These authors conducted a systematic, online search for articles on shoulder arthroplasty using computer guided navigation. They found 6 groups of 247 shoulders from 5 studies that met their inclusion criteria.
The pooled weighted mean difference for deviation from neutral version was -6.4° (95 %CI -7.9 to -5.3) in favor of navigation, but there was no significant difference in tilt.
They concluded that navigation allows for more accurate glenoid version, but the clinical meaningfulness of the absolute improvement over standard techniques is questionable.
Comment: Three issues are surfaced here. (1) While it is recognized that abnormal glenoid version in an arthritic shoulder is associated with inferior clinical results, it has yet to be demonstrated that 'correction' of version to some theoretical 'normal' improves the clinical outcome over the results of arthroplasty that accepts the pathological version and, thereby, preserves glenoid bone stock. Thus, computer guided navigation may lead the surgeon to change the version without consideration of whether this change will be helpful or harmful. (2) There are no data whether an 'improvement' of version of 6.4 degrees has any clinical benefit. (3) There are no data on the cost and time necessary to achieve an 'improvement' of 6.4 degrees in glenoid version.
So at the end of the day we do not know the value (benefit/cost) of computer guided navigation.
Parenthetically, it is of interest that most of the included studies were on cadavers or computer models as opposed to studies of real surgery on real patients.
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