Shoulder arthroplasty: how should we measure the benefit?

Treatment Effects of Reverse Total Shoulder Arthroplasty – A Simple Method to Measure Outcomes at 6, 12, 24 and 60 Months for Each Patient

These authors used a treatment effect effects (TE = (preoperative score – postoperative score) /
preoperative score) to assess outcomes in 183 patients with unilateral cuff arthropathy (Hamada grades >=2) treated with reversed total shoulder arthroplasty (RSA). The patients were assessed with the ASES questionnaire.

Two years postoperatively the mean ASES score improved from 20.5 to 78.7.

The 2 year TE's ranged from 1 to 0.09. We had no patient with a negative TE. A higher Hamada grade was associated with better TE’s.

Patients with higher ASA grade had lower TE’s. 

The mean TE’s diminished with time:  0.77 at 6-months, 0.81at 1 year, 0.76 at 2 years and 0.73 at 5 years.

Comment: Results of arthroplasty have been reported in a number of different ways. 

Let's use the example of a shoulder that improved from 21 to 79.

(1) Post operative score - 79

(2) Amount of improvement: Post operative score - preoperative score = 58

(3) Amount of improvement divided by preoperative score: (Post operative score - preoperative score)/preoperative score) = 2.8

(4) Percent of maximum possible improvement: 100*(Post operative score - preoperative score)/(perfect score-preoperative score) = (79-21)/(100-21) = 74%

It seems that #4 has the advantage of showing the amount of improvement in relation to the potential amount of improvement. This is easy to explain to patients: "this operation will not make your shoulder normal, but in our experience our average patient is improved by 74% the way to a normally functioning shoulder."

While there is current enthusiasm for the MCID (Minimal clinically important difference) the best methodology for determining the MCID is uncertain resulting in MCID valued for the ASES score ranging from 6 to 21 (see this link).

But the MCID has an additional problem
If we take a typical value for the ASES MCID of 20, an improvement from 60 to 79 would fail to meet the criterion of improvement by the MCID yet it would yield an improvement of 90% of the maximum possible improvement.

On the other hand, an improvement from 21 to 42 would meet the criterion for improvement by the MCID, but would only represent 27% of the maximum possible improvement.

Which of these is the better outcome?

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

To see a YouTube of our technique for a reverse total shoulder arthroplasty, click on this link.

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

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.

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'

Total Shoulder and Reverse Total Shoulder - How effective are they in restoring comfort and function?

Correlation of multiple patient-reported outcome measures across follow-up in patients undergoing primary shoulder arthroplasty

These authors performed a retrospective review of a shoulder arthroplasty database that routinely collects three commonly used patient-reported outcome (PRO) measures in this population: the Simple Shoulder Test (SST), Shoulder Pain and Disability Index (SPADI), and the American Shoulder and Elbow Surgeons (ASES) Assessment Form preoperatively and at 3, 6, 12, and 24months postoperatively. The study was limited to 848 patients undergoing primary shoulder arthroplasty were identified.

Preoperative correlations among PROs were moderate to strong (range, 0.66-0.77). Postoperative correlations were strong for all PRO comparisons (range, 0.73-0.94). Postoperative PRO correlations continued to strengthen over longer follow-up, with all values exceeding 0.78 at 2 years postoperatively. 

Comment: These are valuable data because the allow us to determine the percent of maximal possible improvement (%MPI) for anatomic and reverse shoulder arthroplasties. The percent of maximal possible improvement using any outcome measure is calculated as

the improvement: the difference between the postoperative score and the preoperative score

divided by

the maximal possible improvement: the difference between a perfect score and the preoperative score

As can be seen from the graphs below, the %MPI for anatomic and reverse total shoulders is essentially the same, whether measured by the SST, the ASES or the SPADI. 

These graphs also show that while in this series of patients each of these procedures lead to significant improvement, neither procedure fully restores the shoulder to normal patient reported comfort and function.

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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'

Reverse total shoulder: how much does it improve patients - the %MPI

Predicting outstanding results after reverse shoulder arthroplasty using percentage of maximal outcome improvement

These authors correlated the percentage of maximal possible improvement (%MPI) in the Simple Shoulder Test (SST) score and American Shoulder and Elbow Surgeons (ASES) with satisfaction after reverse shoulder arthroplasty (RSA) in 198 patients at a minimum 2-year follow-up.

The % of maximum possible improvement at a given time after surgery is easy to calculate:

They found that 61.3% (P < .001) and 68.2% (P < .001) of maximal possible improvement in the SST and ASES scores, respectively, predicted excellent satisfaction.

Patients achieving 61.3% of maximal possible SST score improvement or 68.3% of maximal possible ASES score improvement can be expected to reach excellent satisfaction about 80% of the time, whereas patients who do not reach these thresholds have excellent satisfaction only about 45% of the time.

Surgery on the dominant hand, greater baseline visual analog scale pain score, and cuff arthropathy were independent predictors for achieving the respective SST and ASES score thresholds.

Comment: There are five compelling features of using the %MPI. First, it is easy for surgeons to calculate. Second it is easy for patients to understand. Third, it avoids the "floor and ceiling" issues. Fourth, in contrast to the MCID (minimal clinically important difference) it differentiates an improvement in SST from 0 to 3 from an improvement in SST from 7 to 10. Fifth,  as shown in this study and in others it yields very similar results for different patient self-assessment tools (note the similarity in values for the SST and ASES score). As a result it enables comparisons of studies in which different outcome measures are used. See for example this study:

One and two-year clinical outcomes for a polyethylene glenoid with a fluted peg: one thousand two hundred seventy individual patients from eleven centers, which showed essentially the same %MPI for the SST, ASES, Constant, and Penn scores.

The utility of the %MPI is that it enables surgeons to contrast the characteristics of patients, shoulders  and techniques that yield outcomes above and below the desired %MPI threshold.
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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'

Total shoulder clinical outcome assessment made simple = percent of maximal possible improvement in the SST or ASES score

Predicting outstanding results after anatomic total shoulder arthroplasty using percentage of maximal outcome improvement

These authors sought to determine the percentage of maximal improvement in the Simple Shoulder Test (SST) or American Shoulder and Elbow Surgeons (ASES) score associated with “excellent” patient satisfaction after total shoulder arthroplasty (TSA).

For 301 and 319 patients with at least 2 years’ follow-up for the SST score and ASES score, respectively, they used receiver operating curve analysis to determine that 72.1% of maximal improvement in the SST score and 75.6% of maximal improvement were the thresholds for excellent satisfaction.

Comment: This article is most reassuring. First of all it supports the concept that use of the percent maximal possible improvement renders similar results for different outcome scoring systems. In their study improvement of 70-76% of the maximal possible improvement was associated with an "excellent" clinical outcome whether the Simple Shoulder Test or the ASES score was used. 

Second, The SST scores improved from 27% to 77% of the maximum score of 12; similarly,  the ASES improved from 31% to 81% of the maximum score of 100.

Third, the distribution of preoperative SST scores for total shoulder patients in this paper 

was virtually identical to that for total shoulders (shown in green below) in a recent paper from a different group of surgeons writing on the "Tipping Point" for surgery (see this link).

The average SST score before total shoulder arthroplasty for patients in both centers was 3.

Thus there is reassuring consistency in the results for different patient reported outcome scales and in the results between different centers.

Here's another related post showing the consistency among outcome scales:

Establishing maximal medical improvement after anatomic total shoulder arthroplasty 

These authors conducted a systematic review  of 13 studies reporting sequential followup of 984 patients at several time points, up to a minimum of 2 years after total shoulder. Assessment for clinically significant improvements between time intervals was made by using the minimal clinically important difference specific to each patient-reported outcome measure.

Clinically significant improvements in patient-reported outcome scores were noted up to 1 year following TSA, but no further clinical significance was seen from 1 year to 2 years.

For both the subjective and objective outcomes, the majority of improvements occurred in the first 3 months after the procedure.

These authors found similar results for reverse total shoulders as shown in this link.

Comment: It is of interest and importance that the Simple Shoulder Test results of our recent, currently unpublished 11 international center study including 1270 patients receiving anatomic total shoulders with a standard (non-augmented) all polyethylene glenoid component (shown below):  

are virtually identical to the Simple Shoulder Test results from this systematic review (shown below):

It also of interest that in this systematic review, the normalized outcomes are essentially independent of the patient reported outcome scale used:

Thus measuring the outcomes of shoulder arthroplasty can be simplified: (1) any of the validated patient reported scoring systems can be used and (2) the one year results are as good as the two year year results (the "standard" requirement for 2 year followup may not be necessary for TSAs). In order for new total shoulder systems to demonstrate that they offer increased value over current approaches, their one year outcomes need to exceed those shown here.

We can conclude that most of the common outcome scores yield similar results and that the percent of maximal possible improvement provides an easy way for patients and surgeons to understand the results.

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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'