Advancements in wrist arthroplasty may improve results

2022-06-13 07:27:45 By : Mr. Li Shihong

Traditionally, wrist fusion has been the gold standard for pan-carpal wrist arthritis due to low complication rates, pain relief and durability.

But one of the disadvantages of wrist fusion lies in the elimination of radiocarpal motion, according to the published literature.

“It is like you have a permanent cast on,” Eric R. Wagner, MD, of the Upper Extremity Center at Emory University, told Orthopedics Today. “So, your fingers are going to be the ones that can move and now you [have to] adjust your shoulders to make up for that. It will put more stress on the rest of the extremity, and it will ... put a strain on your fingers. It is not near as functional of an extremity as when you have even a small amount of wrist motion.”

In comparison, sources who spoke with Orthopedics Today said total wrist arthroplasty (TWA) may not only provide pain relief but also preserve motion.

“It is not normal motion because the native wrist is fairly complex,” Brian D. Adams, MD, professor of orthopedic surgery at Baylor College of Medicine, told Orthopedics Today. “Multiple joints within the wrist are creating the motion that we typically have in our wrist, whereas wrist replacement simplifies the wrist joint and, therefore, it only gives about 50% of normal wrist range of motion.”

However, Adams said 50% of wrist range of motion is all that is needed for most functional activities of daily living and most patients do not recognize there is a limitation in wrist motion.

Arnold-Peter C. Weiss, MD, professor, vice chair and chief of hand surgery at Brown University, said patients do not like the idea of undergoing a fusion, and “if they can get rid of their pain and have decent motion that is going to last for a while, then they tend to pick that.”

“Wrist fusions do have good power associated with them, so there are some advantages, but generally patients want to be as ‘normal’ as they can be, which means they want to have motion,” said Weiss, who has performed TWA for 25 years at a rate of about 25 to 40 cases annually.

As with other arthroplasty procedures, before a patient undergoes surgery for wrist arthritis, they first must try nonoperative options, such as splints, injections and strengthening and subsequent joint stabilization with a hand therapist, according to Wagner.

Weiss said physical therapy does not make a difference once a patient has bone-on-bone arthritis in one or two of their wrist joints.

“It is basically a mechanical problem,” Weiss told Orthopedics Today. “It is a raw bone on a raw bone. You cannot exercise that away. It is not like a muscle, where you can make it stronger. It is just going to hurt more if you do that.”

Many patients who develop wrist arthritis only develop it in some of the small-bone joints in the wrist, which makes them candidates for a partial procedure that will reduce pain and preserve motion, according to Weiss.

Wagner said some partial procedures that have been found to provide good outcomes include four-corner fusion, radioscapholunate fusion, proximal row carpectomy and partial neurectomy. But although these partial procedures help in the short term, many studies have shown a large percentage of patients still develop arthritis over the long term, Wagner said.

“Although you help them initially for the first 5 or 10 years, their wrists often still progress to having arthritis in the previously spared joints, leading to pain and limiting their function,” said Wagner, who has studied these procedures and TWA extensively over the last decade.

While partial procedures to manage wrist arthritis are good procedures for the short term, Wagner said the investment that surgeons made into developing and using those procedures “took away from the need to innovate in total wrist replacements.”

“Whereas, in the knee and hip there were not any other options besides doing the replacement, which created a big push financially to invest in better hip and knee replacements,” he said. “Eventually, over the last 30 years, we got much better implant technology and improved surgical techniques. With the wrist, it has been significantly delayed because of these other reasonable options that our mentors and founders developed.”

TWA is a technically demanding procedure, according to A. Lee Osterman, MD, professor of hand surgery at Thomas Jefferson University and president of the Philadelphia Hand to Shoulder Center.

“Often the distortion of the small bones means that you cannot use premade jigs with great predictability because the one jig that fits the normal arthritic wrist will not fit one that has been eroded by the arthritis,” Osterman, an Orthopedics Today Editorial Board Member, said.

Robin Kamal, MD, MBA, associate professor in the department of orthopedic surgery at Stanford University, said surgical planning and technique are critical to prevent complications, with surgical planning addressing issues such as how much bone is removed, managing limited bone stock and implant fixation.

“In a similar way, the planning of the cuts for implant positioning, soft tissue balancing of the wrist and/or augmenting the soft tissues are critical to ensure stability of the implant,” Kamal, who has performed about one or two TWA cases a year for the past 7 years, told Orthopedics Today. Appropriate fixation of the distal stem of the implant into the carpus and the metacarpals may also prevent complications, he said.

Even with good surgical planning, sources who spoke with Orthopedics Today said complications may occur.

One complication seen in patients who undergo TWA is dislocation, according to Wagner.

“With prior generation implants, this was a much more relevant risk than the more recent fourth generation implants. Furthermore, if you put the prosthesis in reasonably, not tight, but tight enough that intraoperatively you do not have [dislocation] risk when you are stressing the joint, moving the wrist in extremes of motion during trialing, and perform a robust dorsal capsular repair with retinacular augmentation if needed, you can mitigate [the dislocation] risk to where it is not a primary concern,” Wagner said.

Although uncommon, infection can occur in TWA cases, according to Kamal.

Similar to other arthroplasty procedures, Adams said there is the risk of loosening, which may be related to the technical aspects of the procedure, the patient’s bone quality and how much the patient uses the wrist. He said particle disease is another concern with TWA.

“Osteolysis from particle disease does occur and can cause synovitis and eventual loosening,” Adams, who has been performing TWA since 1996 at about 10 to 15 cases per year, said.

Implant design has sometimes been linked with complications, according to Adams. However, he said the design of total wrist implants has evolved substantially from the first generation and it continues to evolve, with newer designs providing more durable results in active patients.

“Specifically, we are no longer relying on fixation by long stems down into the metacarpals, but, instead, we are fixing within the carpus,” Adams said. “To help promote that fixation, we perform an intercarpal fusion concurrently with the implant. So, the goal is to get as close as we can to a surface replacement within the wrist rather than extending fixation well outside the wrist and, with that, I think the durability improves, the morbidity decreases and if any eventual revision surgery is needed, it is simplified.”

Sources who spoke with Orthopedics Today said a combination of improved surgical technique and design of wrist arthroplasty implants may continue to increase the longevity of TWA procedures.

“Historically, the literature has suggested that by 10 years, somewhere around 50% of patients will have some complication from their TWA. So, [rates have] been relatively high compared to a total hip or total knee,” Kamal said. “The more contemporary literature suggests that complication rate is decreasing as we are becoming better at implanting these replacements and the technology is improving.”

However, there is still room for improvement in future implant designs, with the biggest innovation being better carpal fixation, according to sources.

“There are a couple of ways to do that, but one of the ways that I like is better locking technology to improve distal component fixation, including true locking screws into the distal plate so they have a fixed angled construct between the plate and the screws, improving rotational stability and micromotion. This is similar to the early improvements made to the reverse shoulder arthroplasty baseplate. Furthermore, larger surface area or better posts to optimize ingrowth could continue to improve the difficulties with distal component fixation,” Wagner said. “Locking screw technology combined with a better post technology into the carpus would be huge. It gives us more of a true fixed-angle construct with three fixed points between the plate and the screws/post for that carpal component distal fixation.”

Osterman said one area of research that may translate over to the wrist in the future is osseointegration, which involves fixing the prosthesis directly into the bone.

“If we can do it with applied prostheses, some of those techniques may eventually, without specific commitment to the wrist, suddenly become applied to the wrist,” Osterman, who started performing total wrist arthroplasties in 1995 and performs about 20 cases per year, told Orthopedics Today. “Once that happens and we can maintain that good distal fixation, I think you will see an increasing number of wrists put in.”

Weiss said researchers have had ideas of using dual joints in the implant to allow it to more closely mimic an anatomic wrist, but that will require a big study to receive FDA approval.

“How long will it take for that to turn into an implant is, I think it will be a while still,” he said.

Not only should future research focus on improving the technology for TWA, but also identify which patients would benefit most from a total wrist implant, according to Kamal.

Since TWA is performed to preserve motion, lessen pain and maintain or improve function, Osterman said it is generally reserved for patients with end-stage wrist arthritis, such as osteoarthritis, scapholunate advanced collapse and scaphoid nonunion advanced collapse wrist arthritis.

“We traditionally have used it in rheumatoid arthritis, but given the amazing effects of biologics, less and less do we see patients with severe rheumatoid arthritis who are going to need replacement,” Osterman said.

With improvements in treatments for rheumatoid arthritis, as well as improvements in total wrist implants and outcomes, Wagner said the indications for TWA have begun to expand.

Surgeons are now performing more total wrist arthroplasties among patients with OA and post-traumatic arthritis, Weiss said.

“I used to do 95% wrist fusions for osteoarthritis or post-traumatic arthritis and, today, for severe cases, I am doing 80% to 90% wrist arthroplasty instead of fusion,” he said.

Although surgeons may prefer to perform TWA on a patient’s non-dominant wrist to improve durability, Adams said it may have a greater benefit when performed on the dominant wrist where motion is more appreciated. Patients who are older and have lower physical demand tend to be ideal candidates for TWA so they do not cause too much wear on the implant, he said.

In contrast, young patients who place high activity demands on the wrist may experience early implant loosening, Adams said.

“A manual laborer is probably not indicated, somebody who is involved in routine sports is probably not indicated,” Adams said. “However, I think golf is still allowable if done in moderation, but, for instance, if a patient is an aggressive person who works out in the gym and doing weight-lifting, pushups, pull-ups, they are probably not a good candidate.”

He said patients with severe wrist deformity may be contraindicated for TWA, but surgeons could plan how to manage mild to moderate deformity during surgical planning.

“For example, if there has been previous surgery or a lot of erosion, the overall wrist height may have been reduced, in which case somewhat more resection of the radius will be needed in order to make room for the implant,” Adams said. “We try to avoid excessive or increased resection on the carpal side because that is the side that is most likely to have loosening.”

Kamal said patients with poor bone stock may not be able to maintain implant stability with TWA.

However, Weiss said patients with a history of infection or who lack good muscle control or adequate tendons would not be good candidates.

“The wrist implant is just a static implant, so you need to have good tendons and good muscle control in order to make it function correctly,” Weiss said. “If you do not have that, it would not be a good idea.”

Despite the intricacies associated with TWA, when done correctly, Adams said the vast majority of patients report being satisfied with their wrist replacement, with patients experiencing good pain relief, sufficient motion for activities of daily living, 80% to 85% of normal wrist strength and dexterity that allows for fine motion and other activities.

“Our patient-reported outcomes have always been good. When they have been compared to wrist fusion, quality of life metrics have shown that wrist replacement outperforms wrist fusion,” Adams said.

Before considering performing TWA, surgeons should consider what the patient’s expectations are postoperatively, according to Osterman.

“If someone says, ‘I am going to play golf, doctor. I am retiring so I need that wrist in there,’ that wrist is not going to hold up to 18 holes, 3 days a week. So, you have to consider carefully who you are putting [a wrist in], in the end,” Osterman said.

Patients should be educated on what the different surgical options are, as well as the advantages and disadvantages of each, Wagner said.

“It is important to emphasize that, while we think [total wrist arthroplasty] is a much-improved type of procedure, there traditionally has been a high risk of complications over the long term. Without these studies on the recent generation of implants, it is hard to say what is going to happen to their wrist and how much is going to stand up for the long term, especially in younger or higher demand patients,” he said.

Similarly, Adams said proper training on how to perform a TWA is key for surgeons interested in performing this complex procedure.

“We know that most newer procedures being introduced have certain intricacies, nuances and certainly helping to train [surgeons] to understand those is helpful,” Adams said. “For most surgeons, a cadaver workshop is helpful. By actually performing the procedure, rather than just reading the manual or watching a video, I think a lot can be gained.”

Weiss said surgeons can also visit another surgeon who has good experience in TWA or attend a hands-on course to learn some tricks prior to performing the procedure.

“It is the same with hip replacement and knee replacement and shoulder replacement. Little things that make the surgery a lot easier, that is the stuff you need to know before you feel comfortable,” he said.

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