Background: In clavicle reduction surgery one becomes aware that the paired clavicles are not often symmetric. Clavicle lengths are known by numerous anatomic studies to be different between the two sides. My clinical experience confirms this is accurate and careful examination has shown how frequent clavicle length asymmetries are. The longer clavicle length can be on either side but more frequently it occurs on the patient’s left side. This length differences can be factored into the amount of bone removed but may affect how the plate fixation is applied.
One often overlooked feature of the clavicle bone is its angulation. While often referred to as the only horizontally oriented long bone in the body, the actual angulation between the sternoclavicular (SC) and acromioclavicular (AC) joints is never completely horizontal. On a horizontal plane axis the level of the sternal joint and scapular joints of the clavicle are at two different levels with the AC joint higher than the SC joint. As a result when the clavicle is shortened it pulls the shoulder in and downward…more in but a little downward. How much downward movement of the shoulder depends on the angulation of the clavicle bone.
In some patients the clavicle is almost horizontal with the SC and AC joints being nearly at the same horizontal level. This would indicate that the bone removal would then have a completely horizontal inward movement.
Case Study: This female desired shoulder narrowing surgery with a bideltoid distance at 47.5cms, a clavicle bone length of 16.5cms on the left side and 17.5cms on the right side and a height of 5’7”. She also had a very horizontal clavicle line. As seen in the back view the trapezius muscle on the longer side was larger.
Under general anesthesia and through 3.5cm supraclavicualr fossa incisions, 2.2cms of clavicle bone was removed on the shorter left side and 2.7cms of clavicle bone on the longer right side. The cross section of the bone showed a very high spongy bone inner core with a thin surrounding cortical layer of bone. Double plate fixation was applied but on the longer right side only a 5 hole 3.5mm superior plate could be applied as opposed to a 6 holem3.5mm superior plate on the left side.
Her intraop before and after shoulder pictures showed the reduced shoulder width and some improvement in the asymmetry.
When seen two days later similar shoulder changes were seen in the standing position.
Her postoperative x-ray showed good alignment of the bone segments with stable plate and screw fixation devices.
The low clavicle angulation in this patient allowed for a purely horizontal reduction in shoulder width with no lowering or forward rollout all. In the more horizontally oriented clavicle I would presume it exists because of a higher than normal SC joint location.
Key Points:
1) Shoulders often have asymmetry due to different clavicle lengths which can be treated by different amounts of bone removal.
2) The horizontally oriented clavicle will get a more pure horizontal width reduction with bone removal.
3) With clavicle length reduction the available amount of bone may only permit a 5 hole superior plate as opposed to the more desired 6 hole plate.
Dr. Barry Eppley
World-Renowned Plastic Surgeon