Anatomic TSA still relevant as use of RSA increases
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Several reports highlight an increasing incidence of shoulder arthroplasty in the United States during the past decade, which may be due to expanded use and indications, as well as to an uptick in expertise with reverse shoulder arthroplasty.
Included under the same ICD-9 procedure code as anatomic total shoulder arthroplasty until 2010, researchers could not begin to identify trends and changes related to the national incidence of RSA until 2011. A 2021 study published in JBJS Open Access by Kevin X. Farley, BS, and colleagues showed an increase in the incidence of RSA of about 392% from 2002 to 2017. Similarly, a study in the Journal of Shoulder and Elbow Surgery by Matthew J. Best, MD, and colleagues showed the annual incidence of RSA procedures nearly tripled from 2012 to 2017.
Source: John Karsten Moran
“When you start looking at the numbers based on incidence, the rate of growth within shoulder arthroplasty has been huge, but most of that growth has been driven by the use of the reverse total shoulder to the point now where there are more reverse total shoulders done every year than there are anatomic shoulders,” Thomas R. Duquin, MD, clinical associate professor of orthopedics in the Jacobs School of Medicine and Biomedical Sciences at University at Buffalo and orthopedic surgeon at UBMD Orthopaedics and Sports Medicine, told Orthopedics Today.
Consider rotator cuff status
One reason surgeons may choose to perform RSA over anatomic TSA is due to the RSA procedure being more straightforward, especially regarding soft tissue balancing, according to Joseph D. Zuckerman, MD, the Walter A.L. Thompson Professor of Orthopedic Surgery, chair of the department of orthopedic surgery at NYU Langone Health.
“For instance, if I put the glenoid component in 10° or 12° of retroversion, that is probably going to cause a problem and [the patient will] develop posterior instability,” Zuckerman said about performing anatomic TSA. However, relatively small changes to the position of the glenoid component during RSA are better tolerated due to it being a fixed fulcrum device, he said.
Surgeons also may choose RSA over anatomic TSA in older patients who present with an unhealthy rotator cuff, according to Reuben Gobezie, MD, of Gobezie Shoulder Institute.
“[The rotator cuff] is not massively torn, it does not meet that criterion, but it is not normal either and it looks like, over time, they are going to tear it,” Gobezie told Orthopedics Today.
Duquin said a rotator cuff tear or rotator cuff dysfunction that alters the mechanics of the shoulder and leads to implant loosening, loss of function or pain after an anatomic TSA may also lead surgeons to revise the primary TSA using RSA. Surgeons may also choose to perform RSA in younger patients with rotator cuff tears that cannot be fixed, he said.
“Sometimes we have had younger patients who have had multiple attempts at rotator cuff repairs that have failed, and reverse total shoulder often can become an option to treat those patients, as well,” Duquin said.
RSA with glenoid bone loss
Although the techniques for performing RSA and anatomic TSA are similar, Theodore A. Blaine, MD, sports medicine surgeon at Hospital for Special Surgery, said the subscapularis tendon and muscle needs to fully heal for good outcomes after an anatomic TSA, but not for RSA.
“There are some people who will do reverse replacements in a majority of people because they do not want to worry about the healing of the [subscapularis] muscle ... but I think anatomic designs are more normal. They reproduce more normal function in the shoulder with better motion,” Blaine told Orthopedics Today. “I believe that if you can have an anatomic shoulder and your rotator cuff works well and heals well, then you are going to feel like it is more of a normal shoulder.”
Emilie Cheung, MD, associate professor of orthopedic surgery, shoulder and elbow service at Stanford University, said some surgeons favor performing RSA in patients who have rotator cuff tears but no arthritis, as well as in patients with extreme glenoid bone loss with or without an intact rotator cuff.
As anatomic TSA relies on reproduction of the native anatomy, including restoration of the normal bony alignment and mechanical aspects of the shoulder, Duquin said some surgeons find RSA is more reliable for patients with glenoid bone loss due to the flexibility of the nonanatomic reconstruction and better management of the soft tissues.
Improvements in implant design have also led to better glenoid component fixation with RSA, he said.
“Most people who have substantial bone loss would go to a reverse because our fixation methods have become better with the advent of augmented baseplates that help to replace bone with metal or patient-matched implants that allow you to deal with substantial bone loss. Even in bone grafting procedures, having screw fixation in a metal baseplate seems to facilitate the success of those implants,” Duquin said.
Fracture, arthritis considerations
Duquin said surgeons may perform RSA in patients with four-part proximal humeral fractures or other complex fracture dislocations of the proximal humerus.
“There are a lot of people who might have fracture sequelae, so that would be a malunion or a nonunion of the proximal humerus from an injury or a trauma, and those patients also can benefit from a reverse total shoulder because it is a nonanatomic reconstruction. So, it does give you a little bit more flexibility in terms of how to manage some of those more complex problems,” Duquin said.
According to Zuckerman, RSA also plays an important role in patients with posttraumatic arthritis and in patients with significant deformity or scar tissue from a fracture.
“The vast majority of patients with rheumatoid arthritis of the shoulder are better served by reverses,” Zuckerman told Orthopedics Today. “I use it in all of my patients with Parkinson’s disease.”
Not only does injury type factor into whether an RSA or anatomic TSA is performed, but the decision of which procedure is best may also come down to the patient’s activity level and goals for the surgery and future goals, Duquin said. Patients who are not high functioning or highly active, who are willing to accept a little loss of motion and who want an operation that will be reliable for 10 to 15 years may have the most benefit from RSA, he said.
“Whereas, for patients who want more activity, maybe they play tennis or they are into overhead sports or swimming or other activities, a lot of those patients oftentimes, as long as they have a good rotator cuff and not substantial bone wear, they would be good candidates for an anatomic replacement,” Duquin said.
Advantages of anatomic TSA
Because the rotator cuff and fixation of a cemented all-polyethylene glenoid component is not a limiting factor in RSA, Cheung said the published literature has shown the possibility of longer survivorship with RSA compared with anatomic TSA.
“In anatomic shoulder arthroplasty, if you follow those out long term, there are issues with glenoid component loosening over time and rotator cuff failure over time, attritional failure of the rotator cuff, not to mention potential traumatic failure of the subscapularis that can limit the success of an anatomic compared to a reverse,” she said.
However, anatomic TSA has its advantages that may lead it to outperform RSA in most patients with an intact rotator cuff, including better motion and external and internal rotation, Cheung said.
“Patients with a reverse cannot achieve good internal rotation so that limits their ability to reach behind their back,” Cheung told Orthopedics Today.
Duquin said patients also report anatomic TSA feels more natural because it replicates the mechanical aspect of the natural shoulder.
“As long as they have a good rotator cuff, I would say a larger proportion of my anatomic total shoulder patients will go to the point where they forget about their shoulder. They essentially go back to being normal and they do not even think about their shoulder anymore,” Duquin said. “People with the reverse, they tend to always notice that their shoulder is not totally normal. There seems to be this biomechanical sense that it does not function the same way.”
RSA complications
Although Gobezie said registry data show a lower complication rate with RSA, Cheung said some researchers have reported a higher complication profile with RSA.
“Much higher instability rates, hematoma formation, ... infection, the next one would be acromial stress fracture. Another one would be deltoid senescence over time, and nerve injury,” Cheung said. “Because you need to lengthen the arm, there have been more cases reported of brachial plexopathies. Most are temporary, but definitely higher in reverse than with the anatomic.”
Some complications are unique to RSA and not found with anatomic TSA, according to Blaine. He said these include stress fractures of the scapular spine, which can occur in 2% to 4% of RSA procedures, as well as scapular notching.
“There was some risk of a dislocation ... with reverse replacements when we first started doing them,” Blaine said. “The risk was as high as 30%. That has gone down quite a bit. The risk of dislocation now is less than 5%. But, again, that exists for reverse replacement and not as much as an issue with an anatomic replacement.”
Research needs
With almost 20-year follow-up data from the United States and more than 30-year follow-up data from Europe for RSA, Zuckerman said future research should aim to understand the factors that result in a successful outcome vs. a less than successful outcome, as well as the criteria for optimal functional outcomes and long-term implant survival.
“There are some issues out there related to rotator cuff deterioration. People are now talking about deltoid fatigue that develops over time because of the stretching that occurs with a reverse. All of those things have to be documented,” Zuckerman said.
According to Gobezie, future research should identify whether the functional outcomes and longevity of RSA and TSA implants are comparable, as well as identify the appropriate indications for RSA.
“What are the actual indications that fit? Which implant fits best in the particular patient we are talking about? That is something that we do need to understand,” Gobezie said.
RSA stem length is another area of ongoing research, Blaine said.
“On an anatomic replacement, we know the shorter stems and the stemless designs do well,” he said. “We do not know that so much for reverse replacements yet, so that is one area that needs to be worked on.”
In addition, identifying the appropriate soft tissue balance, tension and center of rotation are among the future challenges related to RSA implants, according to Duquin. Big data, navigation and robotics may contribute to a better understanding of implant positioning, as well as functional outcomes over time, he said.
“Over the next 5 to 10 years, I think it will be exciting to see the developments that come out with reverse total shoulder and the understanding that we get for positioning the glenoid component, positioning the humeral component and how best to tension those implants to allow for optimal range of motion and function while preventing complications like acromial fractures or scapular spine fractures, scapular notching,” Duquin said.
Consider the data, patient
As more research on RSA is published, Gobezie said it is important for surgeons to be thoughtful of and critical about the results and mindful of their individual positions regarding RSA adoption.
“Do not keep a position just because you were told to keep it,” Gobezie said. “Keep an open mind and watch your patients over time. I think you will find that you will have something substantive so that when you look your patient in the eye, if you have looked at the data, ... you can back [your opinion] with real data.”
It is also important for surgeons to understand the potential indications for RSA and decide which patients are best suited for the procedure, according to Zuckerman.
However, due to the associated complications and functional outcomes of RSA, Blaine said surgeons should not resort to using RSA in every patient.
“[There are] risks that are unique to a reverse replacement, so, because of those risks, it is not something that should be used in everybody,” Blaine said. “If you can do an anatomic replacement, the patient will likely have more normal motion and do well.”
In light of these complications, surgeons without specific training in shoulder arthroplasty procedures should be cautious about embracing RSA, Cheung said.
“Complications can be devastating. So, things like proper implant positioning [and] proper glenoid exposure are crucial for the success of the operation,” she said.
Source: Best MJ, et al. J Shoulder Elbow Surg. 2021;doi:10.1016/j.jse.2020.08.010.
“If you have a failed total shoulder you can revise that, but if you have a failed reverse total shoulder arthroplasty, there are not many good solutions to address that,” Cheung said.
Surgeons interested in performing RSA should attend courses and cadaver labs to understand the biomechanics and principles associated with performing a successful procedure, according to Duquin. He said surgeons should clearly understand the implant system they are using and what it offers.
“There are a lot of different options out there right now and there is not one that is better than the other, but they are based on a little bit different understanding and principles of reverse, and how you use them might be slightly different,” Duquin said. “It is important for people to understand their implant system and what they are planning on doing biomechanically to optimize the outcomes of reverse total shoulder for their patients.”
In addition, surgeons who are new to performing RSA should not begin with a complex case, Duquin said.
“Starting out with some of the easier cases will build your confidence and understanding of how to do reverse total shoulder arthroplasty and likely will help you become more successful as you do more reverse total shoulder replacements over time,” he said.
Although the choice to perform an RSA or anatomic TSA involves shared decision-making, Zuckerman said the use of RSA is a trend that will continue to increase overtime.
“It is never going to be 100% to 0%, but I think a general 60/40 or 70/30 range is probably what it is going to stack up to overtime,” Zuckerman said. “So, it behooves us, as surgeons, to get experienced in [reverse shoulder arthroplasty]. I do not think it is going to revert back the other way because there are too many diagnostic categories that we know for which the results of anatomic are not as good as we want it to be, and the reverse can help with that.”
- References:
- Thon SG, et al. Curr Rev Musculoskelet Med. 2020;doi:10.1007/s12178-019-09582-2.
- Wagner ER, et al. J Shoulder Elbow Surg. 2020;doi:10.1016/j.jse.2020.03.049.
- Westermann RW, et al. Iowa Orthop J. 2015;35:1-7.
- For more information:
- Theodore A. Blaine, MD, can be reached at 1 Blachley Road, Stamford, CT 06902; email: carnevalen@hss.edu.
- Emilie Cheung, MD, can be reached at 450 Broadway St., Pavilion A, 1st Fl., Redwood City, CA 94063; email: evcheung@stanford.edu.
- Thomas R. Duquin, MD, can be reached at 462 Grider St., Buffalo, NY 14215; email: goldbaum@buffalo.edu.
- Reuben Gobezie, MD, can be reached at 25501 Chagrin Blvd., Suite 200, Beachwood, OH 44122; email: clevelandshoulder@gmail.com.
- Joseph D. Zuckerman, MD, can be reached at 301 East 17th St., New York, NY 10003; email: joseph.zuckerman@nyulangone.org.
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