What's important in anatomic total shoulder arthroplasty?

Anatomic total shoulder arthroplasty reliably provides long term comfort and function for patients with osteoarthritis and an intact rotator cuff, even in patients with deficiencies in glenoid bone (see Anatomic Total Shoulder Arthroplasty with All-Polyethylene Glenoid Component for Primary Osteoarthritis with Glenoid Deficiencies). While some surgeons attempt to "correct" the patient's glenoid version, others "accept" it (see Glenoid Version, Acceptors and Correctors). It either case, one of the most important technical goals of anatomic total shoulder arthroplasty is excellent seating of the glenoid component (see Edge displacement and deformation of glenoid components in response to eccentric loading. The effect of preparation of the glenoid bone).

Good seating is achieved by reaming the glenoid bone to a single concavity

that matches the backside of the glenoid component

so that no cement is placed between the bone and the backside of the prosthesis to fill in the gaps,

backside cement indicates poor seating and risks cement failure

below is an example of a well-seated glenoid component. The only cement visible is in the peg holes.

To further investigate the technical factors associated with anatomic total shoulder (aTSA) outcomes, the authors of Anatomic total shoulder arthroplasty for posteriorly eccentric and concentric osteoarthritis: a comparison at a minimum 5-year follow-up evaluated 210 patients at a minimum of five years after aTSAs performed with conservative glenoid reaming with no attempt at version correction. 

Preoperatively, 98 (47%) had posteriorly decentered humeral heads and 108 (51%) had centered humeral heads. There were 77 shoulders with Walch type A glenoids and 122 with Walch type B glenoids. 

At a mean 8-year follow-up, the final SST score, change in SST score, and percentage of maximal improvement were not correlated with preoperative or postoperative humeral head centering, Walch classification, or glenoid version. 

Two patients (1%) underwent open reoperations during the study period. 

In patients with Walch B1 and B2 glenoids (n = 110), there were no differences in outcome measures between patients that had postoperative retroversion of more or less than 15°. 

Although 15 of 51 patients (29%) with minimum 5-year radiographs had glenoid radioluciences, these radiographic findings were not associated with inferior clinical outcomes. 

On multivariable analysis, glenoid component radiolucencies were most strongly associated with incomplete component seating.

Careful preparation of the glenoid bone. 

From the authors of Edge displacement and deformation of glenoid components in response to eccentric loading. The effect of preparation of the glenoid bone we learn that the wobble and warp of the polyethylene component is minimized by spherically reaming the bone to precisely match the back of the component.

Glenoid bone stock is preserved by reaming only enough to create a single concavity, rather than trying to "correct" glenoid version.

The adequacy of glenoid reaming can be evaluated by using a pegless trial with the same backside curvature as the actual component and assuring that there is no rocking with eccentric loading. The goal is complete congruency.

Assuring optimal seating and cementing of the component. 

From the authors of The radiographic evaluation of keeled and pegged glenoid component insertion we learn that poor seating and poor cement technique contribute to poor fixation as evidenced by radiolucent lines on the immediate postoperative x-rays. 

Poor seating is evidenced by the presence of cement between the glenoid bone and the backside of the component. 

Good seating is indicated by the absence of cement between the component and bone (below top), rather than using cement as putty in an attempt to compensate for inadequate reaming.

A thin layer of cement between the bone and component is brittle and subject to cracking, displacement and loss of support for the glenoid implant.

Optimal cementing is reflected by the absence of radiolucent lines on postoperative radiographs.

We have learned that this can be achieved by drying each fixation hole with a CO2 spray

Immediately before pressurizing the cement into the hole

Comment: The survivorship of cemented, pegged, all-polyethylene glenoid components has yet to be surpassed by other types of glenoid implants (see Total shoulder replacement stems in osteoarthritis-short, long, or reverse? An analysis of the impact of crosslinked polyethylene). Attention to the details of bone-preserving bone preparation, complete seating of the component and modern cement technique may further improve the clinical outcomes of anatomic total shoulder arthroplasty. Our technique for this procedure is shown in this link.

What correlates with glenoid radiolucency at 10 years after total shoulder arthroplasty?

 Computed tomography revealed the correlation between radiolucency and alignment of all-polyethylene pegged glenoid component more than 10 years after total shoulder arthroplasty in the Japanese population

These authors sought to evaluate the long-term outcomes after anatomic total shoulder arthroplasty (TSA) and to identify factors related to radiolucency around the glenoid component using CT after at least 10 years of clinical follow up. 

They defined glenoid superior inclination as the angle between the glenoid and a line perpendicular to the floor of the supraspinatus fossa.

Eighteen shoulders in 16 patients met the inclusion criteria. Mean patient age was 61 years, mean follow up period was 137 months, and mean Yian CT score was 19%. Glenoid radiolucency values were significantly higher in patients with rheumatoid arthritis than in those with osteoarthritis.

CT score for radiolucency was significantly highest in pegs located inferiorly. 

Glenoid superior inclination was significantly lower in shoulders with possible loosening than in cases with no loosening (5 vs 16 degrees) - in other words glenoids that were more inferiorly inclined were more likely to have possible glenoid loosening. Notably, glenoid retroversion, glenohumeral decentering, and critical shoulder angles were not different for the possible loosening and no glenoid loosening groups.

Shoulders with possible glenoid loosening had inferior clinical outcomes.

Comment: While the numbers in this study are small, it is of interest to note the outcomes 10 years after surgery. The hypothesis that needs further testing is that relatively inferior inclination of the glenoid component may create a greater loosening moment for the superiorly directed forces applied by the deltoid with increased traction on the inferior pegs of the component leading to radiolucencies around them,

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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).

Shoulder rehabilitation exercises (see this link).

This is a non-commercial site, the purpose of which is education, consistent with "Fair Use" as defined in Title 17 of the U.S. Code.          

Note that author has no financial relationships with any orthopaedic companies.

 

Total shoulder arthroplasty - glenoid components with pegs and keels, does it matter?

A comparison of pegged vs. keeled glenoid components regarding functional and radiographic outcomes in anatomic total shoulder arthroplasty

These authors conducted a systematic review of total shoulders to consider which fixation options provides optimal long-term functional outcomes with decreased rates of revision surgery and radiolucency. They found 7 comparative studies and 25 noncomparative studies were included in the final analysis, including 4 randomized (level I) studies, 1 level II study, 8 level III studies, and 19 level IV studies.

Meta-analysis of the comparative studies demonstrated a higher rate of revision surgery with keeled fixations compared with pegged fixations (odds ratio, 6.22; 95% confidence interval [CI], 1.38-28.1; P . .02). 

They found that the differences with respect to functional outcomes, such as the American Shoulder and Elbow Surgeons score (mean difference, 9.54)  and Constant score (mean difference 5.31), as well as radiolucency rates (odds ratio, 1.89) were present but not statistically significant with the number of included studies.

Comment: Such studies are confounded by the fact that "pegged" glenoids come in a wide variety of peg types and configurations, each of which may affect its clinical and radiographic durability. So that conclusions about the performance of a "pegged" glenoid with out considering the component design.

 

 

 

Secondly, as is pointed out in the article below, studies of glenoid component durability are as much about the experience and technique of the surgeon as they are about component design.

The Radiographic Evaluation of Keeled and Pegged Glenoid Component Insertion

Background: Radiolucent lines about the glenoid component of a total shoulder replacement are a common finding, even on initial postoperative radiographs. The achievement of complete osseous support of the compo- nent has been shown to decrease micromotion. We evaluated the ability of a group of experienced shoulder surgeons to achieve complete cementing and support in a series of patients managed with keeled and pegged glenoid components.

Methods: We reviewed the initial postoperative radiographs of 493 patients with primary osteoarthritis who had been managed with total shoulder arthroplasty by seventeen different surgeons. One hundred and sixty-five pa- tients were excluded because of inadequate radiographs, leaving 328 patients available for review. Of these, thirty-nine patients had a keeled component and 289 had a pegged component. The method of Franklin was used to grade the degree of radiolucency around the keeled components, and a modification of that method was used to grade the degree of radiolucency around the pegged components. The efficacy of component seat- ing on host subchondral bone was evaluated with a newly constructed five-grade scale based on the percentage of the component that was supported by subchondral bone. Each radiograph was graded four times, by two sep- arate reviewers on two separate occasions.

Results: Radiolucencies were extremely common, with only twenty of the 328 glenoids demonstrating no radi- olucencies. On a numeric scale (with 0 indicating no radiolucency and 5 indicating gross loosening), the mean radiolucency score was 1.8 ± 0.9 for keeled components and 1.3 ± 0.9 for pegged components (p = 0.0004). After defining categories of “better” and “worse” cementing, we found that pegged components more com- monly had “better cementing” than did keeled components (p = 0.0028). Incomplete seating was also com- mon, particularly among patients with keeled components. Ninety-five of the 121 pegged components that had been inserted by the most experienced surgeon had “better cementing,” compared with eighty-five of the 168 pegged components that had been inserted by the remaining surgeons (p < 0.00001).

Conclusions: Perfectly cementing and seating a glenoid replacement is a difficult task. Radiolucencies and in- complete component seating occur more frequently in association with keeled components compared with pegged components. Surgeon experience may be an important variable in the achievement of a good technical outcome.

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Finally, it is important to recognize that glenoid component lucencies do, in fact have clinical consequences as shown in the article below.


Glenoid component lucencies are associated with poorer patient-reported outcomes following anatomic shoulder arthroplasty

Background

High rates of radiographic glenoid loosening following anatomic total shoulder arthroplasty (TSA) are documented at midterm follow-up. Small studies remain conflicted on the impact of lucent lines on clinical outcomes. This study assesses the impact of radiolucent lines on function and patient-reported outcomes (PROs) following TSA.

Methods

We retrospectively evaluated 492 primary TSAs performed between February 2005 and April 2016. Radiographs were evaluated for glenoid loosening according to the Lazarus grade at a mean of 5.3 years (range, 2-12 years). Clinical outcome measures included range of motion and American Shoulder and Elbow Surgeons, Constant, University of California–Los Angeles, Simple Shoulder Test, and Shoulder Pain and Disability Index scores. Outcomes were compared between patients with and patients without glenoid lucent lines and in relation to lucency grade.

Results
At most recent follow-up, 308 glenoids (63%) showed no radiolucent lines (group 0) and 184 demonstrated peri-glenoid lucencies (group 1). The groups were similar regarding age, sex, body mass index, comorbidities, and prior surgery. At follow-up, group 1 demonstrated significantly lower improvements in forward elevation (P = .02) and all PROs (P ≤ .005). Subgroup analysis by radiolucency grade showed that forward elevation diminished with increasing radiolucent score and exceeded the minimal clinically important difference (MCID) above grade 2 lucencies. A similar decline in PROs was observed with increasing lucency grade. These differences did not exceed the MCID below grade 5 lucencies.

Discussion
Peri-implant glenoid lucencies following TSA are associated with lower forward elevation and PROs. Lucencies above grade 2 are associated with clinically important losses in overhead motion. However, differences below the MCID are maintained for PROs below grade 5 glenoid lucencies.


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In our experience, careful conservative carpentry of the glenoid bone to match the geometry of a glenoid component with a fluted central peg and optimal cementing technique leads to minimal issues with lucent lines or fixation failure.  No cement is used on the backside of the glenoid component.

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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

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Total shoulder arthroplasty, glenoid seating and glenoid radiolucencies

The association of incomplete glenoid component seating and periprosthetic glenoid radiolucencies after total shoulder arthroplasty.

These authors evaluated the minimum 2-year follow-up for 36 total shoulder arthroplasties performed for primary glenohumeral osteoarthritis with a partially cemented all-polyethylene glenoid prosthesis.

At a mean of 43 months after surgery, neither Lazarus plain film radiolucency scores nor Yian CT radiolucency scores were associated with Lazarus plain film seating scores. Neither Lazarus plain film radiolucency scores nor Yian CT radiolucency scores were associated with modified Lazarus CT scan seating scores.

Comment: The authors concluded that "Radiolucencies around a partially cemented glenoid component were not associated with the degree of component seating. Complete seating of the glenoid component is not necessary to achieve radiographic implant stability". These statements are not correct.  The surgeon performing these total shoulders is a high volume shoulder surgeon with a great degree of expertise. This is evidence by the observation that of the 210 images, 111 (51%) were graded as ‘‘A,’’ 88 (41%) were graded as ‘‘B,’’ and 7 (3%) were given a grade of ‘‘D.’’ None were graded as ‘‘E.’’ 92% of the glenoids had 'good' seating. Because of the very small number of cases with 'poor seating' this study provides insufficient evidence to state that the degree of component seating is unimportant in the fixation of the glenoid component. It would be unfortunate if this article was used to detract from the need to achieve the best possible seating for the glenoid component. A more appropriate conclusion is the one buried in the Discussion section "a small degree of incomplete glenoid seating is not associated with loosening at a mean of nearly 4 years after surgery."

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Consultation for those who live a distance away from Seattle.

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Radiographic survival in total shoulder arthroplasty

Radiographic survival in total shoulder arthroplasty

The authors reviewed 302 total shoulders with a cemented, keeled glenoid component at an average of 8.6 years after surgery. Of these 151 had preoperative, early postoperative, and most recent radiographs at a minimum 4 years. Fifty-two of 151 glenoid components (34%) showed a shift in position or a complete lucent line ≥1.5 mm. Component survival free from radiographic failure was 99% at 5 years but only 67% at 10 years. Among multiple factors, only late subluxation superiorly was associated with increased risk for radiographic failure, presumably via the 'rocking horse' effect. Glenoid component survivals free from revision at 5 and 10 years for the 302 shoulders were 99% and 93%.

Almost one-third of the glenoid components had a shift in component position between early postoperative and final radiographs and approximately one-third of all components were felt to be
radiographically at risk for clinical failure. These "at risk" changes began to appear at five years after surgery or later.

These results are similar to those of Kasten (Mid-term survivorship analysis of a shoulder replacement with a keeled glenoid and a modern cementing technique. J Bone Joint Surg Br 2010;92:387-92.), Young (A multicenter study of the long-term results of using a flat-back polyethylene glenoid component in shoulder replacement for primary osteoarthritis. J Bone Joint Surg Br 2011;93:210-6.), and Walch (Results of a convex-back cemented keeled glenoid component in primary osteoarthritis: multicenter study with a follow-up greater than 5 years. J Shoulder Elbow Surg 2011;20:385-94.) ( Patterns of loosening of polyethylene keeled glenoid components after shoulder arthroplasty for primary osteoarthritis. J Bone Joint Surgery Am 2012;94:145-50.).

Clearly fixation of the glenoid component remains a concern. It is also of interest that the revision rate lags substantially behind the rate of radiographic loosening.

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Results of Cemented Total Shoulder Replacement with a Minimum Follow-up of Ten Years JBJS

Results of Cemented Total Shoulder Replacement with a Minimum Follow-up of Ten Years JBJS

While most journals require a minimum of two years of followup for reconstructive procedures, patients are interested in knowing longer term outcomes as well. This study is a Level IV followup of 39 out of 60 arthroplasties performed between June 1995 and October 2000 at a minimum of 10 years after a 'third generation' Tornier total shoulder arthroplasty with keeled flat-back glenoid components.  Glenoid anatomy was characterized by standardized anteroposterior and axillary radiographs of the shoulders obtained preoperatively and postoperatively. The morphology of the glenoid was recorded according to the classification described by Walch. The glenoid was type A2 in eleven cases, type B1 in sixteen, type B2 in ten, and type C in two. Loosening was defined as a radiolucent line score of over 12 (out of a maximum of 18), tilting over 5 degrees or subsidence. The authors observed that some shoulders showed loosening only on the AP view, some only on the axillary and some on both. Over a third of the glenoid components were radiographically loose at the time of followup. The mean radiolucent line score for the B2 and C glenoids was significantly greater than that for the A2 and B1 glenoids.

Superior migration of the humeral component was observed in over two thirds of the cases. None of the glenoid components required revision and the Constant scores showed significant improvement.

The high radiographic loosening rates observed in this study for keeled components are consistent with two previous long term result reports, here and here.

So again, glenoid component fixation, especially when the glenoid is biconcave or retroverted, remains a challenge. While shoulders with loose glenoids may remain functional, this loosening remains a concern that has not been resolved by later generation prostheses.

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The early migration of a partially cemented fluted pegged glenoid component using radiostereometric analysis JSES

JSES recently published: The early migration of a partially cemented fluted pegged glenoid component using radiostereometric analysis

The authors conducted a very careful study using radiostereometric analysis and two-year post op CT scans to track the motion of a glenoid component relative to the glenoid bone in eleven shoulders. They found that focal radiolucency around the central peg as shown on this CT scan

was associated with rapid early migration of the glenoid component in six of the eleven cases. When bone grew into the flutes of the central peg, migration did not occur, but when it did not, the component was at risk for migration.

While the clinical results for these shoulders showed significant improvement over the preoperative ASES, Constant and pain scores, the findings of this study raise concerns about the longevity of the glenoid components. 

The authors point to three other reports that are of interest in this regard, each of which pointed to the lack of bone ingrowth in some cases:

Bone presence between the central peg's radial fins of a partially cemented pegged all poly glenoid component suggest few radiolucencies.

Clinical and radiographic analysis of a partially cemented glenoid implant: five-year minimum follow-up

and

Survival and radiographic analysis of a glenoid component with a cementless fluted central peg.

The findings of the authors of the current JSES report are of concern. I know them to be excellent surgeons; it is doubtful that the results are attributable to technical concerns. The illustrations in the manuscript show excellent positioning of the components.  The patients all had osteoarthritis (not RA) and had an average age of 69 years and that nine of the eleven were women, the point being that the authors' findings can probably not be attributed to inflammatory arthritis or to high levels of physical activity. Yet as the authors point out in referring to In vivo measurement of shoulder joint loads during activities of daily living, the shoulder is a major load-bearing joint even in the absence of 'high levels of physical activity'.



So, because the  glenoid component remains the leading cause of failure, we take time to explain the risk of this complication to patients considering a total shoulder and continue to explore the application of the ream and run procedure for carefully selected patients with osteoarthritis.

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