Kinematics and EMG activity in Reverse Total Shoulder Arthroplasty

Smith, Ryan; Woolley, Katherine; Mazzocca, Augustus D.; Feinn, Richard; Cote, Mark P.; Gomlinski, Gregg; Garbalosa, Juan C.; Myrick, Karen M.

doi:10.1016/j.jor.2020.04.017

Cited by 9 publications

(4 citation statements)

References 11 publications

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“…[ 17 ] and Smith al . [ 18 ] showed a significant increase in the EMG activity of the MD after surgery during abduction. Furthermore, Yoon et al .…”

Section: Discussionmentioning

confidence: 99%

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Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study

et al. 2021

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Background Lateralization of the glenoid implant improves functional outcomes in Reverse Shoulder Arthroplasty. Lateralization does not appear to impact the Deltoid’s Moment Arm. Therefore, the stabilizing effect described in the literature would not be the result of an increase this moment arm. A static biomechanical model, derived from Magnetic Resonance Imaging, can be used to assess the coaptation effect of the Middle Deltoid. The objective of this study was to analyze the impact of increasing amounts of glenoid lateralization on the moment arm but also on its coaptation effect. Methods Eight patients (72.6 ± 6.5 years) operated for Reverse Shoulder Arthroplasty were included in the study. Three-dimensional models of each shoulder were created based on imaging taken at 6 months postoperative. A least square sphere representing the prosthetic implant was added to each 3D models. A static biomechanical model was then applied to different planar portions of the Middle Deltoid (from 3D models), first without lateralization and then with simulated lateralization of 6, 9 and 12mm. This static model enables to compute a Coaptation/Elevation Ratio and to measure the Deltoid’s Moment Arm. The inter- and intra-rater agreement of the 3D models was evaluated. Results One patient was excluded due to motion during imaging. The inter- and intra-rater agreement was over 0.99. The ratio increased starting at 6 mm of lateralization (p<0.05), compared to the initial position. The moment arm was not affected by lateralization (p<0.05), except in two slices starting at 9 mm (S1 p<0.05 and S2 p<0.05). Conclusion Our hypothesis that the Middle Deltoid’s coaptation role would be greater with glenosphere lateralization was confirmed. This trend was not found in the moment arm, which showed little sensitivity to lateralization. The stabilizing effect therefore appears to stem from the coaptation role of the Middle Deltoid.

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“…[ 17 ] and Smith al . [ 18 ] showed a significant increase in the EMG activity of the MD after surgery during abduction. Furthermore, Yoon et al .…”

Section: Discussionmentioning

confidence: 99%

“…[ 17 ] and Smith et al . [ 18 ] showed that the Middle Deltoid (MD) has key role after RSA with an increase of EMG activity after surgery. Thus, a specific focus on this part of the deltoid muscle is clinically relevant.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study

et al. 2021

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“…Due to fibrosis and atrophy after arthrodesis, the function of the rotator cuff muscles is absent[ 4 , 6 ]. Therefore, the deltoid muscle function is critical to shoulder function after RSA[ 7 , 8 ]. Li et al[ 8 ] have suggested that preoperative EMG measurements of the deltoid muscle will help to predict the postoperative outcome of RSA.…”

Section: Discussionmentioning

confidence: 99%

Conversion to reverse shoulder arthroplasty fifty-one years after shoulder arthrodesis: A case report

Dogger¹,

Bemmel²,

Alta³

et al. 2020

WJO

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BACKGROUND Patients with a shoulder arthrodesis generally experience restriction in range of motion and limitations in activities of daily living. In addition, up to one-third of the patients deals with serious peri scapular pain. The conversion of a shoulder arthrodesis in a reverse shoulder arthroplasty (RSA) has been described as an effective treatment to achieve better function and decreased pain, although literature is sparse. We present the case of a conversion from a painful shoulder arthrodesis to RSA, after a 51 years interval. CASE SUMMARY A 71-year-old male presented with severe peri scapular pain and limited function 51 years after shoulder arthrodesis. Preoperative workup showed a normal bone stock of the glenoid and an intact axillary nerve, but atrophic posterior part of the deltoid muscle. The shoulder arthrodesis was successfully converted to RSA. Twelve months postoperative the patient was very satisfied. He has no pain at rest, nor with exercise and experienced definite improvements in activities of daily living, despite his limited range of motion. CONCLUSION Conversion from shoulder arthrodesis to a RSA can be performed safely, with a high chance of peri scapular pain relief; even after a longstanding arthrodesis.

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“…Muscle activity or adaptation can be assessed through muscle tests, invasively using small needle electrodes, or with surface electrodes adhered to the skin. Surface electromyography (sEMG) has recently shown to be a valid and noninvasive tool for quantifying individual muscle activation in the shoulder and has been used extensively in clinical diagnostic and rehabilitation settings [3,[6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Surface Electromyography Reveals Middle Deltoid as The Functionally Dominant Shoulder Muscle After Reverse Total Shoulder Arthroplasty

Lau

Pietroski

Franovic

et al. 2021

Preprint

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Background: Reverse total shoulder arthroplasty (RSA) increases deltoid muscle fiber recruitment and tension to compensate for deficient rotator cuff activity; however, it is unclear whether the anterior or middle deltoid becomes dominant and how the muscle activation profile changes postoperatively. Using minimally invasive electromyography, this study evaluated the activity of the deltoid and surrounding muscles during shoulder motion to assess muscle activation changes post-RSA. Methods: In this observational study, we assessed change in preoperative to postoperative shoulder muscle activation in 10 patients over 6 months. Muscle activation was measured using 8 surface electrodes. Activation of the anterior, middle and posterior deltoid and surrounding muscles were recorded during shoulder abduction, flexion, external and internal rotation were quantified. One-way analysis of variance was used to identify significant differences in activation and time or speed. Least significant difference post hoc test was used to determine specific differences in muscle activation at subsequent time points. Results: RSA shoulders at 6 months postoperative showed a significant increase in activity of the middle deltoid predominantly. Middle deltoid activation increased during abduction (P < 0.001), flexion (P = 0.008), external (P < 0.001) and internal (P < 0.001) rotation. Conclusions: Our study demonstrates the middle deltoid predominates in rotator cuff function in RSA as defined by quantitative activation, significant involvement in all shoulder motions, and increased activation at subsequent times. These findings may help guide future RSA designs to optimize deltoid wrapping allowing for maximal strength and efficiency.

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Kinematics and EMG activity in Reverse Total Shoulder Arthroplasty

Cited by 9 publications

References 11 publications

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study

Conversion to reverse shoulder arthroplasty fifty-one years after shoulder arthrodesis: A case report

Surface Electromyography Reveals Middle Deltoid as The Functionally Dominant Shoulder Muscle After Reverse Total Shoulder Arthroplasty

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Kinematics and EMG activity in Reverse Total Shoulder Arthroplasty

Cited by 9 publications

References 11 publications

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study

Conversion to reverse shoulder arthroplasty fifty-one years after shoulder arthrodesis: A case report

Surface Electromyography Reveals Middle Deltoid as The Functionally Dominant Shoulder Muscle After Reverse Total Shoulder Arthroplasty

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Surface Electromyography Reveals Middle Deltoid as The Functionally Dominant Shoulder Muscle After Reverse Total Shoulder Arthroplasty