How should the humeral component be secured in reverse total shoulder arthroplasty?

Are Short Press-Fit Stems Comparable to Standard Length Cemented Stems in Reverse Shoulder Arthroplasty? A Prospective Randomized Clinical Trial

These authors note "there has been a trend away from standard length cemented humeral implants to press-fit stems, and recently to shorter stem implants, " but minimal literature to support this trend.

The goal of their study was to compare clinical outcomes and implant migration between cemented standard length humeral stems and press-fit short stems using radio-stereometric analysis in 41 shoulders randomized to receive each of the two stems. 

Following surgery, the shoulders were imaged sequentially with stereo x-rays.

At six months, one year, and two years postoperatively, press-fit short stems migrated significantly more than cemented stems along the superior-inferior translation axis.

They noted stress shielding at the proximal medial calcar (solid arrow), and increased sclerosis at the medial metaphyseal diaphyseal junction (dashed arrow) with the use of press-fit stems (below).

The authors did not detect a significant difference in the clinical outcomes between the two types of stem fixation.

Comment: The are many different designs of reverse humeral stems with different approaches to lateralization and fixation. 

Our favored approach is shown in this link. It enables secure prothesis alignment in the proximal humerus so that subsidence is minimized

and cementless fixation of a relatively thin stem using impaction autografting. 

so that stress shielding is avoided.

See also Avoiding stress shielding around the humeral implant - are short stems the answer or the problem? 

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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).

The hazards of a press fit humeral stem in total shoulder arthroplasty

Here's an instructive case. 

The patient had bilateral total shoulder arthroplasties, each of which went on to fail because of rotator cuff rupture and rocking horse loosening of the glenoid component.

The x-rays below show that the on each side the humeral component was placed so that the head was too high in relation to the tuberosity placing extra stress on the cuff tendons and preferentially loading the superior aspect of the glenoid component.

Why did this happen?

The answer is found on the films of the entire humerus, where it is seen that the the distal tip of the prosthesis is wedged in the diaphysis preventing more distal seating. Attempting to drive the stem down further would have risked fracture.

In our practice of revision for failed arthroplasties performed elsewhere we encounter this problem frequently as shown again here.
This problem can be avoided by using a smaller stem along with impaction grafting as shown here.

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

Shoulder arthritis articles from June JSES - fixation of humeral component, shoulder arthroplasty complications

There are a number of articles of interest in the June issue of the Journal of Shoulder and Elbow Surgery, but without a doubt is the note on the passing of the Father of Modern Shoulder Surgery, Dr. Neer, a friend, a teacher, a scientist, a surgeon, and an advocate for the best in care for patients with shoulder problems. We will all miss his leadership.

Another article, Cemented versus uncemented fixation of humeral components in total shoulder arthroplasty for osteoarthritis of the shoulder: a prospective, randomized, double-blind clinical trial comes to the conclusion that 'cemented fixation of the humeral component provides better quality of life, strength, and range of motion than uncemented fixation'.  However, the component used in this study, the Bigliani/Flatow Total Shoulder Solution/Zimmer,  (shown below)

has a cylindrical stem that does not have an opportunity for a good press fit in the humeral canal in contrast to the prosthesis shown in our April 6 post. Furthermore, the authors did not use impaction grafting when inserting the prosthesis without cement. Thus the article's title might have been better phrased as "Cemented Fixation vs Simple Press Fitting of a Humeral Component with a Cylindrical Stem For Osteoarthritis of the Shoulder." Given that caveat, the data do indicate that the Bigliani/Flatow Total Shoulder Solution/Zimmer yields better results when cemented. The results of our preferred method are well documented.

A third article, Factors Predicting Complication Rates After Primary Shoulder Arthroplasty,  documents that when shoulder arthroplasty is done for fracture, there are more complications than when the procedure is performed for arthritis. This article also shows that older patients and patients with rheumatoid arthritis had a lower risk of revision surgery, presumably because of lower activity levels. Implant survival rates were not found to be different between total shoulder and hemiarthroplasty procedures.

A fourth article, Ream and Run for Shoulder Arthritis - patients under 55 years, is the topic of the other post from today.

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Ream and Run for Shoulder Arthritis - initial clinical results - research foundation 3

Based on the encouraging laboratory studies demonstrated in the previous posts we began offering the ream and run procedure to selected and informed patients with arthritis of the shoulder who wished to avoid the risk of glenoid component failure and the activity limitations recommended for total shoulder replacement. In this procedure, we expose the arthritic glenoid (shown below),

remove the damaged cartilage, and then ream the bone to a spherical concavity (shown below) before replacing the humeral side of the joint using the technique explained in our April 6 post.

We were truly excited to see that in many cases, after completely removing the cartilage from the surface of the glenoid, new soft tissue regenerated to cover the reamed bony surface as shown by the dark space between the metal ball and the bone of the glenoid shown on x-rays taken a year after surgery. In the x-rays shown below, this regenerative zone is marked with a red "R".

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You may be interested in some of our most visited web pages including: shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery.

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How is the roundness of the humeral head restored in shoulder arthritis?

One of the major barriers to regaining motion in the arthritic shoulder is that the ball of the joint (the humeral head) is no longer smooth and round as shown in the surgical photo below.

As shown below, a metal humeral head prosthesis (cobalt chrome alloy) can restore the roundness and smoothness of the humeral side of the joint.

The humeral head prosthesis is connected to a stem (titanium alloy) the tapered body of which fits inside the humerus.

The inside of the humerus (arm bone) may be cylindrical or tapered.

The inside of the humerus is not of a consistent shape.

Trying to fit a prosthesis by reaming the inside of the bone may substantially weaken it.

Trying to force a tight fit risks fracture.

We find that the safest method for securing the stem within the humeral canal is to use impaction grafting with bone harvested from the arthritic humeral head (which is removed at the time of surgery) to conform the inner surface of the bone to the prosthesis. Some have likened this fitting of the patient's bone the prosthesis to the fitting of the traveler to the bed by the inn keeper Procrustes.

As a result, the tapered stem is securely fixed with a biological press fit that safely distributes the load from the prosthesis to the humerus.

We have published research showing that neither cement nor bone ingrowth is required to securely fix the stem in the humerus as long as the stem has a tapered upper end. We have shown that this impaction grafting improves the fit of uncemented humeral arthroplasty. We have also pointed to the importance of avoiding over reaming the bone in an attempt to achieve secure fixation. 

Impaction grafting is the safest way to fix the stem in that it builds up the inside of the bone - making it stronger - while achieving a secure press fit. Finally, should the stem require revision for any reason, it can be removed without damaging the bone - in contrast to splitting the bone (shown below) which may become necessary in removing a cemented or bone-ingrowth stem.

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Use the "Search the Blog" 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 run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery.

See the countries from which our readers come on this post.