Surgery
The goal of the ream and run procedure is to provide an anatomic shoulder arthroplasty resulting in a mobile and durable joint stabilized by concavity compression (Mechanisms of glenohumeral joint stability) without the use of a plastic socket.
The basic techniques of the ream and run have been published in Current Technique for the Ream-and-Run Arthroplasty for Glenohumeral Osteoarthritis. Here we provide some details about the ream and run principles and procedure using the diagrams crafted by Steven Lippitt. Here is a video showing the steps of the ream and run procedure. The humeral side of the arthroplasty can be managed with a stemmed or a stemless humeral component - in this video a stemmed humeral component is used.
The ream and run can be described as a humeral hemiarthroplasty combined with a non-prosthetic glenoid arthroplasty. The glenoid arthroplasty is necessary because the articular surface of the arthritic glenoid (right) does not distribute the load evenly as in the normal normal glenoid (left). The result is pain, stiffness, progressive wear, a bi-concavity and posterior instabillity.
Simply replacing the arthritic humeral head with a humeral prosthesis does not address the glenoid pathology.
Reaming the glenoid to a single concavity distributes the humeral head evenly across the face of glenoid and allows for regrowth of a fibrocartilage joint surface.
The goal of the non-prosthetic glenoid arthroplasty is to create a smooth single glenoid concavity 2 mm greater in diameter of curvature than that of the humeral head prosthesis. Rather than trying to "correct" glenoid retroversion, we accept the preoperative version, reaming conservatively to preserve glenoid bone stock.
Our preoperative planning does not involve a CT scan or planning software, but rather is based on standardized plain films such as those shown below.
Under general anesthesia (we do not use a nerve block so we can verify the patients neurologic exam immediately post op) the patient is placed in a relaxed beach chair position with the arm draped free. An 18 gauge intravenous catheter is placed in the contralateral arm or the neck. Intravenous antibiotic prophylaxis us usually ceftriaxone and vancomycin.
The shoulder is approached through a standard deltopectoral incision.
Any adhesions in the humeroscapular motion interface are released from the axillary nerve medially, over the top of the humerus to the axillary nerve laterally.
The subscapularis is peeled from the lesser tuberosity, carefully preserving the capsule on the deep surface of the subscapularis tendon and the long head tendon of the biceps.
The subscapularis is often tethered and requires a 360 degree release so that it can reach the lesser tuberosity with the arm in external rotation.
After removing the osteophytes, an anatomic neck cut (red line) is made starting at the "hinge point" (arrow) at 45 degrees with the long axis of the shaft and in 30 degrees of retroversion.
Humeral head components have two dimensions: the diameter of curvature (below left) and the thickness (below center). The dimensions of the resected head can be measured with a cutout template (below right). In general we select a prosthetic head with the same diameter of curvature as the resected anatomic head. We adjust the tightness of the shoulder by varying the thickness of the prosthetic head.
Good glenoid exposure is essential. Here a large Darrach retracts the humerus posteriorly while a sharp Hohmann retracts the subscapularis anteriorly.
The glenoid labrum is preserved because it contributes to glenohumeral stability. The capsule is released inferiorly.
If the shoulder is posteriorly decentered, the release is stopped at 5 o'clock
If the shoulder is centered and tight, a 360 degree capsular release is performed. Twisting the humeral retractor can help expose the posterior capsule.
The glenoid preparation begins with removing the residual articular cartilage. Any ridge between the anterior and posterior concavities is burred down.
The center of the glenoid face is marked, burred and drilled.
The glenoid is reamed to a diameter of curvature 2 mm greater than that of the humeral head prosthesis. We prefer a nubbed (rather than a cannulated) reamer so that its angle can be adjusted to create a single conforming concavity with removal of minimal glenoid bone and accepting the glenoid retroversion. We do not attempt to "correct" glenoid version (below right), in that this unnecessarily removes excessive glenoid bone.
Adequate reaming is verified when "ream lines" are seen across the face of the glenoid and when a there is no tipping of a template with the reamed diameter of curvature.
The trial humeral head is placed. The head should sit just below the "berm" (arrow). Proper "register" is confirmed: the center of the humeral head sits in the center of the glenoid.
The desired range motion is 150 degrees of flexion, external rotation with the subscapularis reapproximated to 40 degrees, 50% posterior translation, and 60 degrees of internal rotation with the arm abducted.
The shoulder is carefully inspected for unwanted contact between the humerus and the glenoid inferiorly (Pooh Corner) and posteriorly (Open Booking).
It is also important to verify that the humeral head does not drop back excessively when the arm is flexed
If there is excessive posterior translation, a thicker humeral component or an anteriorly eccentric humeral head will usually provide the needed stability.
After the head component has been selected, the wound is thoroughly irrigated with antibiotic-containing saline and Betadine. Topical vancomycin is placed in the wound. Six fiberwire sutures are placed securely in the bone of the lesser tuberosity along with two extra sutures in the rotator interval to reinforce the subscapularis repair. The humeral component is placed .
After verifying the desired stability, range of motion and lack of unwanted bone contact, the subscapularis is securely repaired
After the subscapularis is repaired, we check once more to make sure that the shoulder can be easily flexed to 150 degrees. We commonly take a photo in the OR so we can show the patient that "it will go!"
Hemostasis is critical because motion will be started soon after surgery. We use intravenous or topical tranexamic acid routinely. Topical thrombin and hemostatic matrix is used as necessary.
We obtain an anteroposterior view in the plane of the scapula and an axillary "truth" view in the recovery room to evaluate the reconstruction. Here are the postoperative x-rays of a 48 year old bodybuilder, 6 ft 1 in, 293 lbs with a prior proximal humeral fracture.
Assisted forward flexion exercises are started while the patient is in the recovery room. Most patients have little difficulty with this exercises even though they have not had a brachial plexus block.
Because young active patients tend to have a slightly higher risk for Cutibacterium infection, we commonly prescribe 3 weeks of oral doxycyline prophylaxis.