UW Shoulder and Elbow Academy

Thursday, July 25, 2024

Treating rotator cuff tear arthropathy without risking acromial and spine stress fractures

It is well recognized that female sex, osteopenia, rotator cuff tear arthropathy, inflammatory joint disease and thin acromial bone are risk factors for acromial and scapular spine fractures after reverse total shoulder arthroplasty. Unfortunately, these conditions are commonly encountered in shoulder surgery.

A 71 year old woman presented with all of these conditions, retained active elevation above 90 degrees, and answered "yes" to only 3 functions of the 12 Simple Shoulder Test questions.

Her right shoulder x-ray at the time of presentation is shown below, demonstrating a thinned acromion, osteopenia, and acromiohumeral contact.

After discussion of the surgical options, including a reverse total shoulder, she elected to proceed with a CTA hemiarthroplasty. At the time of surgery, her supraspinatus and infraspinatus were detached and irreparable. Her subscapularis was detached but reparable.

A thin humeral stem was inserted with impaction autografting to provide a small filling ratio.

Nine years later she returned for evaluation of her contralateral shoulder.

Her CTA hemiarthroplasty shoulder had 140 degrees of comfortable active elevation.

Her nine year followup film is shown below, demonstrating an intact acromion and no evidence of component loosening.

Comment: In our experience patients selected for the CTA hemiarthroplasty have been free of acromial/scapular spine fractures, dislocations, and prosthetic loosening. See CTA hemiartroplasty or reverse total shoulder for cuff tear arthropathy.

Comments welcome at shoulderarthritis@uw.edu

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/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
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).

Irreparable cuff tear in a 62 year old woman.

A recent American Shoulder and Elbow Surgeons journal club (link) discussed some options for the management of symptomatic refractory irreparable rotator cuff tears. The faculty discussed the a variety of surgical options, their cost and their effectiveness.

Our approach to patients with irreparable cuff tears has remained consistent for the last three decades: starting with a good trial of directed Jackins rehabilitation exercises to first optimize shoulder flexibility

and next to gradually build strength.

we continue to be impressed with the effectiveness of this program, irrespective of the size of the cuff defect.

For patients who have active elevation of the arm above 90 degrees but who continue to have limiting stiffness and pain, we consider the simple, low cost, low risk procedure known as the "smooth and move" . A recent example of the rapid return of function following of this procedure can be seen here.

Here's another recent example of an irreparable cuff tear in a 62 year old woman.

After a trial of the Jackins exercise program she had regained motion her her shoulder, but still had painful, function-limiting crepitus of the shoulder.

With this result from her Simple Shoulder Test

She asked to proceed with a smooth and move procedure at which time we found an irreparable supraspinatus tear with a large lateral flap, intact biceps tendon, intact subscapularis and infraspinatus and smooth undersurface of her coracoacromial arch.

We debrided her hypertrophic bursa and the flap, smoothed her tuberosity, preserved her biceps tendon and performed a manipulation under anesthesia. No patches or bioactive agents were used.

She resumed her active motion and strengthening exercise program immediately after surgery = minimal down time.

At six weeks after surgery she returned for a post op check and demonstrated strong full and comfortable elevation of her arm, reporting that she had returned to work.

Sunday, July 21, 2024

Avoiding baseplate screw failure in reverse total shoulder arthroplasty - innovation without increased cost or complexity

In followup to our post Reverse baseplate failure - fracture of the central screw, the senior author of Avoiding Glenoid Baseplate Fixation Failure by Altering Surgical Technique for Varying Bone Densities offered that "one technical issue leading to incomplete seating is very dense subchondral bone which can provide false sense of the implant being fully seated; another pitiful is if there is some cartilage left on the glenoid which also can lead to incomplete seating booth of these have happened with screw breakage at the interface of the baseplate screw junction"

His conclusions can be summarized as follows:

(1) baseplate failure is an import complication of reverse total shoulder arthroplasty

(2) time zero (immediate post op) stability of the baseplate is important because (a) the patient will load the baseplate before any bone ingrowth has had time to occur and (b) micro motion of the baseplate will inhibit bone ingrowth so that the screws may be all that is holding the baseplate to the glenoid bone leading to the risk of fatigue fracture

(3) failure to remove cartilage and interposed tissue between baseplate and bone may prevent adequate seating of the baseplate

(4) as is the case with all screw fixation in bone, bone quality has a strong effect on the quality of fixation: (a) low bone density may result in lack of a solid "bite" (screw stripping); (b) high bone density may result in incomplete seating

(5) from plain radiographs, the surgeon can preoperatively get an idea of the glenoid bone density: poor (below left), sclerotic (below right).

(6) for bone suspected of having poor bone quality, the author uses some straightforward innovations that do not add time, technology or expense:

(a) for soft bone the glenoid is reamed over a 2.5 mm drill (without using a tap) followed by insertion of the baseplate in the untapped bone

(b) for denser than average bone, a 3.0-mm drill is used for the pilot hole, and then the tap is passed (inserted and removed) a total of 3 times, followed by insertion of the baseplate in the tapped bone

(c) the standard technique is used for average density bone: a 2.5-mm drill is inserted in the central hole to a depth of 30 mm, followed by use of the 6.5-mm tap, reaming of the glenoid, and finally, insertion of the monoblock baseplate

In in vitro testing using a low-density block model, the standard technique gave a compressive force of 112 N compared with 300 N for the soft bone technique.

In the high-density bone model, the standard technique resulted in failure to seat the baseplate, or screw breakage. Performing the dense bone technique, the baseplate was seated without failure, with an average compressive force of 450 N.

Comment: Time zero (initial) fixation is important for minimizing the risk of baseplate failure. This requires adequate bone preparation for maximal baseplate-bone contact, full seating of the baseplate and placement of the peripheral screws in good quality bone.

The inspection of preoperative plain radiographs and the use of the techniques suggested here can reduce the risk of inadequate compression on one hand and incomplete seating on the other.

It is noted that with this implant system, the only screw providing substantial compression is the central one - the others are locking screws.

Finally, in cases where the central screw is stripped, we have found that "match stick" strips of cortical bone can be progressively added to the central hole until good compression is achieved.

Friday, July 19, 2024

Reverse total shoulder complication - fracture of central baseplate screw

Baseplate failure is a serious complication of reverse total shoulder arthroplasty. See Reverse total shoulder, the complication of baseplate failure.

Here's an example case. An active man had multiple prior attempts at rotator cuff repair, but eventually developed cuff tear arthropathy.

This was treated with a reverse total shoulder arthroplasty (RSA).

Of note, the baseplate is not in contact with the genoid bone superiorly (see gap at arrow)

The patient returned to physical activity including pushups. A year after the RSA, the shoulder became painful on use. X-rays showed superior tilting of the glenosphere and bending of the central screw.

Eventually the central screw fractured and the glenosphere fixation failed.

Here is an example of fatigue fracture of the central screw.

This case exemplifies the points made by the authors of

Factors affecting fixation of the glenoid component of a reverse total shoulder prothesis, specifically that the security of baseplate fixation depends in large part on (1) supporting contact between the upper aspect of the baseplate and glenoid bone and (2) strong fixation of the inferior screw in good glenoid bone.

When such support is lacking, there is a risk of fatigue fracture of fixation screws and baseplate loosening.

Loss of superior support for the baseplate can occur when the glenosphere is inferiorly inclined. In other words, inferior inclination requires substantial glenoid reaming to achieve support for the superior baseplate.

Some related articles are referenced below.

How to avoid baseplate failure: the effect of compression and reverse shoulder arthroplasty baseplate design on implant stability

Avoiding Glenoid Baseplate Fixation Failure by Altering Surgical Technique for Varying Bone Densities

Reverse shoulder glenoid loosening: an evaluation of the initial fixation associated with six different reverse shoulder designs

Comment: We invited a very experienced RSA surgeon to give us his perspective. He kindly responded "I too have this failure mode but i think it relates to imperfect seating.

If there is no bony contact of the baseplate inferiorly that leads to lack of ingrowth. There is a small gap inferiorly too of the baseplate.

The lack of ingrowth is why the screws failed at the interface to the screw/baseplate junction. I have not had failures with lack of superior contact

if there is inferior contact."

Thursday, July 18, 2024

A 61 year old women with an irreparable cuff tear

A recent post, Innovation, balloons and irreparable cuff tears, reminded us that (1) rotator cuff integrity was not necessary for satisfactory shoulder function and (2) many treatments for irreparable cuff tears (superior capsular reconstructions, bioinductive grafts, subacromial balloons, tendon transfers, reverse total shoulder arthroplasty) can be more costly, have a longer recovery periods, and have higher complication rates without yielding superior outcomes than simple debridement in appropriately selected cases.

In patients having symptomatic irreparable cuff tears but with retained active elevation above the horizontal, we consider a smooth and move procedure: removing hypertrophic bursa and degenerated cuff remnants, smoothing any tuberosity prominence, manipulation to eliminate any capsular tightness, and preserving the coracoacromial arch and all functional cuff elements (including the long head tendon of the biceps unless it is frayed or unstable). No partial repair is attempted. (see Significant improvement in patient self-assessed comfort and function at six weeks after the smooth and move procedure for shoulders with irreparable rotator cuff tears and retained active elevation and Treatment of irreparable cuff tears with smoothing of the humeroscapular motion interface without acromioplasty

Here is an example from earlier this month. A 61 year old woman had chronic activity-limitng pain in her right shoulder. She answered "no" to all 12 of the Simple Shoulder Test questions

Her shoulder examination is shown below. Her supraspinatus was too painful to test.

Her MRI showed a severely degenerated supraspinatus tendon with an irreparable tear.

Her symptoms did not respond to a course of physical therapy.

After discussion of the non-operative and surgical options, she elected to proceed with a smooth and move procedure.

At surgery, the degenerated supraspinatus tendon was irreparable. It was debrided. The subscapularis and infraspinatus were intact. The intact biceps tendon was preserved. The undersurface of the coracoacromial arch was smooth; it was preserved. The uncovered tuberosity prominence was smoothed. The shoulder was manipulated for a full range of motion. No implants were used.

The patient began active assisted flexion immediately following the procedure without surgeon-imposed restrictions. She returned to the office three weeks after surgery with comfortable active elevation >150 degrees.

Her three week Simple Shoulder Test responses and her active elevation are shown below.

While the smooth and move is not a perfect solution for irreparable cuff tears and while it is not applicable in all such cases, it does have the advantages of effectiveness, low cost, low complication rate, simple rapid rehabilitation, and leaving the door open for additional surgeries in the uncommon event that they become indicated.

Comments welcome at shoulderarthritis@uw.edu

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/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
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).

Sunday, July 14, 2024

Acromial and spine stress fractures after reverse total shoulder.

As is the case for most stress fractures, acromial and spine stress fractures (ASF) after reverse total shoulder (RSA) result from changes in the magnitude, direction and frequency of loads applied to the bone. The observation that ASF are more common in shoulders with cuff deficiency suggests that an intact cuff may reduce the changes in loads on the acromion and scapular spine by assuming a portion of the humeroscapular forces.

Changes in acromial and scapular spine loading result from surgeon-controlled factors, including implant design and implant placement. Glenoid-sided lateralization can increase shoulder range of motion by reducing abutment between the humerus and the scapula as well as reducing the risk of scapular notching. What are the down-sides of glenoid-sided lateralization?

The authors of "Up to 8 mm of glenoid-sided lateralization does not increase the risk of acromial or scapular spine stress fracture following reverse shoulder arthroplasty with a 135 degree inlay humeral component" (recipient of the Robert H. Cofield Award) identified 26 ASFs (5.5%) among 470 RSAs.

In communication with the corresponding author, it was verified that glenoid-sided lateralization in the system used in this study reflects the combination of baseplate offset (0, 2 or 4mm) and glenosphere offset (0 to 8 mm). See red arrow in the figure below.

In this series, glenoid sided lateralization ranged from 0 to 8 mm. The amount of glenoid sided lateralization was not associated with ASF risk: the incidence of fracture did not increase with greater glenoid-sided lateralization (0-2 mm, 7.4%; 4 mm, 5.6%; 6 mm, 4.4%; 8 mm, 6.0).

However, humeral distalization did increase the risk of ASFs. The pre- to postoperative change in acromiohumeral distance (AHD, measured as shown above) was higher in the stress fracture group (2.0 ± 0.7 cm vs. 1.7 ± 0.7 cm). For every centimeter increase in the change in AHD, there was a 121% increased risk for fracture.

It can be concluded that for this implant system (a 135 degree inlay humeral component) the change in humeral position relative to the acromion (whether from inferior tilt of the glenosphere, increased inferior overhang of the glenosphere, as well as from the type and positioning of the humeral implant) can change the magnitude and direction of the forces experienced by the acromion, creating a risk for stress fracture.

Minimizing the surgeon-controlled risk factors - such as avoiding over-lenthening - seems particularly important in shoulders that are intrinsically at increase risk for ASF, such as those with superior displacement of the humeral head relative to the scapula, a thin acromion, osteopenia, inflammatory arthropathy, advanced age and rotator cuff deficiency (see figure below).

Comment to shoulderarthritis@uw.edu

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/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
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).

Friday, July 12, 2024

Shoulder motion, function and satisfaction after arthroplasty

A recent article, Thresholds For Diminishing Returns In Postoperative Range Of Motion After Total Shoulder Arthroplasty, pointed out that satisfaction after shoulder arthroplasty - can be associated with scores on patient-reported outcome measures (PROMs). (See Patient satisfaction after shoulder arthroplasty - anticipation and informing). In turn, PROMs are dependent upon restoring lost shoulder range of motion (ROM). The authors questioned whether there was a threshold in postoperative active ROM beyond which additional improvement in motion was not associated with additional improvement in the PROMs that primarily measured function (Simple Shoulder Test [SST], American Shoulder and Elbow Surgeons [ASES] score, and the Shoulder Pain and Disability Index [SPADI]). (Of note, other outcome measures, such as the Shoulder Arthroplasty Smart Score, primarily measure motion (70% of the total score) attributing only 10% of the points to function).

They included 4,459 TSAs (1,802 aTSAs, 2,657 rTSAs) with minimum 2-year follow-up. Indeed they found thresholds in postoperative ROM that were associated with no further improvement in the standard PROMs.

The "S" shapes of these curves are interesting. See for example the figures below plotting the patient's Simple Shoulder Test (SST) responses against active flexion and active external rotation.

At the left side of these curves, improvement in motion has little effect on the number of SST functions the shoulder could perform. In the middle, there is a steep improvement in function with increasing range. At the right hand of the "S", the curve flattens out so that further improvements in range are not strongly associated with increased function. For the SST the inflection points (thresholds) were 153 degrees for active flexion, 50 degrees of active external rotation, and active internal rotation to L2. Similar thresholds were found for other function-based outcome measures, including the ASES score and the SPADI.

Subjective satisfaction was assessed by asking patients to rate their shoulder as being “worse”, “unchanged”, “better”, or “much better” compared to before surgery. Among shoulders that achieved all ROM thresholds, 93% of patients rated their shoulder as “much better” compared to before surgery.

It is interesting to view these results in the light of data presented in Practical Evaluation and Management of the Shoulder. The authors of that book characterized elevation in terms of the angle of elevation

and the plane of elevation.

They learned that - rather than being confined to "abduction" and "flexion" - different functions were performed in different planes and with different angles of elevation.

It can be seen that the average maximum angle of elevation for eight normal subjects was 148 degrees, and that this range was not necessary for most of the activities of daily living.

Of course the ability to perform functions does not only depend on elevation angle and plane, but also on the rotation of the arm as shown below.

Thresholds For Diminishing Returns In Postoperative Range Of Motion After Total Shoulder Arthroplasty is an important article in that it can help guide motion goals for arthroplasty surgery and postoperative rehabilitation. It suggests that a shoulder that has active elevation to 180, external rotation to 90 and internal rotation to T7 may not be more functional or satisfactory than one has 153 degrees of active flexion, 50 degrees of active external rotation, and active internal rotation to L2.