81 consecutive shoulder computed tomography (CT) scans obtained for preoperative planning purposes for shoulder arthroplasty were analyzed by commercially available software from four companies (Blueprint – Wright Medical; GPS – Exactech; Materialise; and VIP – Arthrex), and by 5 fellowship trained sports medicine/shoulder surgeons.
Inclination, version and subluxation of the humerus were measured in a blinded fashion on axial and coronal sequences at the mid-glenoid.
Surgeon measurements were analyzed for agreement, and were compared to the 4 commercial programs.
Surgeon reliability was acceptable for version, inclination, and subluxation.
Surgeon measurements were analyzed for agreement, and were compared to the 4 commercial programs.
Surgeon reliability was acceptable for version, inclination, and subluxation.
Significant differences were found between surgeon and commercial software measurements in version, inclination, and subluxation.
Software measurements tended to be more superiorly inclined (average -2° to 2° greater), more retroverted (average 2°-5° greater) and more posteriorly subluxed (average 7°-10° greater) than surgeon measurements.
The authors concluded that "preoperative planning software for shoulder arthroplasty has limited agreement in measures of version, inclination and subluxation measurements while surgeons have high interreliability. Surgeons should be cautious when using commercial software planning systems and when comparing publications that use different planning systems to determine preoperative glenoid deformity measurements."
They caution further, "if the templated preoperative plan is inaccurate, the glenoid component can be placed in inappropriate alignment, or, the actual glenoid procedure may be altered or deviate from current best-practice recommendations. Although surgeon input is necessary to create the final preoperative plan in these various software platforms, many surgeons attempt to follow the templatned plan without adjusting intraoperatively. If the software is under or overestimating version, inclination, or subluxation, it is possible to direct the surgeon into improper component placement. Even more concerning is that some surgeons may use these measurements to decide between anatomic and reverse arthroplasty.""final decisions should be predicated on multiple factors including intraoperative findings, preoperative plan, quality of tissue, surgeon experience, and evolving evidence-based outcomes associated with implant longevity and patient function."
Comment: Preoperative CT scans, 3-D planning software and patient specific instrumentation are costly in terms of health care dollars and provider time. Especially during these years when health care budgets are and will continue to be severely stressed by the COVID19 pandemic, we must ask whether these technologies add value in terms of measured improvements in the outcome patients realize from shoulder arthroplasty.
As pointed out by these authors, the type of arthroplasty, the type of components, the size of the components, and the position of these components need to be decided in large part based on intraoperative findings - including the nature of the soft tissues and the dynamic stability - factors that cannot be determined by preoperative static images of the bones. Reliance on 3D planning software may lead to choices that an experienced surgeon would not make.
In the great majority of cases, standardized preoperative plain films provide all the necessary information about the bony anatomy necessary to plan and perform the arthroplasty.
When the axillary view is obtained with the arm elevated in the plane of the scapula it can reveal instability not seen on CT scans obtained with the arm at the side.
This view reveals the key details of the glenohumeral pathoanatomy.
It also enables preoperative to sequential postoperative comparisons that would otherwise require repeated CT scans.
In today's climate, it may be time to reassess the measured (not theoretical) clinical value of 3D planning software to the patient.
As a basis for comparison, the lower line on the graph below from the Australian Orthopedic Assocation registry show a very low ten year revision rate for anatomic total shoulders using an all cross-linked polyethylene glenoid component inserted without 3D planning. Can the results of 3D planning be shown to be better than that?
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