So let's consider the questions we should pose about robotics and shoulder arthroplasty.
We need to ask the right questions before we look for answers.
Keeping in mind that the great majority of anatomic and reverse total shoulder arthroplasties provide good outcomes for patients - whether they are performed in a community hospital or in a high volume center - what problems experienced by patients having shoulder arthroplasty are we trying to solve with robotics?
We know that robots have solved major problems in manufacturing, enabling standardized production of complex products like the Rolls Royce (here's a shot from their factory).
But the Rolls Royce factory bears no resemblance to the operating room.
In the Rolls Royce factory, the plan has been clearly laid out by the designing engineers; in shoulder surgery the plan is not clear - the desired position of the implants is variable patient to patient and planning cannot anticipate the soft tissue balancing needed to assure mobility and stability.
In the Rolls Royce factory, each chassis is identical and the landmarks are clear; in shoulder surgery each patient is different and the landmarks are much less clear.
In the Rolls Royce factory, the robot is firmly fixed to the chassis; in shoulder surgery the robot is - at best - loosely fixed to the patient.
In the Rolls Royce factory, the materials are of high and consistent quality; in shoulder surgery the patient's bone quality and rotator cuff integrity are variable.
In the Rolls Royce factory, there is no need for a human to be concerned about safety; in shoulder surgery, the surgeon's (but not the robot's) concern is for patient safety: avoiding infection, nerve and vessel injury, instability, fracture, limited motion, and component loosening.
So here are some important questions that we need to answer
(1) Do we know preoperatively what arthroplasty geometry we should be planning for in a given case (e.g. where do we want the center of rotation to be? does the desired amount of postoperative humeral distalization depend on the preoperative distalization? how much global lateralization is desirable and does this depend on cuff status, preoperative stiffness, or preoperative instability?)
(2) Given that the justification for robotics is to optimize the transfer of a preoperative geometric plan to the execution of the arthroplasty, what percent of poor arthroplasty outcomes can be attributed to the failed transfer of the preoperative plan to the patient? This fundamental information is currently unavailable, yet robotics is being promoted without evidence of the problem's magnitude.
(3) How sensitive are shoulder arthroplasty outcomes to minor "malpositions" in the range of 5-10 degrees or millimeters? A field goal kicker scores with a kick passing anywhere between two uprights 18.5 feet apart; how tight is the tolerance for arthroplasty component positioning?
(4) What improvement in patient reported outcomes would justify the cost of robotics for high-volume surgeons who already have a great success rate without using robotics?
(5) Most shoulder arthroplasties are performed by "low volume" surgeons who perform less than 10 a year. How likely is it that these surgeons would have access to and training in the effective, efficient and safe use of robotics? Or would hands-on skills courses teaching them conventional techniques be of more use in optimizing their patient outcomes?
(6) Does use of robotics enhance a surgeon's ability to manage the wide variety of arthritic shoulder pathologies they encounter, or does it lead technological dependency?
In conclusion, we should ask "to what degree will the application of robotics to execute a preoperative plan address the primary causes of shoulder arthroplasty failure - infection, instability, acromial fracture, limited motion, and component loosening?"
A prickly topic
Cactus Wren
Tucson, AZ
2020
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link)
The total shoulder arthroplasty (see this link)
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link)
Shoulder rehabilitation exercises (see this link).
