Like all joints in the body, the shoulder is formed by 2 bones, the cup (glenoid) and ball (humerus). The surfaces of the ends of these bones is covered a smooth, pearly white layer hard fibrous tissue called cartilage that acts as both a shock absorber and helps the 2 bones glide smoothly over one another. As the shoulder joint ages, this cartilage can become damaged or worn down, leading to osteoarthritis of the joint. The cartilage surface may become rough and irregular, or may wear completely down to the bone. This usually leads to the development of pain and bone spurs as the body tries to compensate for the loss of cartilage. Additionally, the loss of joint space can change how the shoulder functions and force other muscles to compensate for the altered joint kinematics. Unfortunately, the body only produces a finite number of cartilage-producing cells, and even the most recent advances in medicine have yet to find efficient mechanisms for regrowing the lost cartilage. In cases of advanced wear, a total shoulder replacement can greatly reduce symptoms.
One very viable option to restore normal joint mechanics and relieve pain is a total shoulder replacement or total shoulder arthroplasty (TSA). When performed properly, a TSA can relieve pain by removing the arthritic joint surfaces and replacing them with metal and plastic, returning the bones of your shoulder to their normal anatomic position. A perfect shoulder replacement is very difficult to perform since every shoulder is different and may require different components.
To optimize results, we utilize highly specific imaging in the form of a specialized CT scan designed to give the most detailed image of your shoulder anatomy in regards to arthritic changes. These images can then be uploaded to a specialized computer program that allows digital implantation of a vast array of different components. This allows every TSA to be specifically tailored to each patient and ensures a fully functioning, pain free shoulder. These scans require a specialized protocol to be used by the technician performing the scan. Unfortunately, these protocols are currently limited to only a few imaging centers in Tennessee, but our staff can help you find a convenient location in Knoxville if the time comes!
Prior to surgery, patients will be sent for their CT scan and any pre-admission testing that may be required. Patients usually stay overnight after surgery, but if your shoulder replacement is done early in the morning you may be able to return home the same evening. For the operation, an incision is made from just above your armpit to a few inches down your arm. During surgery, the top part of the humerus is cut off and a specialized implant is fitted for your shoulder. Then, the glenoid is careful reamed down to a uniform surface before a cutting-edge polyethylene cup is implanted into several small holes drilled in the bone. This cup is made of a special type of polyethylene that is infused with Vitamin E during manufacturing. This has been shown to greatly improve the strength and lifespan of the plastic, with some wear simulators showing lifespans of up to 20-25 years.
Stemless Total Shoulder Replacement
Pictured here is the latest generation in stemless shoulder replacement (DJO CS Edge), designed and used by Dr. Edwin Spencer
THIS SPOT IS HELD FOR A TECHNIQUE VIDEO. The video can be temporarily accessed here
Glenoid Augments
Recent advances in shoulder arthroplasty have focused on the plastic cup implanted onto the glenoid. As noted in the chart above, some cases involve patients that are missing substantial amounts of bone on the back side of the cup. Standard components are designed for a wear pattern that is more “normal” around the entire cup, so these implants require considerable modifications to joint preparation and component selection. One answer for this problem is known as a Posterior Augmented Glenoid or PAG. PAG’s include a wedge on the backside of the implant that helps to fill the void left by this missing bone and allows for a more anatomic and functional shoulder replacement.
As part of his design efforts, Dr. Spencer and the folks at DJO global have released the latest in PAG components. Not only do these components come in a number of different measurements to address a variety of wear patterns, they are also manufactured using the latest in Vitamin E infused polyethylene technology.
Vitamin-E infused polyethylene (or “poly”) has been shown to demonstrate a superior lifespan compared to standard polyethylene, with some wear simulators showing a lifespan of 20+ years. Vitamin E acts as a powerful antioxidant during production of this polyethylene, which increases the number of links between each “strand” of polyethylene (known as “crosslinking”). This dramatically increases the strength and longevity of the component, reducing the risk of the plastic component weakening or breaking.
Historically, this technology has been relegated to weightbearing joint replacements such as hips and knees. However, Dr. Spencer feels that maximizing the lifespan of each joint replacement is a crucial part of offering patients the best possible implant. For this reason, every possible patient receives a specialized glenoid component manufactured with this crosslinked polyethylene, ensuring that every one of his patients is able to truly maximize their new shoulder replacement for years to come.
The components used in each arthroplasty at the Shoulder and Elbow Center are hand-selected by Dr. Edwin Spencer. Not only has Dr. Spencer performed over 3000 shoulder arthroplasties, he has designed many of the components that he uses, including a revolutionary stemless humeral implant as well as a specialized cup designed to reduce specific wear patterns seen in males (known as a Posterior Augmented Glenoid or PAG). While many surgeons may use an entire set of components from the same manufacturer, Dr. Spencer combines over 15 years of experience with the latest advancements in CT imaging and computer-aided design software to determine the best combination of components that will provide the best long-term results, leaving patients with a pain-free, well functioning shoulder for years to come. For a full video of an anatomic shoulder replacement using the new DJO EDGE System or the older Simpliciti Shoulder System, both designed by Dr. Edwin Spencer, see one of the videos below.
As one of the top shoulder surgeons in Tennessee, Dr. Spencer is highly specialized in these types of surgeries. If you believe you may be in need of our services, don’t hesitate to submit an appointment request on our Homepage and get set up at one of our Knoxville clinics.
***WARNING- THESE ARE SURGICAL VIDEOS THAT INCLUDE DISSECTION AND EXPOSURE OF REAL PATIENTS’ SHOULDER JOINTS. VIEWER DISCRETION IS ADVISED***
Dr. Spencer performing a total shoulder arthroplasty using the new CS EDGE TSA System by DJO Global. ***WARNING- GRAPHIC CONTENT***
