In followup to the previous post, What type of rTSA should I use and how should I position it? Insights from 13 Recent Studies On Prosthesis and Position, we now take a look at some recent publications regarding rTSA outcomes and the factors that may be associated with them. My summary is (1) that it is important to define the outcome measure of interest clearly and in quantitative terms, (2) some of the proposed predictors of of outcome show statistical significance, but not clinically important significance, and (3) the geometries of the rTSA have important effects on both its stability and range of motion and vary widely among different implants.
How are we measuring outcomes?
There are many methods for documenting the results of rTSA, including pain relief, function, patient reported scores, quality of life, satisfaction, range of motion, strength, return to sport, return to work, complication rate, revision rate, and radiographic measurements. Notably there is surprisingly little correlation among these different measures. In evaluating the outcomes of different approaches to rTSA, surgeon scientists choose a primary outcome variable and seek clinically significant (rather than only statistically significant) results.
Creatively, the authors of Evaluation of New Normal After Shoulder Arthroplasty: Comparison of Anatomic versus Reverse Total Shoulder Arthroplasty introduced the concept of “new normal” after shoulder arthroplasty which they defined as a Single Assessment Numeric Evaluation (SANE) score ≥95 at a minimum 2-year follow-up for 849 aTSA and 745 rTSA patients. The SANE asks patients to rate their shoulder on a scale of 0 to 100, with 100 representing their normal shoulder function
40% of aTSA and 26% of rTSA patients attained this “new normal”.
aTSA significantly outperformed rTSA in total Simple Shoulder Test score (as well as the ability perform individual functions of the SST (reach a high shelf, lift 10 pounds, perform usual work and usual sport), lift 8 pounds, and carry 20 pounds) as well as the American Shoulder and Elbow Surgeons score; and range of motion. A subanalysis among patients treated for osteoarthritis with an intact rotator cuff produced similar results, with aTSA patients outperforming rTSA patients in many higher demand functions.
Defining the Minimal Clinically Important Difference and Patient Acceptable Symptom State Following Reverse Shoulder Arthroplasty for Glenohumeral Arthritis or Cuff Tear Arthropathy at Minimum 5-Year Follow-Up sought to determine the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) at mid-term followup for 80 patients having rTSA
The thresholds for MCID achievement and percentages that reached achievement were as follows: ASES, 11.4 (88.8%); SANE, 14.8 (85.0%); VR 12 Physical, 4.9 (66.3%).
The thresholds for PASS achievement and percentages that reached achievement were as follows: ASES, 80.8 (65.0%); SANE, 75.9 (66.3%); VR 12 Physical, 44.4 (57.5%).
Factors associated with failure to achieve these thresholds included worker’s compensation coverage, prior ipsilateral shoulder procedure, and tobacco use. Higher preoperative scores were (expectedly) associated with failure to reach MCID levels of improvement.
Radiological Outcome in Reverse Shoulder Arthroplasty does not correlate with patient satisfaction or quality of life correlated radiological findings with clinical outcomes, patient satisfaction, and health-related quality of life (HRQoL) at a minimum of 2 years postoperatively for 49 patients.
Postoperative health-related quality of life (HRQoL) showed strong positive correlations with all clinical scores.
Distalization had a negative impact on external rotation and strength capacity while medialization of the COR showed a contrary relationship to external rotation and strength.
Radiological measurements predicted postoperative ROM and scapular notching yet failed to accurately predict HRQoL or clinical outcome.
What are some of the patient factors that affect outcome?
Patient Characteristics
Patients and surgeons usually think about shoulder function in terms of the arm position in relation to the body. Yet most of shoulder surgery focuses on the glenohumeral joint. The position of the scapula and the thoracic posture may affect the motion and function of the upper extremity. Patients posture affects clinical outcomes and range of motion after reverse total shoulder arthroplasty: A clinical study aimed to correlate preoperatively photo-documented posture to scapula orientation using CT and analyze their relation to the functional outcome following rTSA implantation in 360 patients with a minimum follow-up of 2 years.
Each patient’s posture was analyzed using standardized pre- operative photo and video documentation. The posture was defined following the classification system of Moroder et al as type A (upright posture, retracted scapulae), type B (intermediate), and type C (kyphotic posture with protracted scapulae).
According to the photo-documented posture types, the patients were divided into posture types A (N 59), B (N 253) and C (N 48). The posture types were not strongly associated with the CT measurements of scapular position.
Average absolute Constant-Murley Score differed slightly among the groups (A 69, B 69 and C 64).
In terms of ROM, types A and B exhibited somewhat better flexion and abduction (flexion 124 and 123 vs113; abduction 140 and 137 vs.128). Patients with posture type A demonstrated better internal and external rotation.
The authors concluded that patients with clinical posture types A and B exhibited improved ROM values and clinical outcomes compared to type C postures and that the patient’s posture should be considered in rTSA planning.
However, as can be seen from the charts below, the differences are small and there were quite a few outliers.
So once again we’re faced with statistically significant differences that are not clinically significant.
It is unclear how the patients posture should influence the type and position of arthroplasty components used.
Increasing Use of Reverse Total Shoulder Arthroplasty in Younger Adults Despite Higher Complication Rates sought to evaluate the trends of rTSA use in the United States and to evaluate medical and surgical complications in patients under 60 years of age undergoing rTSA using the Premier Healthcare Database.
The diagnoses treated were similar for the two groups: osteoarthritis ~75% and rotator cuff tear ~25%
From 2016 to 2020, there was a substantial increase in the proportion of reverse TSAs used, with rTSA comprising 49% of all TSA in patients <60 years old in 2016 and rising to 59% by 2020. After propensity score matching, 3,087 patients <60 years old and 9,261 patients ≥60 years old remained. The authors observed 1.53 times greater odds of 90-day surgical complications in patients <60 years old, without a difference in odds of medical complications.
Of note, the differences between these arbitrarily delineated age groups are not large, suggesting that factors other than age may be driving the rate of complications in these patients having rTSA. Age “cutoffs” may not be clinically useful.
The influence of sex: A Deep Dive into Reverse Total Shoulder Arthroplasty Outcomes found that out of 2,747 RTSA cases, 1,804 (65%) were performed on female patients. The preoperative diagnoses were similar
While some statistically signficant differences were noted between males and females, none of the 24 month follow-up values were clinically significant (i.e. they did not differ by an amount exceeding the minimal clinically important difference) The MCID for the SPADI is 8-13, for the QuickDASH is 12, and for the Constant score is 10 points.
No differences were noted in any of the radiological outcomes over time.
Implant Characteristics
Large variability in degree of constraint of reverse total shoulder arthroplasty liners between different implant systems confirmed the large variations in the degree of constraint of rTSA liners between different implant systems, and in many cases even within the same implant systems. While greater D/r ratios (percentage capture) is expected to confer greater stability to the rTSA, it also increases the risk of limitation of range of motion from unwanted contact between the liner and the scapula.
D/r ratio is but one of elements determining rTSA stability from concavity compression. Others include the size of the glenosphere, and factors that affect the magnitude and direction of the compressive force, such as strength of the deltoid and remaining cuff muscles, baseplate position and inclination, humeral neck-shaft angle, and impingement as well as humeral and glenoid lateralization .
The authors also pointed to the importance of the liner stability ratio. The liner stability ratio is the force needed to dislocate the shoulder divided by the compressive load across the joint.
They calculated the liner stability ratios of common implants from the formula LSR = (square root (1 − (r − d/r)2)) / (r − d/r)
To assess superior-lateral stability, the authors developed the intraoperative two-hand lever test (2HLT)
In 63% (31/49) of their cases, the 2HLT detected superior-lateral instability with standard liners, leading to the use of a retentive 135° liner.
Lots of things we need to think about.
Yellow headed blackbird considering which fly to go after
Malheur
May 2025
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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).
