# Long-term clinical and radiological outcomes of a stemless reverse shoulder implant that is fallen out of favor - stemless nano-reverse shoulder arthroplasty

## TL;DR

This study evaluates the long-term outcomes of a stemless reverse shoulder implant, finding mixed results with good clinical scores but high complication rates.

## Contribution

The study provides long-term clinical and radiological data on a stemless reverse shoulder implant that is no longer commonly used.

## Key findings

- The implant showed good clinical outcomes with average Constant score of 82.9 and low pain scores.
- Radiolucency lines and implant-related complications were observed in some patients.
- Revisions were needed for complications like peg breakage and septic loosening.

## Abstract

The purpose of this study was to assess the long-term results of the stemless onlay Comprehensive Nano reverse total shoulder arthroplasty (rTSA) system.

We evaluated 35 shoulders at an average follow-up of 106 ± 14.6 months (range, 80–135) (follow-up rate 66%). Patients were evaluated via the Constant–Murley scale, the DASH score (Disabilities of the Arm, Shoulder and Hand) and the subjective shoulder value (SSV). Furthermore, a visual analog scale (VAS) for pain intensity was used. The passive glenohumeral range of motion and active total range of motion were recorded.

Radiographic assessment was performed on true antero-posterior and axillary views.

The mean age at surgery was 72.8 ± 6.7 years (range, 47–82). Four patients were revised to a stemmed implant during the follow-up period and were excluded from further assessment. In the remaining group, the Constant score was 82.9 ± 13.1 (range, 40–97), the DASH score was 10.6 ± 17.3 (range, 0–77.5), the SSV was 85.0 ± 18.1 (range, 10–100), and the VAS score for pain was 0.9 ± 1.7/10 (range, 0–7).

The mean active flexion and abduction values were 159.8 ± 13.8 and 155.9 ± 20.1, whereas the active external and internal rotation values averaged 34.8 ± 15.3 and 88.9 ± 7.9, respectively.

Grade I radiolucency lines (RLLs) were found in 4 patients (14.3%). RLLs > 1 mm were not observed. Two patients experienced early varus displacement of the humeral tray with full reintegration without revision. Revisions to a stemmed implant were performed for atraumatic peg breakage of the humeral tray in 2 patients, early septic loosening in one patient and periprosthetic fracture in one patient.

Grade 1 notching was found in 17.9%, and acromion stress fracture was found in 3.6%. Three patients experienced postoperative neurological deficits, with complete recovery in 2 patients.

Compared with published data on stemmed and stemless rTSA, the comprehensive Nano rTSA system in the present study has comparable or even superior clinical outcomes at long-term follow-up. The rates of implant-associated complications and revision, however, are high compared with those reported in the literature.

Retrospectively registered on 6th August 2025 German Clinical Trial Register, clinical trial number DRKS00037624, https//www.drks.de/DRKS00037624.