• BACKGROUND
    • Postoperative rehabilitation of deltoid function is crucial for optimizing outcomes after reverse shoulder arthroplasty (rTSA). Prior studies have shown that the maximal functional gains after rTSA occur 1 year after surgery. Adjunct therapies such as functional electromyostimulation (FES) may enhance muscle activation and improve shoulder function after the previous reported plateau time point. The aim of this study was to investigate the efficacy of therapy with FES augmentation for rTSA patients initiated 1 year after surgery. We hypothesized that FES yield superior improvements in Constant Score compared to a control group treated without FES.
  • MATERIALS AND METHODS
    • Thirty four patients who underwent rTSA (Ascend Flex, Stryker Inc.) in one specialized shoulder center with a minimum follow-up of one year were included in this prospective, randomized controlled study and randomly assigned equally to the intervention or control group. A 6-week home exercise program using FES with progressive exercises aimed at enhancing shoulder mobility and deltoid strength was used in both groups. However, the FES device was only activated in the intervention group. Shoulder function was assessed pre- and postrehabilitation with the Constant Score, Subjective Shoulder Value, deltoid strength, abduction range of motion (ROM) and flexion ROM by clinical examination and automated measurement using ShowMotion software. This trial was conducted and reported in accordance with the CONSORT guidelines.
  • RESULTS
    • Thirty-four patients were randomized into the intervention group (n = 17) and control group (n = 17) with similar demographics and baseline shoulder function (P > .05). A total of n = 28 patient completed the study protocol (n = 14 intervention group; n = 14 control group). Significant improvements in Constant Score (65.7 to 79.5, P < .001), Subjective Shoulder Value (from 70.1% to 91.1%, P < .001), and abduction ROM (from 106° to 120°, P = .041) were observed in the intervention group. However, the control group showed no significant changes compared to baseline (P > .104). Patients treated with FES achieved a significantly higher mean Constant Score (Control: 65.7 ± 13.2 Points vs Intervention: 79.5 ± 7.9 points, P = .003) and abduction ROM (Control: 94 ± 30° vs Intervention: 121 ± 32°; P = .038) compared to the control group. No significant differences were found in strength and flexion ROM.
  • CONCLUSION
    • Self-directed functional FES improves rTSA function when initiated one year after primary surgery. FES may be a beneficial adjuvant to rTSA rehabilitation due to its low adverse event rate and its availability for home-based training. Further research is needed to examine if the results remain advantageous at mid-to-long-term follow-up.