Shoulder arthroplasty outcomes - it's not academic, it's personal

Many articles written about measuring surgical outcomes fail to emphasize the greatest value of collecting followup data - the opportunity for self-improvement. As the inscription on the Temple of Apollo states: "physician, know thyself".

The phrase "the surgeon is the method" means that each surgeon's indications, technique and outcomes are particular to her or him. While it is of interest to know how patients fare at some famous center, it is more important for each of us to know the characteristics of the patients we treat and how they do with the treatments we provide for them. In order for us to "own our outcomes" we need to collect our results in a systematic way that minimizes selection bias. We need to follow each of our patients long enough to know if our treatment was successful and to ask "if not, why not" (Codman: A Study of Hospital Efficiency).

Yet it is surprising how few surgeons (whether in community or academic practice) have implemented a meaningful followup system that will help improve their practice. The best time to implement such a self-improvement system is now - for surgeons new to practice, start on day one before things get "too busy". It's a gift that will keep on giving.

To attain this goal, a practical method of following patient comfort and function is needed - one that is accessible for all patients treated (including those who cannot use computers or tablets, those who cannot return to the office for periodic followup, and those who have a limited command of the language). An inexpensive, validated method approach is provided by the Simple Shoulder Test, the SST: 12 simple "yes" or "no" questions that can answered with nothing more than a pencil and then mailed in to the surgeon's office. The SST is now being used in multiple languages, including Arabic, Argentinian, Chinese, Dutch, Italian, Japanese, Lithuanian, Persian, Polish, Portuguese, Spanish, and Turkish.

Patients can be encouraged to participate in long term followup with periodic completion of the SST by explaining, "I care about how my patients do over time after their treatment. When patients fill out this simple followup form, it lets me learn how well things are working out and what adjustments I may need to make in my approach to get the best possible results in the future. What I know today is based on past patients helping me in this effort".

The value of systematic followup is shown in the figure below that presents the results of 176 patients having the ream and run procedure for glenohumeral arthritis. The SST score is on the vertical axis and the years after surgery are shown on the horizontal axis. The solid line shows excellent average long-term outcomes (the dotted lines represent the standard deviations). End of story? No! The opportunities for practice improvement lie in the red box. The surgeon can learn by studying each of these cases: wrong indication? wrong patient? wrong implant? wrong technique? wrong rehabilitation? or subtle complication (e.g. delayed Cutibacterium infection)?

An important additional value of the SST is provided by its granularity, which presents data on the ability to perform specific functions before and after surgery in a form that is meaningful to surgeons and patients alike. This is in contrast to presenting the data as single number ASES, Codman, SAS, SANE, or PROMIS score or as the percent of patients that exceeded the minimal clinically important difference (MCID) - neither of which are likely to be as helpful to surgeons and to their patients as information on the improvement in the ability to perform specific shoulder functions.

The figure below shows the preoperative and minimum two year post-operative functions performable by patients with cuff tear arthropathy with retained active elevation having a CTA hemiathroplasty. These are the personal results from an individual surgeon presented in a form easily understood by the surgeon and patients alike.

An additional way of presenting a surgeon's outcome data is discussed by the authors of Quantifying Success After Anatomic Total Shoulder Arthroplasty: the Minimal Clinically Important Percentage of Maximal Possible Improvement. They point to the value of the percent maximal possible improvement (%MPI) as a way of communicating the improvement after shoulder arthroplasty. This concept was introduced in The Prognosis for Improvement in Comfort andFunction After the Ream-and-Run Arthroplastyfor Glenohumeral Arthritis and is defined as the amount of improvement divided by the maximum possible improvement:

%MPI = 100% X (post operative score - preoperative score/(maximum possible score - preoperative score).

For the SST the maximum possible score is 12.

Thus a patient with a preoperative SST score of 2 and a postoperative score of 10 would have achieved 100% X (10-2)/(12-2) or 80% maximum possible improvement.

They conducted a retrospective review of 1,593 primary anatomic total shoulders having a minimum of 2 year followup.

They found that the SST, ASES, UCLA had higher rates of patients achieving a %MPI > 30%, but lower rates of achieving the minimum clinically important difference (MCID). Conversely, the Constant and SAS scores had higher rates of patients achieving the MCID, but a lower rate of achieving %MPI > 30%.

They concluded that the %MPI offers a simple method to quickly assess improvements across patient outcome scores.

If a surgeon knows her or his average %MPI after anatomic shoulder arthroplasty (say 45%) is easy for the patient to understand this information: "in my experience patients with your findings before surgery regain about 45% of their normal comfort and function".

That is easier to understand than the more abstract concept of the MCID:"You have an X% chance of an improvement exceeding a calculated minimal clinically important difference (which may vary according to which procedure is performed as pointed out by the authors of The minimal clinically important differences of the Simple Shoulder Test are different for different arthroplasty types).

An issue with applying the MCID as a threshold for success is that it does not differentiate between different situations in which the improvement exceeded the MCID. For example an improvement after aTSA from 2 to 4 (a modest result) and an improvement from 9 to 11 (an excellent outcome) are not at all the same, even though both had an improvement in excess of the MCID of 1.6 for aTSA. It seems of greater value to use %MPI which is (4-2)/(12-2) or 20% for the first case and (11-9)/(12-9) or 67%.

Comment: Following patients to determine their outcome is the responsibility of each surgeon. As illustrated above, systematic followup can be both simple and powerful. The keys are (1) starting now, (2) using a outcome measure that is both practical and that does not systematically exclude patients because of inability to return to the office or inability to use computers or tablets, (3) analyzing and learning from the causes of failure to achieve the desired result, and (4) sharing the data with patients in a manner they can easily understand.

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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).