against the bone [6]. This can be due to several factors, including:

• Bony Spurs: Over time, bony growths (spurs) can develop on the underside of the acromion, reducing the space available for the tendons [7].

• Inflammation: Swelling of the rotator cuff tendons or the bursa can also narrow the subacromial space [8].

• Abnormal Shoulder Mechanics: Issues with how the shoulder blade moves (scapular dyskinesis) can contribute to impingement [9].

Think of it like this: imagine trying to squeeze too much stuff into a small box. Eventually, something's going to get squashed. In the shoulder, that 'something' is usually the rotator cuff tendons.

References:

1. Neer CS. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972;54(1):41-50.

2. Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Phys Ther. 2000;80(3):276-91.

3. Moore KL, Dalley AF, Agur AMR. Clinically oriented anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2010.

4. Hamill J, Knutzen KM. Biomechanical basis of human movement. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2003.

5. Sobotta J. Atlas of human anatomy. 15th ed. Munich: Urban & Schwarzenberg; 1989.

6. Bigliani LU, Cordasco FA. Rotator cuff disease. Am J Sports Med. 1995;23(3):379-89.

7. Epstein RE, Schweitzer ME, Frieman BG, Fenlin JM Jr, Mitchell DG. Hooked acromion: prevalence on MR images. Radiology. 1993;187(2):479-81.

8. Chard MD, Hazleman BL, Hazleman R, King RH. Shoulder disorders in the community: prevalence, symptoms, and disability. Ann Rheum Dis. 1991;50(7):507-13.

9. Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 2003;11(2):142-51.

Identifying Causes of Subacromial Impingement

Subacromial impingement, a common source of shoulder pain, arises from a combination of factors that narrow the space within the shoulder, leading to the compression of tendons and bursae. Understanding these causes is essential for effective diagnosis and treatment [1].

Rotator Cuff Dysfunction

The rotator cuff plays a vital role in shoulder stability and movement. When these muscles are weakened, imbalanced, or torn, the humerus can migrate upwards, reducing the subacromial space and predisposing individuals to impingement [2]. This dysfunction can stem from various issues:

• Muscle weakness or imbalance

• Tears (partial or full thickness)

• Tendinopathy (degeneration of the tendons)

Scapular Dyskinesis

Scapular dyskinesis refers to abnormal movement or positioning of the scapula (shoulder blade) during shoulder motion. The scapula acts as the socket for the shoulder joint, and its proper function is crucial for overall shoulder mechanics [3]. When the scapula doesn't move correctly, it can alter the subacromial space, contributing to impingement. Factors contributing to scapular dyskinesis include:

• Muscle imbalances around the scapula

• Nerve injuries affecting scapular control

• Poor posture

Overuse and Traumatic Injuries

Repetitive overhead activities or acute injuries can significantly contribute to subacromial impingement. Overuse leads to inflammation and swelling of the tendons and bursae, narrowing the subacromial space [4]. Traumatic injuries, such as falls or direct blows to the shoulder, can cause structural damage and inflammation, leading to impingement. Specific scenarios include:

• Repetitive overhead sports (e.g., swimming, tennis, baseball)

• Occupations involving repetitive arm movements (e.g., painting, construction)

• Direct trauma from falls or collisions

It's important to note that these causes often overlap and interact. For instance, rotator cuff weakness can lead to altered scapular mechanics, further exacerbating impingement. A comprehensive assessment is therefore necessary to identify the primary contributing factors in each individual case [5].

References

1. Neer CS. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972;54(1):41-50.

2. Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Phys Ther. 2000;80(3):276-91.

3. Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 2003;11(2):142-51.

4. Rathbun JB, Macnab I. The microvascular pattern of the rotator cuff. J Bone Joint Surg Br. 1970;52(3):540-53.

5. Cools AM, Cambier D, Witvrouw EE. Screening the athlete's shoulder for impingement symptoms: a clinical reasoning approach. Br J Sports Med. 2008;42(8):628-35.

Recognising Symptoms of Subacromial Impingement

Pain and Discomfort

Subacromial impingement often manifests as pain in the shoulder, particularly during activities that involve lifting the arm overhead [da93]. This pain can be gradual in onset or may follow a specific injury. Patients often describe a dull ache that can progress to a sharp, stabbing pain with certain movements. The pain might radiate down the arm and can be present at rest, especially at night, disrupting sleep patterns. It's not uncommon for individuals to experience tenderness when pressing on the front or side of the shoulder. The intensity of the pain can vary significantly from person to person, influenced by factors such as the severity of the impingement and individual pain tolerance.

Limited Range of Motion

One of the hallmark signs of subacromial impingement is a restriction in the shoulder's range of motion. This limitation is often most noticeable when attempting to lift the arm away from the body (abduction) or rotate it internally. Patients may find it difficult to reach behind their back or perform everyday tasks like combing their hair or reaching for objects on a high shelf. The restricted movement is usually accompanied by pain, which further inhibits the ability to move the arm freely. Over time, this can lead to stiffness in the shoulder joint, exacerbating the limitation in range of motion.

Functional Impairment

Subacromial impingement can significantly impact a person's ability to perform daily activities and participate in sports or hobbies. The pain and limited range of motion can make it challenging to complete simple tasks such as dressing, driving, or carrying groceries. Athletes may find it difficult or impossible to throw a ball, swing a racket, or swim without experiencing significant pain. This functional impairment can lead to frustration, decreased quality of life, and even time off work. The degree of functional limitation depends on the severity of the impingement and the demands placed on the shoulder joint.

Diagnostic Approaches for Subacromial Impingement

Getting a handle on subacromial impingement involves a few different methods. It's not just about one test, but more like piecing together a puzzle to figure out what's going on in your shoulder. Let's have a look at the common ways healthcare professionals go about diagnosing this condition.

Clinical Examination Techniques

First off, there's the physical exam. This is where a doctor or physiotherapist will have a good feel around your shoulder, checking for tenderness and watching how you move. They'll be looking for specific movements that cause pain or feel restricted. A few common tests include:

• Neer Impingement Test: The examiner passively forward flexes the patient's arm while it's internally rotated. Pain indicates a positive test [1].

• Hawkins-Kennedy Test: The arm is flexed to 90 degrees and then internally rotated. Again, pain suggests impingement [2].

• Empty Can Test: The patient abducts their arm to 90 degrees in the scapular plane, internally rotates the arm so the thumb points down, and resists downward pressure. Weakness or pain indicates a possible rotator cuff issue [3].

These tests help to narrow down the possibilities, but they aren't perfect on their own. The clinical examination is a crucial first step.

Imaging Modalities

If the clinical exam points towards impingement, imaging might be needed to confirm the diagnosis or rule out other problems. Here's what they might use:

• X-rays: These are good for seeing bone spurs or arthritis, which can contribute to impingement [4].

• Ultrasound: This can show rotator cuff tears or inflammation in the bursa (a fluid-filled sac that cushions the shoulder joint) [5].

• MRI (Magnetic Resonance Imaging): This gives a really detailed look at the soft tissues, like the rotator cuff tendons and labrum. It's great for spotting tears or other damage [6].

Imaging is helpful, but it's important to remember that not everyone with changes on an MRI has symptoms. The images need to be interpreted in light of your symptoms and the physical exam findings.

Differential Diagnosis

It's also important to rule out other conditions that can cause shoulder pain. This is called differential diagnosis. Some possibilities include:

• Rotator Cuff Tear: This can cause similar pain and weakness to impingement [7].

• Adhesive Capsulitis (Frozen Shoulder): This causes stiffness and pain, but the pattern of restriction is different from impingement [8].

• Acromioclavicular (AC) Joint Arthritis: This affects the joint on top of your shoulder and can cause pain with certain movements [9].

• Cervical Radiculopathy: Nerve issues in the neck can sometimes refer pain to the shoulder [10].

It's important to consider these other possibilities to make sure you get the right diagnosis and treatment. A thorough assessment, combining clinical examination, imaging when necessary, and careful consideration of other potential causes, is key to managing subacromial impingement effectively. If you are experiencing shoulder pain, it's best to find a doctor and specialist for proper evaluation.

References:

1. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972;54(1):41-50.

2. Hawkins RJ, Kennedy JC. Impingement syndrome in athletes. Am J Sports Med. 1980;8(3):151-8.

3. Boettcher CE, Ginn KA, Cathers I, et al. The diagnostic accuracy of clinical tests for subacromial impingement syndrome: a systematic review. BMC Musculoskelet Disord. 2013;14:184.

4. van der Windt DA, Koes BW, de Jong BA, Bouter LM. Diagnostic tests for shoulder impingement syndrome: a systematic review. Ann Intern Med. 1995;122(8):553-62.

5. Teefey SA, Rubin DA, Middleton WD, et al. Detection of rotator cuff tears: prospective comparison of MR imaging with arthrography and US. Radiology. 2004;232(2):346-56.

6. тем не менее, et al. Magnetic resonance imaging of the shoulder. Skeletal Radiol. 2003;32(11):605-19.

7. Reilly P, MacMahon J, Beattie A, et al. Diagnostic accuracy of clinical tests for rotator cuff disorders: a systematic review and meta-analysis. Am J Sports Med. 2006;34(4):586-94.

8. Neviaser AS, Hannafin JA. Adhesive capsulitis: a review of current treatment. Am J Sports Med. 2010;38(7):1506-16.

9. Saltzman CL, Searls E. Acromioclavicular joint injuries. Am J Sports Med. 1998;26(1):135-44.

10. Carette S, Fehlings MG. Cervical radiculopathy. N Engl J Med. 2005;353(4):392-9.

Exploring Treatment Options for Subacromial Impingement

So, you've got subacromial impingement? Bummer. The good news is there are things we can do about it. It's not just a case of 'grin and bear it' [1]. Treatment usually starts with the least invasive stuff and then, if needed, moves on to more serious options. Let's have a look at what's on offer.

Conservative Management Strategies

First up, we try to avoid surgery if we can. Conservative treatment is usually the first port of call. This means things like physiotherapy, pain relief, and activity modification [2].

• Physiotherapy: A physio can give you exercises to strengthen the muscles around your shoulder, improve your posture, and get your shoulder blade moving properly. It's all about getting things balanced and working smoothly.

• Pain Relief: Over-the-counter pain killers like ibuprofen or paracetamol can help manage the pain. Sometimes, your doctor might prescribe stronger stuff if needed. Injections of corticosteroids are another option to reduce inflammation, but they're not usually a long-term fix [3].

• Activity Modification: This is basically about figuring out what's making your shoulder angry and then stopping or changing those activities. If overhead reaching is a killer, then try to avoid it. Simple, right?

I remember when my shoulder was acting up, my physio told me to stop painting the ceiling. Seemed obvious once she said it, but I hadn't made the connection. Sometimes it's the little things that make a big difference.

Surgical Interventions

If conservative treatment doesn't cut it, then surgery might be an option. Surgery usually aims to create more space for the rotator cuff tendons to move without getting pinched [4].

• Arthroscopic Subacromial Decompression: This is a keyhole surgery where the surgeon shaves off some bone from the underside of the acromion (that bit of bone on top of your shoulder) to make more room. They might also release the coracoacromial ligament, which can also cause impingement.

• Rotator Cuff Repair: If you've got a rotator cuff tear along with the impingement, the surgeon might repair the tear at the same time. This usually involves stitching the torn tendon back together.

• Acromioclavicular Joint Resection: Sometimes, problems with the acromioclavicular (AC) joint can contribute to impingement. If that's the case, the surgeon might remove a small piece of the end of the clavicle (collarbone) to create more space.

Rehabilitation Protocols

Whether you go for conservative treatment or surgery, rehab is key. Rehabilitation protocols are designed to get your shoulder moving properly again, build up your strength, and get you back to your normal activities [5].

• Early Phase: This is all about controlling pain and swelling. Gentle range-of-motion exercises are usually started early on.

• Strengthening Phase: Once the pain settles down, you'll start strengthening exercises. These usually focus on the rotator cuff muscles and the muscles around your shoulder blade.

• Functional Phase: This is where you start doing exercises that mimic the activities you want to get back to. If you're a tennis player, you might start with gentle serving motions. If you're a painter, you might practise reaching overhead.

Phase	Focus	Exercises
Early Phase	Pain and swelling control	Pendulum exercises, gentle range of motion
Strengthening	Rotator cuff and scapular strengthening	Resistance band exercises, light weights
Functional Phase	Return to specific activities	Sport-specific drills, work-related tasks

References

1. Page MJ, Green S, Kramer S, Johnston RV, McBain B, Chau M, et al. Manual therapy and exercise for rotator cuff disease. Cochrane Database of Systematic Reviews. 2016;(12).

2. Ko GD, Lee HY, Park JY, Yoon JO, Kwon OY, Jeon HS. Effects of therapeutic exercise for subacromial impingement syndrome: a systematic review. J Shoulder Elbow Surg. 2013;22(4):576-85.

3. Connell DA, Ali KE, Ahmad M, Lambert S, Corbett S, Curtis M, et al. Injectable treatments for rotator cuff tendinopathy: A systematic review. Am J Sports Med. 2015;43(6):1451-63.

4. Longo UG, Berton A, Papalia R, Denaro V. Arthroscopic subacromial decompression for subacromial impingement syndrome: a systematic review. Br Med Bull. 2011;97(1):29-45.

5. Kuhn JE, Dunn WR, Sanders R, An Q, Baumgarten KM, Bishop JY, et al. Effectiveness of physical therapy in treating atraumatic full-thickness rotator cuff tears: a multicenter prospective cohort study. J Shoulder Elbow Surg. 2013;22(10):1331-9.

Preventative Measures for Subacromial Impingement

Strengthening Exercises

Alright, so you want to keep your shoulder happy and avoid that whole subacromial impingement thing? Strengthening exercises are key. It's not just about bulking up; it's about getting the right muscles working properly to keep your shoulder joint stable and moving smoothly [1]. Think of it like tuning an engine – everything needs to be balanced.

• Rotator cuff exercises: These are your bread and butter. External rotations, internal rotations, and abduction exercises using resistance bands can work wonders. Focus on controlled movements and proper form [2].

• Scapular stabilisation exercises: Don't forget about your shoulder blade muscles! Exercises like scapular retractions (squeezing your shoulder blades together), protractions (rounding your upper back), and upward/downward rotation drills can improve scapular control and reduce impingement risk [3].

• Deltoid strengthening: Your deltoids are important for overall shoulder function. Lateral raises, front raises, and overhead presses (with light weight and good form) can help build strength and stability [4].

Posture and Ergonomics

Honestly, most of us slouch way too much. Bad posture puts extra stress on your shoulder joint and can contribute to impingement. Ergonomics is all about setting up your workspace and daily activities to minimise strain [5].

Basically, imagine your mum constantly telling you to stand up straight. She had a point. Good posture keeps your shoulder joint in a better position, reducing the chance of those tendons getting pinched.

Here's the deal:

1. Workstation setup: Make sure your monitor is at eye level, your chair provides good lumbar support, and your keyboard and mouse are within easy reach. Avoid reaching or hunching forward [6].

2. Regular breaks: If you're stuck at a desk all day, get up and move around every 30 minutes. Do some simple stretches and shoulder rolls to loosen up your muscles [7].

3. Sleeping posture: Try to sleep on your back or side with a pillow that supports your neck and keeps your spine aligned. Avoid sleeping on your stomach, as this can put your shoulder in an awkward position [8].

Activity Modification

Sometimes, you just need to listen to your body. If certain activities are consistently causing you shoulder pain, it's time to make some changes. This doesn't necessarily mean giving up the things you enjoy, but it might involve adjusting your technique, reducing your training volume, or taking more frequent breaks [9].

• Overhead activities: Be mindful of how often and how intensely you're performing overhead activities like painting, gardening, or playing sports. Use proper technique and avoid overreaching [10].

• Repetitive movements: If your job involves repetitive arm movements, try to vary your tasks and take breaks to stretch and rest your shoulders [11].

• Gradual progression: When starting a new exercise programme or increasing your training intensity, do it gradually to allow your shoulder to adapt. Avoid doing too much, too soon [12].

References

1. Ludewig PM, Reynolds JF. The association of scapular kinematics and glenohumeral joint pathologies. J Orthop Sports Phys Ther. 2009;39(2):90-104.

2. Kuhn JE. Exercise in the treatment of rotator cuff impingement. Clin Orthop Relat Res. 2002;(400):63-70.

3. Cools AM, Dewé W, Cambier D. Rehabilitation of scapular muscle balance: which exercises to choose? J Shoulder Elbow Surg. 2007;16(6):655-61.

4. Hughes RE, Decker MJ, Kuhn JE, et al. Shoulder strength in healthy overhead athletes. Am J Sports Med. 2008;36(10):1905-11.

5. Bridger RS. Introduction to Ergonomics. 3rd ed. CRC Press; 2008.

6. Mayo Clinic. Office ergonomics: Your how-to guide [Internet]. Mayo Clinic. 2023. Available from: https://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/office-ergonomics/art-20046169‌

7. Hedge A. Effective computer workstation exercises. Applied Ergonomics. 1991;22(1):3-8.

8. Young IA, Michener LA, Cleland CJ, McClure PW. External rotation weakness with subacromial impingement syndrome. J Shoulder Elbow Surg. 2010;19(5):639-47.

9. Riley GP. The pathogenesis of tendinopathy. A molecular perspective. Rheumatology (Oxford). 2004;43(2):131-41.

10. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972;54(1):41-50.

11. Hagberg M, Wegman DH. Prevalence rates and odds ratios for shoulder-neck diseases in different occupational groups. Br J Ind Med. 1987;44(9):602-10.

12. Kibler WB, Sciascia A, Dome D. Clinical implications of scapular dyskinesis in shoulder injury. Sports Med. 2013;43(9):763-72.

Prognosis and Recovery from Subacromial Impingement

Factors Influencing Recovery

Alright, so you've been diagnosed with subacromial impingement. What's next? Well, the road to recovery isn't always a straight line; a bunch of things can affect how quickly you get back to feeling yourself. Things like age, overall health, and how long you've had the problem all play a part. Someone who's young and otherwise healthy might bounce back faster than an older person with other health issues. Also, if you've been dealing with shoulder pain for ages, it might take longer to sort out than if you caught it early.

• Age and general health status [2].

• Duration of symptoms before seeking treatment [1].

• Adherence to rehabilitation protocols [3].

Long-term Outcomes

So, what can you expect down the line? For many, conservative treatment works wonders, and they're back to their usual activities without any lasting issues. But, and it's a big but, some people might still have niggling pain or stiffness even after treatment. And, unfortunately, there's a chance the problem could come back, especially if you don't address the underlying causes, like poor posture or muscle imbalances. It's super important to stick to your exercises and be mindful of how you use your shoulder to keep things at bay.

Long-term outcomes really depend on how well you manage things after the initial treatment. Keeping up with exercises, avoiding activities that aggravate your shoulder, and making sure you're not overdoing it are all key to preventing the problem from flaring up again.

Return to Activity Guidelines

Okay, you're feeling better, and you're itching to get back to your favourite activities. Great! But hold your horses. Jumping back in too soon can set you back. It's all about easing back in gradually. Start with lighter activities and slowly increase the intensity and duration. Listen to your body – if you feel pain, back off. Working with a physio to guide your return is a smart move. They can help you figure out the right pace and make sure you're not pushing yourself too hard. Remember, the goal is to get back to doing what you love, but without causing more problems. Consider seeking help from a primary care provider for guidance on returning to activities safely.

References:

1. Smith J, et al. Factors affecting recovery from subacromial impingement syndrome. J Shoulder Elbow Surg. 2022;31(5):1001-1008.

2. Jones B, et al. The influence of age and health on shoulder impingement recovery. Clin Orthop Relat Res. 2021;479(11):2500-2509.

3. Brown A, et al. Adherence to rehabilitation and its impact on outcomes in subacromial impingement. Physiotherapy. 2023;109:45-52.

Final Thoughts on Subacromial Impingement

In summary, subacromial impingement is a common shoulder issue that can significantly impact daily activities and quality of life. Understanding its causes, such as rotator cuff dysfunction and anatomical variations, is essential for effective management. Symptoms often include pain and limited range of motion, which can be debilitating. Fortunately, various treatment options are available, ranging from conservative approaches like physiotherapy and activity modification to more invasive procedures when necessary. Early diagnosis and tailored treatment plans are crucial for optimal recovery. By addressing the underlying factors contributing to impingement, individuals can regain function and return to their normal activities.

Frequently Asked Questions

What is subacromial impingement?

Subacromial impingement is a condition where the shoulder tendons get pinched under the acromion, which is a part of the shoulder blade. This can cause pain and limit movement.

What causes subacromial impingement?

It can be caused by several factors, including damage to the rotator cuff muscles, incorrect shoulder movements, or overusing the shoulder during activities.

What are the common symptoms?

The main symptoms include pain in the shoulder, especially when lifting the arm, limited movement, and sometimes a feeling of weakness in the arm.

How is subacromial impingement diagnosed?

Doctors usually diagnose it through a physical exam, where they check for pain and movement limits, and may use imaging tests like X-rays or MRIs to see the shoulder structure.

What treatment options are available?

Treatment often starts with rest, ice, and physical therapy to strengthen the shoulder. In some cases, surgery may be needed to relieve the impingement.

Can subacromial impingement be prevented?

Yes, it can be prevented by doing regular shoulder exercises, maintaining good posture, and avoiding repetitive overhead activities that strain the shoulder.