A day in the laboratory
A Saturday in August 2017 spent in a cadaver laboratory workshop, practising implantation of the Exactech Equinoxe shoulder replacement prosthesis.
This system uses a wifi guidance system to help determine the position of the implant. Practising with an unfamiliar system in a laboratory, rather than learning it on an operating list, is the appropriate order of things.
What a shoulder replacement involves
In a shoulder replacement the worn surfaces of the joint are replaced with artificial components. In an anatomic replacement the ball and socket are reproduced in roughly their natural arrangement, which relies on the rotator cuff still working. In a reverse replacement the arrangement is inverted, with the ball fixed to the socket side and the cup to the upper arm bone, which allows the deltoid muscle to lift the arm when the rotator cuff can no longer do so. Which is appropriate depends on the condition of the joint surfaces, the bone and the rotator cuff. Individual results vary.
Why implant position matters
Shoulder replacement components have to be placed within fairly narrow tolerances. The socket side in particular offers a limited amount of bone, and the orientation of the component affects how the joint moves and how load is transmitted into the bone around it. Guidance systems exist to give the surgeon information during the operation about where an instrument sits relative to the patient's own anatomy, rather than relying on visual judgement alone.
Why cadaver laboratory days exist
A new implant system brings new instruments, a new sequence of steps and, in this case, new technology to interpret. Working through all of that for the first time on a cadaveric specimen means the surgeon can take as long as needed, repeat a step, and be corrected by the faculty standing alongside. None of those things is possible on an operating list, and a patient should not be the occasion for a surgeon's first use of an unfamiliar system.
Related information
See our anatomic total shoulder replacement and reverse total shoulder replacement pages, and our post on robotic assistance in shoulder replacement.