Nerve injuries after reverse total shoulder arthroplasty.

Persistent and Profound Peripheral Nerve Injuries Following Reverse Total Shoulder Arthroplasty

These authors point out that peripheral nerve injuries associated with reverse total shoulder arthroplasty (rTSA) are uncommonly recognized and are often dismissed as neuropraxias, particularly in the setting of perioperative nerve blocks. 

They conducted a retrospective review of 22 patients referred to a nerve injury service who had undergone rTSA and had a concomitant major nerve injury. The average time from surgery to referral to a nerve injury practice was 9.0 months.

 

Injury patterns were variable and involved diffuse pan-plexopathies with severity localized to the posterior and medial cords (11), the upper trunk (5), lateral cord (2) and axillary nerve (4). 

The average postoperative acromiohumeral distance (AHD) was 3.7 cm with an average change of 2.9 cm. 

17 patients were confirmed to have undergone preoperative nerve blocks, which were initially attributed as the etiology of nerve injury. 

18 patients were initially treated with observation: 11 experienced residual debilitating neuropathic pain and/or disability and 7 had substantial improvement. 

Complete axillary nerve injury was seen in 4 patients, of which none resolved spontaneously. Patients with upper trunk or lateral cord injuries spontaneously resolved over the course of their 18.8 month follow-up.  There were 13 cord level injuries of which 11 were medial/posterior cord combined injuries. These were the most serious, especially the medial cord injuries which severely affected hand function via ulnar nerve injury. Of these 11 posterior/medial cord injuries, all had altered ulnar nerve function with loss of intrinsic function, thumb adduction and digital flexion with altered ulnar nerve sensation. Four of the 11 required reconstructive hand surgery to improve their pattern of grasp. All 11 had disabilities consistent with permanent ulnar nerve dysfunction as evidenced by their high Quick DASH scores and need for neuropathic medications.

The authors concluded that these nerve injuries were secondary to traction at the time of arthroplasty, and/or substantial distalization and lateralization of the implants.

Comment: One of the important lessons from this study is that the use of nerve block anesthesia may prevent the surgeon from promptly recognizing a postoperative nerve injury and eliminate the possibility of prompt intervention. A second lesson is that these nerve injuries can be long lasting and disabling in terms of pain and loss of function.  A third lesson is that the average distalization of the humerus in these cases was 2.9 cm. While there is not a comparison group of measurements in reverses without nerve injuries, it seems likely that distalization can result in a traction injury to the nerves of the plexus as explained nicely in this link.

The nerve injuries reported in this article were major. It seems likely that many less severe injuries occur in association with reverse total shoulder arthroplasty and that these injuries might account for compromised deltoid function as well as postoperative pain.

While some surgeons prefer substantial distalization (below left), our technique (see this link) strives for a more anatomic reconstruction with only a small amount of distalizalization and less tension on the nerves (below right). We also avoid brachial plexus blocks on our patients having shoulder arthroplasty so that a complete examination can be documented in the recovery room.

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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).

 

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.

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).

Nerve and brachial plexus injuries during shoulder arthroplasty - causes and prevention

Brachial Plexus Injuries During Shoulder Arthroplasty: What Causes Them and How to Prevent Them

This very nice review points out that neurological complications have been reported to occur in 3% of hemiarthroplasties, 0.1% to 4% of anatomic total shoulder arthroplasties, and 2% to 4% of reverse total shoulder arthroplasties. The brachial plexus is most commonly involved. Observations in cadaver studies have suggested that the most likely etiology of these neuropathies is stretch of the brachial plexus secondary to patient arm positioning.

Nerves appear to be able to tolerate stretching of up to 10% of their length for short periods, but more stretching and longer periods can disrupt the blood supply or the anatomic integrity of the nerve. Cadaver and intraoperative nerve monitoring studies have identified shoulder abduction of >90 degrees; combinations of abduction, external rotation, and either flexion or extension; and combinations of adduction, extension, and either internal or external rotation as positions which cause nerve dysfunction.

While it is suggested that many of these injuries are transient, it is estimated that one in 100 shoulder arthroplasties are complicated by long lasting or permanent nerve injury.

Comment: While published data may suggest that one in 25 shoulder arthroplasties is complicated by a neurologic injury, we can suspect that the actual incidence is higher - both because such injuries may go unnoticed and because they are likely to be underreported. This article points out that at arthroplasty the nerves can be exposed to extraordinary stretching because the protective effects of pain and muscle tightness are removed by anesthesia, the protective effects of soft tissue contracture are removed by surgical releases, and the humerus is put in unnatural positions as the surgeon resects humeral osteophytes and exposes the glenoid for arthroplasty. 

While some surgeons rely on nerve monitoring to prevent clinical neurological injury, our approach is to recognize the 'positions of risk' and to assure that the surgical time spent in these positions is short, allowing for periods of 'nerve rest' with the arm back in a neutral position and with the retractors relaxed. We are particularly concerned about shoulders that have been very stiff prior to arthroplasty as well as shoulders of patients with diabetes or those on medications such as methotrexate. Positions of particular concern include (1) humeral external rotation and extension which stretches the median nerve, (2) coracoid muscle retraction to expose the glenoid which stretches the musculocutaneous nerve, and (3) traction on the arm which stretches the upper trunk of the brachial plexus (especially if the head is turned and inclined to the contralateral side). Overlengthening of the arm in reverse total shoulder is also known to be a risk factor for plexus injury. And, of course, brachial plexus block anesthetic carries a risk of neurologic injury.

Addition posts of interest can be found here.

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Nerve injuries in shoulder surgery

Iatrogenic Nerve Injuries During Shoulder Surgery

These authors reviewed the records of patients evaluated in a brachial plexus specialty clinic from 2000 to 2010 identifying 26 patients with iatrogenic nerve injury secondary to shoulder surgery (neurologically intact prior to surgery, treated with an open or arthroscopic shoulder procedure, and with a postoperative nerve injury). 

The average age was 43 years (17 - 72). The patients presented to the clinic at an average of 5.4 months after surgery.  7 nerve injuries resulted from open instability procedures, 9 from arthroscopic surgery, 4 from total shoulder arthroplasty, and 6 from a combined open and arthroscopic operation. The injury occurred at the level of the brachial plexus in 13 patients and at a terminal nerve branch in 13. 15 patients (58%) did not recover nerve function after observation. A structural nerve injury (laceration or suture entrapment) occurred in 9 patients (35%), including eight of the thirteen who presented with a terminal nerve branch injury and one of the thirteen who presented with an injury at the level of the brachial plexus.

Of particular interest to the shoulder arthroplasty surgeon is the observation that 3 of the 4 injuries associated with shoulder arthroplasty involved C5 and C6 nerve roots and/or the upper trunk of the brachial plexus. Two of these patients had regional nerve blocks, raising the possibility of block related nerve injury. There were no structural nerve injuries. 

As has been pointed out in the article Peripheral nerve function during shoulder arthroplasty using intraoperative nerve monitoring, the extreme positions necessary to perform a shoulder arthroplasty may put the upper plexus at risk from traction. Of particular concern is the 'barber poling' of the musculocutaneous nerve (C5 and 6) around the humerus when the arm is externally rotated and extended. This seems to be a particular problem in patients having limited external rotation before surgery. 

Our current practice is to limit to to 10 seconds the time the humerus is in an extreme position, giving the nerves 'a drink' with the arm in neutral before returning to the extreme position.

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Anesthesia for shoulder surgery, interscalene brachial plexus block vs. general anesthesia

In most cases, we prefer general anesthesia over brachial plexus block anesthesia for our shoulder arthroplasty and rotator cuff procedures.

The reasons for our recommendation are several:
General anesthesia allows us to monitor nerve function during and after the case - this is important with major shoulder reconstruction.
General anesthesia does not produce a transient paralysis of the diaphragm on the side of surgery.
General anesthesia wears off while the patient is in the recovery room when the high level of nursing is immediately available in contrast to blocks which wear off in the early hours of the morning when nurses are less available.
While the complication rate of either method is low, the complications of brachial plexus block anesthesia include the possibility of long lasting or permanent nerve injury.
We do consider brachial plexus anesthesia when there are special circumstances, such as opiod intolerance or strong patient preference.

Those considering brachial plexus block anesthesia may wish to check out the following link (Complications).
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Shoulder arthritis articles from the July issue of the Journal of Bone and Joint Surgery

The July JBJS publishes an article by Gilles Walch and colleagues on Prevalence of Neurologic Lesions After Total Shoulder Arthroplasty. These authors recognize that the nerves of the brachial plexus are at risk in major shoulder surgery. They used electromyography to study patients with reverse total shoulders and with anatomic arthroplasty. Importantly, 9 of 19 shoulders in the reverse group and 13 of 23 shoulders in the anatomic group had neurologic lesions detected BEFORE their joint replacement. At a month after surgery, nine of 19 patients with reverse total shoulders and one of 23 anatomic total shoulders had evidence of new nerve injury, with a rate 10 times higher in the reverse total shoulders. Three additional reverse total shoulder patients had worsening of preoperative nerve deficits. The most commonly involved nerve was the axillary nerve. Eight of these resolved in less than 6 months. They suggested that arm lengthening in reverse total shoulder may be responsible for some of these nerve lesions, although this difference did not appear to be statistically significant with the small number of cases included.

We now understand that there are many possible factors that could contribute to compromised neurological function after shoulder joint replacement, including pre-existing cervical spine or shoulder nerve injuries, nerve injury from brachial plexus block, direct surgical injury, and injury from arm lengthening in reverse total shoulder.  These considerations indicate the need for a complete evaluation of the patient before surgery, a detailed discussion of the risks of nerve injury with the patient, and careful attention to surgical technique.

The observation that one nerve lesion in the 41 shoulders had a new nerve lesion that had not resolved by 6 months is a concern for two reasons. One, if this rate is applied to all of the shoulder arthroplasties performed, it would indicate a rather large number of patients with iatrogenic chronic nerve injury. Secondly, the arthroplasties studied in this paper were performed by one of the most experienced shoulder surgeons in the world. It would seem likely that this nerve injury rate would be much lower than that of less experienced surgeons who perform most of the joint replacements.

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