Preoperative deltoid assessment by contrast-enhanced ultrasound (CEUS) as predictor for shoulder function after reverse shoulder arthroplasty: a prospective pilot study.
INTRODUCTION
Although the deltoid represents the main motor muscle after reverse shoulder arthroplasty (RSA), its standardized preoperative assessment regarding morphology and function is still not established. Its clinical relevance and interactions with major biomechanical parameters like the medialization of the center of rotation (COR) regarding shoulder function after RSA are yet unknown. We evaluated contrast-enhanced ultrasound (CEUS) of the deltoid as possible surrogate marker for individual deltoid properties of patients receiving an RSA, and its predictive value for postoperative shoulder function.


MATERIALS AND METHODS
35 patients were prospectively assessed. Before and 6 months after RSA, dynamic deltoid perfusion, caliber and a combination of both (PE*caliber, named DeltoidEfficacy) was quantified by CEUS. Changes of deltoid properties and the predictive value of preoperative CEUS-based deltoid properties for shoulder function after RSA were assessed. To analyze interrelating effects with deltoid properties, COR-medialization and deltoid lengthening were quantified.


RESULTS
Deltoid caliber and perfusion significantly increased after RSA (p = 0.0004/p = 0.002). Preoperative deltoid caliber, perfusion and the combined value DeltoidEfficacy significantly correlated with shoulder function after RSA within the whole study cohort (caliber: r = 0.445, p = 0.009; perfusion: r = 0.593, p = 0.001; DeltoidEfficacy: r = 0.66; p = 0.0002). The predictive value of DeltoidEfficacy for shoulder function after RSA varied among patient subgroups: Multivariate regression analysis revealed the strongest prediction in patients with either very high or very low deltoid properties (Beta = 0.872, r = 0.84, p = 0.0004), independent from COR-medialization or deltoid lengthening. Contrary, in patients with intermediate deltoid properties, COR-medialization revealed the strongest predictive value for shoulder function after RSA (Beta = 0.660, r = 0.597; p = 0.024).


CONCLUSION
Deltoid CEUS seems to allow an assessment of individual deltoid properties and deltoid adaptations after RSA. Deltoid CEUS seems to predict shoulder function after RSA and might support an identification of patients requiring special attention regarding COR positioning.
['Fischer|Christian|C|', 'Flammer|Sophie|S|', 'Kauczor|Hans-Ulrich|HU|', 'Zeifang|Felix|F|', 'Schmidmaier|Gerhard|G|', 'Kunz|Pierre|P|']
D000072228:Arthroplasty, Replacement, Shoulder D003287:Contrast Media D057645:Deltoid Muscle D006801:Humans D010865:Pilot Projects D011300:Preoperative Care D011446:Prospective Studies D012782:Shoulder D014463:Ultrasonography
Deltoid assessment CEUS Predictor Reverse shoulder arthroplasty RSA Center of rotation