What happens to the brachial plexus after reverse total shoulder arthroplasty?

 Elongation of the brachial plexus after reverse shoulder arthroplasty: an anatomical study 

These authors remind us that the reverse total shoulder (RSA) lowers and medializes the center of rotation of the shoulder causing an arm lengthening. Although the reported rate of neurological complications is low, the brachial plexus is put under additional tension by this procedure.

Their goal was to quantify the lengthening of the terminal branches of the brachial plexus associated with RSA implantation (SMR®(Lima) and Delta  Xtend®(DePuy-Synthes) in 20 embalmed cadavers.

The mean arm elongation was 10.5 mm. The subacromial space was increased by 20.5–29.8%. 

All the neurovascular structures were elongated: median nerve 23.1%, musculocutaneous nerve 22.1%, ulnar nerve 19%, radial nerve 17%, axillary nerve 12–14.5%, axillary artery 24.8%. 

See this related post on nerve injuries after RSA (see this link).

Here are two related articles

Arm lengthening after reverse shoulder arthroplasty: a review

These authors find that "arm lengthening during RSA, because of its nonanatomical design and/or manoeuvre of glenohumeral reduction, may be a major factor responsible for the increased prevalence of neurological injury."

Is radiographic measurement of acromiohumeral distance on anteroposterior view after reverse shoulder arthroplasty reliable?

These authors observe that different techniques have been described to determine postoperative lengthening of the arm after reverse total shoulder arthroplasty. They evaluated the reliability of the acromiohumeral distance (AHD) in determining arm lengthening after reverse shoulder arthroplasty. 
The AHD was defined as distance between the most lateral part of the undersurface of the acromion perpendicular to a line parallel to the top of the greater tuberosity.

They studied 44 patients who had received a reverse shoulder arthroplasty, examining preoperative and postoperative radiographs on anteroposterior view in neutral rotation. 

Mean arm lengthening averaged 2.5 cm (range, 0.3-3.9 cm) according to AHD measurement. Significant differences in interobserver and intraobserver variability for postoperative AHD measurements were found (P < .01). The mean intrapatient difference was 0.5 cm (range, 0.02-1.5 cm). They concluded that the AHD is not a reliable measurement technique to determine arm lengthening after reverse shoulder arthroplasty.

Two patients sustaining a fracture of the scapular spine were successfully treated conservatively; postoperative arm lengthening in these cases averaged 2.5 cm.

Comment:  These authors state "Reverse shoulder arthroplasty leads to arm lengthening." This is surely borne out by this study in which the average arm lengthening was one inch and the maximum lengthening was one and one half inch. This lengthening results in part from the nature of the reverse and in part from the technique of positioning the glenoid baseplate flush or below the inferior aspect of the glenoid and with some inferior inclination.

The inferior displacement of the humeral tuberosity results in an increase in the distance between the acromion and the greater tuberosity and carries the potential risk of acromial fatigue fracture (see this link) and  excessive traction on the brachial plexus (see this link). A recent article (see this link) concludes "Excessive arm lengthening should be avoided, with zero to two centimeters of lengthening being a reasonable goal to avoid postoperative neurological impairment."

We note that another way of assessing inferior humeral displacement is to look at the integrity of the Arch formed by the medial proximal humerus and the lateral border of the scapula. By comparing the preoperative and postoperative views one can see the discontinuity of the Arch in this particular case of reverse total shoulder.

 

We will leave it to the reader to decide if the normal shoulder has a Roman Arch like the Arch of Caracalla at Volubilis

Or a Gothic Arch like the portal of Notre Dame in Paris

Some refer to the Arch as "Shenton's line," but we know that the Shenton line is one drawn along the inferior border of the superior pubic rams and along the inferior medial border of the neck of the femur. 

Others refer to the Arch as "Bani's line" which was described in 1981 (Bandi W (1981) Die Läsion der Rotatorenmanschette. Helv Chir Acta 48:537-549). 

We like just calling it the Arch; any disruption is apparent.

An approach to reverse total shoulder arthroplasty that relies more on "East-West" soft tissue tensioning rather than only on "Southern" deltoid tensioning may reduce the amount of arm lengthening as shown by less disruption of the Arch.

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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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 - what factors affect the outcome and complications?

Outcomes after a Grammont-style reverse total shoulder arthroplasty?

These authors evaluated 230 RTSAs performed by the senior author with 70% follow-up at a median of 3.4 years.

Increased postoperative glenoid inclination was significantly associated with increased VAS pain scores postoperatively. 

Female gender, and lower body mass index (BMI) were associated with worse Simple Shoulder Test (SST) scores, ASES scores, and VAS-pain scores. 

Female gender and lower BMI were associated with worse SST scores. 

Postoperative distalization was associated with reoperation or complication. Adjusting for the other variables in the model, a 1-mm increase in distalization was associated with a 6% increased odds of reoperation or complication.

Of the included shoulders, 18% (41/230) suffered either a complication or reoperation postoperatively; 3.4% of shoulders had postoperative instability (8/230). One percent of shoulders developed a recurrence of a prior known infection (3/230), and 4% (9/230) of shoulders suffered a new postoperative infection (3 in primary RTSAs and 6 in revision RTSAs). Of these, 1% (3/230) were deep infections requiring operative irrigation and debridement and the other 3% (6/230) were superficial infections responding to antibiotics. Three percent of shoulders had a postoperative acromial fracture (7/230), and none of these

patients had a history of trauma. One percent of shoulders had persistent pain at the strap tendon requiring operative release (3/230), and 1% of shoulders had postoperative hematomas (2/230). Two percent of shoulders had glenoid loosening (2 in the context of a glenoid bone graft and 1 in the context of infection, 4/230). One percent (3/230) of shoulders had nerve injuries (1 median, 1 ulnar, and 1 diffuse plexopathy), all of which resolved. Two percent of shoulders (5/230) had other complications including a postoperative seizure, a postoperative fall with a glenoid neck fracture, and postoperative thromboembolic events.

Comment: This is an interesting study of the outcomes of a large single-surgeon experience. While 71% of the patients were female, female patients tended to have inferior outcomes. Contrary to common understanding, lower BMI was a risk factor for inferior outcomes. Superior gleonoid inclination was all a risk factor. And finally, increased distalization of the humerus was associated with inferior outcomes and complications. Of note the average distalization was 29 mm in this series.

To see a YouTube of our technique for a reverse total shoulder arthroplasty in which we try to minimize distalization, click on this link.

To support our research to improve outcomes for patients with shoulder problems, click here.

To subscribe to this blog, enter your email in the box to your right that looks like the below

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

We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Reverse total shoulder: does prior acromioplasty increase the risk of acromial fracture?

 Incidence and risk factors of acromial fracture following reverse total shoulder arthroplasty

These authors sought to determine the incidence and risk factors for acromial fractures after reverse total shoulder (RTSA), comparing 29 patients with acromial fracture and 758 without this complication (3.7% incidence).

Acromial fractures were detected at a mean of 10.0 months (range 1-66) postoperatively. The occurrence of an acromial fracture was associated with a previous operation, deltoid lengthening, and low bone mineral density.

Eleven cases with postoperative acromial fractures had a history of a shoulder operation (rotator cuff repair with acromioplasty in 8, infection control surgery for pyogenic arthritis in 2, and total shoulder arthroplasty in 1).

Acromioplasty thins the acromion, making it more susceptible to fracture. Secondly, acromioplasty involves transection of the coracoacromial ligament, which, as shown in the article below, increases strain on the scapular spine.

Scapular Ring Preservation: Coracoacromial Ligament Transection Increases Scapular Spine Strains Following Reverse Total Shoulder Arthroplasty

Stating that the coracoacromial ligament (CAL) is often transacted during surgical exposure for reverse total shoulder arthroplasty (RSA), these authors hypothesized that the CAL contributes to the structural integrity of the “scapular ring” and that the transection of this ligament during RSA alters the scapular strain patterns in a way that may contribute to scapular fractures following this procedure.

They performed RSA on 8 cadaveric specimens and measured strains at the acromion and scapular spine before and after CAL section while a shoulder simulator positioned the joint in 0, 30, and 60 of glenohumeral abduction.

With the CAL intact, there was no significant difference between strain experienced by the acromion and scapular spine at 0, 30, and 60 of glenohumeral abduction. 

CAL transection generated significantly increased strain in the scapular spine at all abduction angles compared with an intact CAL. 

They concluded that the  CAL is an important structure that completes the “scapular ring” and therefore serves to help distribute strain in a more normalized fashion. 

In his 1934 book, E. A. Codman wrote prophetically, "The coracoacromial ligament has an important duty and should not be thoughtlessly divided at any operation."

We have not found it necessary to divide the CAL "at any operation." Not only is it a halyard stabilizing the scapular spine and acromion to the robust coracoid process, as suggest by this study, but it is also an essential element of the stabilizing coracoacromial arch.

which, when sacrificed, risks anterosuperior escape

which, in turn, is one of the reasons for performing a reverse total shoulder. 

So, we agree with Codman, "The coracoacromial ligament has an important duty and should not be thoughtlessly divided at any operation."

To see a YouTube of our technique for a reverse total shoulder arthroplasty, click on this link.

To support our research to improve outcomes for patients with shoulder problems, click here.

To subscribe to this blog, enter your email in the box to your right that looks like the below

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

We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Reverse total shoulder - arm length, function and complications

Does arm lengthening affect the functional outcome in onlay reverse shoulder arthroplasty?

These authors have introduced an onlay design reverse shoulder arthroplasty to overcome complications observed with the traditional Grammont-type prosthesis. This study aimed to determine the influence of arm lengthening on the short-term clinical outcome in onlay reverse shoulder arthroplasty and investigate the effect of humeral tray offset positioning on arm lengthening and range of motion in 56 patients at a minimum 2 years’ follow-up. 

The Constant score improved from 25.5 to 71.5 points at a mean follow-up.  Mean postoperative anterior elevation was 145.2° and external rotation was 30.7°  Arm lengthening exceeding 2.5 cm was related to a decrease in anterior elevation. 

Arm lengthening averaging 1 to 2.5 cm was found to be the best compromise on postoperative range of motion.

Humeral tray positioning demonstrated no influence on the functional outcome.

Postoperative complications occurred in 8 patients (14%)  There was no significant difference in arm lengthening compared with patients without complications. 

Three patients sustained a fracture of the acromion or scapular spine at 2, 3, and 36 months.  All fractures were treated conservatively in an abduction brace for 6 weeks. 

There were 2 dislocations at 3 and 18 months postoperatively treated with open reduction and exchange of the polyethylene liner.

A postoperative brachial palsy developed in 1 patient and was revised 8 weeks later. Arm lengthening compared with the contralateral side was 5 cm.

Aseptic glenoid loosening occurred in 1 patient at 25 months.

A chronic infection with Staphylococcus saprophyticus developed in 1 patient at 21 months.

Comment: These authors have developed a new design feature of the reverse total shoulder. It is not clear whether the ability to adjust the position of the humeral tray will improve outcomes or decrease complications. They point to the potential risks of over lengthening the arm.

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The reader may also be interested in these posts:

Healing through joint replacement

Supporting progress in shoulder surgery

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book.

Click here to see the new Rotator Cuff Book

Information about shoulder exercises can be found at this link.

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.

Perfusion and stiffness of the deltoid after reverse total shoulder

Dynamic contrast-enhanced ultrasound and elastography assess deltoid muscle integrity after reverse shoulder arthroplasty.

These authors point out that the functioning of a reverse shoulder arthroplasty (RSA) depends on the condition of the deltoid muscle. They studied 64 patients having RSA using postoperative contrast-enhanced ultrasound (CEUS) to assess perfusion and acoustic radiation force impulse (ARFI) to assess elasticity of the deltoid muscle and compared these results with the clinical and functional outcome.

After RSA, they found that deltoid perfusion was inferior compared with the contralateral side. The perfusion deficit was associated with a limited range of motion and poorer clinical outcomes. The deltoid of the operated shoulder showed higher stiffness than the contralateral muscles. EMGs excluded functionally relevant axillary nerve injuries in the study population.

They conclude that functional shoulder impairment after RSA might be predicted by noninvasive CEUS as a measure of the integrity of the deltoid muscle.

Comment: A difficulty with this study is that we cannot be sure what the contrast-enhanced ultrasound (CEUS) and acoustic radiation force impulse (ARFI) showed before surgery. If, as the authors suggest, functional shoulder impairment after RSA might be predicted by noninvasive CEUS and ARFI, it would be important to obtain theses studies before surgery to determine how well they predicted the result.

There is another consideration, and that is that the perfusion and stiffness of the deltoid after RSA surgery may be caused by the arm lengthening that may accompany this procedure as shown below and as discussed in this link.

Our approach to reverse total shoulder arthroplasty is shown in this link. We attempt to minimize arm lengthening by avoiding excessive inferior placement and tilt of the glenosphere.

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Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.

 

Reverse total shoulder lengthens the arm - Roman and Gothic arches

Is radiographic measurement of acromiohumeral distance on anteroposterior view after reverse shoulder arthroplasty reliable?

These authors observe that different techniques have been described to determine postoperative lengthening of the arm after reverse total shoulder arthroplasty. They evaluated the reliability of the acromiohumeral distance (AHD) in determining arm lengthening after reverse shoulder arthroplasty. 
The AHD was defined as distance between the most lateral part of the undersurface of the acromion perpendicular to a line parallel to the top of the greater tuberosity.

They studied 44 patients who had received a reverse shoulder arthroplasty, examining preoperative and postoperative radiographs on anteroposterior view in neutral rotation. 

Mean arm lengthening averaged 2.5 cm (range, 0.3-3.9 cm) according to AHD measurement. Significant differences in interobserver and intraobserver variability for postoperative AHD measurements were found (P < .01). The mean intrapatient difference was 0.5 cm (range, 0.02-1.5 cm). They concluded that the AHD is not a reliable measurement technique to determine arm lengthening after reverse shoulder arthroplasty.

Two patients sustaining a fracture of the scapular spine were successfully treated conservatively; postoperative arm lengthening in these cases averaged 2.5 cm.

Comment:  These authors state "Reverse shoulder arthroplasty leads to arm lengthening." This is surely borne out by this study in which the average arm lengthening was one inch and the maximum lengthening was one and one half inch. This lengthening results in part from the nature of the reverse and in part from the technique of positioning the glenoid baseplate flush or below the inferior aspect of the glenoid and with some inferior inclination.

The inferior displacement of the humeral tuberosity results in an increase in the distance between the acromion and the greater tuberosity and carries the potential risk of acromial fatigue fracture (see this link) and  excessive traction on the brachial plexus (see this link). A recent article (see this link) concludes "Excessive arm lengthening should be avoided, with zero to two centimeters of lengthening being a reasonable goal to avoid postoperative neurological impairment."

We note that another way of assessing inferior humeral displacement is to look at the integrity of the Arch formed by the medial proximal humerus and the lateral border of the scapula. By comparing the preoperative and postoperative views one can see the discontinuity of the Arch in this particular case of reverse total shoulder.

 

We will leave it to the reader to decide if the normal shoulder has a Roman Arch like the Arch of Caracalla at Volubilis

Or a Gothic Arch like the portal of Notre Dame in Paris

Some refer to the Arch as "Shenton's line," but we know that the Shenton line is one drawn along the inferior border of the superior pubic rams and along the inferior medial border of the neck of the femur. 

Others refer to the Arch as "Bani's line" which was described in 1981 (Bandi W (1981) Die Läsion der Rotatorenmanschette. Helv Chir Acta 48:537-549). 

We like just calling it the Arch; any disruption is apparent.

An approach to reverse total shoulder arthroplasty that relies more on "East-West" soft tissue tensioning rather than only on "Southern" deltoid tensioning may reduce the amount of arm lengthening as shown by less disruption of the Arch.

=====

To see a YouTube of our technique for a reverse total shoulder arthroplasty, click on this link.

===

To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.

Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'