Shoulder impingement syndrome is a prevalent and painful condition affecting the upper extremity, stemming from the narrowing of the subacromial space. Accurate Shoulder Impingement Syndrome Diagnosis is primarily achieved through a detailed patient history and thorough physical examination. Early identification of this condition, before the onset of degenerative changes, is crucial. Treatment strategies mainly involve physical therapy exercises aimed at strengthening the shoulder girdle and pharmacological interventions to manage inflammation. This article provides an in-depth overview of the evaluation and management of shoulder impingement syndrome, emphasizing the importance of an interprofessional healthcare team in delivering optimal patient care and outcomes.
Objectives:
- Delve into the various causes of shoulder impingement syndrome.
- Detail the methodologies for effective shoulder impingement syndrome diagnosis.
- Explore the range of management options available for shoulder impingement syndrome.
- Underscore the significance of interprofessional team strategies in improving care coordination and communication to enhance patient outcomes in shoulder impingement syndrome.
Introduction
Shoulder pain stands as a frequent complaint leading individuals to seek medical consultation in primary care and orthopedic settings globally. The estimated occurrence of shoulder issues ranges from 7% to 34%, with shoulder impingement syndrome frequently identified as the root cause.[1] Since its initial description in 1852, shoulder impingement syndrome is recognized as the most common source of shoulder pain, accounting for a substantial 44% to 65% of all shoulder-related complaints.[2] In the United Kingdom, among the 20% to 50% of individuals consulting general practitioners for shoulder pain, a quarter are subsequently diagnosed with shoulder impingement syndrome. Adding to the challenge, shoulder pain is often persistent or recurrent, with over half of affected individuals reporting ongoing symptoms even after three years.[3] Therefore, accurate and timely shoulder impingement syndrome diagnosis is paramount for effective management and patient recovery.
Etiology
It is essential to differentiate between shoulder external impingement and internal impingement as distinct clinical entities. The rotator cuff serves as the primary anatomical boundary distinguishing these two forms. Internal impingement typically arises from repetitive overhead motions, common in athletes and manual laborers, leading to articular-sided rotator cuff pathology, glenohumeral internal rotation deficit (GIRD), and superior labrum anterior posterior (SLAP) tears.[4, 5, 6, 7, 8] In contrast, external impingement, frequently referred to simply as shoulder impingement, is characterized by pain resulting from inflammation, irritation, and degeneration of structures within the subacromial space.[2, 9] It’s important to note that shoulder impingement syndrome is now understood as a cluster of symptoms and anatomical features rather than a singular diagnosis in itself.[10] Therefore, a comprehensive approach to shoulder impingement syndrome diagnosis is necessary to identify the specific underlying issues.
The subacromial space, critical in understanding impingement, is defined by specific anatomical borders: the acromion and coracoacromial ligament anteriorly, the acromioclavicular (AC) joint superiorly, and the humeral head inferiorly.[2] The shape of the acromion is considered a significant factor in the development of external, or “outlet-based,” impingement. Bigliani and Morrison categorized acromion shapes into three common types:[6]
- Class I: Flat acromion
- Class II: Curved acromion
- Class III: Hooked acromion
During shoulder movements like abduction, forward flexion, and internal rotation, the subacromial space naturally narrows. Normally measuring 1.0 to 1.5 cm in width, this space decreases further with the upward movement of the humeral head towards the acromion’s anteroinferior edge.[11] Pain, the hallmark symptom of shoulder impingement, occurs when the humeral head compresses the rotator cuff, the subacromial bursa, or both.[2] Understanding these biomechanics is crucial for accurate shoulder impingement syndrome diagnosis.
The relationship between repetitive compression, rotator cuff tendon degeneration, and subacromial space narrowing is complex. It remains unclear whether tendon damage precedes impingement or vice versa.[2] Further research is needed to fully elucidate this interplay and refine shoulder impingement syndrome diagnosis and treatment strategies.
Shoulder impingement syndrome can be classified based on the impingement location (external or internal) and the underlying cause (primary or secondary).[10, 12, 13] External, or subacromial impingement, arises from mechanical obstruction within the subacromial space. Internal impingement, conversely, occurs when rotator cuff tendons are compressed between the humeral head and glenoid rim, most commonly affecting the supraspinatus and infraspinatus tendons.[10] Differentiating between these types is a key aspect of shoulder impingement syndrome diagnosis.
Primary impingement involves a structural narrowing of the subacromial space due to factors like a hooked class III acromion or soft tissue swelling. Secondary impingement, however, occurs despite normal resting anatomy, developing during shoulder motion, often due to rotator cuff weakness leading to excessive humeral head translation.[10, 12, 13] Weakness in the trapezius and serratus anterior muscles can also contribute to secondary impingement by limiting scapular rotation and further narrowing the subacromial space during arm abduction.[2] Identifying primary versus secondary impingement is vital for accurate shoulder impingement syndrome diagnosis and targeted treatment.
Neer categorized shoulder impingement into three stages of severity. Stage I is characterized by edema and hemorrhage, typically from overuse. Stage II involves fibrosis and irreversible tendon changes. Stage III represents tendon rupture or tear due to chronic fibrosis.[14, 15] Staging helps in understanding the progression of the condition and guides treatment decisions following shoulder impingement syndrome diagnosis.
Epidemiology
Shoulder impingement syndrome is most frequently observed in individuals engaged in sports and occupations that involve repetitive overhead activities. These include sports like handball, volleyball, and swimming, as well as professions such as carpentry, painting, and hairdressing.[4] Additional risk factors that may predispose individuals to impingement syndrome include carrying heavy loads, infections, smoking, and the use of fluoroquinolone antibiotics.[2] The incidence of shoulder impingement syndrome increases with age, peaking in the sixth decade of life.[12] Understanding these epidemiological factors can aid in risk assessment and early shoulder impingement syndrome diagnosis in at-risk populations.
History and Physical Examination for Shoulder Impingement Syndrome Diagnosis
A comprehensive history and physical examination are the cornerstones of shoulder impingement syndrome diagnosis. Patients often report pain when lifting their arm or lying on the affected side. They may present with limitations in motion or nighttime pain that disrupts sleep. Weakness and stiffness are common secondary symptoms resulting from the pain.[16] The onset of pain is typically gradual, developing over weeks or months, and patients often cannot pinpoint a specific traumatic event.[12, 17] Pain is commonly localized over the lateral acromion, often radiating down the lateral mid-humerus. A detailed history is crucial for effective shoulder impingement syndrome diagnosis.
Clinicians should gather detailed information about the nature of the shoulder pain, including onset, quality, exacerbating and relieving factors, previous interventions, clinical responses, and any history of injuries to the affected extremity. Special attention should be paid to overhead and repetitive activities. Patients may find relief with rest, anti-inflammatory medications, and ice, but symptoms often return with activity resumption. This detailed history is integral to the process of shoulder impingement syndrome diagnosis.
The physical examination should include inspection, palpation, passive and active range of motion assessment, and strength testing of both the neck and shoulder, comparing bilaterally. Patients often exhibit weakness in abduction and/or external rotation on the affected side.[10, 12] Scapular dyskinesis may be observed during arm elevation. Tenderness to palpation is typically present over the coracoid process of the affected arm. These physical findings contribute significantly to shoulder impingement syndrome diagnosis.
Special tests are critical components of the physical examination for shoulder impingement syndrome diagnosis.[8] Tests specific to shoulder impingement syndrome include the Hawkins test, Neer sign, Jobe test, and assessment of a painful arc of motion. While individual tests may have limited sensitivity and specificity, their combined use enhances diagnostic accuracy.[10]
Hawkins Test: This test is performed by passively internally rotating the patient’s arm while the shoulder is flexed forward at 90 degrees and the elbow is flexed. Pain over the acromion suggests subacromial impingement, although it may be negative in cases of internal impingement.[10] A positive Hawkins test is a valuable indicator in shoulder impingement syndrome diagnosis.
Neer Sign: With the scapula stabilized in a depressed position, the examiner maximally forward flexes the patient’s arm passively. Localized anterior shoulder pain indicates subacromial impingement, whereas posterior shoulder pain may suggest internal impingement. The Neer sign is another key element in shoulder impingement syndrome diagnosis.
Jobe Test (Empty Can Test): This test involves positioning the patient’s arms at 90 degrees of abduction in the scapular plane, maximally internally rotating the arms, and resisting further abduction. Localized pain in the affected arm constitutes a positive test.[10] The Jobe test aids in confirming shoulder impingement syndrome diagnosis.
Painful Arc of Motion: This physical exam finding is characterized by pain during arm abduction between 70 and 120 degrees and with forced overhead movement.[12] Observing a painful arc of motion is diagnostically relevant in shoulder impingement syndrome diagnosis.
Tests to evaluate shoulder instability, such as the sulcus sign, anterior apprehension, and relocation tests, are typically negative in shoulder impingement syndrome. These help differentiate impingement from instability issues in shoulder impingement syndrome diagnosis.
Sulcus Sign: Performed with the patient seated and arm relaxed, the clinician stabilizes the shoulder and applies an inferiorly directed force at the elbow. Inferior humeral head displacement indicates a positive test.[18] A negative Sulcus sign supports shoulder impingement syndrome diagnosis by ruling out instability.
Anterior Apprehension Test: With the patient supine, the shoulder is abducted to 90 degrees and externally rotated to 90 degrees. Gentle external rotation is applied while supporting the proximal shoulder. A positive test is indicated by the patient reporting a feeling of impending subluxation or dislocation.[18] A negative anterior apprehension test is consistent with shoulder impingement syndrome diagnosis rather than instability.
Relocation Test: This test follows a positive anterior apprehension test. After eliciting apprehension, a posteriorly directed force is applied to the anterior humeral head, relieving the patient’s symptoms. [18] A negative relocation test further supports shoulder impingement syndrome diagnosis by distinguishing it from anterior instability.
Evaluation and Diagnostic Imaging for Shoulder Impingement Syndrome Diagnosis
While physical examination demonstrates a reported diagnostic sensitivity as high as 90%, imaging studies are often used to confirm the shoulder impingement syndrome diagnosis and exclude other potential pathologies.[12] When radiographs are indicated, bilateral imaging, rather than only of the affected side, is recommended to assess for anatomical variations and rule out conditions like calcific tendinitis or arthritic changes.
Standard plain radiographs of the shoulder typically include two views: Anteroposterior (AP) and lateral/scapular Y. The AP view can be used to measure the critical shoulder angle (CSA), which reflects the extent of lateral acromial coverage and glenoid inclination. CSAs greater than 35 degrees are associated with an increased likelihood of rotator cuff involvement in impingement syndrome. Acromiohumeral distance (AHD), measured from the inferior acromion edge to the humeral head, can also indicate rotator cuff pathologies. Normal AHD ranges from 7 to 14 mm in men and 7 to 12 mm in women. A reduced AHD suggests rotator cuff pathology. The scapular Y view aids in evaluating humeral head positioning on the glenoid. An outlet view radiograph is optimal for visualizing and assessing acromion shape, contributing to a comprehensive shoulder impingement syndrome diagnosis.[12]
Ultrasound and magnetic resonance imaging (MRI) are also valuable imaging modalities for shoulder impingement syndrome diagnosis. MRI is recommended if clinical improvement is not observed after 6 weeks of conservative therapy.[19] MRI provides detailed visualization of both bony and soft tissue structures within the shoulder girdle. Ultrasound, a readily available bedside imaging option, is particularly useful for assessing soft tissue factors such as bursitis, tendinopathy, and tendon ruptures.[12, 20] These advanced imaging techniques complement physical examination in achieving accurate shoulder impingement syndrome diagnosis.
Treatment and Management Strategies Following Shoulder Impingement Syndrome Diagnosis
The cornerstone of management for shoulder impingement syndrome, following shoulder impingement syndrome diagnosis, traditionally involves rehabilitative exercise programs, with surgical intervention considered if conservative measures fail or if specific anatomical pathologies are identified. In the absence of structural damage, non-operative treatments including controlled exercise programs, nonsteroidal anti-inflammatory drugs (NSAIDs), and subacromial injections are typically the initial approach for the first 3 to 6 months.[2]
Exercise therapy has been shown to yield better outcomes compared to placebo or control treatments in the sub-acute phase of injury.[21] Physiotherapy for shoulder impingement syndrome should focus on strengthening the rotator cuff muscles, particularly the supraspinatus and infraspinatus, as well as the trapezius and serratus anterior muscles. Exercises to correct scapular dyskinesia and address strength imbalances in the upper extremities are also crucial. Combining exercise with other conservative therapies leads to greater pain reduction than either treatment alone. Physiotherapy combined with localized injections has been shown to maximize treatment effects compared to injections alone.[15] Moderate evidence supports the addition of hyperthermia to physical therapy, although symptom relief may be short-term.[21] These conservative treatments are typically initiated after shoulder impingement syndrome diagnosis.
Various techniques exist for corticosteroid injections, with the posterior subacromial approach being commonly used due to its relative simplicity and reduced need for precision.[22] A 1.5-inch, 21 or 22-gauge needle with lidocaine and corticosteroid is typically employed. In this approach, the posterior shoulder portal, located 1 cm medial and inferior to the posterior corner of the acromion, is identified. The needle is directed towards the underside of the acromion in an anterosuperior direction. Injection should proceed smoothly without resistance; resistance may indicate needle placement within a rotator cuff tendon, requiring slight inferior redirection. While landmark-based injections offer clinical benefit, ultrasound-guided injections may provide superior symptom relief.[23] These injections are often part of the treatment plan after shoulder impingement syndrome diagnosis.
A systematic review of randomized controlled trials comparing surgical intervention versus conservative therapy indicated moderate evidence that surgery was not more effective than impingement-focused physical therapy for pain reduction.[24] Arthroscopic subacromial decompression (ASD) involves acromioplasty at the anterolateral edge, bursal debridement, and resection of the coracoacromial ligament.[2] ASD or similar procedures are considered when patients with severe, persistent subacromial shoulder pain and functional impairments do not improve with conservative treatment.[1, 12, 17] Combining ASD with treatments like radiofrequency ablation and arthroscopic bursectomy has shown more benefit than open subacromial decompression (OSD) with platelet-leukocyte gel injection.[15] However, a 2018 systematic review found no additional pain reduction benefit from ASD surgery compared to placebo surgery at 12 months.[25] Alternative surgical options include acromioplasty or bursectomy alone, but like ASD, these interventions appear to offer minimal additional benefit.[26] Surgical options are considered if conservative management fails following shoulder impingement syndrome diagnosis.
Comparing surgical intervention plus physiotherapy to surgery alone, no statistically significant or clinically meaningful difference in pain was observed at 3 months, 6 months, 5 years, and 10 years. Similarly, no significant differences in function were noted at 3 months, 6 months, and 1-year follow-up between these groups.[1] This highlights the importance of conservative management as the primary approach after shoulder impingement syndrome diagnosis.
Differential Diagnosis
Accurate shoulder impingement syndrome diagnosis requires considering and excluding other conditions that may present with similar symptoms. The differential diagnosis includes:
- Adhesive capsulitis (Frozen Shoulder)
- Rotator cuff tear
- Acromioclavicular joint arthritis
- Acromioclavicular joint sprain
- Trapezius muscle spasm
- Biceps tendonitis
- Biceps tendon rupture
- Calcific tendonitis
- Glenohumeral arthritis
- Distal clavicle osteolysis
- Cervical radiculopathy
- Thoracic outlet syndrome
Prognosis
With conservative treatment, including physical therapy, NSAIDs, and corticosteroid injections, approximately 60% of patients with shoulder impingement syndrome experience satisfactory outcomes within two years.[2, 12] This underscores the generally favorable prognosis following shoulder impingement syndrome diagnosis and appropriate management.
Complications
Complications arising from shoulder impingement syndrome primarily result from the underlying structural damage within the subacromial space, altered biomechanics, or disuse atrophy. Potential complications include rotator cuff tendinitis or tear, bicipital tendonitis or tear, and adhesive capsulitis. Early and accurate shoulder impingement syndrome diagnosis and management can help mitigate these risks.
Deterrence and Patient Education
Patient education is crucial in managing shoulder impingement syndrome. It should emphasize adherence to physical therapy and home exercise programs, as well as activity modifications, such as limiting overhead activities until pain subsides. Lifestyle modifications, like “living within the window,” which involves restricting movements to the anterior portion of the body (approximately a 2 to 3 feet rectangle) and minimizing overhead reaching or reaching behind the back, can be beneficial.[12, 17] Educating patients about their condition and management strategies is a vital component of care following shoulder impingement syndrome diagnosis.
Enhancing Healthcare Team Outcomes
Effective treatment and recovery from shoulder impingement syndrome necessitate strong interprofessional healthcare team collaboration. This includes primary care clinicians providing initial pain relief and referrals for physiotherapy. Physical therapists lead office-based and home exercise programs. Regular communication between physical therapists and primary care clinicians is essential to guide further imaging and treatment decisions. For patients requiring surgical intervention, referral to an orthopedic surgeon is necessary. Orthopedic nurses play a crucial role in patient assessment, education, and communication of patient status changes to the orthopedist. [Level 5] This interprofessional approach is paramount for optimal patient care and outcomes after shoulder impingement syndrome diagnosis.
Review Questions
(Original article contains review questions here)
References
(References are the same as the original article)
1.Nazari G, MacDermid JC, Bryant D, Athwal GS. The effectiveness of surgical vs conservative interventions on pain and function in patients with shoulder impingement syndrome. A systematic review and meta-analysis. PLoS One. 2019;14(5):e0216961. [PMC free article: PMC6541263] [PubMed: 31141546]
2.Consigliere P, Haddo O, Levy O, Sforza G. Subacromial impingement syndrome: management challenges. Orthop Res Rev. 2018;10:83-91. [PMC free article: PMC6376459] [PubMed: 30774463]
3.Lewis JS. Rotator cuff tendinopathy/subacromial impingement syndrome: is it time for a new method of assessment? Br J Sports Med. 2009 Apr;43(4):259-64. [PubMed: 18838403]
4.Davis DD, Nickerson M, Varacallo M. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Nov 22, 2023. Swimmer’s Shoulder. [PubMed: 29262079]
5.Varacallo M, Tapscott DC, Mair SD. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Aug 4, 2023. Superior Labrum Anterior Posterior Lesions. [PMC free article: PMC538284] [PubMed: 30855868]
6.Varacallo M, El Bitar Y, Sina RE, Mair SD. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Mar 5, 2024. Rotator Cuff Syndrome. [PubMed: 30285401]
7.Miniato MA, Anand P, Varacallo M. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Jul 24, 2023. Anatomy, Shoulder and Upper Limb, Shoulder. [PubMed: 30725618]
8.Varacallo M, El Bitar Y, Mair SD. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Aug 4, 2023. Comprehensive Shoulder Evaluation Strategies. [PubMed: 30855893]
9.Varacallo M, El Bitar Y, Mair SD. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Aug 4, 2023. Rotator Cuff Tendonitis. [PubMed: 30335303]
10.Cools AM, Cambier D, Witvrouw EE. Screening the athlete’s shoulder for impingement symptoms: a clinical reasoning algorithm for early detection of shoulder pathology. Br J Sports Med. 2008 Aug;42(8):628-35. [PubMed: 18523035]
11.Maruvada S, Madrazo-Ibarra A, Varacallo M. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Mar 27, 2023. Anatomy, Rotator Cuff. [PMC free article: PMC441844] [PubMed: 28722874]
12.Garving C, Jakob S, Bauer I, Nadjar R, Brunner UH. Impingement Syndrome of the Shoulder. Dtsch Arztebl Int. 2017 Nov 10;114(45):765-776. [PMC free article: PMC5729225] [PubMed: 29202926]
13.Ellenbecker TS, Cools A. Rehabilitation of shoulder impingement syndrome and rotator cuff injuries: an evidence-based review. Br J Sports Med. 2010 Apr;44(5):319-27. [PubMed: 20371557]
14.Tsai YH, Huang TJ, Hsu WH, Huang KC, Li YY, Peng KT, Hsu RW. Detection of subacromial bursa thickening by sonography in shoulder impingement syndrome. Chang Gung Med J. 2007 Mar-Apr;30(2):135-41. [PubMed: 17596002]
15.Dong W, Goost H, Lin XB, Burger C, Paul C, Wang ZL, Zhang TY, Jiang ZC, Welle K, Kabir K. Treatments for shoulder impingement syndrome: a PRISMA systematic review and network meta-analysis. Medicine (Baltimore). 2015 Mar;94(10):e510. [PMC free article: PMC4602475] [PubMed: 25761173]
16.Dhillon KS. Subacromial Impingement Syndrome of the Shoulder: A Musculoskeletal Disorder or a Medical Myth? Malays Orthop J. 2019 Nov;13(3):1-7. [PMC free article: PMC6915323] [PubMed: 31890103]
17.Koester MC, George MS, Kuhn JE. Shoulder impingement syndrome. Am J Med. 2005 May;118(5):452-5. [PubMed: 15866244]
18.Lizzio VA, Meta F, Fidai M, Makhni EC. Clinical Evaluation and Physical Exam Findings in Patients with Anterior Shoulder Instability. Curr Rev Musculoskelet Med. 2017 Dec;10(4):434-441. [PMC free article: PMC5685956] [PubMed: 29043566]
19.Jaggi A, Lambert S. Rehabilitation for shoulder instability. Br J Sports Med. 2010 Apr;44(5):333-40. [PubMed: 20371558]
20.Kadi R, Milants A, Shahabpour M. Shoulder Anatomy and Normal Variants. J Belg Soc Radiol. 2017 Dec 16;101(Suppl 2):3. [PMC free article: PMC6251069] [PubMed: 30498801]
21.Gebremariam L, Hay EM, van der Sande R, Rinkel WD, Koes BW, Huisstede BM. Subacromial impingement syndrome–effectiveness of physiotherapy and manual therapy. Br J Sports Med. 2014 Aug;48(16):1202-8. [PubMed: 24217037]
22.Shang X, Zhang Z, Pan X, Li J, Li Q. Intra-Articular versus Subacromial Corticosteroid Injection for the Treatment of Adhesive Capsulitis: A Meta-Analysis and Systematic Review. Biomed Res Int. 2019;2019:1274790. [PMC free article: PMC6815644] [PubMed: 31737653]
23.Daniels EW, Cole D, Jacobs B, Phillips SF. Existing Evidence on Ultrasound-Guided Injections in Sports Medicine. Orthop J Sports Med. 2018 Feb;6(2):2325967118756576. [PMC free article: PMC5826008] [PubMed: 29511701]
24.Saltychev M, Äärimaa V, Virolainen P, Laimi K. Conservative treatment or surgery for shoulder impingement: systematic review and meta-analysis. Disabil Rehabil. 2015;37(1):1-8. [PubMed: 24694286]
25.Lähdeoja T, Karjalainen T, Jokihaara J, Salamh P, Kavaja L, Agarwal A, Winters M, Buchbinder R, Guyatt G, Vandvik PO, Ardern CL. Subacromial decompression surgery for adults with shoulder pain: a systematic review with meta-analysis. Br J Sports Med. 2020 Jun;54(11):665-673. [PubMed: 30647053]
26.Vandvik PO, Lähdeoja T, Ardern C, Buchbinder R, Moro J, Brox JI, Burgers J, Hao Q, Karjalainen T, van den Bekerom M, Noorduyn J, Lytvyn L, Siemieniuk RAC, Albin A, Shunjie SC, Fisch F, Proulx L, Guyatt G, Agoritsas T, Poolman RW. Subacromial decompression surgery for adults with shoulder pain: a clinical practice guideline. BMJ. 2019 Feb 06;364:l294. [PubMed: 30728120]
