Deltoid muscle volume affects clinical outcome of reverse total shoulder arthroplasty in patients with cuff tear arthropathy or irreparable cuff tears

Abstract

We aimed to estimate the interrelation between preoperative deltoid muscle status by measuring the 3-dimensional deltoid muscle volume and postoperative functional outcomes after reverse total shoulder arthroplasty(RTSA). Thirty-five patients who underwent RTSA participated in this study. All patients underwent preoperative magnetic resonance imaging(MRI) as well as pre- and postoperative radiography and various functional outcome evaluations at least 1 year. The primary outcome parameter was set as age- and sex-matched Constant scores. The 3-dimensional deltoid muscle model was generated using a medical image processing software and in-house code, and the deltoid muscle volume was calculated automatically. Various clinical and radiographic factors comprising the deltoid muscle volume adjusted for body mass index(BMI) were analyzed, and their interrelation with the outcome parameters was appraised using a multivariate analysis. As a result, all practical consequences considerably improved following surgery(all p<0.01). Overall, 20 and 15 indicated a higher and a lower practical consequence than the average, respectively, which was assessed by the matched Constant scores. The deltoid muscle volume adjusted for BMI(p = 0.009), absence of a subscapularis complete tear (p = 0.040), and greater change in acromion-deltoid tuberosity distance(p = 0.013) were associated with higher matched Constant scores. Multivariate analysis indicated that the deltoid muscle volume was the single independent prognostic factor for practical consequences(p = 0.011). In conclusion, the preoperative deltoid muscle volume significantly affected the functional outcome following RTSA in patients with cuff tear arthropathy or irreparable cuff tears. Therefore, more attention should be paid to patients with severe atrophied deltoid muscle who are at a high risk for poor practical consequences subsequent to RTSA.

Current Outcomes Following Reverse Total Shoulder Arthroplasty: A Composite

“…These findings stress the importance of patient selection, expectations for RTSA, expertise in intraoperative optimization, and strict postoperative physical therapy management. The concept of rapid improvement during the first 6 months with plateau at 12 months was also reported by Muller and colleagues in 2017 [24], in which flexion, abduction, and external rotation in 90 degrees of abduction demonstrated profound increases by 42°, 38° and 33° respectively at 6 months. Additional follow-ups at 12, 24, and 60 months displayed minimal additional improvement [24].…”

“…The concept of rapid improvement during the first 6 months with plateau at 12 months was also reported by Muller and colleagues in 2017 [24], in which flexion, abduction, and external rotation in 90 degrees of abduction demonstrated profound increases by 42°, 38° and 33° respectively at 6 months. Additional follow-ups at 12, 24, and 60 months displayed minimal additional improvement [24]. Supplementary evidence of RTSA success was seen by Yoon and colleagues [25] in 2017 with forward flexion increase of 64°, external rotation increase of 13° and pain reduction of (−3) at 12 months postoperatively.…”

“…Two factors that have been shown to increase CMS and ROM testing during the short-term period are deltoid volume [25] and glenosphere size [24] respectively. Preoperative deltoid muscle volume was an independent prognostic factor for functional outcomes with CMS (p = 0.011), underscoring the importance of patient selection and discussing the potential for negative outcomes such as atrophied deltoid muscle [25].…”

Relation between preoperative electromyographic activity of the deltoid and upper trapezius muscle and clinical results in patients treated with reverse shoulder arthroplasty

“…12 In a previous study, the volume of a 3-dimensional deltoid muscle model created from MRI using image-processing software was related to the prognosis of RSA. 35 However, methods using static images cannot measure dynamic muscle activity. Therefore, we used EMG to evaluate the dynamic function of the deltoid and upper trapezius.…”

“…4,10,25,33 Magnetic resonance imaging (MRI) and computed tomography can be used to evaluate the condition of the deltoid muscle but have limited ability to evaluate dynamic muscle motion. 12,18,35 Therefore, we used dynamic EMG measurements to evaluate the activity of the deltoid and upper trapezius muscles. We hypothesized that patients with greater EMG activity of the deltoid or upper trapezius preoperatively would have greater shoulder strength or active ROM after RSA.…”