Subacromial Impingement Syndrome: Biomechanics, Pathology, Diagnosis, and Treatment

Subacromial Impingement Syndrome:

Biomechanics, Pathology, Diagnosis, and Treatment

Jeremy Bradford, SPT

Background

For the past five+ years I have practiced hand balancing, progressing from simple yoga poses to now training for the one-armed freestanding handstand. What started as a hobby interest has burgeoned into a daily passion. However, my own passion for hand balancing has led to my experience of shoulder pain which is what initially directed my clinical interests towards shoulder pathology, injury prevention, and treatment.

My first formal introduction to pathomechanics of the shoulder came during the Spring 2016 semester in our Musculoskeletal I course. That class opened my eyes to what a complex, interconnected, and fascinating topic the shoulder is. It was there that I first learned of shoulder impingement syndromes. In the following summer, I participated in my first student physical therapist clinical experience, working in a privately owned outpatient clinic. In that setting I had the chance to evaluate and treat numerous patients with shoulder conditions including: osteoarthritis, tendinopathy, subacromial impingement syndrome, and patients status post arthroscopic rotator cuff repair or shoulder arthroplasty. I practiced the shoulder assessment and special tests that I acquired from my program instructors, and from my first CI, I learned how to progress a shoulder rehabilitation program. I deepened my understanding of the shoulder in the Fall of 2017 in our Advanced Orthopaedics Assessment and Intervention course. I chose to make the focus of my final project for that course rotator cuff tendinopathy. Not only did I learn about the critical role that individual tissue biomechanics play in injury and healing, I learned that one of the most fundamental aspects of physical therapy is understanding the MOI. When the clinician is able to appreciate the MOI, then a purposeful and well-constructed rehabilitation program can be implemented to improve patient outcomes and reduce the likelihood of future re-injury. In the case of subacromial impingement syndrome, an appreciation for the factors concerning the MOI is essential.

This capstone project is an opportunity for me to dive much more deeply into a pathology that I find to be so personally and professionally intriguing.

Statement of Need

One third of all musculoskeletal pain is attributable to the shoulder,¹ and subacromial impingement syndrome (SIS) is the most commonly reported shoulder pathology, accounting for nearly two-thirds of all shoulder pain diagnoses.² SIS is an umbrella term that encompasses a spectrum of shoulder pathologies, including: bursitis, rotator cuff tendinitis/tendinosis, and both partial and full-thickness rotator cuff tears.³ It is responsible for persistent pain, loss of function, disability, and financial burden. In the United States, MRIs are routinely ordered for diagnosis,² and between 75,000 to 250,000 surgical repairs for SIS occur annually.⁴ However, in many cases, physical therapy offers a cost-effective and reliable alternative for diagnosis and non-operative treatment of SIS.^1,5

While SIS has been well-studied, the topic is very widespread, perspectives have evolved, and there is no consensus on best treatment. The chief aim of this capstone project is to consolidate existing evidence about SIS and present this information to licensed clinicians in the hopes of sharpening clinical diagnosis, judgment, and treatment. It is hoped that this information about SIS will inform practical consideration and application of therapy. There are both extrinsic and intrinsic biophysical factors that influence SIS and being able to discern the degree to which these factors affect a particular patient will advise best practice.^2,5 Furthermore, beliefs and behavioral characteristics of the patient have also been found to determine outcomes in SIS.⁶ The role of patient expectations is another important dimension for the clinician to consider, and this issue is addressed by this capstone project.

Project Overview

Much of the work for this project centered on research concerning the topic of SIS, and the literature review is the major product. My target audience is the practicing physical therapist. Within the paper I review biomechanics and pathology in SIS; discuss accurate diagnosis and special tests for the physical therapist; summarize popular operative and non-operative treatments; and give consideration to rehabilitation protocols to inform best practice. In addition, I have drafted a convenient one-sheet (front and back page) reference guide for clinicians treating patients presenting with SIS. The reference guide is meant to be practical and gives quick reminders for appropriate interventions to use depending upon the stage of recovery.

In addition, I have produced a tri-fold brochure for patients with SIS. In fabricating this product, I have incorporated ideas about patient health literacy.⁷ The brochure format is ideal because it is compact, convenient, and contains bite-sized information that will not overwhelm the reader. I have adjusted the language so that it is roughly at the 5^th grade reading level for widespread accessibility, limiting myself to mostly simple sentences and avoiding medical jargon.

Finally, I will deliver a presentation to licensed physical therapists in a privately owned clinic on May 23, 2018. The setting is ideal since musculoskeletal disorders are regularly treated at the facility. The presentation will be an interactive experience that seeks to add value to these clinicians’ practice.

Products

• Patient Brochure
• Clinicians’ Reference Guide
• Literature Review
• PowerPoint Presentation

Evaluation and Self-Assessment

In developing my capstone products I have sought constructive feedback from my committee members and made changes along the way. In developing the patient brochure I distributed drafts to peers and even children to make sure that the material was written at an age-appropriate level and was written clearly.

I will present my capstone in May while on my final UNC DPT clinical rotation, and that experience will serve as a major point of evaluation for this project. Here is the Presentation Review Form. The presentation review form provides me with an objective measure for how well I was able to collect, distill, and communicate the most important features of SIS relevant to physical therapy practice.

Acknowledgements

First, I would like to thank Mike Gross, PT, PhD, FAPTA for serving as both my DPT program advisor and my capstone project advisor. His counsel was invaluable in deciding my final project topic and for developing my products. What’s more, his engaging delivery of information and wealth of knowledge made his Advanced Orthopaedics course one my most favorite and enriching classes. The lessons learned from that course and this capstone project will influence my clinical practice for many years. Next, I would like to thank Mike McMorris, PT, DPT, OCS, AAOMPT for serving on my committee and for bringing discerning expertise to my capstone products. He is the person who first introduced me to the topic of SIS and peaked my interest in kinematics of the shoulder. I would also like to thank Baker Campbell, DPT for serving on my committee, taking the time to review my capstone products, and for being both a friend and resource. In addition, I would like to thank my future clinical instructor, S. Kate Taylor, PT, DPT, OCS. Despite having not yet met in person, she secured the date, time, and location for my capstone presentation. Finally, thank you to all my DPT classmates, my friends, and family. Without your support, I wouldn’t have made it this far. I have much love and gratitude for you all.

References

1. Michener LA, Walsworth MK, Doukas WC, Murphy KP. Reliability and diagnostic accuracy of 5 physical examination tests and combination of tests for subacromial impingement. Arch Phys Med Rehabil. 2009 Nov;90(11):1898-903.
2. Singh B, Bakti N, Gulihar A. Current Concepts in the Diagnosis and Treatment of Shoulder Impingement. Indian J Orthop. 2017 Sep-Oct;51(5):516-523.
3. Silva L, Andréu JL, Muñoz P, Pastrana M, Millán I, Sanz J, Barbadillo C, Fernández-Castro M. Accuracy of physical examination in subacromial impingement syndrome. Rheumatology (Oxford). 2008 May;47(5):679-83.
4. Kromer TO, de Bie RA, Bastiaenen CH. Effectiveness of physiotherapy and costs in patients with clinical signs of shoulder impingement syndrome: One-year follow-up of a randomized controlled trial. J Rehabil Med. 2014 Nov;46(10):1029-36.
5. Dunn WR, Kuhn JE, Sanders R, An Q, Baumgarten KM, Bishop JY, Brophy RH, Carey JL, Harrell F, Holloway BG, Jones GL, Ma CB, Marx RG, McCarty EC, Poddar SK, Smith MV, Spencer EE, Vidal AF, Wolf BR, Wright RW; MOON Shoulder Group. 2013 Neer Award: predictors of failure of nonoperative treatment of chronic, symptomatic, full-thickness rotator cuff tears. J Shoulder Elbow Surg. 2016 Aug;25(8):1303-11.
6. Michener LA, McClure PW, Karduna AR. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech (Bristol, Avon). 2003 Jun;18(5):369-79.
7. Mostrom E. Chapter 12: Patient Education and Health Literacy. In: Jensen G. Teaching and Learning for Physical Therapists, 3^rd St. Louis, Missouri: Elsevier Inc; 200-16.