Design: Prospective, randomized clinical trial, of 120 patients requiring a total shoulder replacement (TSR).

Purpose: To collect and evaluate long-term clinical data on patients whose total shoulder replacement (TSR) is performed using the traditional surgical approach (called the subscapularis release approach) as compared to patients who have a TSR procedure done using a newer surgical approach (called the rotator cuff sparing approach).

Design: Prospective, randomized clinical trial, of 120 patients requiring a total shoulder replacement (TSR).

Purpose: To collect and evaluate long-term clinical data on patients whose total shoulder replacement (TSR) is performed using the traditional surgical approach (called the subscapularis release approach) as compared to patients who have a TSR procedure done using a newer surgical approach (called the rotator cuff sparing approach).

For patients with arthritis, TSR can successfully improve pain and restore function. As a result, TSR has become the treatment of choice for patients with shoulder arthritis. Despite these generally good outcomes, however, there are concerns that rotator cuff function is suboptimal after surgery. One of the rotator cuff tendons is usually cut during the TSR procedure to insert the prosthesis and then repaired at the end of the surgery. If the tendon does not heal adequately, patients may experience persistent weakness, pain, and even failure of the replacement. Recently, a surgical technique called rotator cuff sparing TSR has been described where the procedure can be performed without ever cutting any of the rotator cuff tendons. As such, there should be minimized risk to the rotator cuff function after the surgery. Our study proposes to enroll two groups of patients with shoulder arthritis. The first group will be treated with the traditional TSR procedure. The second group will be treated with this new rotator cuff sparing surgical technique for TSR where the rotator cuff is never violated. After surgery, we will examine motion, strength, and functional use of the shoulder. In addition, we will specifically test the rotator cuff strength after the surgery. In this fashion, we plan to test the hypothesis that rotator cuff sparing TSR can improve the rotator cuff function while maintaining the excellent pain relief and motion that is normally observed after the traditional TSR procedure.

Enrollment: A total of approximately 120 subjects will be enrolled and treated at NYU Hospital for Joint Diseases. Subjects participating in the study will be randomly assigned to have their total shoulder replacement done using the traditional surgical approach (called the subscapularis release approach) or by the newer surgical approach (called the rotator cuff sparing approach). For each patient, a number will be created by a random number generator. Patients randomized to the even number (2) will receive a traditional TSA procedure that includes incision and repair of the subscapularis tendon during the procedure. Patients randomized to the odd number (1) will receive the rotator cuff sparing TSA. Regardless of the procedure, patients will remain "blind" to the type of procedure they received until completion of their 2 year follow up.

Follow-Up Requirements: Office Visits: Patients' participation will involve five (5) office visits (after surgery) over a period of two (2) years. At each visit, as part of the patients' regular care, they will have standard x-rays of their shoulder. All patients will complete self-administered questionnaires to assess the clinical outcome of the surgery and patients satisfaction. The patient administered outcome questionnaires will include the SF-12, and Patient Assessment Case Report Form.

Inclusion Criteria:

• Patient is indicated for shoulder joint replacement
• Patient is at least 21 years of age
• Patient is expected to survive at least 2 years beyond surgery
• Patient is willing to participate by complying with pre-and post-operative visit requirements
• Patient is willing and able to review and sign a study informed consent form

Exclusion Criteria:

• Prior arthroplasty in the affected shoulder.
• Significant deformity of the proximal humerus that requires a custom made implant or where osteotomy of the shaft and / or the tuberosity has to be considered.
• Significant medial erosion of the glenoid such that lateral edge of the humeral head lies medial to the lateral rim of the acromion.
• Significant injury to the brachial plexus
• Inability or unwillingness to participate in the post operative evaluation for the entire 24 months period.
• Pregnant and lactating women will be excluded