Shoulder Resurfacing is Now AvailableHip resurfacing has been around for almost 30 years. This treatment technique has been proven safe and effective. Instead of removing bone and replacing the joint, the surface of the bone is smoothed over and capped with a metal component. Now shoulder resurfacing is becoming more popular. And for the same reasons that hip resurfacing has been used: less bone is destroyed, fewer fractures occur, and the patient can still convert to a total joint if needed later.
In this review, orthopedic surgeons from three different well-known centers bring us up-to-date on the use of shoulder resurfacing. They describe when and how these implants are used along with photos and a discussion of the surgical procedure. The latest in design and expectations for the future are also considered.
Surgeons have several implant designs to choose from when performing a shoulder resurfacing procedure. The implants are made of cobalt-chromium or titanium-alloy. Some have a ceramic surface coating. Others provide a titanium porous (with holes) coating on the undersurface where the implant rests against the bone. The advantage of a porous surface is that the body can fill in the holes with bone to help cement the implant-joint interface together.
Early shoulder resurfacing implants had problems with loosening. Changes in the design seem to have helped reduce this problem. A recent development in shoulder resurfacing is the use of an implant that looks like a giant screw. This method allows for partial resurfacing of the humeral head (round ball at the top of the upper arm). It is used for patients who have smaller defects in the humeral head but don't really need the entire surface smoothed and capped.
The shoulder has a wide range of motion and each patient has differences in normal shoulder anatomy. This is true from person to person but even from one shoulder to the other shoulder in the same person. Choosing the right implant type and size is an important first step. The surgeon must study the joint carefully to identify the shape of the humeral head, the angle of the humeral head, and the way the head fits into the socket.
Muscle tension around the joint is another consideration. The surgeon tries to restore as normal of biomechanical motion as possible. Getting the correct center of rotation and accurate placement of the implant can be a challenge with a total joint replacement. Many surgeons say that shoulder resurfacing makes these tasks much easier.
Not everyone is a good candidate for shoulder resurfacing. Patients who benefit most are those with pain from arthritis who have completed a program of physical therapy with little or no change in their painful symptoms and function.
Resurfacing is particularly attractive for younger, more active adults. This type of procedure cannot be done on people with severe osteoporosis (brittle bones) or fractures in the humerus. The authors comment that in their experience, a minimum of 60 per cent of normal humeral head bone stock is needed for patients with osteoporosis to be considered for resurfacing. So, having osteoporosis doesn't mean shoulder resurfacing is out of the question. Their guideline of 60 per cent has not been studied or validated but provides surgeons with a helpful standard until evidence is provided.
The surgery itself is done with an open incision. The use of general anesthesia, regional anesthesia, or a combination of both is determined by the anesthesiologist at the time of the operation. This is based on patient needs, general health, preferences, and consideration of any comorbidities (other medical problems or conditions) present.
Diagrams, line drawings, and photographs are used to show how shoulder resurfacing can be done to preserve normal preoperative humeral head angles, position, and curvatures. The authors also describe their method for releasing the soft tissues around the joint and gaining access to the glenoid (socket). Any damage to the muscles around the shoulder present from before surgery is repaired (if possible). Any bone spurs along the clavicle (collar bone) are shaved off.
Sometimes there is a bit of trial and error as the surgeon fits different size implants in place. Shoulder motion and stability are checked before securing the implant. Muscle balance and tension is checked before closing the incision. Muscles around the shoulder that are too loose or too tight can result in shoulder dislocation.
The jury is not in yet on the best type of postoperative program for shoulder resurfacing. Some surgeons encourage their patients to move the arm right away. Others say to wait four to six weeks before rotating the joint fully in either direction (internal or external). The idea is to give the muscles a chance to heal after being cut during surgery. And some surgeons are combining a bit of both approaches by allowing some (but not all) motions right away. They gradually add in the other movements through full motion and then progress to a strengthening program over a period of weeks to months.
What are the results published so far for shoulder resurfacing? Only short-term and mid-term studies are available. But they show that 90 per cent of the patients report significant improvements in motion, pain, and strength. All of that leads to better function in daily activities, leisure activities, and sports participation. Patients say they can do just about anything they want from yoga to golf to mountain biking, hockey, even power lifting.
Compared with a total shoulder replacement, there are fewer complications and problems after shoulder resurfacing. Operative time is shorter and fewer days in the hospital are typical with shoulder resurfacing compared with joint replacement. There's also less blood loss. And, of course, the main advantage is the availability of treatment for young, active patients who are limited by their pain.
The surgeon is faced with one other major decision during shoulder resurfacing. Should the socket side of the joint be replaced as well? There are pros and cons in this argument. Results of studies are from short-term follow-up. So far, there's been some evidence that results are better when both sides of the joint are resurfaced. More study is needed in this area before clinical guidelines can be established and published.
What does the future look like for shoulder resurfacing? The authors expect it will be used more and more as time goes by. The results of current studies will show its benefits. Better materials and less invasive techniques will add to its appeal. Eventually, it may be possible to do the procedure arthroscopically. Already some surgeons are trying to do the partial resurfacing using an arthroscope. The less the soft tissues are disrupted, the better.
Derrick L. Burgess, MD, et al. Shoulder Resurfacing. In The Journal of Bone and Joint Surgery. May 2009. Vol. 91. No. 5. Pp. 1228-1238.
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