A Prospective, Randomized Study Comparing The Outcome of Large-Diameter vs Small-Diameter Glenospheres in Primary Reverse Shoulder Arthroplasty Using the ReUnion System
Phase: NA
Conditions: Glenohumeral Joint Degeneration
Sponsor: Mayo Clinic

 
A Prospective, Randomized 
Study Comparing The Outcome 
of Large-Diameter vs Small-
Diameter Glenospheres in 
Primary Reverse Shoulder 
Arthroplasty Using the ReUnion 
System 
 
NCT# 02768597 
 
November 17, 2016 

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November 17, 2016 
Protocol title: 
A Prospective, Randomized Study Comparing The 
Outcome of Large-Diameter vs Small-Diameter 
Glenospheres in Primary Reverse Shoulder 
Arthroplasty Using the ReUnion System 
 
Principal Investigator: 
Dr. Mark Morrey MD 
Co-Principal Investigator: 
Dr. Joaquin Sanchez-Sotelo MD PhD 
 
Sub-Investigators: 
 
Mrs. Ashley Pountney PA-C 
 
 
Mr. Jordan Becker PA-C 
 
Investigator Address: 
Dr. Mark Morrey MD 
 
 
Consultant and Professor of Orthopedic Surgery 
 
 
Mayo Clinic 
 
 
200 First Street SW 
 
 
Rochester MN 55905 
 
Summary 
 
A prospective, randomized, blinded clinical trial is proposed to compare the outcome 
of primary reverse shoulder arthroplasty using the Stryker ReUnion system with 
implantation of either a 40 mm glenosphere or a 36 mm glenosphere, both with either 
a +2 mm or a +6 mm offset. The Stryker ReUnion is a shoulder arthroplasty system 
approved by the FDA. 
 
Each shoulder will be assessed preoperatively, at 3 weeks, 3 months, one year and 
two years. The primary end-point will be range of motion at one year. Additional end-
points will include dislocation, stress fractures of the acromion, metal ion levels in 
peripheral blood, neurovascular complications, radiographic notching, implant 
mechanical failure and revision surgery. 
 
Introduction 
 
Reverse shoulder arthroplasty has emerged as a very successful procedure for 
selected patients with severe degeneration of the glenohumeral joint and a deficient 
rotator cuff. All reverse systems incorporate various degrees of modularity to adapt 
size, length and other biomechanical parameters to each specific individual. One such 
parameter is the size of the glenosphere. Smaller glenospheres are easier to implant 
and seem to provide a good outcome with many reverse systems. Theoretically, a 
larger glenosphere could provide larger arcs of motion, decrease notching and 
increase soft-tissue tension. However, the effect of glenosphere size on motion and 
complications is largely unknown; to date, no study has specifically analyzed clinically 
the effect of sphere size on reverse outcome.  
Modularity with use of multiple metal trunions and Morse tapers also creates 
concerns regarding metal ions in peripheral blood, a problem well identified in the 
field of total hip arthroplasty. 

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November 17, 2016 
 
Purpose 
 
The purpose of this study is to compare the outcome of primary reverse shoulder 
arthroplasty using the Stryker ReUnion system with implantation of either a large (40 
mm) or a small (36 mm) glenosphere, both with either a +2 mm or a +6 mm of lateral 
offset. 
 
Materials and Methods 
 
Study design 
 
This will be a prospective, randomized, blind clinical trial. Physician’s assistants will 
supervise the running of the study and evaluate all patients. Randomization will be 
provided through a password-protected computer program developed by Mayo 
Clinic Division of Biostatistics personnel and communicated to the surgical team for 
listing. Physician assistants will be blinded regarding glenosphere size at the time of 
follow-up evaluations. 
 
The indications and contraindication as outlined in Stryker’s labelling will be strictly 
followed. Off-label use of the device is prohibited. 
 
Inclusion and exclusion criteria 
 
Inclusions: 
- 
Subjects willing to sign the informed consent 
- 
Male and non-pregnant female subjects ages 50 – 90 at the time of surgery 
- 
Subjects requiring a primary reverse total shoulder arthroplasty 
- 
Subjects with the diagnosis of cuff-tear arthropathy (CTA), massive 
irreparable rotator cuff tear (MRCT) or osteoarthritis (OA) with marked 
posterior subluxation or bone loss 
 
Exclusions: 
- 
Inability to comply with follow-up requirements 
- 
Subjects with inflammatory arthritis 
- 
Subjects with proximal humerus fractures 
- 
Subjects with sequels of trauma 
- 
Subjects that are immunologically compromised 
- 
Subjects with an active or suspected latent infection in or about the shoulder 
- 
Need to add a tendon transfer 
- 
Need for structural humeral bone graft 
- 
Pregnant subjects 
 
 
Randomization 
 

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In order to assign patients to specific treatment groups in an unbiased manner, 
randomization will occur prior to surgery. 
  
After the patient has met the inclusion criteria and given full informed consent, 
he/she will be assigned to the treatment group. The randomization will be stratified 
by variables with potential confounding effects on the outcomes of interest. 
Specifically, patients will be stratified by gender (male/female), age group (50-65/ 66 
– 80 / 81+) and underlying diagnosis. Within each stratum, subjects will be assigned 
to one of the two treatment groups using a computerized dynamic allocation program 
as mentioned before. 
 
Sample size 
The target sample size was estimated using shoulder range of motion as the primary 
outcome, and a 15° between-group difference as being a clinically meaningful 
difference.  In a recent study of a cohort of patients undergoing primary RSA, Steen 
et al (Steen, JSES, 2015) reported the following means and standard deviations of 
postoperative shoulder flexion, abduction, and external rotation: 153.3 ± 32.7, 140.4 
± 37.4, and 47.1 ± 38.9, respectively.  If similar variability is observed in the 
proposed study, a sample of 100 subjects in each of the two groups (200 total) will 
provide 80% power to detect a difference of at least 13.1° in shoulder flexion, 14.9° 
in abduction, and 15.5° in external rotation as being statistically significant (alpha = 
0.05, two-sided).  In order to protect against a potential subject attrition rate of up 
to 10% due to drop out or loss to follow-up, the target sample size of 100 in each of 
the two main groups (36mm glenosphere and 40 mm glenosphere) will be 
increased to 110 per group (220) total. Although the primary comparisons will be 
between the 36mm and 40mm study groups, subjects will be enrolled and 
randomized such that within each group, half of the subjects will have a +2mm 
offset, and half will have a +6mm offset.  Thus there will be 55 subjects with a 36 + 
2mm glenosphere, 55 subjects with a 36 + 6mm glenosphere, 55 subjects with a 40 
+ 2mm glenosphere, and 55 subjects with a 40 + 6 mm glenosphere.   
 
 
 
Surgical technique 
 
All procedures will be performed by two shoulder arthroplasty surgeons: Drs. Mark 
Morrey MD and Joaquin Sanchez-Sotelo MD PhD. The surgeons will implant the 
prosthesis according to the standard surgical technique for this particular implant 
system. A biceps tenotomy and tenodesis will be performed in all patients. The 
subscapularis tendon will be repaired at the end of the procedure when possible. 
Patients will receive one preoperative dose and two postoperative doses of IV 
antibiotics separated by a 6-8 hour period. All patients will receive an interscalenic 
brachial plexus block for pain control unless medically contraindicated. A shoulder 
immobilizer will be placed in the operating room once the procedure is completed 
and used for three weeks.  
 

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Hospitalization 
 
Patients will be admitted to the hospital on the day of their surgery, unless medical 
problems dictate earlier admission. Hospitalization of 1 day is routine for these 
patients, although uncontrolled pain or medical complications could lead to a more 
prolonged admission.  
 
Physical therapy 
 
Both treatment groups will undergo the same program of postoperative care and 
physical therapy. A shoulder immobilizer will be used for three weeks. Active and 
active-assisted motion exercises for the elbow, wrist and hand will be initiated on day 
1. Shoulder active-assisted motion exercises will be initiated at week 3. Isometrics 
will be added at week 6. Therabands will be added at week 8. 
 
Data collection 
 
Operative data collected 
 
- 
Surgical time 
- 
Cuff status preimplantation 
- 
Biceps status preimplantation 
-  Glenoid bone loss (photograph) preimplantation 
- 
Increase in muscle strain as measured with ultrasound elastography in the 
conjoined and deltoid muscles 
- 
Implants used 
- 
Intraoperative motion 
- 
Subscapularis repair 
 
Clinical data collected 
 
- 
Demographic data 
- 
Pain (visual analogue scale) 
- 
Subjective shoulder value 
- 
Active and passive range of motion in elevation, external rotation and internal 
rotation 
- 
Strength in abduction, external rotation, and internal rotation 
- 
Pain along the biceps tendon 
- 
Biceps cramping 
- 
Speed test 
- 
Neurovascular exam 
- 
Oxford shoulder score 
- 
Quick-DASH score 
- 
ASES score 
- 
Satisfaction (visual analogue scale) 
- 
Muscle strain measured with ultrasound elastography 

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Laboratory studies 
 
- 
CBC, sedimentation rate and C-reactive protein 
- 
Metal ion levels for chrome, cobalt and nickel 
 
Imaging studies 
 
- 
Plain radiographs (AP in external rotation, axillary, whole humerus markers) 
- 
In-growth xrays (only postoperatively) 
- 
Preoperative CT-Scan 
- 
CT-scan at one year postoperatively 
 
Radiographic analysis 
 
Preoperative radiographs and CT scans will be measured for canal sizing, bone 
dimensions and bone loss. 
 
Postoperative radiographs will be measured for length, offset and glenoid version. 
They will be analyzed for component fixation, glenoid notching, stress fractures of the 
acromion and screw position. Post-op CT at one year will be obtained. 
 
Visits 
 
#1. Preoperative visit 
- 
Clinical evaluation 
- 
Plain radiographs 
- 
CT scan with three dimensional reconstruction 
- 
Laboratory studies 
- 
Muscle strain measured with ultrasound elastography 
 
#2. Intra-Operative 
- 
Muscle strain measured with ultrasound elastography 
 
#3. First postoperative visit at 3 weeks 
- 
Plain radiographs 
 
#4. Visits at 3 mo, 1 yr, 2 yr, 5 yrs 
 
- 
Clinical evaluation 
- 
Plain radiographs + ingrowth radiographs 
- 
Laboratory studies 
- 
CT Scan (only at one year) 
- 
Muscle strain measured with ultrasound elastography (only at one year) 
 
Complications 

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Any serious complication that occurs related to the device will be documented. If 
patients are lost to follow-up, it will be noted accordingly. 
 
Recruitment 
 
The physician assistant or research coordinator will carry this out. The study will be 
described to the patient in detail, and a consent form clearly stating the background 
and reasoning, will be given to the patient. A consent form will be signed by the 
patient and a study person authorized to obtain consent. One copy will be given to the 
participant, a second copy will be scanned in the patient’s electronic medical record, 
and the original consent will be kept in the patient’s study folder. 
 
Competency 
 
Study participants must be able to give informed consent. 
 
Gender and Racial/Ethnic Distribution 
 
No gender or racial/ethnic group will be intentionally excluded from this study. 
 
Risks 
 
Participation in this study, involving FDA-approved devices, poses no increased risk 
to patients undergoing reverse total shoulder arthroplasty surgery. Risk and 
complications of this procedure include infection, nerve injury, bleeding, blood clots, 
persistent pain, persistent stiffness, loosening, wear, osteolysis and other forms of 
mechanical failure. 
 
Analysis and Intended Publications 
 
The primary outcome will be shoulder range of motion in elevation, external rotation, 
and internal rotation at 1 year post surgery.  Additional outcomes will include 
strength, pain, speed test, Oxford Shoulder Score, ASES score, Quick-DASH score, and 
patient satisfaction.  The analysis will focus on comparing the subjects randomized to 
the small glenosphere to the patients randomized to the large glenosphere, at 1 year. 
Additional comparisons will be performed to evaluate data collected at the 3-month, 
2-year, and 5-year time points.  Variables comprised of discrete data will be analyzed 
using chi-square tests or Fisher’s exact tests (if low expected cell counts are 
observed).  Continuous variables will be analyzed using two-sample t-tests or 
Wilcoxon rank sum tests, if necessary and appropriate.  Two-factor models may be 
used to analyze the effect of study group and time since surgery simultaneously, 
including the evaluation of potential interactions between these two factors.  
Modeling tools may include ANOVA, logistic regression, or generalized linear models, 
as appropriate based on examination of the data distribution and structure.  
Furthermore, separate analyses may be undertaken on specific patient subsets, 

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including those with a primary diagnosis of OA, CTA, or MRTC.  Other possible 
analyses may involve metal ion levels following RSA, correlation of sarcomere length 
(as measured with ultrasound elastography) with radiographic parameters, biceps 
symptoms, and screw location and length.  All statistical tests will be two-sided and 
p-values less than 0.05 will be considered significant. 
 
Budget 
 
See enclosed documents 
 
1-75 
 
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