Clinical implications of scapular notching at 2 and 5-year follow-up after reverse total shoulder arthroplasty

The Influence of Component Design and Positioning on Soft-Tissue Tensioning and Complications in Reverse Total Shoulder Arthroplasty: A Review

» Reverse total shoulder arthroplasty was designed to function in the rotator cuff deficient shoulder by adjusting the glenohumeral center of rotation (COR) to maximize deltoid function.» Adjustments in the COR ultimately lead to changes in resting tension of the deltoid and remaining rotator cuff, which can affect implant stability and risk of stress fracture.» Soft-tissue balance and complication profiles can be affected by humeral component (version, neck shaft angle, and inlay vs. onlay) and glenoid component (sagittal placement, version, inclination, and lateralization) design and application.» A good understanding of the effects on soft-tissue balance and complication profile is critical for surgeons to best provide optimal patient outcomes.

CT versus MRI planning for reverse geometry total shoulder arthroplasty

Introduction

Preoperative planning for Reverse Total Shoulder Arthroplasty (RTSA) using CT or MRI is well described.1, 2, 3, 4, 5, 6, 7 We aimed to compare pre-operative CT versus MRI measurement accuracy for predicting intra-operative glenoid implant sizing.

Methods

All patients with a preoperative CT or MRI undergoing RTSA at our tertiary referral center from October 2017 to February 2020 were included. Data was collected from theatre and implant registers. Glenosphere Width (GW) and Baseplate Central Screw Length (BCSL) were independently predicted from pre-operative CT or MRI imaging by 2 blinded senior authors. A sub-group analysis was also performed between trauma and non-trauma CT cases. SPSS v26 was used for statistical comparison between predicted and actual implants.

Results

71 data sets from 69 patients were included for analysis: 31 CT predictions and 40 MRI predictions. 61.3% of CT measured GW predictions were accurate compared to 82.5% of MRI predictions (p = 0.045). BCSL predictions were 77.4% and 70% accurate for CT and MRI respectively, without significant difference. There was no significant difference in sub-group analysis for trauma vs elective CT accuracy of BCSL or GW measurements.

Conclusion

MRI imaging may be superior to CT for predicting GW and no less accurate than CT for predicting BCSL in the elective setting. No difference in CT measurement accuracy was seen between trauma and elective settings. While simultaneously clearly defining shoulder soft tissue anatomy, MRI may also be the preferred modality for bony measurements during pre-operative planning for elective RTSA.