UW Shoulder and Elbow Academy

Monday, May 6, 2024

Anatomic or reverse total shoulder for primary glenohumeral osteoarthritis? What do 10 recent articles say?

There is a growing trend to treat primary glenohumeral osteoarthritis in older individuals with reverse total shoulder arthroplasty (RSA). However, as pointed out by the authors of Limited Preoperative Forward Flexion does not Impact Outcomes Between Anatomic or Reverse Shoulder Arthroplasty for Primary Glenohumeral Arthritis (Sears 2024), "RSA has been shown to generally result in diminished range of motion, particularly internal rotation, compared to anatomic TSA. Additionally, RSA has several unique complications not seen in TSA patients including dislocation, component dissociation, scapular spine fractures and scapular notching."

These authors compared the minimum two year outcomes between TSA and RSA in matched patients under the age of 80 years with primary glenohumeral arthritis and limited preoperative active forward flexion (≤90 degrees). The average preoperative active forward flexion was 68±20 for the TSA and 64±19 for the RSA groups. The post operative ranges of active flexion were 141±22 and 139±21.

They also examined a subset of matched patients having TSA and RSA with severely limited preoperative forward flexion (≤70 degrees). They found no significant differences in postoperative forward flexion, external rotation, strength, ASES score, VAS, Constant score, SANE score or revision rates between the the TSA and RSA groups. The limited active forward flexion TSA group achieved significantly improved internal rotation compared to the RSA group.

This article prompted a review of some of the other articles published in 2023 and 2024 that compared TSA and RSA. Eight of these articles addressed particular subsets of patients with glenohumeral arthritis/intact cuff: limited active flexion, limited external rotation range, weak external rotation, and age. The chart below allows the reader to compare the pre and final post operative range of active forward flexion for the shoulders in these eight articles.

Here is a brief review of the articles.

Comparison between Anatomic Total Shoulder Arthroplasty and Reverse Shoulder Arthroplasty for Older Adults with Osteoarthritis without Rotator Cuff Tears (Kim 2024) compared the clinical outcomes of anatomic TSA and reverse shoulder arthroplasty (RSA) in patients aged over 70 years with primary glenohumeral osteoarthritis without rotator cuff tears. Of the 67 patients included in this study, TSA was performed in 41 patients, and RSA was performed in 26 patients. The two groups had no clinical differences in the patients’ preoperative demographic and radiographic data. At final follow-up, both groups showed improved pain, ROM, and functional outcomes. The TSA group demonstrated significantly better postoperative ASES and Constant-Murley scores than the RSA group. The TSA group showed significantly better postoperative active forward flexion, external rotation and internal rotations than the RSA group.

In Reverse shoulder arthroplasty with preservation of the rotator cuff for primary glenohumeral osteoarthritis has similar outcomes to anatomic total shoulder arthroplasty and reverse shoulder arthroplasty for cuff arthropathy (Nazzal 2023) TSA was compared to RSA in shoulders with preservation of the rotator cuff. While the TSA patients had more external and internal rotation, there were no significant differences in outcome scores or complication rates.

Patients 75 years or older with primary glenohumeral arthritis and an intact rotator cuff show similar clinical improvement after reverse or anatomic total shoulder arthroplasty (Ardebol 2023) studied patients 75 years of age or older who underwent TSA (n=67) or RSA (n=37) for primary GHOA with an intact rotator cuff with a minimum 2-year follow-up. The TSA cohort showed significantly greater improvement in external rotation; however both TSA and RSA provided similar clinical outcomes otherwise.

Clinical outcomes of anatomic vs. reverse total shoulder arthroplasty in primary osteoarthritis with preoperative rotational stiffness and an intact rotator cuff: a case control study (Hao 2023) compared stiff patients(ER ≤ 0 degrees) having RSAs to matched stiff patients having TSAs. Postoperative outcome scores were similar across all matched cohort comparisons. Preoperative limitations in passive ER did not appear to be a limitation to utilizing TSA.

Clinical outcomes of anatomical versus reverse total shoulder arthroplasty in patients with primary osteoarthritis, an intact rotator cuff, and limited forward elevation (Trammel 2023) compared the minimum 2 year outcomes in matched patients with glenohumeral osteoarthritis, an intact rotator cuff, and limited forward elevation (FE ≤ 105°) having TSA (n=344) or RSA (n=163). The outcome scores were significantly better in stiff RSAs compared with stiff TSAs. The complication rate did not significantly differ between stiff TSAs and stiff RSAs, but there was a significantly higher rate of revision surgery in stiff TSAs.

After accounting for confounders, the authors of Similar rates of revision surgery following primary anatomic compared with reverse shoulder arthroplasty in patients aged 70 years or older with glenohumeral osteoarthritis: a cohort study of 3791 patients (Orvets 2023) observed no significant difference in all-cause revision risk for RSA vs. TSA . The most common reason for revision following RTSA was glenoid component loosening. Over half of revisions following TSA were for rotator cuff tear. No difference based on procedure type was observed in the likelihood of 90-day ED visits or 90-day readmissions.

Clinical outcomes of anatomic vs. reverse total shoulder arthroplasty in primary osteoarthritis with preoperative external rotation weakness and an intact rotator cuff: a case-control study (Hones 2024) analyzed the two year minimum outcomes for 333 TSAs and 155 RSAs performed for primary cuff-intact osteoarthritis and having ER weakness (strength <3.3 kilograms (7.2 pounds)). When comparing weak TSA vs.weak RSA, no differences were found in postoperative outcome measures, rate of complications or rate of revision surgery.

Reverse total shoulder arthroplasty for primary osteoarthritis with restricted preoperative forward elevation demonstrates similar outcomes but faster range of motion recovery compared to anatomic total shoulder arthroplasty (Karimi 2024) sought to determine whether there was a difference in functional outcomes and postoperative range of motion between TSA and RSA in patients with preoperative restricted motion (≤90 degrees of active elevation). There was no difference in outcome scores between RSA (57 patients) and TSA (59 patients). Postoperative active ROM was similar between RSA and TSA cohorts in forward flexion and external rotation. However, internal rotation was less in the RSA group. There was no statistically significant difference in complication rates between cohorts.

Reverse total shoulder replacement versus anatomical total shoulder replacement for osteoarthritis: population based cohort study using data from the National Joint Registry and Hospital Episode Statistics for England (Valsamis 2024) sought to compare the risk-benefit and costs associated with reverse total shoulder replacement (RSA) and anatomical total shoulder replacement (TSR) in patients having elective primary shoulder replacement for osteoarthritis. RSA had a reduced hazard ratio of revision in the first three years with no clinically important difference in revision-free restricted mean survival time, and a reduced relative risk of reoperations at 12 months. Serious adverse events and prolonged hospital stay risks, change in Oxford Shoulder Score, and modelled mean lifetime costs were similar. Outcomes remained consistent after weighting. Despite a significant difference in the risk profiles of revision surgery over time, no statistically significant and clinically important differences between RSA and TSA were found in terms of long term revision surgery, serious adverse events, reoperations, prolonged hospital stay, or lifetime healthcare costs.

Comment: These articles show similar outcomes for anatomic and reverse total shoulder arthroplasty in treating patients with primary osteoarthritis with an intact rotator cuff, even for older patients, stiff shoulders and weak shoulders.

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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).

Saturday, May 4, 2024

Recurrent infection after two-stage revision arthroplasty

We prefer to treat suspected periprosthetic shoulder infections with a single stage revision: thorough debridement, antibiotic/Betadine irrigation, topical antibiotics, complete exchange of implants, and a course of postoperative antibiotics. Two stage revision is usually reserved for cases of draining sinus, infection with particularly virulent organisms, or failed prior single stage revision. Completion of a two stage procedure requires (a) removal of implants and insertion of a spacer at the first stage and (b) insertion of new implants at a second procedure. Not only does the two stage require two surgeries, it also subjects the patient to increased challenges of spacer fixation/removal and challenges of fixation of the final implants. A substantial percentage of patients planned for a two stage never end out having the second stage completed.

Evaluating whether a revision surgery has failed to eliminate an infection is a problem because the only sure evidence of a failed revision for infection is evidence that the organism cultured at the first stage persists in the shoulder. This evidence can come from cultures obtained at the second stage (or a joint aspirate, arthroscopic biopsy, or draining sinus) that are positive for the original causative organism.

Because the organisms that are most commonly isolated from failed shoulder arthroplasties tend to form biofilms on implants, it is preferable to remove all metal and plastic components and cement when performing a revision for suspected periprosthetic shoulder infection. However, complete removal of cement and retained fragments of broken hardware can be not only difficult, but also hazardous, risking the integrity of bone and the surrounding neurovascular structures.

Against this background, let's look at a recent article Does retained cement or hardware during 2-stage revision shoulder arthroplasty for infection increase the risk of recurrent infection? that compared the rates of repeat infection after 2-stage revision for PJI in patients who had retained cement or hardware compared to those who had complete removal. The authors retrospectively analyzed two-stage revision total shoulder arthroplasties (TSAs) performed for infection with minimum two-year follow-up. Postoperative radiographs after the first-stage were reviewed to evaluate for retained cement or hardware. Repeat infection was defined as either ≥2 positive cultures at the time of the second-stage with the same organism that was cultured during the first-stage revision or repeat surgery for infection after the two-stage revision in patients that met the ICM criteria for probable or definite infection.

Thirty-seven patients were included in the analysis. Stage one revision failed to resolve the periprosthetic infection in ten patients (27%). The authors found that the risk of recurrent infection was not associated with age, BMI, comorbidity index, patient, sex, or presence of diabetes.

Only two of the 10 (20%) of the cases of recurrent infection were culture positive for Cutibacterium at the index surgery, while 16 of the 27 (59%) of the cases without recurrent infection were culture positive for Cutibacterium at the index surgery. 70% of the recurrent infections were due to Staph Aureus or were polymicrobial.

Six patients had retained cement and one patient had two retained broken glenoid baseplate screws after first-stage revision. All retained cement identified in this study was distal to the humeral stem

Of the ten cases of recurrent infection, one case involved retained cement/hardware.

The authors point out that surgeons must balance the potential benefit of complete cement/hardware removal against the risks.

Comment: It is interesting that while 1 of 7 patients with retained cement or hardware were documented has having recurrent infection, 9 of 30 patients without retained cement or hardware had recurrent infection. Thus we must wonder why the initial surgery failed to achieve its objective of successful infection resolution in these 9 cases of complete cement and hardware removal. The pie graphs shown above suggest that a determinant of the percentage of success in resolving the infection at the first stage may be whether the infection was due to Cutibacterium (lower risk of failure) versus Staph aureus or polymicrobial (higher risk of failure). Not assessed in this study are the possible effects on infection recurrence of adjunctive measures at the first stage procedure, such as antibiotic and Betadine irrigation, topical antibiotics, and postoperative antibiotic choice, route of administration and duration.

Bodybuilding championship after ream and run

A 60 year old bodybuilder who presented with glenohumeral arthritis.

After a discussion of the risks and benefits of a standard anatomic total shoulder and the ream and run procedure, he elected the latter.

His followup x-rays 18 months after surgery are show below showing no evidence of stress shielding or glenoid wear.

He recently sent the news that he had won a local bodybuilding championship in his age division and was headed for the national championship.

Wednesday, May 1, 2024

Stemless to stemless revision for overstuffing

A 55 year old may presents with pain and stiffness in his left shoulder that came on after a stemless ream and run procedure performed almost two years prior. His pre ream and run film is shown below.

Below is his postoperative film at the time of his presentation to us showing overstuffing related in part to a conservative head cut.

On examination his active and passive flexion were limited to 30 degrees limited by extreme pain.

After discussion of the options, he decided to proceed with a revision ream and run arthroplasty after discussion of the risks and alternatives of total shoulder arthroplasty.

At surgery there was no evidence of synovitis. Specimens were sent for Cutibacterium-specific cultures; a vigorous release of the sub scapulars and capsule was preformed. The prior implant was removed, preserving as much bone a possible. A new head cut was made using the hinge point as a reference. The glenoid was re-reamed to a smooth surface. Impaction grafting was used to fix a #2 nucleus and a 50 18 humeral head. The subscapularis was securely repaired. The postoperative films are shown below, showing restoration of the desired anatomy.

His procedure was performed under general anesthesia without a plexus block. The morning after surgery he had assisted elevation to 160 degrees.

Of mousetraps and anatomic glenoid components.

Ralph Waldo Emerson is credited with the saying, "build a better mousetrap and the world will beat a path to your door".

A similar sentiment may drive the marketing of many different types of glenoid components in anatomic shoulder arthroplasty. Almost all have a polyethylene surface for articulation with the humeral component. The difference lies in the mechanism for fixation to the bone of the glenoid. Below are a few of the many.

One innovation uses porous metal into which bone can grow for fixation. The question is "does this innovation improve outcomes for patients?" A recently study, A multicenter, randomized controlled trial comparing a second-generation uncemented trabecular metal-backed vs. cemented polyethylene glenoid component in total shoulder arthroplasty: 5-year results compared cemented all polyethylene glenoid components to uncemented trabecular metal glenoid components.

This study found no statistical or clinically relevant advantage of the trabecular metal-backed cementless component over the all polyethylene cemented component. No glenoid implant failures were reported, and complication rates were similar between groups. Metal debris was observed in 11 (23.9%) of the patients receiving trabecular metal components (see circle on x-ray below).

In addition, on the x-ray above it is not clear how much of the original polyethylene remains between the metal backing and the humeral component (red arrows).

The problem of accelerated polyethylene wear with metal backed components was pointed out in Metal-backed glenoid implant with polyethylene insert is not a viable long-term therapeutic option, the authors of which concluded "uncemented MB [metal backed] glenoid resurfacing is not a viable long-term therapeutic option because of accelerated PE [polyethylene]wear leading to early revision surgery". See also

Metal-Backed Glenoid Components Have a Higher Rate of Failure and Fail by Different Modes in Comparison with All-Polyethylene Components: A Systematic Review

The authors of Comparable low revision rates of stemmed and stemless total anatomic shoulder arthroplasties after exclusion of metal backed glenoid components: a collaboration between the Australian and Danish national shoulder arthroplasty registries found that "The adjusted hazard ratio for revision of total shoulder arthroplasties with metal backed glenoid components compared to all-polyethylene glenoid components was 2.54 (95% CI 1.70-3.79, p < 0.001) in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) and 4.1 (95% CI 1.92-8.58, p<0.001) in the Danish Shoulder Arthroplasty Registry (DSR). The authors concluded "We advocate that metal-backed glenoid components should be used with caution and not on a routine basis."

The Australian Orthopaedic Association National Joint Replacement Registry further studied cumulative percent revision rates by glenoid type including modular metal backed (orange), non-modular metal backed (red), cemented all poly (green), and all poly with a modified central peg (blue).

An example of an all poly glenoid component with a central peg modified to allow bone ingrowth is shown below.

It is apparent that long term, population-based studies are the key to tracking the outcome of different glenoid component designs. In the meanwhile, we should be prepared for the continued marketing of new glenoid prostheses, such as the 'inset' design shown below.

Sunday, April 28, 2024

Stemless ream and run: the importance of handcraft.

We have found that stemless humeral components can work well with the ream and run procedure. Our experience has taught us that - even in this age of 3D CT planning and cutting guides - a well-done freehand cut yields precision and accuracy of humeral head position.

We preserve the biceps tendon, remove the anterior and inferior osteophytes, mark the superior margin of the articular surface (the "hinge point"), make the cut at 135 degrees with the shaft and in 30 degrees of retroversion while aiming the saw so that it exits the humerus just anterior to the posterior cuff insertion. Everyone on the surgical team "coaches the cut".

Using the x-rays obtained in the recovery room, we "grade" each of our cases with respect the position of the humeral head prosthesis while the case is still fresh in our mind.

We measure the varus/valgus angulation, comparing it to the desired 135 degrees. We also fit a circle to the humeral articular surface, comparing it to the desired "perfect circle", shown below.

When there is deviation from the desired position, the shoulder is likely to have restricted motion from overstuffing as in this case from an outside institution.

Here are some of our most recent cases. While they are not all perfect, grading them immediately after surgery helps us learn to do better on the next case.

Comment: In our practice, the ream and run with a stemless component depends on handcraft.

Sunday, April 7, 2024

What is a shoulder infection?

While the diagnosis of obvious shoulder infection is easy: the patient has local and systemic signs of inflammation, abnormal joint fluid and serum lab tests, and positive cultures for indisputable pathogens.

On the other hand, the diagnosis of a stealth shoulder infection is complicated: the most frequently implicated bacteria (Cutibacterium) is a commensal organism commonly isolated from normal skin, normal deep tissues and healthy shoulder joints. In a stealth infection the usual clinical evidence of infection is absent.

A pragmatic definition of bacterial infection is "bacteria doing harm". That is, the presence of bacteria in and of itself is not sufficient to prove infection. Bacteria in the large intestine; bacteria in sebaceous glands; bacteria recovered from normal joints would not meet the definition whereas E. coli colitis, acne, and joint sepsis would.

A recent paper,The incidence of subclinical infection in patients undergoing revision shoulder stabilization surgery: a retrospective chart review, exemplifies the challenge. The authors sought to identify the incidence of subclinical infection in 107 patients undergoing revision shoulder stabilization surgery by an experienced shoulder surgeon. Notably the average time from the instability repair to revision was 8 years. The reasons for revision were not provided. Surgical findings (synovitis, purulence, gram stain results) were not given.

Twenty-nine patients (27.1%) had positive cultures. Patients had multiple specimens sent for culture; the average and range for the number of cultures submitted is not provided. Thirteen patients had only1 positive culture (11 for Cutibacterium). 9 patients had two positive cultures Eight had 3 or more positive cultures (all for Cutibacterium).

The paper does not state whether the patients were given antibiotic coverage for the several weeks while the culture results were pending rather than waiting until the results were finalized. The treatment for those patients with positive cultures is not provided.

Twenty-six of these patients (90%) had positive Cutibacterium cultures. The average time to culture positivity was 11 days.

The paper does not state whether any patients developed clinical manifestations of infection.

Comment: It is difficult to know whether these positive cultures obtained on average 8 years after surgery in the absence of other supporting evidence actually represent an infection, i.e. did the bacteria cause harm?

If the surgeon is suspicious of an infection, a reasonable strategy would be to perform a thorough debridement and irrigation at the time of revision, take cultures for Cutibacterium, consider topical antibiotics, and postoperative antibiotics to be continued until the culture results are finalized. Bases covered.