At the conference in Sydney
A pleasure to discuss experience with the Blueprint planning software and the Tornier shoulder replacement system, covering both the anatomic and the reverse designs, at a conference in Sydney.
What planning software does
Planning software builds a three-dimensional model of the patient's shoulder from their CT scan, which allows the size and position of the implant components to be worked out before the operation rather than judged in theatre. In a shoulder where the socket has worn unevenly, that planning stage is where most of the decisions about component position are actually made.
Anatomic and reverse replacement
A shoulder replacement system generally provides for both forms of the operation. In an anatomic replacement the normal layout of the joint is reproduced: a ball on the upper arm bone articulating with a socket component on the shoulder blade. This relies on the rotator cuff tendons being intact, since they are what positions and steadies the joint through its range.
In a reverse replacement the layout is inverted, with a socket on the arm bone and a ball fixed to the shoulder blade. That alters the mechanics so the deltoid, the large muscle over the outside of the shoulder, can raise the arm without help from the rotator cuff. It is used where the cuff tendons are no longer working, and in certain patterns of bone loss and fracture. Individual results vary, and which form suits a particular shoulder is determined by assessment, examination of cuff function and imaging rather than by preference.
Why surgeons compare notes on implant systems
Implant systems differ in their instrumentation, in the way components are fixed, and in how much adjustment they permit during the operation itself. Those differences have practical consequences that are not apparent from a catalogue, and they show up most clearly in the awkward cases: a shoulder with little bone left in the socket, a very small patient, or a revision in which previous components have to come out first.
Meetings at which surgeons using the same system discuss it are the main way that experience is shared. Registry data will eventually show how a design performs over years, but a surgeon weighing up a system now benefits from hearing how it behaves in theatre from people already using it.
Related information
See our anatomic total shoulder replacement and reverse total shoulder replacement pages, and our post on the Simpliciti stemless system.