What’s New for Rheumatologists in Hip and Knee Replacement

Hip and knee replacements are increasingly predictable and durable, with a better patient experience and a “declining revision burden,” as demand increases from both an aging population and younger adults experiencing posttraumatic osteoarthritis (OA), orthopedic surgeon William D. Bugbee, MD, said at the Rheumatology Winter Clinical Symposium (RWCS) 2025.

“It’s really changed, so don’t be afraid to refer” patients, from the nonagenarian patient whose OA causes significant quality-of-life issues to the 40-year-old athlete, said Bugbee, head of the Division of Lower Extremity Reconstruction, director of Cartilage Transplant and Joint Preservation, and clinical director of the Shiley Center for Orthopaedic Research and Education at Scripps Clinic in La Jolla, California.

The causes of failure have shifted such that infection and fracture play a greater role than loosening and wear. “Infection is the number one cause…and fracture is a worry, with people in their 80s and 90s who had their joint replacement 20 years ago falling and breaking their hip or knee,” he said. “That’s what’s happening now — it’s not as much loosening of the implant from the bone, not wearing out of the parts.”

In addition to having a relationship with “a skilled and caring orthopedic joint replacement specialist,” rheumatologists can play a role by helping patients to reduce modifiable risk factors associated with increased complications of joint arthroplasty; avoiding opioids in medical management when possible; and working with the orthopedist on implementing 2022 consensus guidelines for perioperative management of antirheumatic medication.

Postoperatively, he said, after orthopedic visits wind down, it’s important to appreciate that while x-rays should be ordered every 5 years, “for a painful [hip or knee replacement], the answer is not usually on the x-ray but in the exam,” Bugbee said, referring to soft tissue problems such as iliopsoas impingement and tendinitis, and hip abductor tendinosis and tears.

Implant Survivorship, Materials Used

Approximately 82% of total knee replacements and 70% of partial knee replacements lasted 25 years, according to pooled registry data published in The Lancet in 2019, and the 25-year pooled survival of hip replacements in another 2019 meta-analysis was 77.6% from case series and 58% from registries.

However, the outlook is better than these data indicate, Bugbee said. Modern knee replacements have improved designs, and for hips, “58% sounds horrible, but [the period of analysis] included the metal-on-metal debacle, with huge failure rates for 5-10 years,” he said. “Now, I’m more confident about a modern hip replacement than I am about a modern knee replacement.”

Partial knee replacements often have shorter lives due to disease progression. “People will get OA on their lateral compartment after having a medial knee replacement,” he said. “That’s the most common scenario [in my experience].”

Bugbee tells his patients undergoing total hip or knee arthroplasty to expect a failure rate of 0.5%-1.0% per year. There are “encouraging data which aren’t necessarily yet reflected” in published registry analyses, he said. “We’ve seen the curve for revision rates slowly lowering.”

Most total hip arthroplasties (THAs) done today involve a 36-mm ceramic head with a highly crosslinked polyethylene liner and a cementless titanium stem and cup with an ingrowth surface. Cement is used only in much older patients and in special cases. “The 36-mm head is slightly larger than what we used to use, so that decreases the dislocation rate…and the crosslinked polyethylene makes it durable,” Bugbee said.

Prior metal-on-metal bearing surfaces were initially thought to have a “fantastic wear pattern” but ended up frequently causing metal ion release into the tissues, trunnionosis, and implant failure. “But we’ve come through this, and ceramic has won the day,” he said. “Almost everyone, whether young or old, will get a ceramic and polyethylene hip in almost every practice in America.”

Measuring cobalt and chromium ion levels in patients with metal-on-metal hip replacements is crucial even in asymptomatic patients because high levels can signal potential issues with the implant and potential soft tissue destruction, he said. (A patient who has lived with such an implant for at least a year “should probably be screened if no test has been done in the previous 2 years,” he added in an interview after the meeting.)

Asked at the meeting about the use of cement in older people undergoing THA, Bugbee explained that while he does not use cement fixation in his practice given the improved design of newer implants, cement “is generally [used in older patients] because their bone morphology changes. They get what we call a ‘stovepipe femur’…and it’s more predictable [for some surgeons] to fill it with cement in order to lower the fracture risk.”

There is increasing interest in cementless fixation during total knee arthroplasty (TKA) as well. Cobalt-chromium and titanium are commonly used for the femoral and tibial components, respectively, and crosslinked polyethylene is used as a tibial liner. “The big improvements [in TKA relate to] conformity and shape…we have high-flexion designs to try to mimic the kinematics of the knee, which are way more complicated than the hip,” he said.

The cobalt-chromium alloys may have small amounts of nickel, so “we always ask patients if they’ve had any problems with jewelry,” he said, noting that data on whether nickel may be responsible for any complications with TKA is “very equivocal.”

Preoperative Management, Impact of Age

“The big thing we’ve gotten better at over the last 5-10 years is preoperative management — optimizing patients for surgery by looking at modifiable risk factors” that can increase the risk for complications after joint arthroplasty, Bugbee said at RWCS 2025.

One study he referenced of almost 7000 joint arthroplasties found that malnutrition, anemia, obesity, diabetes, narcotic use, and smoking were associated with significant increases in intensive care unit admission, emergency department visits, and readmission and that several of these factors were associated with increases in length of stay.

A body mass index (BMI) of > 40 and an A1c over 7% are often considered “lines in the sand,” necessitating medical attention before THA and TKA, he said, noting that risk rises with BMI > 35 and BMI < 20. Staphylococcus aureus colonization, depression, and disease-modifying antirheumatic drugs/biologics are also considered to be risk factors.

Regarding age, in a 2022 study of 58 nonagenarians matched with octogenarians and septuagenarians undergoing THA and TKA at Scripps, Bugbee and his colleagues found a statistically higher rate of medical complications (33% vs 14% and 3%). Rates of orthopedic complications and readmission were higher in nonagenarians but not statistically different from the younger groups. Overall, nonagenarians were 3.1 times more likely to have a complication after joint arthroplasty.

The higher risk is “real and what you’d expect, but what you really want to know is, are people dying? And they’re not,” he said. So “as a result, we’re willing to offer [elective joint arthroplasty] to patients in their 80s and 90s…They don’t need to suffer with mobility issues.”

Trends in Perioperative Management, Pain Control, Recovery

Outpatient joint replacement has become more common — with Medicare having removed TKA and THA from its inpatient-only list in 2018 and 2020, respectively — and accelerated care paths can facilitate ambulation and discharge within 1-2 hours.

“The therapist sees the patient in the recovery room, and that’s because of what we’ve done on the front end with anesthesia techniques and multimodal pain management,” Bugbee said. Some patients are hospitalized overnight — most commonly, much older patients — but discharge to skilled nursing facilities is uncommon and “only for patients who live alone and don’t have resources or help.”

Either light general anesthesia or regional anesthesia is typically used in combination with motor-sparing nerve blocks. Intravenous narcotics are avoided, and opioids are used sparingly. The real “game changer,” however, has been perioperative steroid administration. “The single best thing I’ve done in my practice is give people Decadron [dexamethasone] perioperatively. It makes them feel better and potentiates pain management with no nausea,” he said. “And now we administer a tapered dose after surgery for a few days.”

Use of the antifibrinolytic agent tranexamic acid during THA and TKA is now common, Bugbee noted. “It has essentially eradicated blood transfusions in our patients, except for those with anemia and some chronic diseases,” he said. “The transfusion rate 15 years ago was 25, 50%. Now it’s under 1%. And it’s a wonder drug with its [low] cost.”

Postoperatively, in addition to a short course of steroids, pain management protocols include about a month of cyclooxygenase-2 inhibition, the use of high-dose acetaminophen, and opioids as needed. (Opioid prescriptions are typically limited today to 30 pills of oxycodone for THA and 45 for TKA, and “most of the time people don’t use this much,” he said.)

Other postoperative trends for THA and TKA include a reduction of formalized, therapist-directed physical therapy and an increasing use of online tools and apps for self-administered therapy; discontinuation of hip precautions that restricted certain movements; and the use of peddler/cycle devices for knee rehab.

For THA, he noted, there is a trend toward an anterior surgical approach because surgeons believe it may be associated with less early perioperative pain, improved ambulation, and even a lower risk for dislocation. At the current time, however, studies show no difference in outcome within 3 months with an anterior vs a posterior approach, he said.

Asked about perioperative use of antiresorptive and anabolic osteoporosis medications, Bugbee said that “in the world of hip and knee implants, even with bone ingrowth implants, we don’t care too much [about adjusting regimens]. With cementless joints, we tell people not to take the dose just before [surgery], but that’s all.”

Patients are told to stop nonsteroidal anti-inflammatory drugs a week before hip or knee arthroplasty, he said. For perioperative use of traditional disease-modifying antirheumatic drugs, biologic agents, and other medications used for adults with inflammatory arthritis and lupus, Bugbee advised following protocols in the 2022 American College of Rheumatology/American Association of Hip and Knee Surgeons guideline for use of these medications in THA and TKA.

Concerns and Pitfalls

According to the 2024 report of the American Academy of Orthopaedic Surgeons Joint Replacement Registry, the top diagnosis associated with both hip and knee revisions from 2012 to 2023 was “infection and inflammatory reaction,” reported in 21% of hip revisions and 33% of knee revisions.

At RWCS 2025, Bugbee said the occurrence of infection is disconcerting. “I’ve seen enough studies in which fragments of [microbial] DNA and RNA are found inside normal joints, which is scary because we’re putting implants there,” he said. A “next wave of research is asking, does this matter [and what can be done about it]?”

He referred to a literature review published last year, concluding that evidence supports the role of the gut microbiota in the development of complications such as aseptic loosening and periprosthetic joint infection after THA and TKA. In the past decade, researchers have described a “gut-bone axis” as a mediator in bone health and have called for more research on the potential use of microbial therapies to lessen the rate of infection-caused revisions.

Total hip replacements are still plagued by soft tissue complications such as trochanteric abductor dysfunction, iliopsoas impingement, and tendinitis/bursitis. “With the latter, [at least] 5% of patients will come back with groin pain. It’s impingement, or underlying synovitis in the iliopsoas bursa that was present [prior to THA] but masked by the hip arthritis,” he said. Treatments include injection, tendon release, and revision for an anterior “overhanging” cup component.

Abductor tendon lesions are an even larger problem. “You know [trochanteric abductor dysfunction] as trochanteric bursitis…but I know it as tendinosis and gluteus medius or minimus tears,” Bugbee said. An estimated “4%-28% of people who undergo a hip replacement have abductor tendon pathology — tendinosis or frank tears.”

Gluteus tendinopathy is a major cause of persistent peritrochanteric pain and limp before and after hip replacement, and it is not readily identifiable on plain hip x-rays. “The problem is, we don’t use advanced imaging to do THA…and now most of us are using an anterior approach, and we don’t see it,” he said.

Detection, he said, requires a careful physical exam with a side-lying abduction test and palpation to differentiate pain from the bursa vs tendinosis and tears.

“Hip replacement leads to such improvements in patients’ well-being that we tend to ignore minor residual pain that patients may report,” Bugbee said after the meeting. “I think the first step is to ask specifically about trochanteric or groin pain. If it’s more than minor, then one should look for these soft tissue issues. Ultrasound is a useful diagnostic tool in this [context].”

Bugbee disclosed receiving royalties from Smith & Nephew, Enovis, and OrthAlign, Inc.; holding stock or stock options with OrthAlign, Inc., Icarus Medical, Overture Orthopaedics, and Restoration Biologics; and performing consultancy work with JRF Ortho, Arthrex, and Moximed.