Have you ever been told you have "tight" upper traps causing shoulder pain? Perhaps someone has said your shoulder blade moves abnormally causing "impingement"? Maybe you've been told to avoid certain movements, like upright rows, because it's bad for your shoulder health. If you've heard these narratives or other explanations for shoulder pain then this guide is for you. In this guide we will seek to bring clarity to shoulder pain while providing research based information regarding the legitimacy, or lack thereof, for common narratives used to explain shoulder pain. Finally, we will lay out a practical path forward for dealing with the issue. Let's get started.
Basic Anatomy Lesson
The shoulder consists of two primary joints:
Glenohumeral (GH) joint
Acromioclavicular (AC) joint
The GH joint is considered a "ball and socket" joint where the head of the humerus articulates with the glenoid cavity of the scapula. The GH joint has significant freedom for movement. The AC joint is created by the clavicle (i.e. collar bone) articulating with the acromion process of the scapula (see Figure 1). From a sport related injury perspective, we often hear of folks dislocating the GH joint while separating the AC joint.
Although this region of the body involves many muscles, we will focus on four:
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Collectively, the above muscles are known as the rotator cuff, a common area receiving surgical intervention.
Shoulder Pain
Although many claim to know the exact answer to "Why does my shoulder hurt?", rarely do we as healthcare professionals have a specific tissue issue to put our finger on that needs direct intervention. Rather, shoulder pain is a multifactorial experience and there are only a few key scenarios in which immediate healthcare consultation is needed to ensure long-term positive outcomes (e.g. function) are achieved. These scenarios include:
Accompanying chest pain with shoulder/arm pain
Recent trauma (e.g., fall) resulting in fracture, dislocation, or separation
Progressive neurological symptoms (e.g., loss of arm or hand movement, worsening numbness/tingling in arm(s) or hand(s))
Although these scenarios can be concerning, they are not as common as general shoulder pain. We can think of general shoulder pain as shoulder pain that may or may not occur with radiating symptoms into the arm and hand where no trauma occurred and no other symptoms are ongoing. Note, having such a label as general shoulder pain is good news and means we do not have to unnecessarily worry ourselves with finding a specific tissue issue to try and fix. Rather, we can look ahead on how to move forward on the path to recovery. Before moving on to answering the question, "Why does my shoulder hurt?", be sure to checkout the blog - What is pain?
Causes of Shoulder Pain
In this section we will discuss common explanations for shoulder pain while exploring supportive, or lack thereof, evidence for the narrative.
There are 4 common narratives used to explain shoulder pain:
Scapular Dyskinesis
External Impingement
Internal Impingement
Rotator Cuff Tears
Scapular dyskinesis is a medical phrase for saying the shoulder blade is moving
abnormally. Previous understanding of arm movement stipulated that when the arm is being raised to the side (see Figure 3), the scapula should upwardly rotate, posteriorly tilt, and internally/externally rotate - together these movements are known as scapulohumeral rhythm. Theoretically, this normative movement avoids damage of subacromial tissue (e.g., supraspinatus tendon). Although superficially this sounds plausible, when we dive deeper into the understanding of movement, tissue alteration, and relationship to pain the narrative lacks foundational support. In this context, the operational model for examining movement is known as the kinesiopathological model (KPM), which creates a false dichotomy of good vs bad or normal vs abnormal movement. Since the 1940s, proponents of this model have postulated the idea of a 2:1 scapulohumeral ratio in which every 2 degrees of humeral elevation results in 1 degree of scapular upward ratio. If someone visually appears to deviate from this movement pattern, then their movement is labeled as abhorrent or demonstrating dyskinesis.