The Influence of Repairing the Sub-scapularis on Outcomes After Reverse Arthroplasty

A Prospective Multicenter Study to Examine the Influence of Repairing the Sub-scapularis on Outcomes After Reverse Arthroplasty: A Randomized, Controlled Trial.

The study is a prospective, multi-center, randomized blinded study to determine how repairing the subscapularis vs. not repairing the subscapularis when subjects are implanted with the AltiVate Reverse® Shoulder System for reverse total shoulder arthroplasty affects isometric and isokinetic internal rotational strength. It is hypothesized that patients in which the subscapularis is repaired will have improved postoperative isometric and isokinetic internal rotational strength.

Reverse shoulder arthroplasty (RSA) is performed to provide improvement in pain relief and restoration of function in patients with rotator cuff tear arthropathy and massive irreparable rotator cuff tears . Traditional total shoulder designs failed to address the unique mechanics of shoulders with deficient rotator cuffs. Different prosthesis designs exist for RSA, all of which increase the deltoid lever arm to provide a stable fulcrum for active elevation in a rotator cuff deficient shoulder.

The Reverse® Shoulder Prosthesis (RSP®) (DJO Surgical) sought to address issues correlated to the Grammont design by lateralizing the center of rotation as well as utilizing a central compressive screw with a 5.0-mm peripheral locking screws for fixation and a glenosphere .

Despite the success of the lateralized design, the effect of the repair of the subscapularis tendon during RSA on shoulder strength, range of motion, and shoulder function remains inconclusive. The rationale for repairing the subscapularis during RSA include anatomic preservation of a functioning rotator cuff muscle, an increased potential for internal rotation, better joint protection, and more stability. The reasoning for not repairing the subscapularis include that it may be biomechanically unfavorable for both the deltoid and the posterior rotator cuff, limiting the range of motion.

As such, this randomized study aims to address if subscapularis repair impacts isometric and isokinetic internal rotational strength, with shoulder function and complications as secondary objectives, when patients are implanted with the AltiVate Reverse® device.

The study will take place at multiple sites across the United States and will be managed by the DJO Surgical Clinical Affairs Department.

Inclusion Criteria:

1. Subject is ≥21 years of age
2. Subject is scheduled for reverse shoulder arthroplasty with the AltiVate Reverse device due to primary diagnosis of severe arthropathy with a grossly deficient rotator cuff
3. Subject's sub scapularis has been determined from MRI to be sufficient to repair
4. Subject is willing and able to comply with the study schedule and assessments
5. Subject is likely to be available for evaluation for the duration of the study
6. Subject is willing and able to sign the informed consent

Exclusion Criteria:

1. Subject is indicated for reverse shoulder arthroplasty for other indications (revision arthroplasty, proximal humerus fracture, etc.), addition of latissimus transfer or pectoralis major transfer
2. Subject has metal allergies or sensitivity
3. Subject has an active infection at or near the site of implantation
4. Subject has a nonfunctional deltoid muscle
5. Subject has neuromuscular compromise condition of the shoulder
6. Subject has known active metastatic or neoplastic diseases, Paget's disease or Charcot's disease
7. Subject is currently on or planning to be on chemotherapy or radiation
8. Subject has had chemotherapy or radiation within the last 6 months
9. Subject is currently taking > 5mg/day corticosteroids (e.g. prednisone), excluding inhalers, within 3 months prior to surgery
10. Female subjects who are pregnant or planning to become pregnant within the study period
11. In the investigator's opinion, the subject is unable to understand the study or be compliant with the follow up or has a history of non-compliance with medical advice
12. Subject has a history of any cognitive or mental health status that would interfere with study participation
13. Subject is abusing alcohol or drugs or is undergoing active treatment for substance abuse (e.g., recreational drugs, narcotics, or alcohol).