The scapular is the medical term used to describe the shoulder blade. The scapular is a flat bone which sits on the upper thorax. Due to the fact that it down not have any significant bony connections it is termed a “floating bone”. Although there are no actual joints in the main body of the scapular the underside of the scapular does contact the ribs as they pass horizontally around the chest wall.
The shoulder complex is moved with the help of large groups of muscles some of which attach to the underside of the scapular. With any muscle attachment to bone, there forms a ridge or a point to the attachment as the bone is pulled as we develop.
Snapping scapular is the term given to the grating or “snapping” sensation or noise as the scapular moves on the ribcage. A snapping scapular may be painful or not depending on the cause and individual concerned.
The causes of a snapping scapular are varied but all involve the underside of the scapular grating or snapping on the ribs underneath. The main causes of this problem are mechanical anomalies, either developmental or post trauma to the scapular itself or the ribs.
Normal variant of posture
For some individuals, their scapular may form with more significant ridges to the underside of the bone as muscle attachments. In rare circumstances these ridges themselves may create a snapping over the ribs with shoulder movements in the absence of any obvious trauma or wider structural abnormality. This will most often manifest during adolescence and
Another postural variant which may manifest during adolescence is a rotational scoliosis. Developmental scoliosis may create a varying degree of prominence through the middle and upper ribs known as a “rib hump” clinically. A rib hump will create more friction on the underside of the scapular and a common secondary problem may be a snapping scapular.
Scapular or rib fractures
In the vast majority of individuals, they will have smooth enough interfaces between their scapular and the corresponding ribs. Fractures in this area are rare and normally the result of significant trauma. However, in these rare circumstances, the reformed shape to the rib angles or the scapular may increase friction and cause scapular snapping.
Muscle denervation & weakness
For some individuals with certain neurological diseases or those who have had a trauma or inflammatory reaction to the nerves innervating the muscles controlling the scapular their shoulder movements may become significantly altered. This may lead to “winging” or elevation of the scapular during shoulder movements.
The scapulothoracic bursa is a fluid filled sac to reduce friction and aid movements between these two areas when we lift our arms. Due to trauma or as a result of repeated, unaccustomed movement or pre-existing problems noted above, this bursa may itself inflame and become part of the main problem.
A GP, physiotherapist or consultant may all reliably diagnose a snapping scapular. However, depending on the individual presentation it may be necessary to image the area to determine any possible anatomical cause for the problem.
Imaging techniques used may include an xray initially to give a reasonable view of the bony architecture including any anomalies to the scapular itself or any of the rib angles. An MRI scan may be requested to view these possible bony causes but also to image whether there may be any bursal inflammation or swelling as well as any inflammation of any of the local bony anatomy.
A CT scan may in some cases be necessary to image specific bony anomalies in even greater detail.
Treatment of a snapping scapular depends on the underlying cause.
In situations where there are no obvious structural causes or where there is significant neurological muscle weakness around the scapular physical rehabilitation exercises will be the main stay of treatment. Often, optimising the activity or strength of the serratus anterior muscle which stabilises the scapular and is known as the “punching muscle” will be targeted. These exercises may involve push up variations or reaching or punching exercises which load the muscle preferentially.
Severe or worsening scoliosis may be treated by progresisve bracing during development and in some circumstances an operation to de-rotate the spine and fusion. Physical rehabilitation exercises may be offered to complement these treatments.
Scapular fractures and unstable rib fractures which lead to secondary, painful snapping scapular movements may also be rectified by surgery to resect the portion of the bone causing the excess friction.
In the rare circumstance that imaging finds any mass which may be non-musculoskeletal in nature, surgical removal will normally be offered.