Total Shoulder Arthroplasty (Anatomic)

Why this approach — at MOS

Pre-operative CT-based planning is standard for every total shoulder arthroplasty at our practice. Three-dimensional reconstruction of the glenoid allows precise measurement of version (the backward tilt of the glenoid in most arthritic shoulders), the extent of posterior erosion, and the bone stock available for glenoid component fixation. This guides implant selection — whether a standard posterior-augmented glenoid is needed, or whether corrective reaming is sufficient.

The most common mode of total shoulder arthroplasty failure over the long term is glenoid component loosening, often called "the rocking horse" phenomenon — the back of the polyethylene glenoid rocks off the bone under repetitive load. Proper glenoid version correction at the time of surgery is the most important variable the surgeon controls to reduce this risk. We pay particular attention to restoring neutral glenoid version when posterior erosion has created a retroverted socket.

The subscapularis repair at the end of the case is critical for shoulder stability and internal rotation strength. We repair it with heavy suture and protect it with a controlled post-operative protocol that limits active internal rotation and reaching behind the back for the first 6 weeks.

We follow every shoulder arthroplasty patient with radiographic surveillance annually to monitor glenoid component position and detect early lucencies that may indicate loosening before they progress to catastrophic failure.

Who is a candidate?

Indications

• Glenohumeral osteoarthritis (the most common indication) with pain, stiffness, and radiographic joint space narrowing
• Rheumatoid arthritis of the glenohumeral joint with failed medical management
• Post-traumatic glenohumeral arthritis from prior fracture or dislocation
• Avascular necrosis of the humeral head (Ficat stage III or IV)
• Intact and functioning rotator cuff (essential requirement for anatomic design)
• Symptoms severe enough to significantly limit daily activities, work, or sleep despite non-operative treatment

Contraindications

• Irreparable rotator cuff tear or massive rotator cuff tear with fatty infiltration (reverse shoulder arthroplasty is indicated instead)
• Active joint or systemic infection
• Neuropathic (Charcot) shoulder arthropathy
• Axillary nerve palsy with non-functioning deltoid
• Severe glenoid bone loss without reconstructable glenoid
• Patients medically unsuitable for surgery

Conservative Treatment First

Total shoulder arthroplasty is an elective procedure. Surgery is not recommended until a thorough course of non-operative treatment has been completed. Non-surgical options include oral analgesics (acetaminophen, NSAIDs), activity modification to reduce pain-provoking movements, physical therapy focused on rotator cuff strengthening and scapular positioning to offload the glenohumeral joint, corticosteroid injections for acute flares, and viscosupplementation (hyaluronic acid injections) in patients who do not respond adequately to corticosteroids.

Physical therapy cannot reverse cartilage loss, but it can optimize the function of the muscles around the shoulder to distribute load more evenly. Many patients with mild to moderate arthritis achieve meaningful pain relief and functional improvement with consistent therapy and injection management for months to years before requiring surgery. The decision to proceed with arthroplasty is made when quality of life is significantly impaired by pain and loss of function that has not responded adequately to these conservative measures over a reasonable period — typically at least 3–6 months of active treatment.

Patients throughout the Montgomery County area can be evaluated for non-surgical management first, with surgery scheduled when the timing is right for them.

The procedure

What Is Total Shoulder Arthroplasty (Anatomic)?

Total shoulder arthroplasty (anatomic) replaces the worn ball and socket of the shoulder with metal and plastic implants that match normal shoulder geometry. It is performed when shoulder arthritis causes severe pain and stiffness that has not responded to non-surgical treatment, and when the rotator cuff is intact.

The shoulder is a ball-and-socket joint: the humeral head (ball) articulates with the glenoid (socket), both covered by a smooth layer of hyaline cartilage. Osteoarthritis, rheumatoid arthritis, post-traumatic arthritis, and avascular necrosis all destroy this cartilage over time. When the cartilage is gone, the raw bone surfaces grind against each other with every movement — causing a deep, aching pain that worsens with activity, progressive stiffness, and night pain that disrupts sleep.

The anatomic total shoulder replaces both surfaces: a polished metal humeral head component fits on a stem secured inside the humerus, and a high-density polyethylene (plastic) socket component is cemented to the prepared glenoid. The geometry of the implant replicates the natural shoulder — the same ball-and-socket relationship as a healthy joint. Because the design preserves normal biomechanics, it requires an intact, functioning rotator cuff to work properly.

This distinguishes anatomic total shoulder arthroplasty from reverse shoulder arthroplasty. In an anatomic replacement, the rotator cuff must be present and functional — it centers the ball in the socket and coordinates shoulder motion. When the rotator cuff is massively and irreparably torn, the reverse design is necessary instead, because it transfers the job of arm elevation from the absent rotator cuff to the deltoid.

Total shoulder arthroplasty is among the fastest-growing joint replacement procedures in the United States and consistently produces high rates of pain relief and functional improvement in appropriately selected patients.

What Happens During Total Shoulder Arthroplasty?

Before Surgery

Pre-operative evaluation includes blood tests, imaging (X-ray and CT for implant templating), EKG, and medical clearance. You will meet with the anesthesiologist before surgery. A pre-operative physical therapy consultation is helpful for familiarization with the post-operative exercises. You arrive at the hospital 2 hours before the scheduled time.

Positioning and Anesthesia

General anesthesia is administered and you are positioned in the beach chair position. The operative shoulder and upper extremity are cleaned and draped. Fluoroscopy may be used for intraoperative implant position verification.

Deltopectoral Approach

A 10–15 cm incision is made along the deltopectoral groove. The deltoid and pectoralis muscles are separated without cutting either. The subscapularis tendon is carefully released from the anterior humerus — it will be repaired at the end of the case. The capsule is opened and the humeral head is delivered.

Humeral Preparation and Stem Insertion

The humeral head is resected at the anatomic neck angle using a cutting guide. The humeral canal is opened with reamers and sized. A trial stem is placed and the appropriate head size is selected to match the patient's native anatomy. Modern systems offer varying degrees of head eccentricity and version adjustment. Once confirmed, the definitive stem — cemented or press-fit depending on bone quality and surgeon preference — is inserted.

Glenoid Preparation and Component Fixation

The glenoid is exposed and any osteophytes are removed. The articular surface is reamed and shaped to accept the polyethylene component. Small pegs or a keel on the back of the glenoid component are cemented into prepared drill holes. Proper version, tilt, and height are verified with trial components before cementing the final implant.

Trial Reduction and Final Implant Placement

The shoulder is reduced and range of motion, stability, and tension are tested with the trial components before definitive implant placement. Final humeral head selection optimizes stability and range of motion. The final components are assembled and the shoulder is reduced.

Subscapularis Repair and Closure

The subscapularis is repaired to the humerus with high-strength sutures. This repair must be protected during early recovery. The deltopectoral interval is closed, subcutaneous tissue and skin are closed in layers, and a drain may be placed for 24 hours.

Hospital Recovery

You are monitored in the recovery room before transferring to a hospital room. A 1–2 night stay is standard. Ice, elevation, and scheduled analgesics manage pain. Physical therapy begins on post-operative day 1.

Recovery timeline

Frequently Asked Questions

Meet the surgeons

Christopher S. Raffo, MD

Orthopedic Surgery · Sports Medicine

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John J. Christoforetti, MD

Orthopedic Surgery · Sports Medicine · Hip Preservation Surgery

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