The risk behind Scapula Winging or a Protruding Shoulder Blade

21 June 2021

Introduction to the Scapula Bone

We zero in on one of the most common presentations in a dysfunctional shoulder — scapula winging. The scapula is a bone plate not unlike the shape of a triangle that rests on the upper back ribs, held up by an array of muscles.

How to identifying Scapula Winging

Scapula Wing on a boy
Scapula Wing

Scapula winging occurs as a bony protrusion along the spinal region of the scapula, whether at rest or during movement.

While its appearance can cause alarm, rest assured it is usually the result of a weak serratus anterior muscle that fails to anchor down the shoulder blade.

Scapula Winging and the Serratus Anterior Muscle

We must first remember that our muscles do not operate singularly or independently — rather, muscles work together, in tandem with others to achieve mobility and maintain body stability.

Similarly, the serratus anterior is no exception — it stabilises the scapula and facilitates its upward rotation by engaging other muscles. This muscular mechanism helps you reach overhead or bear weight with minimal strain to the shoulder joint.

When the Serratus Anterior system fails

scapula winging

Imagine a large gear in a clock, unable to move — the surrounding gears will have to work even harder to keep the clock ticking.

That’s what happens when the serratus anterior muscle is weak. The tandem muscles, such as the upper trapezius or levator scapula muscle, work harder to compensate for the shortfall in powering the upward rotation, eventually causing tightness along the top of the shoulder, side of the neck or base of the skull.

Additionally, a weakened serratus anterior leads to lower stability for the scapula; the scapular then loses its anchor and protrudes like a wing.

What’s behind a weak Serratus Anterior Muscle?

Many different theories point to how serratus anterior muscles become weak. The 3 most common are:

  1. Firstly, Severe impact to a shoulder injury to shoulder may lead to a reluctance in performing overhead movements. In this scenario, one would end up underutilising the serratus anterior, therefore weakening it.
  2. Secondly, Over-activation of upper rotator muscles when the upper trapezius muscles overused, the serratus anterior overpowered as well. The serratus anterior weakens from excessive load, and in extreme cases, loses its ability to be activated.
  3. Lastly, The nerve-wracking situation has been theorised that the serratus anterior can be weakened when the nerve supply is severed. However, this known to be an extremely rare occurrence.

Alleviating the pain

Like any muscle rehabilitation, treatment is usually centred on the aim of muscle strengthening.

Therefore, a series of progressive exercises are usually prescribed to overcome scapula winging, starting with a wall push-up that gradually requires bearing weight in a four-point kneeling position.

Progressing the exercises are important, not just for strengthening the key muscles, but also for engaging the other tandem muscles. Particularly the upward rotator muscles, so that motor control (neuromuscular) established and/or re-trained.

Experiencing shoulder pain? Find out more about physiotherapy and how our physiotherapist at Core Concepts Singapore can help resolve your pain. 

References

  1. Fiddian, N. J., & King, R. J. (1984). The winged scapula. Clinical orthopaedics and related research, 185, 228-236.
  2. Iceton, J. O. H. N., & Harris, W. R. (1987). Treatment of winged scapula by pectoralis major transfer. Bone & Joint Journal, 69(1), 108-110.
  3. Akgun, K., Aktas, I., & Terzi, Y. (2008). Winged scapula caused by a dorsal scapular nerve lesion: a case report. Archives of physical medicine and rehabilitation, 89(10), 2017-2020.
  4. Kuhn, J. E., Plancher, K. D., & Hawkins, R. J. (1995). Scapular wingingJournal of the American Academy of Orthopaedic Surgeons, 3(6), 319-325.