Showing posts with label pegged. Show all posts
Showing posts with label pegged. Show all posts

Monday, August 5, 2019

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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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 runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Friday, September 22, 2017

Total Shoulder Arthroplasty – glenoid component failure is progressive and is associated with inferior clinical outcomes.

Radiographic and clinical comparison of pegged and keeled glenoid components using modern cementing techniques: midterm results of a prospective randomized study

These authors point out the that most frequent indication for revision total shoulder arthroplasty is loosening of the glenoid component, which has been correlated radiographically with the appearance of lucencies around the glenoid component.

They evaluated the radiographic and clinical outcomes of patients with primary osteoarthritis randomized to receive either a Tornier smooth pegged glenoid component or a Tornier keeled glenoid (see below)  at minimum 5-year follow-up. Surgeries were all performed by an individual highly experienced shoulder surgeon.



Of note is that the great majority of these cases had simple (A1) glenohumeral pathoanatomy.



Of the 50 patients (59 shoulders) initially enrolled, 10 died.

Three patients with keeled components had early failure and were revised before 5-year follow-up. In all, 20% of the keeled shoulders (6 of 30) and 7% of the pegged shoulders (2 of 29) underwent revision surgery.

Eight shoulders did not return for followup at a minimum of 5 years. 38 of 46 shoulders (30 patients) were available with minimum 5-year follow-up (82.6%) At an average of 7.9 years, all but 2 shoulders showed at least grade 2 lucency and approximately 40% of shoulders in each group showed either grade 4 or 5 lucency (see below)


Importantly, the shoulders with high radiolucency scores had worse clinical outcomes.



Comment: This report is a followup of a shorter term study (see this link) on the same initial patient cohort. The findings of the earlier paper were:

"After an average follow-up of 26 months, the rate of glenoid lucency (of at least grade 2) was significantly higher in patients with a keeled glenoid component (46%) compared to patients with a pegged glenoid component (15%).

Glenoid lucency progressed (at least 1 grade) between postoperative radiographs and follow-up radiographs in 29% of patients, including 10 patients with keeled glenoid components (42%) and 3 patients with pegged glenoid  components (14%). The rate of progression and the final grade of glenoid lucency were higher in patients with keeled glenoid components compared to patients with pegged glenoid components."



The important findings from both of these reports are that glenoid loosening is common and progressive with time. The 20% revision rate for keeled in the hands of an experienced surgeon is a concern. Furthermore, this study points out that the rate of surgical revision does not reflect the rate of glenoid failure: apparently a substantial percentage of patients with high grades of lucency and inferior clinical outcomes are reluctant to have a revision procedure.

As for the comparison of smooth non-ingrowth peg versus keeled glenoid components, this study suggests an early loosening problem with the keeled components. The pegged component used in this study does not take advantage of the fluted central peg which is now available (see below) so the results with the modern design are not reflected in this study.

It is of note that these authors conclude, “ given that biomechanical data have shown pegged glenoid superiority, with clinical and radiographic data showing improved early results, we continue to use pegged glenoid components.”

Finally, the observation that patients accept deterioration in shoulder function for an extended period of time prior to revision, suggests that monitoring function may be a more cost effective method than sequential x-rays for tracking the long term outcome of shoulder arthroplasty.

This point is made in the paper referenced below.

Patient functional self-assessment in late glenoid component failure at three to eleven years after total shoulder arthroplasty

"Failure of the glenoid component is the most common indication for late revision of a total shoulder arthroplasty (TSA). This is the first study to characterize the deterioration in patient self-assessment of shoulder function occurring with glenoid component failure at times remote from the index surgery. Of 115 total shoulders, 11 had revision by the original surgeon for isolated glenoid loosening. Simple Shoulder Test scores averaged 4.4 before TSA, rose to a mean of 11.3 after surgery, and fell to a mean of 4.6 before revision for glenoid loosening performed at a mean of 7 years after TSA. All shoulders showed a drop of at least 3 points between the peak Simple Shoulder Test score and the prerevision Simple Shoulder Test score. Periodic self-assessment of shoulder function may offer a method of screening patients for the possibility of late glenoid component failure. "




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The reader may also be interested in these posts:





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 runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'






Friday, July 28, 2017

How long do total shoulders last? The Great Paradox

Survival of the pegged glenoid component in shoulder arthroplasty: part II

Theses authors point out that loosening of the glenoid component is a primary reason for failure of an anatomic shoulder arthroplasty. These authors evaluated the midterm clinical and radiographic survival of an in-line pegged glenoid component and identified risk factors for radiographic loosening and clinical failure at an average clinical follow-up of 7.2 years




287 had presurgical, initial postsurgical, and late postsurgical radiographs (mean radiographic follow-up, 7.0 years). At most recent follow-up, 30 glenoid components had been revised for aseptic loosening. The rate of glenoid component survival free from revision for all 330 shoulders of 99% at 5 years and 83% at 10 years. 



Of 287 glenoid components, 120 (42%) were considered loose on the basis of radiographic evaluation. Four humeral components were considered loose. Component survival (Kaplan- Meier) free from radiographic failure at 5 and 10 years was 92% and 43%. 



Severe presurgical glenoid erosion (Walch A2, B2, C) and patient age <65 years were risk factors for radiographic failure. Late humeral head subluxation was associated with radiographic failure.

Comment: This paper shows the importance of longer term followup. Both radiographic failure and the need for surgical revision for this component was not apparent until after five years - a time well after the usual 2-year followup required for publication in most journals. 

This article also points out that the rate of revision at any time point after surgery underestimates the rate of radiographic glenoid failure.

A case example from this paper shows late loosening of an initially well-fixed glenoid component

 The late followup x-ray shows superior displacement of the humeral head with superior angulation of the glenoid component.
This is the type of component loosening that has been associated with rotator cuff failure via the 'rocking horse' mechanism.

The authors point out that their results with this peg configuration were inferior to those they achieved with the corresponding keeled fixation.
One of the challenges we face in clinical orthopaedic research what we refer to as the Great Paradox: the long term data we have relates to components that are no longer in use.

The authoring surgeons have moved on to other designs for which 10 year outcomes are not available:



Nevertheless, the problem of glenoid component failure retains its position as a leading cause of poor total shoulder outcomes. Some of the risk factors for failure identified in this study are likely to remain in effect with any glenoid component design: young age, advanced glenoid erosion, and glenohumeral instability. 

Finally, an understanding of the factors associated with component failure may be most reliably obtained from national registry data such as that provided by the Australian Orthopaedic Association 









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The reader may also be interested in these posts:





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 runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'


Saturday, July 22, 2017

Glenoid components: pegged or keeled?

Comparison of Pegged and Keeled Glenoid Components for Total Shoulder Arthroplasty: A Systematic Review

These authors conducted a systematic review of level I, II, and III studies comparing the development of radiolucent lines and glenoid failure after total shoulder arthroplasty with pegged or keeled glenoid components. Four articles were included in the final analysis with 107 pegged and 96 keeled glenoid components.



Development of radiolucent lines was less likely with pegged glenoid components with a risk difference of 0.32 (95% CI 0.62, 0.03) favoring the pegged design. 



With the number of cases and the duration of followup in these studies, there was no statistically significant difference in the rate of radiographically at-risk glenoids, clinical glenoid failure, or the composite endpoint.



Comment: In considering the survivorship of glenoid components, it is important recognize that problems of glenoid component failure usually do not become evident until 5 or more years after the procedure. So comparative studies of revision rates for different components need to be extended well beyond the one year minimum applied in this study. Furthermore as evidenced in the study below, the rate of glenoid component failure is multifactorial.

Failure of the Glenoid Component in Anatomic Total Shoulder Arthroplasty
Although glenoid component failure is one of the most common complications of anatomic total shoulder arthroplasty, substantial evidence from the recent published literature is lacking regarding the temporal trend in the rate of this complication and the risk factors for its occurrence. We conducted a systematic review and identified twenty-seven articles presenting data on glenoid component failure rates that met the inclusion criteria. These articles represented data from 3853 total shoulder arthroplasties performed from 1976 to 2007. Asymptomatic radiolucent lines occurred at a rate of 7.3% per year after the primary shoulder replacement. Symptomatic glenoid loosening occurred at 1.2% per year, and surgical revision occurred at 0.8% per year. There was no significant evidence that the rate of symptomatic loosening has diminished over time. Keeled components had greater rates of asymptomatic radiolucent lines compared with pegged components in side-by-side comparison studies. However, as a result of wide variability in outcomes reporting, only sex, Walch class, and diagnosis were significantly associated with the risk of glenoid component failure in the overall analysis. 

It is always of interest to review the data from the Australian NATIONAL JOINT REPLACEMENT REGISTRY (see this link), which demonstrates that an all polyethylene pegged glenoid component has a lower revision rate that keeled or metal backed components.







See also:
Rates of Radiolucency and Loosening After Total Shoulder Arthroplasty with Pegged or Keeled Glenoid Components

There is no question that survivorship of the glenoid component is the key to survivorship of a total shoulder arthroplasty. We have presented our approach to glenoid arthroplasty here.


This is an important study in that it seeks literature evidence on the cost-effectivenss of pegged vs. keeled glenoid components with particular emphasis on the risk of revision surgery. After a thorough analysis of the published data, they found that pooled risk ratio for revision was 0.27 (95% CI, 0.08 to 0.88) in favor of pegged components (p = 0.028). Their value analysis indicated that pegged glenoid designs were more cost-effective than keeled glenoid designs.

One of the key differences between a pegged and keeled component is that with a pegged component the geometry of the fit is more precisely controlled by the fact that concentric reaming takes place around the same axis as is used to fix the component.

Thus the risk of poor bony support for the component (shown below) is reduced. 



Finally, it is worth noting that all pegged components are not the same. Some have three smooth pegs in a row
and others have out of plane peripheral pegs with a fluted central peg.





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The reader may also be interested in these posts:





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 runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'


Wednesday, June 14, 2017

Total shoulder: pegged or keeled glenoid?

Comparison of Pegged and Keeled Glenoid Components for Total Shoulder Arthroplasty A Systematic Review

These authors conducted a systematic review of level I, II, and III studies comparing the development of radiolucent lines and glenoid failure after total shoulder arthroplasty with pegged or keeled glenoid components was conducted. Four articles were included in the final analysis with a total of 203 total shoulder arthroplasties comprising 107 pegged and 96 keeled glenoid components.

They found that the development of radiolucent lines was less likely with pegged glenoid components with a risk difference of −0.32 (95% CI −0.62, −0.03) favoring the pegged design. There was no statistically significant difference in the rate of radiographically at-risk glenoids, clinical glenoid failure, or the composite endpoint.

Comment: There are many factors that influence the survivorship of a glenoid component. First and foremost are (1) the quality of preparation of the glenoid bone that supports the component and (2) the soft tissue balancing that assures centering of the humeral component on the glenoid. With respect to pegs vs. keels,

it is important to recognize that all pegged designs are not alike. Some offer out of plane anterior and posterior pegs with a fluted central peg for bone ingrowth


while others offer only smooth pegs all in the same plane.

Such differences can confound the comparisons published in the literature. 

While it is technically more demanding, we prefer a pegged glenoid with a central fluted peg because it offers ingrowth fixation without a metal back and because it preserves the glenoid bone stock that is lost when a slot is created for a keeled component.

Our approach to glenoid arthroplasty briefly described here.
The goals for total shoulder arthroplasty include establishing maximal stability and maximal contact area for distribution of the humeral load to the glenoid. In addition, the procedure needs to achieve support of the prosthetic glenoid by precisely contouring the bone supporting it as well as secure and durable fixation of the component to the underlying bone. In that glenoid bone stock is a most precious commodity when performing shoulder arthroplasty and in that excessive reaming has been associated with increasing rates of glenoid component failure, preservation of glenoid bone is a high priority. Both bone preservation and the quality of fixation are enhanced by the precise drilling of the holes for peg fixation of a glenoid component rather than the less precise preparation for a keeled component. This precision has the additional benefit of minimizing the amount of cement used, reducing the risk of thermal damage.

The glenoid is exposed by excising the labrum from the bony glenoid, removing any tissue that may interfere with complete glenoid component seating. If the preoperative axillary view shows posterior humeral head decentering, the inferior glenohumeral capsule is left intact.

The size of the glenoid component is determined using round back glenoid trials. The center of the glenoid face is marked and a burr hole is made at this point to guide the drill for the reamer. The angle of glenoid reaming is adjusted to preserve as much glenoid subchondral bone as possible. Glenoid bone is preserved by orienting the reaming and the component along the glenoid axis rather than the scapular axis. Reaming is always started by hand; power is used very sparingly except in hard bone. Appropriate positioning of retractors facilitates this reaming. In that the goal of reaming is to conservatively establish a single glenoid concavity, it is important to check the progress of reaming frequently so that the reamer does not inadvertently remove more bone than necessary. The adequacy of the glenoid bone preparation is checked by inserting the round back glenoid trial component and ensuring that it does not rock even when eccentric loads are applied to the rim.

After the hole for the central peg is drilled, the peripheral drill guide is inserted into the central peg hole and set firmly on the reamed glenoid surface to precisely guide the drilling of the additional holes for the peripheral pegs. The drill guide needs to be oriented to take maximal advantage of the available glenoid bone; care must be taken to assure that the drill guide sits flush on the reamed glenoid surface so that the hole position will match the position of the component pegs. After each peripheral hole is drilled, a derotation peg is placed in it to maintain alignment of the guide while the subsequent holes are completed and to make sure that the hole is of the proper depth. Each hole is checked to determine whether it penetrates the scapula.

After irrigation with antibiotic containing saline solution, the holes are cleaned and dried with a spray of sterile CO2 gas removing all tissue and fluid from the holes so that the injected cement will directly contact bone without interposed fluid or the blood clot that results from the use of thrombin. It is apparent that neither fluid nor clot will turn into bone or cement, so the presence of either will compromise the quality of fixation.



Unpenetrated holes are pressurized with a syringe. Penetrating holes are cemented, but the cement is not pressurized. The use of a carbon dioxide gas spray and cement pressurization has essentially eliminated the problem of postoperative radiolucent lines


 




No cement is placed on the bony face of the glenoid; if the back of the glenoid component matches the prepared bony face, there is no advantage to an interposed layer of cement, which could fail and become displaced and consequently leave the glenoid component relatively unsupported as shown below.


While some surgeons have been concerned about avoiding penetration of the holes for glenoid fixation, glenoid perforation does not appear to affect the clinical outcome of total shoulder arthroplasty. It is evident, however, that penetration is more likely in severely pathological glenoids that have substantial medial or posterior bone erosion and for this reason, rather than the penetration itself, shoulder arthroplasty may be less successful in cases of particularly severe arthritic deformity.

Reamed bone retrieved during the glenoid preparation (reaming and drilling) is used to create a bone paste that is interposed between the flutes of the central anchor peg to help facilitate bone tissue integration. The glenoid component is firmly impacted into position, assuring that its posterior aspect is completely seated on bone by sliding a finger over the back of the component to feel the bone that should lie immediately beneath. The joint space is checked to assure that no bits of cement or bone remain. From the time the glenoid component is in place, it is important to prevent the humerus from dislodging it by the ‘bottle cap’ mechanism; we use a broad flat retractor to safely deliver the proximal humerus into the wound after the glenoid has been implanted.

Here is a related post: Rates of Radiolucency and Loosening After Total Shoulder Arthroplasty with Pegged or Keeled Glenoid Components

There is no question that survivorship of the glenoid component is the key to survivorship of a total shoulder arthroplasty. We have presented our approach to glenoid arthroplasty here.


This is an important study in that it seeks literature evidence on the cost-effectivenss of pegged vs. keeled glenoid components with particular emphasis on the risk of revision surgery. After a thorough analysis of the published data, they found that pooled risk ratio for revision was 0.27 (95% CI, 0.08 to 0.88) in favor of pegged components (p = 0.028). Their value analysis indicated that pegged glenoid designs were more cost-effective than keeled glenoid designs.

One of the key differences between a pegged and keeled component is that with a pegged component the geometry of the fit is more precisely controlled by the fact that concentric reaming takes place around the same axis as is used to fix the component.

Thus the risk of poor bony support for the component (shown below) is reduced. 



=====
The reader may also be interested in these posts:



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