Anatomic and reverse total shoulder arthroplasty - comparing functional outcomes

How arthroplasty outcomes are measured matters.

Some measures, such as the VAS Pain score , ask the patient characterize their pain as a single number on a visual analog scale extending from 0 (no pain) to 10 (worst possible pain). Other measures, such as the SANE score, ask the patient to rate the shoulder on a scale from 0 to 100, with 100 being the patient’s normal. By contrast, the Simple Shoulder Test provides greater granularity of outcome asking the patient to indicate their ability to perform each of 12 activities relating to their shoulder comfort and function, recognizing that some of these functions may be important to one patient, but less important to another.

Which metric to use depends on the question being addressed. The importance of selecting the appropriate outcome measure is demonstrated by Internal rotation based activities of daily living show limitations following reverse shoulder arthroplasty versus anatomic shoulder arthroplasty The authors of this work conducted a retrospective study of patients who underwent total shoulder arthroplasty between 2009-2020. 

Included were 208 patients, 114 anatomic total shoulders (aTSA), and 94 reverse total shoulders (rTSA). While the age, sex and followup averages for the two groups were similar, the indications for surgery were different: 110/114 aTSAs were performed for arthritis, 70/94 rTSAs were performed for cuff tear arthropathy.

As shown below, the SANE, VAS pain and ASES scores were similar for the two procedures, whereas the total SST scores averaged lower for the rTSA group.

The activities that showed significant disparity between aTSA and rTSA were toileting (p=0.001), donning a coat (p=0.017), reaching one’s back (p=0.017), as well as throwing overhand (0.013) with rTSA patients reporting more difficulty in all these ADLs. 

Comment: An interesting facet of this study is that the measured ranges of motion were similar for the two procedures (144 degrees of forward flexion and internal rotation to L5), however patients with rTSA had less functional ability to lift 1 and 8 pounds onto a shelf, lifting 10 pounds overhead, throwing overhand, toileting, dressing, and reaching behind the head.  These functional differences may relate to the difference in cuff status between the to groups.

This study points to the value of outcome metrics that provide information on specific functions, rather than reporting a single number. Only with function specific measures will researchers be able to identify the factors associated with the patient's ability do perform their desired activities.

Comments welcome at shoulderarthritis@uw.edu

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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). 

Internal rotation after Grammont-style reverse total shoulder - what factors are important?

Internal rotation in adduction is needed for activities of daily living, such as tucking in a shirt, fastening a bra, and perineal hygiene. Disabling loss of the ability to reach behind the body occurs frequently after reverse total shoulder arthroplasty (RTSA).

The authors of High and low performers in internal rotation after reverse total shoulder arthroplasty: A biplane fluoroscopic study sought to compare three dimensional humerothoracic, scapulothoracic, and glenohumeral joint relationships in patients one year after rTSA with and without functional internal rotation using biplane fluoroscopy.

All shoulders had a Grammont-style rTSA without offset of the glenosphere center of rotation

Subjects could either perform internal rotation in adduction with their hand at T12 or higher (high, N=7), or below the hip pocket (low, N=8).

Scapular and humeral positions were measured:

They found that the Simple Shoulder Test was highest in the high group (11±1 versus 9±2).
Both question #3 (Can you reach the small of your back to tuck in your shirt with your hand?) and #11 (Can you wash the back of your opposite shoulder with the affected extremity?) were less frequently answered “yes” by the low group (4/8) in comparison to the high group (6/7).

In the internal rotation in adduction position, the high group showed higher axial rotation of the humerus ( >45°) and a greater change in scapular tilt (15-30° ) than the low group.

In this study, notching and impingement below the glenoid were not found to correlate with internal rotation in adduction.

The conclusion is that both glenohumeral rotation and scapulothoracic mobility are important contributors to the ability to reach up the back after rTSA

The authors of another recent study, Extension of the Shoulder is Essential for Functional Internal Rotation After Reverse Total Shoulder Arthroplasty proposed that limitation of reach behind the body after RTSA may not be primarily related to a deficit of glenohumeral internal rotation but rather due to a lack of humerothoracic extension.

Fifty patients having RTSA were examined with special attention to reach behind the body: “reaching the back pocket”, “personal toileting hygiene”, “tucking a shirt into the pants behind the back”, “pulling-up pants behind the back”. For analysis, patients were divided into a group with poor reach behind the body (n=19) and a group with good reach behind the body (n=31).

Active extension of the arm in relation to the body for the opposite shoulders was similar in both groups (60±11 and 66±14) (measured as shown below).

After RTSA, active humerothoracic extension on the operated side averaged 55±14 degrees in the shoulders with good reach behind the body and 39±11 degrees in the shoulders with poor reach behind the body. The differences in extension between the RTSA side and the contralateral side averaged 11 degrees for those with good reach behind the body and 21 degrees in the shoulders with poor reach behind the body.

No patient with good reach behind the body had active humerothoracic extension less than 40 degrees.

The authors concluded that good reach behind the body after RTSA requires at least 40° of humerothoracic extension. If reach behind the body is unsatisfactory despite 40° of humerothoracic extension, restriction of internal rotation in full extension may be the limiting factor.

Comment: This is an important paper because it points out that while the ability to reach various anatomic landmarks behind the body is often referred to as "internal rotation", the situation is a bit more complex because functions behind the body depend on humerothoracic and humeroscapular motion

The importance of distinguishing humerothoracic and humeroscapular motion was pointed out in two articles published in 1992, Laxity of the normal glenohumeral joint: A quantitative in vivo assessment and A system for describing positions of the humerus relative to the thorax and its use in the presentation of several functionally important arm positions. In these papers, the motion of the humerus relative to the thorax and the motion of the humerus in relation to the scapula were tracked separately and simultaneously in living subjects using electromagnetic receivers attached to pins inserted in the scapula (S), and humerus (H), while a transmitter was fixed to the thorax (T). Direct attachment of the sensors to bone avoided the artifacts associated with markers placed on the skin. This system enabled real-time recording of the six-degree-of freedom relationships among the humerus, scapula and thorax during active motions in vivo.

Some of the key findings from these studies are presented in the 1994 book, Practical Evaluation and Management of the Shoulder - a free copy of which can be obtained here.

The plane of humeral motion in relation to the plane of the body along with the degrees of elevation was recorded for each of the common activities of daily living.






The results can be displayed on a global diagram in the lateral and frontal projections as shown below.





Here are the humerothoracic positions for common activities. Note that in contrast to the other activities, reach behind the body (tucking in the shirt behind - gold dot in the figure below) required elevation in extension (i.e. in a plane posterior to the plane of the body). All of the other functions were performed in planes anterior to the plane of the body.




This result is also shown in the table below





The humerothoracic planes of elevation needed for seven of the Simple Shoulder Test functions are shown below.


The discussion above pertains to motion of the humerus relative to the plane of the body.


A similar analysis can be performed for the motion of the humerus relative to the plane of the scapula.

and displayed on humeral scapular global diagrams in which the plane of the scapula is the reference.

Note that reach up the back (tucking in the shirt) requires humeroscapular extension (gold dot).








Thus, reach behind the body requires humerothoracic extension (elevation in a plane posterior to the plane of the body) which is provided by humeroscapular extension (elevation posterior to the plane of the scapula). This is because the ability of the scapula to "extend" on the thorax is limited.




This analysis of in vivo relative motions of the humerus, scapula and thorax during functions of daily living also reveals that reach up the back (tucking in a shirt) also requires internal rotation of the humerus relative to the scapula (gold dot).


From the foregoing we can conclude that the functionally import motions requiring reach behind the body depend on both humerothoracic extension (which relates closely to humeroscapular extension) and humeroscapular internal rotation.

In trying to optimize the function of our patients having RTSA, we should consider whether tightening the strap muscles (which lie anterior to the glenohumeral joint) during RTSA may be one of the potential causes of limited extension and whether contact between the lesser tuberosity and the glenoid may be one the potential causes of limited humeroscapular internal rotation.


As always, there's a trade off. The combination of adduction, internal rotation, and extension is recognized as the position in which dislocation of a RTSA is most likely: "The simple act of reaching behind to scratch the middle of your back or (for women) undoing a bra-strap can dislocate a reverse shoulder implant. This action places the arm in a position of extension, adduction (arm close to the body), and internal rotation." (see this link and this link and this link).

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link.

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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).

Reverse total shoulder: how to get the "internal rotation" needed for function

 Extension of the Shoulder is Essential for Functional Internal Rotation After Reverse Total Shoulder Arthroplasty

These authors point out that the ability to reach behind the body enables critical activities of daily living, such as perineal hygiene, reaching a wallet in the back pocket, tucking in a shirt and fastening a bra. They observe that disabling loss of the ability to reach behind the body occurs frequently after reverse total shoulder arthroplasty (RTSA).

They proposed that limitation of reach behind the body after RTSA may not primarily related to a deficit of glenohumeral internal rotation but rather due to a lack of humerothoracic extension.

Fifty patients having RTSA were examined with special attention to reach behind the body: “reaching the back pocket”,  “personal toileting hygiene”, “tucking a shirt into the pants behind the back”, “pulling-up pants behind the back”. For analysis, patients were divided into a group with poor reach behind the body (n=19) and a group with good reach behind the body (n=31).

Active extension of the arm in relation to the body for the opposite shoulders was similar in both groups (60±11 and 66±14) (measured as shown below).

After RTSA, active humerothoracic extension on the operated side averaged 55±14 degrees in the shoulders with good reach behind the body and 39±11 degrees in the shoulders with poor reach behind the body. The differences in extension between the RTSA side and the contralateral side averaged 11 degrees for those with good reach behind the body and 21 degrees in the shoulders with poor reach behind the body.

No patient with good reach behind the body had active humerothoracic extension less than 40 degrees.

The ability to reach behind the body correlated better with humerothoracic extension than with "internal rotation" measurements.

The authors concluded that good reach behind the body after RTSA requires at least 40° of humerothoracic extension. If reach behind the body is unsatisfactory despite 40° of humerothoracic extension, restriction of internal rotation in full extension may be the limiting factor. 

Comment: This is an important paper because it points out that while the ability to reach various anatomic landmarks behind the body is often referred to as "internal rotation", 

the situation is a bit more complex because functions behind the body depend on humerothoracic and humeroscapular motion 

The importance of distinguishing humerothoracic and humeroscapular motion was pointed out in two articles published in 1992,  Laxity of the normal glenohumeral joint: A quantitative in vivo assessment and A system for describing positions of the humerus relative to the thorax and its use in the presentation of several functionally important arm positions. In these papers, the motion of the humerus relative to the thorax and the motion of the humerus in relation to the scapula were tracked separately and simultaneously in living subjects using electromagnetic receivers attached to pins inserted in the scapula (S),  and humerus (H), while a transmitter was fixed to the thorax (T). Direct attachment of the sensors to bone avoided the artifacts associated with markers placed on the skin. This system enabled real-time recording of the six-degree-of freedom relationships among the humerus, scapula and thorax during active motions in vivo.

Some of the key findings from these studies are presented in the 1994 book, Practical Evaluation and Management of the Shoulder - a free copy of which can be obtained here.

The plane of humeral motion in relation to the plane of the body along with the degrees of elevation was recorded for each of the common activities of daily living.

The results can be displayed on a global diagram in the lateral and frontal projections as shown below.

Here are the humerothoracic positions for common activities. Note that in contrast to the other activities, reach behind the body (tucking in the shirt behind - gold dot in the figure below) required elevation in extension (i.e. in a plane posterior to the plane of the body). All of the other functions were performed in planes anterior to the plane of the body.

This result is also shown in the table below

The humerothoracic planes of elevation needed for seven of the Simple Shoulder Test functions are shown below.

The discussion above pertains to motion of the humerus relative to the plane of the body.

A similar analysis can be performed for the motion of the humerus relative to the plane of the scapula.

and displayed on humeral scapular global diagrams in which the plane of the scapula is the reference.

Note that reach up the back (tucking in the shirt) requires humeroscapular extension (gold dot).

Thus, reach behind the body requires humerothoracic extension (elevation in a plane posterior to the plane of the body) which is provided by humeroscapular extension (elevation posterior to the plane of the scapula).  This is because the ability of the scapula to "extend" on the thorax is limited. 

This analysis of in vivo relative motions of the humerus, scapula and thorax during functions of daily living also reveals that reach up the back (tucking in a shirt) also requires internal rotation of the humerus relative to the scapula (gold dot).

From the foregoing we can conclude that the functionally import motions requiring reach behind the body depend on both humerothoracic extension (which relates closely to humeroscapular extension) and humeroscapular internal rotation. 

In trying to optimize the function of our patients having RTSA, we should consider whether tightening the strap muscles (which lie anterior to the glenohumeral joint) during RTSA may be one of the potential causes of limited extension and whether contact between the lesser tuberosity and the glenoid may be one the potential causes of limited humeroscapular internal rotation.

As always, there's a trade off. The combination of adduction, internal rotation, and extension is recognized as the position in which dislocation of a RTSA is most likely: "The simple act of reaching behind to scratch the middle of your back or (for women) undoing a bra-strap can dislocate a reverse shoulder implant. This action places the arm in a position of extension, adduction (arm close to the body), and internal rotation." (see this link and this link and this link). 

Follow on twitter: https://twitter.com/shoulderarth

Follow on facebook: https://www.facebook.com/frederick.matsen

Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

How you can support research in shoulder surgery Click on this link.

Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link)

Shoulder arthritis - x-ray appearance (see this link)

The smooth and move for irreparable cuff tears (see this link)

The total shoulder arthroplasty (see this link).

The ream and run technique is shown in this link.

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

Measuring internal rotation in abduction - the key to diagnosing posterior capsular tightness

Accuracy and reliability testing of two methods to measure internal rotation of the glenohumeral joint

The authors compared the accuracy and reliability of a traditional method of measurement (most cephalad vertebral spinous process that can be reached by a patient with the extended thumb) to estimates made with the shoulder in abduction to determine if there were differences between the two methods.

Internal rotation estimates made with the shoulder abducted demonstrated interobserver reliability superior to that of spinous process estimates, and reproducibility was high.

Comment: We use this method as well. Here's a nice illustration from a website:

It nicely shows how to examine the shoulder for loss of internal rotation with the arm abducted.

Interestingly, pain on this test used to be called a positive 'impingement sign'.

Such an internal rotation deficit can often be resolved by the sleeper stretch.

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