To gain an understanding of how patients having had reverse total shoulder arthroplasty (rTSA) accomplish HT elevation, the authors of Reverse Total Shoulder Arthroplasty Alters Humerothoracic, Scapulothoracic, and Glenohumeral Motion During Weighted Scaption studied ST and GH motion during elevation of the unweighted and weighted arm in the plane of the scapula (scaption).
The subjects included 10 patients >1 year after rTSA (six males, four females; age 73 ± 8 years) who could perform pain-free scaption of the unweighted arm.
All rTSA patients received Grammont-style implants inserted by the same highly experienced surgeon.
These patients were compared to 10 participants with non-pathologic shoulders (five males, five females; age 58 ± 7 years).
Participants in both groups performed scaption without and with a 2.2-kg handheld weight while being imaged with biplane fluoroscopy. Maximum humerothoracic elevation and 3D scapulothoracic and glenohumeral kinematics across their achievable ROM were collected via dynamic imaging.
When compared with unweighted scaption, maximum humerothoracic elevation decreased during weighted scaption for patients who underwent rTSA (-25° ± 30°; p = 0.03) but not for the control group (-2° ± 5°; p = 0.35).
For the rTSA group the addition of 2.2 kg to the arm during scaption resulted in severe decreases in maximum HT elevation (> 35°) for 4 patients, moderate decreases (10° to 20°) for 3 patients, and negligible decreases (< 10°) in 3 patients.
Participants in both groups performed scaption without and with a 2.2-kg handheld weight while being imaged with biplane fluoroscopy. Maximum humerothoracic elevation and 3D scapulothoracic and glenohumeral kinematics across their achievable ROM were collected via dynamic imaging.
When compared with unweighted scaption, maximum humerothoracic elevation decreased during weighted scaption for patients who underwent rTSA (-25° ± 30°; p = 0.03) but not for the control group (-2° ± 5°; p = 0.35).
For the rTSA group the addition of 2.2 kg to the arm during scaption resulted in severe decreases in maximum HT elevation (> 35°) for 4 patients, moderate decreases (10° to 20°) for 3 patients, and negligible decreases (< 10°) in 3 patients.
Information on the positioning and orientation of the glenosphere and humeral components for these different groups is not provided.
The control participants showed no loss of active elevation with the addition of the weight.
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
The control participants showed no loss of active elevation with the addition of the weight.
The figure below compares the maximum active scaption for unweighted (left) and weighted arms for patients having rTSA (in red) and controls (in black).
For the 4 rTSA patients having good active elevation of the unweighted arm but weighted scaption of less than 90°, humerothoracic elevation was accomplished using almost exclusively scapulothoracic motion, with little glenohumeral contribution as shown in the diagram below ("A" unweighted, "B" weighted).
Weighted scaption demonstrated a strong correlation with the Simple Shoulder Test score (r = 0.76; p = 0.01).
For the 4 rTSA patients having good active elevation of the unweighted arm but weighted scaption of less than 90°, humerothoracic elevation was accomplished using almost exclusively scapulothoracic motion, with little glenohumeral contribution as shown in the diagram below ("A" unweighted, "B" weighted).
Weighted scaption demonstrated a strong correlation with the Simple Shoulder Test score (r = 0.76; p = 0.01).
Comment: These results suggest that - in some patients having rTSA - the deltoid is unable to generate sufficient force to elevate the modestly loaded arm resulting in reduced comfort and function as reflected by lower Simple Test Scores. It is not clear to what degree the inability to actively elevate the loaded arm is the result of poor conditioning of the deltoid muscle or to differences in muscle tensioning and moment arms related to implant size and position.
We are left with at least two questions:
(1) can rehabilitative exercises directed at the deltoid muscle improve active elevation of the weighted arm after rTSA?
(2) what rTSA implant selection and positioning variables correlate with the ability to actively elevate the weighted arm?
You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link.
To add this blog to your reading list in Google Chrome, click on the reading list icon
Follow on twitter: https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
