Is It Finally Time to Accept Scapular Dyskinesis as Normal?

The question “Is it Time to Normalise Scapular Dyskinesis?” is posed in a recent study (Salahm 2023). The evidence that “abnormal” scapular mobility may result in shoulder discomfort is examined in a comprehensive review. It makes me think of a study by McQuade from a few years ago titled “Critical and Theoretical Perspective on Scapular Stabilisation: What Does It Really Mean, and Are We on the Right Track?”

Here are some of each paper’s main ideas

⇒It’s difficult to characterize scapular dyskinesis

Typically, scapular dyskinesis is characterised as a pathological “abnormality” in scapular posture or movement. What constitutes a strange movement? There are a number of different tests that have been suggested, and they all include searching for subtle or blatant indications of increased medial border prominence and superior translation, and/or decreased posterior tilt and upward rotation. Why are certain movement patterns pathogenic rather than just variations in movement? Their potential to create instability or shoulder impingement is one of the reasons given. This idea, according to McQuade, is dubious since it is difficult to categories motions into correct and wrong because to their intrinsic complexity and variability. This is especially true for the scapula, whose movements are very complicated and changeable. The scapula is a unique bone in many respects.

lacks a strong bone connection to the rest of the body, it “floats” on the rib cage;

• It has unlimited freedom of translation and rotation
• while having significant ranges of motion, its ends do not endanger other joints
• There are numerous distinct scapular tasks, each requiring a particular set of motions (e.g., throwing, reaching, pushing, sustaining body weight, etc.).

Due to these factors, it is highly challenging to create guidelines that define appropriate and inappropriate movement patterns that are applicable to all individuals and situations.

⇒Scapular dyskinesis is frequent and not usually related to pain

The Salahm research analyses 34 papers that looked at the relationship between 2,400 people’s shoulder discomfort and scapular dyskinesis. It was shown that scapular dyskinesis was only somewhat more prevalent (60%) in those with shoulder discomfort and highly common (48%) in those without shoulder pain.

For overhead athletes, the association is much more pronounced: 81% of those who have shoulder discomfort also experience scapular dyskinesis, compared to only 42% of those who do not experience pain.

This does not, however, demonstrate that discomfort is being caused by strange movement. Perhaps the painful movement results from it. Furthermore, given that “abnormal” scapular motions in swimmers tend to become worse with both short-term and long-term training, it is possible that they are an adaptation to the demands of the activity.

Initially, it might seem as though these findings point to a weakness or compensatory mechanism that needs to be addressed; however, given that all of these athletes were competing at a high level without experiencing any symptoms, it’s possible that this change is the result of a normal adaptation related to the entire shoulder complex. This would be comparable to what is known about a baseball pitcher’s gleno-humeral joint’s growth in external rotation range of motion over the course of a season. This adaptability is not only typical of baseball pitchers but also crucial for them to execute at a high level.

Using the evidence provided, Salahm draws the following conclusions

The significance of this discovery won’t be clear until long-term studies that track the scapular dyskinesis prognostic value over time among asymptomatic groups are finished.

The McQuade article also comes to the following conclusion

We suggest that the majority of the observed scapular dyskinesia probably corresponds to typical movement variability.
Variability has been interpreted by the conventional orthopaedic biomechanical model as a sign of improper movement patterns. Dynamic systems theory, on the other hand, contends that variability represents the range of coordination patterns utilised to execute a job and that variability is proof of the neuromuscular system’s flexibility and adaptability in exploring novel movement solutions.

Additionally, McQuade points out that popular exercises used to correct scapular mobility may result in the development of abilities that do not transfer to everyday jobs and that they may lessen discomfort even in the absence of a correction.

Therefore, McQuade advises that attempts to enhance scapular performance should put more of an emphasis on building comprehensive movement capacity in a range of functional shoulder activities, rather than on seeming “normal” during motions that are unconnected from actual function.

Scapular dyskinesis—what is it?

Is it time to consider scapular dyskinesis normal now? That question strikes me as a little strange; it’s similar to asking if being weird is normal. I believe a better question to pose is whether the idea of scapular dyskinesis, as it is now defined, is helpful. I would reply that, based on the available data, probably not.