Anatomic total shoulder arthroplasty - optimizing glenoid component fixation.

Glenoid Radiolucent Lines in Anatomic Total Shoulder Arthroplasty are Unaffected by Thrombin Glenoid Preparation 

It is recognized that Glenoid component lucencies are associated with poorer patient-reported outcomes following anatomic shoulder arthroplasty.

These authors identified patients undergoing primary anatomic TSA using two glenoid types. Group A glenoids had a cemented central peg without peripheral peg cementation

and Group B glenoids had cemented peripheral pegs without central peg cementation

After reaming the glenoid, all glenoids were irrigated with pulsatile lavage and suction dried. Next, all glenoids in Groups A and B had either Surgicel (Ethicon, Johnson & Johnson, Somerville, NJ) alone or Surgicel soaked in thrombin for preparation. The Surgicel was placed into the peg holes that were to be cemented and then removed prior to cementing. Polymethyl methacrylate cement (Simplex, Stryker, Kalamazoo, MI) was applied using a catheter-tipped syringe for pressurization. 

All patients had the same glenoid preparation except some had the addition of thrombin as a preparation agent. Group A glenoids were implanted by the same surgeon at three different hospitals, one where thrombin was used and two where thrombin was not used. Group B glenoids were implanted by one surgeon who routinely used thrombin and another surgeon who did not at the same hospital. 

The first postoperative radiograph was assessed for radiolucent lines. 

They identified 83 Group A glenoids with and 63 without thrombin glenoid preparation, and 109 Group B glenoids with and 48 without thrombin preparation. 

None of the Group A glenoids had radiolucent lines and 5 (3%) Group B glenoids had radiolucent lines. 

Use of thrombin showed no difference in early radiolucencies (p=1.00) in either Group. 

Comment: It seems likely that radiolucent lines are the result of failure to remove fluid or clot from the holes and failure to adequately pressurize the cement.

In this study the surgical technique combining Surgicel hemostasis and pressurization of each hole effectively minimized postoperative radiolucent lines.

An alternative to Surgicel for removing blood from the peg holes prior to cement pressurization is the use of a carbon dioxide spray to dry each hole immediately before pressurizing the cement assuring that no fluid or clot remains.

This technique, like that of the authors, routinely yields glenoid fixation without radiolucent lines as shown below.

There are other elements that are essential for securing the glenoid component as shown in this link.

The importance of minimizing glenoid component lucencies is demonstrated in this article

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

These authors point out the high rates of radiographic glenoid loosening following anatomic total shoulder arthroplasty (TSA). They studied the association of radiolucent lines with shoulder function and patient-reported outcomes (PROs) in 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) after surgery.

All-polyethylene keeled components (below left) were used in 186 shoulders All-polyethylene pegged glenoids (below right) were used in 306 shoulders.

An example of radiographic loosening is shown below.

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 with peri-glenoid lucency's demonstrated significantly lower improvements in forward elevation (P .02) and all PROs (P .005). The improvement in Simple Shoulder Test averaged 7.3 for the 308 shoulders without radiolucent lines and 5.6 for the 184 shoulders with radiolucent lines.

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; the differences exceeded  the MCID for grade 5 lucencies.

Complications and reoperations were more common in group 1 (16% vs. 5% [P < .001] and 11% vs. 3% [P < .001], respectively). Glenoid component loosening was the most common cause of reoperation in group 1, representing the indication for revision in 14 of 21 reoperations.

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Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (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.

Radiolucent lines correlate with poorer outcomes after shoulder arthroplasty

Long-term survival of the glenoid components in total shoulder replacement for arthritis

These authors present 5 to 12 year follow-up on 39 total shoulders for osteoarthritis using a keeled, polyethylene, convex-backed component implanted with minimal reaming, compaction bone grafting of the glenoid and minimal addition of cement.

The glenoid morphology was A1 in 25 shoulders, A2 in ten, B1 in four and no B2 or C.

The glenoid preparation included limited reaming, creation of a central keel slot, impaction of cancellous bone chips harvested from the humeral head into the keel slot with a glenoid punch, and insertion of a convex backed polyethylene with low viscosity cement at the keel.

Radiolucent lines were assessed on anteroposterior radiographs.

Constant scores, active elevation, and comfort were improved.

Radiolucency around the components increased with time. 16% had definite radiological glenoid loosening at last followup.

Constant scores deteriorated with the progression of glenoid radiolucency.

The rate of revision surgery for glenoid loosening was 2.5 %.

Comment: This is an interesting single surgeon study of the use of a keeled glenoid component in shoulders with relatively benign glenoid pathoanatomy (35 of 39 type A glenoids). Emphasis was placed on preservation of the glenoid bone stock.

The authors showed that increased glenoid radiolucency was associated with poorer shoulder comfort and function.

One of the cases shown (figure 2f) shows a substantial amount of glenoid osteolysis - similar to that seen with Propionibacterium, but culture results are not presented.

A final observation is that many patients apparently would rather accept the symptoms of a loose glenoid rather than having a revision.

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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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Ten year outcomes of total shoulders

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

This is a report on the clinical and radiographic long-term outcomes of 39 shoulders treated with a third-generation cemented total shoulder replacement with a keeled all polyethylene flat backed cemented glenoid component (Aequalis Total Shoulder) and followed for at least ten years.

On average, the Constant Score increased from  27 points preoperatively to  61 points postoperatively. Shoulder flexion increased from 84° preoperatively to 133° postoperatively. Although no humeral components were loose, 36% of the glenoid components were radiographically loose at the time of follow-up. Kaplan-Meier survivorship of the glenoid component was 100% after thirteen years with revision as the end point, whereas survivorship with radiographic loosening as the end point was only 48% after thirteen years.  Cranial migration of the humerus was seen in 69% of the cases. The migration was mild in ten cases (37%), moderate in twelve (44%), and severe in five (19%).

This is an important study. The patterns of glenoid radiographic loosening included superior rocking horse loosening in cases of superior migration resulting from presumed rotator cuff failure

 and posterior rocking horse loosening.

There was no significant difference in the clinical outcomes between patients with and those without radiographic loosening of the glenoid component. There was a trend toward inferior outcomes in cases with severe migration.

It was of interest to see that the onset of radiographic loosening was often after the 10 year mark.

Only one of these patients has required revision surgery.

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Incidence of early radiolucent lines after glenoid component insertion for total shoulder arthroplasty: a radiographic study comparing pressurized and unpressurized cementing techniques.

Incidence of early radiolucent lines after glenoid component insertion for total shoulder arthroplasty: a radiographic study comparing pressurized and unpressurized cementing techniques.

Radiolucent lines are a problem in glenoid component fixation. These lines represent areas filled with fluid or debris between the bone and the cement. These zones do not have the potential to turn into either bone or cement and as such represent insecure fixation of the component that can only progress, but not regress. In the figure below, note that there are lucencies around each of the pegs. There are also lucencies beneath cement placed beneath the articular surface of the component - a practice we avoid because this thin cement layer is brittle and can crack, leaving the component unsupported.

In a prospective study of 130 shoulders, the authors of this paper found sigificantly fewer lucent lines in a group of shoulders having a 3-step pressurization as opposed to a group that underwent minimal manual pressurization. In their 3-step technique,  the cement was first pressurized by injecting the cement into each peg hole using a syringe that fit perfectly into the peg hole. The second pressurization was completed by pushing a polished metal rod into each hole. Finally, cement in its doughy state was manually pressurized into each peg hole, followed by placement of the final implant.

We have taken a simpler approach to avoiding radiolucent lines - using a carbon dioxide jet to remove all fluid and tissue from the drill hole immediately prior to cementing. This method has virtually eliminates the radiolucent lines from our post operative films as shown in this film from last week after a total shoulder we performed for a gentleman from California. Note the absence of cement between the face of the component and the bone ( 'bone backing').

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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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Polyethylene glenoid component for total shoulders - JBJS

In the February Journal of Bone and Joint Surgery, our colleagues Wirth, Rockwood, Iannotti et al have published a Level IV study on 44 shoulders with primary or secondary arthritis having total shoulder arthroplasty with a new design of all polyethylene glenoid component that has flanges on the central peg.  

The authors were careful to disclose consultancy, speakers bureau, patents, royalties, employment, stock/stock option relationships with the company that makes this glenoid prosthesis, DePuy.

These authors have been avid students of the problems patients experience with total shoulders, having reported previously that component loosening accounted for a large percentage of the complications reported for shoulder arthroplasty. Like many others, these authors again identify glenoid component loosening as ‘the foremost cause of medium and long-term failure of shoulder replacements’. 

The authors used the method we published previously for evaluating the x-rays of these shoulders. Initial post-operative x-rays showed 35 of 44 shoulders had a perfect radiolucency grade (80%). At a mean of three years the number of shoulders with a perfect radiolucency grade had diminished to 20 (45%). Three of the shoulders had glenoid osteolysis. The 24 shoulders with glenoid retroversion had poorer glenoid fixation than the 20 shoulders without glenoid retroversion. 

Although there are no direct comparisions to other arthroplasty systems, this glenoid component may have the advantages of using pegs over keels, pegs offset in the superior/inferior and anteroposterior directions, a central peg with flanges to provide initial fixation, and the need for minimal cement.  It is the component we use here at the University of Washington for total shoulder arthroplasty.

It is concern that even though all of these arthroplasties were performed by the individual surgeon inventor who has extensive experience in this procedure, the radiographic results appear to have worsened over the relatively short mean followup period of three years. We look forward to the medium and long term results with this innovative prosthesis.

In this study, seven of the original 51 shoulders (14%) were lost to followup. For the remainder, mean SST scores improved from 3 to 9.  It is of interest that the improvement in shoulder comfort and function in this series of total shoulder arthroplasties, as indicated by the Simple Shoulder Test, are essentially the same as those that have been achieved with the ream and run procedure that avoids the risks associated with glenoid component failure (SST results with ream and run).

Finally, this paper points out that 33,000 of these glenoid components have been installed whereas outcome information is only available (from this and two other papers) on 100 or 0.3% of them. It is worthwhile considering the 'external validity question':  how generalizable is this sample of surgeries carried out by experts in the field to the remaining 29,900 or 99.7% of the arthroplasties for which the results are unavailable?  This comment is not a specific critique of this paper, but rather a reflection on how little we know about the results of shoulder arthroplasty across the country and world, especially since such a large percentage are performed by 'occasional' shoulder arthroplasty surgeons.

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Total shoulder replacement: x-ray evidence of loosening

In yesterday's post, we discussed radiolucent lines (RLL's) and the possible role of heat generated in the preparation of the glenoid in their creation. Here are two x-rays showing RLL's from our artilce on
failure of the polyethylene glenoid component.

In the first, an axillary view, one can see the metal humeral component at upper left. The small metal oval in the center of the picture is a marker in the plastic glenoid component. The plastic glenoid component itself cannot be seen on x-ray. Below this oval is the keel of the component and surrounding cement shown in white, surrounded by a darker area indicated by the small arrows. This darker zone is the radiolucent line. The larger arrow points to a radiolucent line underneath the face of the plastic glenoid component.

In the second x-ray, an anteroposterior view of the shoulder, the arrows point to a radiolucent line between cement on beneath the glenoid component  (the thin white curved line) and the bone that normally would support the glenoid component. The darker area between the cement and the humeral prosthesis is the location of the face of the glenoid component.

These radiolucent lines seen on x-ray represent areas where there is no bone, cement, or glenoid prosthesis. Instead the area is filled with fibrous tissue that does not securely fix the component to the bone. As pointed out in previous posts, these lines are often progressive and lead to symptoms of glenoid component loosening.

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Total shoulder replacement: avoiding heat damage

One of the concerns about fixation of the glenoid component in total shoulder replacement is the observation that 'radiolucent lines (RLL's)' may develop between the bone on one hand and the component and cement on the other. These RLL's suggest that the connection of the component to bone is not as strong as it should be. Of greater concern is that these RLLs are often progressive, that is, the fixation of the component becomes less secure with time. This is well shown in the article by Walch et al in the SUNDAY, MAY 1, 2011 post. 

There has been little study of the factors that may contribute to the development and progression of RLL's, especially in cases where no lucent lines are seen immediately after surgery.

One factor that we have studied is the possibility of heat damage to the bone of the glenoid causing local death and resorption of the bone over time with progressive mechanical loosening.  In a study with shoulder fellows Churchill, Boorman and Fehringer, Glenoid cementing may generate sufficient heat to endanger the surrounding bone, we found that the amount of heat generated was related to the volume of cement used in fixing the glenoid component. This is because cement cures with an exothermic, or heat generating reaction. With larger amounts of cement, the temperature of bone can rise to a level that can kill the bone.

This observation led us to explore methods of glenoid fixation that used only minimal amounts of cement: precise 'carpentry' with the removal of a minimal amount of bone.

In second study by shoulder fellows Clinton and Lynch along with resident Olson, we found that reaming of the bone could cause thermal damage: Thermal effects of glenoid reaming during shoulder arthroplasty in vivo. The figure below was taken during surgery using a thermal camera. 

We found that irrigating the wound with cool saline solution at the time of reaming kept the temperature of the bone within safe limits.

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Total shoulder: the glenoid component, Part III

We have spent a substantial amount of effort in identifying causes of failed total shoulder arthroplasty; examples are the investigations of our shoulder fellows Hasan and Franta. One of the most common causes of total shoulder failure is failure of the glenoid component. In our research on this issue we have identified a number of factors, very important among which is the technique of insertion of the glenoid component. Our shoulder fellow Lazarus conducted a multicenter study in which radiographic evaluation of glenoid components demonstrated that many components inserted around the country were not well seated and or not well fixed. This may be due in part to the observation by our shoulder fellow Hasan that many surgeons doing shoulder joint replacement have less experience than those doing hip or knee surgery.

When the glenoid bone surface is not properly contoured to fit the back of the glenoid component, bone cement can be used to fill in the gaps as shown in the left hand diagram below. However, loading of the glenoid component can lead to fracture and loosening of this thin layer of cement, leading to its displacement and loss of support for the glenoid component as shown on the right hand diagram below.

In the investigation by Lazarus, glenoid component designs with pegs outperformed glenoid component designs with keels. This article also pointed out the importance of the experience of the surgeon: 80% of the glenoid components inserted by the most experienced surgeon had better cementing in comparison to 50% for the remaining surgeons. There are some other important articles relating to the effect of surgeon experience to the outcome of shoulder arthroplasty. An article by Hasan shows that 75% of shoulder arthroplasties are done by surgeons performing only one or two per year. Articles by Hammon and Jain show that surgeons performing higher numbers of shoulder arthroplasties have a lower rate of complications.

At present, the optimal approach to glenoid fixation combines (a) reaming the glenoid bone to precisely fit the back of the glenoid component

(b) drying the bone with a carbon dioxide jet to remove blood, fluid and debris before cement is inserted (as the divers among you will recognize, we use CO2 because of its solubility in water and blood, so that nitrogen bubbles (the bends) are avoided).

(c) pressurizing the cement in to the holes

(d) removing the excess cement so that none remains on the surface of the bone

(e) inserting the component so that the precise geometry of the pegs and back surface of the component meet the precise geometry of the holes and reamed surface of the glenoid bone

and (f) vigorously impacting the component into the prepared bone

This technique minimizes the amount of cement used, so that excessive heat is not generated by the curing of the methylmethacrylate, a risk pointed out by our shoulder fellow Churchill.
A detailed view of the postoperative film shown in yesterday's post reveals excellent seating of the glenoid component on the prepared bone surface with penetration of the pressurized cement into the bone (arrow) - note the absence of radiolucent lines.

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