A universal humeral component for anatomic shoulder arthroplasty?

There is a rapidly expanding number of humeral components being sold for anatomic arthroplasty. 

Let's consider the features of a legacy "universal" anatomic humeral component system against which these newer alternatives can be compared. 

The primary principles are (1) bone preservation, (2) avoidance of stress shielding, and (3) availability of humeral head options to manage the variations in arthritic pathoanatomy. 

These goals can be achieved with a standard length smooth stem with a low filling ratio fixed with impaction grafting coupled with a versatile selection of heads, including eccentric and cuff tear arthropathy options. NB: the author has no ties with any implant company, so this is not a sales pitch, but rather a perspective gained from almost 50 years of practice in shoulder arthroplasty.

Bone preservation: the head cut is the same as for short stemmed and stemless

Bone is not removed from the canal by reaming

instead, a stem diameter is selected that is smaller than the internal diameter of the diaphysis, yielding a small filling ratio without violating the bone of the canal.

The irregular internal anatomy of the humerus 

is fit to the stem using impaction grafting

    

The security of this fixation obviates the need for ingrowth surfaces on the implant, which can complicate removal of the stem should it become necessary.

The bone graft spreads the load broadly across the interface between the stem and bone minimizing the risk of stress shielding.

Stress shielding can be a problem when an implant is fit tightly against the distal cortical bone.

The use of a thin stem enables proper seating of the component

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avoiding the issue of incomplete seating that can be seen with a large stem

Because the shaft is not weakened, the thin stem with impaction grafting technique minimizes the risk of intraoperative and postoperative fractures.

 

The thin stem with impaction grafting can be applied to special situations, for example when a plate is retained to protect the humerus.

The thin stem with impaction grafting technique can be safely applied to osteopenic bone, without being concerned about the results of the "thumb test"

or the need for intraoperative conversion from a stemless to a stemmed component (see Pre-operative Metaphyseal Cancellous Bone Density is Associated with Intraoperative Conversion to Stemmed Total Shoulder Arthroplasty).

A single piece body 

avoids the potential risk of corrosion, loosening and disassembly that can be an issue with mutlipart stems

Having the male taper on the head, rather than the body keeps it from blocking access to the glenoid

The prosthetic head should come in a wide variety of diameters of curvature to match different glenoid curvatures

Each head diameter of curvature should have different thicknesses 

so that the soft tissue tension can be adjusted to meet the 40, 50, 60 rules

 Eccentric / offset options should be available to manage excessive posterior translation

Extended articular surface options should be availabe to manage cuff tear arthropathy in CTA shoulders with retained active elevation.

These two non-anatomic strategies are difficult to accomplish with a stemless system.

Comment: There is a vast set of options available for the the humeral side of a glenohumeral arthroplasty. Surgeons seem to be switching from one to another to see which they like best. 

The challenge is to determine which, if any, are of greater value (benefit/cost) to the patient than the legacy approach presented above. Long term studies will be required, such as that presented by the population-based Australian Orthopaedic Association's National Joint Replacement Registry showing long term data for some of the options for treating primary osteoarthritis of the glenohumeral joint. Note the option that got gold.

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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).

How to secure the humeral component safely and securely

An impaction grafted standard length humeral stems provides secure fixation that preserves bone, enables the use of eccentric head components of different thickness, avoids stress shielding and fracture, and permits easy removal should revision become necessary. 

Impaction grafting effectively manages the challenge of the variable medullary anatomy of the humerus (which cannot be matched by any prosthesis), while avoiding the problem of endosteal notching.

Impaction grafting fits the patient to the prosthesis, in this is regard it reminds us of the mythological character, Procrustes (see this link).

Here are some relevant references

Boorman, R., Hacker, S., Lippitt, S.B., and Matsen III, F.A.:  A Conservative Broaching and Impaction Grafting Technique for Humeral Component Placement and Fixation in Shoulder Arthroplasty: The Procrustean Method. Techniques in Shoulder & Elbow Surgery. 2(3): 166-175, September 2001.

 

Hacker, S., Boorman, R., Lippitt, S.B., and Matsen III, F.A.:  Impaction grafting improves the fit of proximal humeral arthroplasty. JSES, 12(5):431-435, 2003.

 

Lucas RM, Hsu JE, Gee AO, Neradilek MB, Matsen FA 3rd. Impaction autografting: bone-preserving, secure fixation of a standard humeral component. J Shoulder Elbow Surg. 2016 Nov;25(11):1787-1794.

 

Denard PJ, Hsu JE, Whitson A, Neradilek MB, Matsen FA 3rd. Radiographic outcomes of impaction-grafted standard-length humeral components in total shoulder and ream-and-run arthroplasty: is stress shielding an issue? J Shoulder Elbow Surg. 2019 Nov; 28(11): 2181-2190.

How you can support research in shoulder surgery Click on this link.

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).

Humeral component loosening and radiolucent lines.

Humeral stem lucencies correlate with clinical outcomes in anatomic total shoulder arthroplasty

These authors compared clinical outcomes of 288 anatomical total shoulders (aTSA) with and without radiolucencies around an uncemented grit-blasted metaphyseal-fit humeral stems at a minimum of 5-years after surgery.

The operations were performed by fellowship trained surgeons from 14 different centers across the world.  Exclusion criteria included revision shoulder arthroplasty, rheumatoid arthritis, and post-traumatic arthritis. The article does not provide details of surgical technique, for example how the humerus was prepared, how the size of the implant was selected and whether impaction grafting was used.

Two-hundred forty-three humeral stems showed no radiolucent lines. Among the 37 humeral stems with lucent lines, lines were most common in zones 8, 4, 7, and 3. 

The clinical outcomes were inferior for those shoulders with humeral component loosening

Gross humeral loosening was noted in 4 of the 37 patients in the humeral lucent line group (11%). Other complications besides humeral loosening were more common in the humeral lucent line group.

Comment: This minimum 5 year follow up is informative. 13% of these stems had either gross humeral loosening or showed humeral radiolucent lines. These findings were associated with inferior clinical outcomes.

The association of humeral loosening or lucency with glenoid loosening brings up the possibility that a low grade infection might be at play in these cases. Alternatively, cement or polyethylene debris from glenoid failure might have contributed to the humeral changes.

The results of this study can be compared to those in a recent publication using a smooth humeral stem inserted with impaction autographing (see this link)

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To see a YouTube of how we do total shoulder arthroplasty, click on this link.

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How you can support research in shoulder surgery Click on this link.

To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.

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 run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Shoulder arthroplasty - how should the humeral component be fixed?

Cemented humeral stem versus press-fit humeral stem in total shoulder arthroplasty

These authors analyzed 36 studies with 927 cemented humeral stems and 1555 press-fit stems. The revision rate was 5.4% (95% confidence interval (CI) 3.9 to 7.4) at a mean of 89 months for cemented stems, and 2.4% (95% CI 1.1 to 4.7) at a mean of 40 months for press-fit stems. A priori subgroup analysis to control for follow-up periods demonstrated similar revision rates: 2.3% (95% CI 1.1 to 4.7) for cemented stems versus 1.8% (95% CI 1.4 to 2.9) for press-fit stems.

They concluded that cement fixation had similar revision rates when compared to press-fit stems at short- to midterm follow-up. Rotator cuff pathology was a prevalent complication in both groups but is likely not related to fixation type. Overall, with comparable revision rates, possible easier revision, and decreased operative time, humeral press-fit fixation may be an optimal choice for primary anatomical TSA in patients with sufficient bone stock. 

Comment: Here are some principles we use for humeral component fixation

(1) "Press-fit" of the stem in the humeral canal carries the risk of "too-high" positioning because the component is tight in the diaphysis. We call this "diaphyseal incarceration."

(2) "Platform" stems are designed to facilitate revision without stem removal, but in most revision cases, the stem is malpositioned so that stem removal is needed.

(3) Impaction grafting enables a standard smaller sized implant to be secured in the canal, minimizing the risk of stress shielding and facilitating component removal should revision be necessary.

Here are the x-rays from two cases done this week in which impaction grafting was used to secure the humeral component. Note the absence of diaphyseal incarceration.

(4) Cement is reserved for cases in which the height and version of the humeral component cannot be achieved with impaction grafting

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We have a new set of shoulder youtubes about the shoulder, check them out at this link.

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

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

How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages   arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'