The study will enroll 60 patients into a randomized clinical trial, 30 in the standard of care surgery group and 30 in the IRI surgical group. Investigators will have two surgeons with experience in shoulder arthroplasty and the IRIS and SmartBones technology. Investigators will require a minimum of ten patients in each surgical group (n=20) from any one surgeon. Enrollment by any one surgeon will be limited so that all surgeons achieve a minimum of 20 cases enrolled. All patients will have the standard of care indications for an anatomic total shoulder arthroplasty and will give informed consent for both the surgery and participation in this study. Consent and enrollment will be obtained by the surgeon during a routine office evaluation. All patients will get standard of care pre operative x-rays and CT scan at least three weeks prior to surgery. Scan quality must meet study specific criteria and we expect but will not require that the scans will be performed at the Cleveland Clinic. The pre operative CT scan will be placed within the investigators' pre operative planning software (OrthoVis Cleveland Clinic). The surgeon will use this software to assess the glenoid bone pathology and select the optimal implant and placement of that implant. After pre operative planning each patient will be randomized into either an IRIS group which will use the pre-operative 3D surgical planning software and the data from this software to create a sterile SmartBone model containing the desired location of the glenoid guide pin and instructions for use of an intelligent reusable instrument to assist the surgeon in placement of the guide pin within the patient's glenoid. In the standard treatment group the surgeon will receive the data from the pre operative surgical simulation and use the instruments provided by the implant manufacturer. Statistician provided randomization envelopes will be provided to sort the patients into experiment and standard of care groups.

Patients will have standard of care indications for primary anatomic arthroplasty and be able to get a pre-operative shoulder CT scan at the Cleveland Clinic or at an outside facility so long as the study includes the entire scapula and has 1mm or thinner sections. These parameters are required for accurate pre operative planning as well as comparison with the post operative CT scans. Standard of care pre- and post-operative x-rays (AP and axillary views) will also be obtained and can be preformed at the Cleveland Clinic or acquired from another health care facility. In all patients the standard x-rays and CT images provided by the radiology department will be available to the surgeon before and during the surgery.

For the experimental group, the cannulated IRIS instrument designed for glenoid pin placement is placed over the guide wire that is contained within the sterile SmartBone and the legs of the instrument are adjusted to record the relationship (location and trajectory) of the guide pin in relation to the patient specific glenoid anatomy. This is done at the time of surgery to properly mimic the desired pin placement. The location of each leg of the IRI is marked on the SmartBone with a surgical pen. The instrument is then removed from the smart bone model. The SmartBone model is visually compared by the surgeon to the exposed bone surface to ensure that the two match for shape and size. Any adjustments to the surgical site may be done by the surgeon to optimize the match between the model and the exposed glenoid surface. The marks placed by the surgeon on the model are then transferred to the patient bone using a surgical marker or bovie. These marks are in a general location as determined by the surgeon and assist in the placement of the IRI. The IRI is placed onto the patient bone surface in the same manner as it was placed on the SmartBone model and a guide pin provided by the manufacturer is placed into the desired position. The surgeon then removes the IRI and compares by visual inspection the location and trajectory of the guide pin in relation to the patients bone surface and that within the SmartBone's model. Any adjustments in guide pin position can be performed by the surgeon based upon surgical judgment. The surgeon can make any change needed and use any means or instrument that would otherwise be used for standard of care surgery to place the guide pin in any position that the surgeon believed to be best for the patient. If the pin is changed without the use of the IRI then the patient will be excluded from this study and the reasons for failure of the IRI technology to provide accurate pin placement based upon the surgeon's sole determination of accuracy will be recorded and later analyzed as a failure to treat. These patients will not receive post operative CT Scans as we would not be able to use the data within any one group as defined by this study. After placement of the guide pin the remainder of the procedure is completed in the same manner for both groups, using the implant manufacturer's equipment.

In the standard instrument group the surgeon will use the pre operative CT Scan at least two weeks prior to surgery to define the glenoid pathology, select the implant of choice and place that implant in the desired position. This information will be available to the surgeon at the time of surgery but the SmartBone models and the IRI will not be available. The surgeon will have the pre operative x-rays and the pre operative CT scan provided by the radiology department for intra - operative use. The surgeon will perform the surgery using any of the instruments provided for guide pin placement. These include a wide variety of free hand and adjustable guides that assist the surgeon for placement of the guide pin for location and trajectory. Which tools are used for each case will be recorded at the time of surgery.

Prior to discharge, the patient will receive a post-operative CT scan. This will be a CT scan performed with the patient's arm by the side in a supine position using metal artifact reduction techniques. In addition patients will receive a second CT scan performed 1 year (± 1 month) from surgery. These scans will be performed with the patient in the lateral decubitus position with their arm in the overhead position again using metal artifact reduction techniques. The second set of images produced with a different body and arm position will generate much less metal artifact than those obtained immediately after surgery. This position can not be safely obtained until 3- 6 months after surgery and requires healing of the tissues and rehabilitation of the shoulder. We have shown that in a small number of patients the glenoid component can shift in position within the first 3-6 months after surgery making the first CT scan more accurate for implant position. The images obtained from the post-operative CT scans are placed back into the surgical software and the 3D reconstruction of the post-operative scapula with the implants is compared to the pre-operative plan. Using measurement tools within the software, developed at the Cleveland Clinic, we will compare the position of the actual glenoid component placed in the patient with the desired position specified by the plan. The use and validation of these imaging methods to precisely measure implant position has been performed at the Cleveland Clinic in a prior IRB approved clinical trial (IRB 10-582).

The participating surgeons will be Dr. Joseph Iannotti and Dr. Eric Ricchetti.