Effects of Increased Retroversion Angle on Glenoid Baseplate Fixation in Reverse Total Shoulder Arthroplasty: A Finite Element Analysis

Ten technical aspects of baseplate fixation in reverse total shoulder arthroplasty for patients without glenoid bone loss: a systematic review

The aim of this systematic review was to collect evidence on the following 10 technical aspects of glenoid baseplate fixation in reverse total shoulder arthroplasty (rTSA): screw insertion angles; screw orientation; screw quantity; screw length; screw type; baseplate tilt; baseplate position; baseplate version and rotation; baseplate design; and anatomical safe zones. Five literature libraries were searched for eligible clinical, cadaver, biomechanical, virtual planning, and finite element analysis studies. Studies including patients >16 years old in which at least one of the ten abovementioned technical aspects was assessed were suitable for analysis. We excluded studies of patients with: glenoid bone loss; bony increased offset-reversed shoulder arthroplasty; rTSA with bone grafts; and augmented baseplates. Quality assessment was performed for each included study. Sixty-two studies were included, of which 41 were experimental studies (13 cadaver, 10 virtual planning, 11 biomechanical, and 7 finite element studies) and 21 were clinical studies (12 retrospective cohorts and 9 case-control studies). Overall, the quality of included studies was moderate or high. The majority of studies agreed upon the use of a divergent screw fixation pattern, fixation with four screws (to reduce micromotions), and inferior positioning in neutral or anteversion. A general consensus was not reached on the other technical aspects. Most surgical aspects of baseplate fixation can be decided without affecting fixation strength. There is not a single strategy that provides the best outcome. Therefore, guidelines should cover multiple surgical options that can achieve adequate baseplate fixation.

Treatment of Glenoid Wear with the Use of Augmented Glenoid Components in Total Shoulder Arthroplasty: A Scoping Review

» Treatment of glenoid bone loss continues to be a challenge in total shoulder arthroplasty (TSA). Although correcting glenoid wear to patient's native anatomy is desirable in TSA, there is lack of consensus regarding how much glenoid wear correction is acceptable and necessary in both anatomic and reverse TSA.» Use of augmented glenoid components is a relatively new treatment strategy for addressing moderate-to-severe glenoid wear in TSA. Augmented glenoid components allow for predictable and easy correction of glenoid wear in the coronal and/or axial planes while at the same time maximizing implant seating, improving rotator cuff biomechanics, and preserving glenoid bone stock because of off-axis glenoid reaming.» Augmented glenoid components have distinct advantages over glenoid bone grafting. Glenoid bone grafting is technically demanding, adds to the surgical time, and carries a risk of nonunion and graft resorption with subsequent failure of the glenoid component.» The use of augmented glenoid components in TSA is steadily increasing with easy availability of computed tomography-based preoperative planning software and guidance technology (patient-specific instrumentation and computer navigation).» Although different augment designs (full wedge, half wedge, and step cut) are available and a particular design may provide advantages in specific glenoid wear patterns to minimize bone removal (i.e. a half wedge in B2 glenoids), there is no evidence to demonstrate the superiority of 1 design over others.

Baseplate retroversion does not affect postoperative outcomes after reverse shoulder arthroplasty

BACKGROUND

There is concern that excessive glenoid component retroversion leads to altered biomechanics and baseplate failure in reverse shoulder arthroplasty (RSA). However, much of this has been rooted in the total shoulder arthroplasty experience. In the current literature, it is not well defined whether glenoid baseplate positioning in reverse arthroplasty affects functional outcomes. Our practice has been to preserve glenoid bone stock without aiming for a certain degree of retroversion. We aimed to evaluate the correlation between pre- and postoperative retroversion in a cohort of RSAs and determine the effect of glenoid retroversion on functional outcomes, range of motion, and postoperative complications.

METHODS

A retrospective review of patients who had an RSA between 2017 and 2019 was performed. Preoperative computed tomography scans were used to assess preoperative retroversion, and axillary radiographs were used for postoperative retroversion. Outcome measures included American Shoulder and Elbow Surgeons score, visual analog scale for pain score, Single Assessment Numeric Evaluation score, range of motion, radiographic lucency, and complications.

RESULTS

A total of 271 patients were eligible for the study. There was a 76.9% 2-year follow-up rate. In total 161 patients had postoperative retroversion ≤15° (group A), and 110 patients had retroversion >15° (group B). There were no significant differences in American Shoulder and Elbow Surgeons, visual analog scale, or Single Assessment Numeric Evaluation scores. There were also no significant differences in postoperative range of motion. There was 1 baseplate failure in each group, and there was 1 patient in group B with asymptomatic radiographic loosening (baseplate at risk). The mean change in pre- to postoperative retroversion was 1° and 4° in groups A and B, respectively.

CONCLUSION

There was no significant difference in postoperative functional outcomes, range of motion, or complications between patients who had baseplate retroversion ≤15° vs. those who had retroversion >15°.