It’s very disturbing to have shoulder surgery and still end up with pain, stiffness, and a feeling that the shoulder just isn’t going to hold up. Sometimes it’s not just a bad feeling — the shoulder may be unstable enough to dislocate repeatedly. That’s a condition referred to as shoulder instability. When it occurs after surgery to repair a shoulder injury, then it’s considered a failed shoulder stabilization surgery.
In this article, surgeons who specialize in sports surgery present a review of all the factors to consider in failed shoulder stabilization surgery. They discuss diagnosis issues, technical errors during the initial repair surgery, and risk factors for repair failure. They also help surgeons identify complications and offer suggestions for ways to treat those problems.
The majority of failed shoulder surgeries are attributed to failure to diagnose the full extent of the problem. It’s not that the surgeon didn’t know what was wrong with the shoulder. In 84 per cent of all cases, there was more than one problem. And the additional problems weren’t recognized or repaired, leaving the shoulder at risk for failed surgery. The surgeon evaluating patients with shoulder instability following surgery must go back to the beginning. With a thorough history, physical exam, and review of risk factors, the full scope of problems can be identified. Then a treatment plan to address each one is developed.
Finding the source (or sources) of the failure is important before just going back in with more surgery. There are some routine questions that must be asked like what kind of surgery was done, did it have any effect, and was there another injury or athletic event that led up to a reinjury and now the current instability? The surgeon will also look for common risk factors such as the patient’s age, inappropriate activity level (too much, too soon), or inadequate rehab after surgery.
There’s always a list in the back of the surgeon’s mind of other risk factors out of the patient’s control. This could include poor quality of soft tissue or bone, damage to the joint cartilage, and technical problems from the surgery. A careful physical exam will show how much motion the athlete has, strength and function, as well as the degree of instability (mild-moderate-severe). By comparing the unstable side to the uninvolved, stable shoulder, it’s possible to get an idea of ligamentous integrity and just where the instability is coming from.
Loss of motion, too much motion, and/or loss of strength in any particular direction provides helpful information. For example, the patient who can externally rotate the arm past 90 degrees is showing some shoulder joint instability from lax or loose ligaments. If the shoulder capsule is stretched out too much, the patient will be able to move the arm away from the body (a motion called abduction) 20-degrees or more on the unstable side compared to the other (uninvolved) side.
Testing shoulder muscle strength is a good way to look for rotator cuff tears or nerve damage. Loss of normal muscle function from either of these problems can lead to biomechanical dysfunction. With as many as 30 per cent of shoulder surgery failure, it’s not uncommon to find both muscle and nerve injury or damage to more than one muscle.
Once the physical exam has been completed, the surgeon puts the whole picture together and decides what kind of imaging might be helpful. Sometimes the original misdiagnosis occurred because there was inadequate imaging. Certain X-ray view may be needed (e.g., West Point axillary view, Stryker Notch view, scapular-Y view) or a three-dimensional (3-D) CT scan to look for specific types of lesions. Bone loss, location (e.g., humeral head or glenoid fossa) of that bone loss, and extent of bone loss are all important variables to look for before attempting another operation.
The humeral head is the round ball of bone at the top of the humerus (upper arm bone). The glenoid fossa is the shoulder socket. It is usually very shallow and flat. Together, these two components make up the shoulder joint. Not only does the 3-D CT scan show the integrity of the bone, but it also shows the joint surface and any lesions that might be present there. CT scans also help the surgeon see if there were technical errors from the first operation. This could be the improper placement of suture anchors or not enough anchors to hold the soft-tissue repair in place until healing could take place.
Sometimes more than one imaging study is needed. Surgeons get different information from X-rays and CT scans than from MRIs. It may be that all three are ordered and reviewed. Whereas CT scans give some idea of the condition of the bone, MRIs provide a way to examine the soft tissues around the shoulder (e.g., capsule, rotator cuff, labrum or cartilage around the rim of the shoulder).
When all the pieces of the diagnostic puzzle are put together, then a treatment plan is defined. Each complication or problem calls for a different approach. The surgeon faces an even greater challenge when there is more than one pathology. The authors present some tips for some of the more common problems including bone loss, Hill-Sachs lesions, rotator cuff insufficiency, and capsular injury.
Bone loss is often unrecognized during the first surgery. Without full diagnostic imaging, the surgeon may not see how severe the condition is. If it’s bad enough, open surgery and bone grafting might be necessary. One way to give the shoulder more stability is to deepen the socket. This can be done by adding a rim of bone along the front edge of the glenoid fossa. That will help keep the humeral head in the socket and prevent it from popping out anteriorly (forward direction). Another way to prevent chronic anterior dislocations is to join two tendons together that can resist forward movement of the humerus during motions that can push the head out of the socket.
With repeated dislocations, damage can occur to the head of the humerus. The smooth surface of the humerus hits against the bony edge of the glenoid (socket). The collision causes a dent in the bone of the humerus called a Hill-Sachs lesion. The presence of a Hill-Sachs lesion increases the risk of shoulder redislocation and instability. The defect will have to be filled in either with a bone graft, synthetic plug, or tendon transfer.
Rotator cuff injuries are often missed at the time of diagnosis of the original shoulder instability. One (or more) of the four tendons that make up the rotator cuff (and usually the subscapularis muscle/tendon) may be partially or completely torn. Without the proper pull, support, and coordinated control that the rotator cuff provides, the repaired shoulder can become unstable again. As with the Hill-Sachs bony lesion, this soft tissue lesion can be repaired or reconstructed. The surgeon makes the decision based on all of the factors discussed so far.
And then there’s the management of capsular injuries. The shoulder joint is surrounded by a watertight sac called the joint capsule. The joint capsule holds fluids that lubricate the joint. The walls of the joint capsule are made up of ligaments. Ligaments are connective tissues that attach bones to bones. The joint capsule has a considerable amount of slack, loose tissue, so that the shoulder is unrestricted as it moves through its large range of motion.
The shoulder joint relies on the ability of these ligamentous tissues to hold the shoulder in place. Damage to the capsule or too much laxity can contribute to shoulder instability. Surgical repair is possible by harvesting ligamentous tissue from elsewhere and transferring it to the area of capsular deficiency.
The surgeons’ decision about the best way to approach failed surgery for shoulder instability is not over yet. Knowing what tissues are involved and to what extent is just the starting point. Now, the method of operation must be considered. Is an open incision required or can this be done arthroscopically? This is a decision that is made on a patient-by-patient and surgeon-by-surgeon basis.
Studies show that the results are fairly comparable for shoulder revision surgeries between arthroscopic and open-incision approaches. Some repairs are just easier to make one way versus the other. Open-incision is preferred when there are multiple areas of damage that require attention and especially when there is severe bone loss. Surgeons are aware of the fact that when successful, a revision surgery won’t yield the same positive results as the initial repair.
And finally, as mentioned briefly before, there are decisions to be made about what and how much hardware to use (e.g., anchors) to hold it all together (not to mention where to place the anchors). The wrong placement can result in bone wearing, soft tissue fraying, and subsequent osteoarthritis. That just adds one more problem to the list of things that could go wrong after surgery for shoulder instability.
Hopefully, you can see from this long list of problems just why it is that there’s a 30 per cent failure rate for surgical procedures designed to restore shoulder stability. Between patient factors (things that can and cannot be controlled), incomplete diagnosis, and surgical technical errors, there’s plenty of room for failure and loss of function as well as performance.
For athletes interested in getting back into action as soon as possible, the decision treatment that yields optimal results may not be simple or quick. The careful surgeon will take his or her time to get to the bottom of the problem(s) and solve them. That can take time but the favorable results desired are worth the time and effort it takes to thoroughly evaluate the case and carry out the treatment plan.