Is there an advantage of using a humeral surface replacement in total shoulder arthroplasty?

Comparative study of total shoulder arthroplasty versus total shoulder surface replacement for glenohumeral osteoarthritis with minimum 2-year follow-up.

These authors compared patients having a Tornier conventional total shoulder arthroplasty (TSA - cemented anatomical humeral stem)

performed with a complete resection of the humeral head

with those having a Tornier total shoulder with a surface replacement of the humeral head  (TSSR)

used with the goal of preserving a bit more of the humeral head

Both types of humeral component were paired with a cemented, curved, keeled, all-poly glenoid component.

They suggest that TSSR may offer advantage of preservation of bone stock and shorter surgical time, possibly at the expense of glenoid component positioning and increasing lateral glenohumeral offset. 

In the TSSA shoulders the authors state that extensive releases of the posterior and inferior capsule had to be performed to gain exposure of the glenoid.

After 29 and 34 months of mean follow-up, respectively, TSA (n = 29) and TSSR (n = 20) groups showed similar median adjusted Constant Scores (84% vs. 88%), Oxford Shoulder Scores (44 vs. 44), Disabilities of the Arm, Shoulder and Hand scores (22 vs. 15), and Dutch Simple Shoulder Test scores (10 vs. 11). 

One intraoperative glenoid fracture occurred in the TSSR group. They point out that with the resurfacing implant,the "surgeon is presented with challenges related to a more difficult exposure because less humeral bone is resected. Indeed, the glenoid fracture in our TSSR group was probably caused by a more forceful glenoid exposition."

Comment: It is unclear what criteria led to the use of a resurfacing vs a standard humeral  component in this series of cases.

In that most total shoulder failures are related to the glenoid component, it would seem that safely optimizing glenoid exposure is a high priority, outweighing the theoretical advantage of preserving a bit more of the humeral head.

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Revision of surface replacement and stemmed arthroplasties

Revision shoulder arthroplasty: does the stem really matter?

These authors reviewed 17 revisions of stemmed arthroplasties (STAs) and 23 revision of surface replacement arthroplasties (SRAs).

95% of the revisions (38 of 40) were due to rotator cuff failure. In 3 cases in each group (6 cases overall), implant loosening was evident as well.

While the operation time, need for humeral osteotomy, need for structural allograft, and number of intraoperative fractures were significantly higher in the STA group, there were no significant  difference between the Constant scores of the 2 groups preoperatively or postoperatively.

Comment: The results of revision arthroplasies depend on many factors, including the diagnosis for which the original arthroplasty was performed. In this series the two groups were not comparable. As shown below surface replacement arthroplasties were used for the simpler pathologies of OA and RA, while stemmed arthroplasties were used for more complex cases, such as fracture, fracture sequelae, and cuff tear arthropathy.

Revisions are highly individualized and depend on factors other than whether the index surgeon felt the need to use a stemmed component.

It is recognized, however, that stemmed arthroplasties need not be fixed with ingrowth or cement, so that revision, if necessary is facilitated. We find that an impaction-grafted humeral component not only preserves but adds bone to the humerus, enables positioning of the humeral articular surface in the desired location (including an eccentric offset when needed as shown in this link) and is applicable to essentially the full range of shoulder arthroplasty indications, rather than being subject to the anatomical restrictions for a resurfacing or stemless device.

We use a chrome cobalt humeral head prosthesis connected to a stem (titanium alloy) the tapered body of which fits inside the humerus.

We note that the humeral canal may be cylindrical or tapered.

and that the cross sectional geometry varies 

We agree that trying to fit a prosthesis by reaming the inside of the bone may substantially weaken it.

and that trying to force a tight fit risks fracture.

Our preferred method for securing the stem within the humeral canal is to use impaction grafting with bone harvested from the arthritic humeral head 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, avoiding stress shielding which has been noted with short stem prostheses (see this link).

The amount of bone removed with an impaction grafted stem is minimal, leaving ample bone stock for revision should it become necessary.

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Resurfacing hemi and total shoulder arthroplasty in young patients

Surface replacement arthroplasty for glenohumeral arthropathy in patients aged younger than fifty years: results after a minimum ten-year follow-up

These authors present a case series of 54 cementless surface replacement arthroplasties (49 patients (25 men, 24 women)(average age 38.9 years (range, 22-50 years)) performed between 1990 and 2003. Of these, 38 patients (42 shoulders) were available for followup at a mean of 14.5 years (range, 10-25 years) after surgery.

17 were total shoulder replacements with metal back keeled glenoids, and 37 were humeral head resurfacing with microfracture of the glenoid.

It is of note that the diagnoses in this report from the UK were as follows:

avascular necrosis, 16

rheumatoid arthritis, 20

instability arthropathy, 7

primary osteoarthritis, 5

fracture sequelae, 3

postinfection arthritis, 2

psoriatic arthritis, 1

These are different from the usual indications for shoulder arthroplasty in the U.S., where primary osteoarthritis dominates, although the diagnostic spectrum is different in younger individuals even on this side of the pond.

17 cases had full thickness cuff tears or poor quality rotator cuffs.

The deltopectoral approach was used in 20 shoulders and the  anterosuperior (Neviaser-Mackenzie) approach in 34. The anterosuperior approach became the preferred approach in1993.

The mean relative Constant score increased from 11.5% to 71.8%, the results with humeral head resurfacing with microfracture of the glenoid (77.7%) were superior to those with total resurfacing arthroplasty that included a glenoid component (58.1%). 

The best results were observed for the AVN patients, with Constant score improving from 13%  to 85%. These were followed by the primary osteoarthritis group results and the rheumatoid arthritis group which had more modest results but high levels of satisfaction.

In 35 of 38 shoulders the humeral implants showed no lucencies. All of the humeral lucencies were observed in cases having a glenoid component. There were 9 glenoid implants of which 4 were loose.
15 had severe superior migration, 5 had moderate superior migration, and 2 had mild superior migration. 16 shoulders showed no superior migration.

Moderate to severe glenoid erosion was present in 12 of the shoulders at an average follow-up of more than 14.5 years. Glenoid erosion was correlated with superior migration of the humeral head and was more prevalent in patients with rheumatoid arthritis.

The mean time from the index arthroplasty to the revision surgery was 12 years

2 shoulders required early arthrodesis due to instability and deep infection. 

In addition, 10 of 54 shoulders required revision arthroplasty.

The indications for revision arthroplasty were rotator cuff failure in 4 shoulders (3 HSA and 1 TSA), glenoid loosening and humeral loosening in 4 TSA shoulders, glenoid erosion in 1 HSA

shoulder, and 1 traumatic periprosthetic fracture.

7 were revised to stemmed prosthesis: 1 for traumatic fracture and 1 for glenoid erosion 16 years after the index procedure.5 shoulders in 4 patients (4 rheumatoid arthritis, 1 avascular necrosis) were revised at 8 to 14 years after surgery for cuff failure and loosening. 

3 were revised to stemless reverse total shoulder arthroplasty due to rotator cuff failure at 23, 16, and 13 years after surgery.

Comment: This is an interesting and candid report by authors that include the designer of this system. Firstly, all shoulder surgeons recognize that the <50 year old patient needing an arthroplasty provides special challenges due to expectations, activities, and relatively uncommon diagnoses. Secondly, the patients in this series had a high preoperative incidence of rotator cuff issues, which place arthroplasty at increased risk of failure. Thirdly, the high rate of glenoid component loosening (often accompanied by humeral component loosening) and low clinical scores in the total shoulder group may be in part due to the technical challenge of glenoid arthroplasty when a substantial amount of the humeral head bone is retained as in these resurfacing arthroplasties - a feature that may compromise exposure.

Points of interest include the use of microfracture, the fact that 7 of the 10 revision arthroplasty were from resurfacing to stemmed prostheses, and the use of arthrodesis for two of the failures. 

All in all, this article provides an interesting contrast to our local practice and it will be of interest to see how all of us evolve in our management of the young, arthritic shoulder.

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Click here to see the new Shoulder Arthritis Book

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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 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'