The purpose of this study is to demonstrate safety and efficacy of the Simpliciti Shoulder System in total shoulder arthroplasty.

Inclusion Criteria:

• Adult subject 22 years or older
• Clinical indication for total shoulder replacement due to primary diagnosis of arthritis. Primary arthritis for this study includes osteoarthritis, and/or traumatic arthritis.
• Scapula and proximal humerus must have reached skeletal maturity
• Subject with a Constant Score ≥ 20
• Willing and able to comply with the protocol
• Willing and able to sign the informed consent (or the Legally Authorized Representative will sign for the subject)

Exclusion Criteria:

• Lack of sufficient sound bone to seat and support the implant such as:

  1. Rapid joint destruction, marked bone loss or bone resorption;
  2. Destruction of the proximal humerus that precludes rigid fixation of the humeral component; and
  3. Osteomalacia

• Metal allergies or sensitivity, including a known allergic reaction to implant metals (e.g., nickel) or polyethylene

• Infection at or near the site of implantation, including:

  1. Glenohumeral joint infection
  2. Osteomyelitis

• Distant or systemic infection

• Medical conditions or balance impairments that could lead to falls

• Prior open shoulder surgery on the shoulder to be treated in the study including failed rotator cuff surgery, but excluding successful shoulder arthroscopy

• Any full thickness rotator cuff tear at the time of surgery or a nonfunctional rotator cuff

• Excessive glenoid bone loss defined by preoperative computed tomography (CT) scans of the shoulder which show insufficient glenoid bone, or insufficient bone identified at the time of surgery

• Metabolic disorders which may impair bone function

• Nonfunctional deltoid muscle

• Neuromuscular compromise condition of the shoulder (e.g., neuropathic joints or brachioplexus injury with a flail shoulder joint)

• Known active metastatic or neoplastic diseases, Paget's disease or Charcot's disease

• Currently, or within the last 6 months, or planning to be on chemotherapy or radiation

• Currently taking > 5mg/day corticosteroids (e.g. prednisone) excluding inhalers, within 3 months prior to surgery

• Female subjects who are pregnant or planning to become pregnant within the study period

• In the surgeon's opinion, the subject is unable to understand the study or be compliant with the follow up or have a history of non-compliance with medical advice

• History of any cognitive or mental health status that would interfere with study participation

• Alcohol or drug abuse

• Engages in manual labor or sports activities that could affect shoulder outcome

• Currently enrolled in any clinical research study that might interfere with the current study endpoints