Symposium explores trends and treatment options
Knee arthritis is catching up to the youngest baby boomers—those in their 40s and 50s, said John J. Callaghan, MD, moderator of the 2008 AAOS Annual Meeting symposium Choices and Compromises for the Treatment of Knee Arthritis in the Baby Boomer. Aging boomers and an escalating obesity rate mean that orthopaedists should expect to treat record numbers of patients for this debilitating condition.
“Data suggest that the prevalence of arthritis increases with age and that people with higher body mass indexes (BMIs) have a greater chance of developing arthritis in the knee,” he explained. “A significant portion of people in the 50- to 70-year-old baby boomer range have BMIs that are greater than 30, which is outside the healthy range. Evidence shows that around 20 percent of those people will develop knee arthritis.”
The demand for TKA
A recent study projected a 673 percent increase in the demand for primary TKA by 2030—a figure that translates to 3.48 million procedures. According to Dr. Callaghan, the number of TKAs being performed will skyrocket because this surgical procedure often provides the best relief for patients with knee arthritis.
“Although TKA is considered the end-stage procedure for the arthritic knee,” he said, “most would also consider it the most predictable option.” He cautioned, however, that although TKA is often the best option for treating knee arthritis, results in younger boomers may be poorer than expected.
“We always think that the patients in this age group are going to do extremely well and will not have any range of motion problems,” said Dr. Callaghan. But an analysis of his own patients and a recent study of TKA patients found poorer results than expected. The study, which evaluated 32 TKAs performed on patients younger than age 40 with a 5-year minimum follow-up, found an average flexion of 110 degrees. In addition, four revision surgeries were required to address component loosening.
According to Dr. Callaghan, this high rate of loosening correlates to problems caused by polyethylene sterilized by the gamma-irradiated in air technique. That technique has been replaced by gamma sterilization without oxygen. Problems associated with the outdated implant sterilization method are particularly significant for some of his youngest TKA patients.
“Unfortunately, many young boomers—those who were younger than age 40 at the time of surgery—had knee replacements using polyethylene that was gamma-irradiated in air,” he said. “Our biggest concerns with these patients will be wear and osteolysis (Fig. 1).”
Treating tibial-femoral arthritis
Panelist Annunziato Amendola, MD, focused on nonsurgical treatments for tibial-femoral arthritis that improve the function of the muscular soft-tissue envelope. These treatments optimize the joint/soft-tissue balance by improving muscular strength, endurance, joint flexibility, and range of motion.
“Soft-tissue work is important, regardless of the amount of arthrosis,” said Dr. Amendola. “Medication or injections can be used to decrease pain for a few weeks or months to enable these patients to perform muscular exercises to get their joint functional. Viscosupplementation is also of some value; I use it to achieve a short-term effect until the mechanics of the joint are back to normal.”
Dr. Amendola said that orthopaedists should approach surgical options for baby boomers with caution because patients in this age group often have high expectations.
“The goal of the surgery will affect your decision,” he noted. “To decrease pain and improve function during daily activities, you may opt for surgery that’s not as aggressive. However, restoring the joint so the patient can return to a more strenuous activity requires a more aggressive approach.”
Whether the patient has arthritis, instability, articular cartilage degeneration, or meniscal deficiency, said Dr. Amendola, orthopaedists need to consider the mechanical alignment before choosing a surgical procedure. “If you don’t correct the mechanical alignment,” he concluded, “then other surgery is not going to work in the long-term.”
Surgical treatment options in younger patients include allograft resurfacing, arthroscopic débridement, marrow stimulation, autologous chondrocyte transplantation (ACT), and tibial osteotomy. Allograft resurfacing is performed more commonly in patients with larger lesions and bone loss, said Dr. Amendola, while ACT is useful in patients with more diffuse involvement and no bone loss.
“Performing a tibial realignment osteotomy in patients with primary osteoarthritis of the knee is controversial; it requires careful evaluation and planning,” said Dr. Amendola. “For these reasons, unicompartmental arthroplasty and TKA are common in this population.”
Treating patella-femoral arthritis
Many patients with patella-femoral arthritis are best served through pain management and bracing, rather than surgical treatment, said panelist Jean-Noel A. Argenson, MD.
“Physical therapy should focus on releasing the lateral structures and strengthening the vastus medialis; water exercises are helpful,” he said.
According to Dr. Argenson, if nonsurgical treatment fails, several surgical options are available.
“Arthroscopy to release the lateral retinacular structure is one option,” he said.
“Arthroscopy is also useful for cartilage débridement of the joint and is particularly indicated when a lateral tilt is detected on radiographs and computed tomography scans.”
Osteotomy of the tibial tubercle is indicated if the disease is limited to the lateral patellar facet, even if there is advanced osteoarthritis. According to Dr. Argenson, roughly two-thirds of patients describe improvement after this procedure.
Recently, autologous cartilage resurfacing has been suggested for arthritis specific to the patella-femoral joint. Removing the patella is a procedure that is rarely used nowadays, said Dr. Argenson, because “the consequence is roughly a 25 percent decrease in the force of the extensor mechanism, which can be an important issue.”
According to Dr. Argenson, when the disease is limited to the lateral facet and the extensor mechanism has the correct alignment, lateral patelloplasty “can be an interesting alternative to the complete patellectomy.”
“Of course,” he continued, “isolated patella-femoral arthritis can be treated by TKA; however there is also a place for patellofemoral arthroplasty (PFA). Osteoarthritis following instability with a correct alignment of the extensor mechanism is probably the best indication for PFA. Posttraumatic cases and primary osteoarthritis are also indications when the disease is limited to the patellofemoral joint and there is a lack of important femorotibial deformity.”
By the time an orthopaedist considers unicompartmental knee arthroplasty (UKA), acknowledged panelist Adolph V. Lombardi, Jr., MD, he or she may also be considering TKA. So why opt for UKA? Dr. Lombardi noted that this surgical procedure retains the cruciate mechanism. Most studies, he continued, find better range of motion and function, with pain relief equivalent to TKA; additionally, patients say the knee feels more normal.
“Another reason to consider UKA is that it can be performed using a minimally invasive approach. When you don’t violate the superpatellar pouch, patients don’t need a lot of postoperative physical therapy,” he said.
Indications for UKA include loss of cartilage, arthritis confined to a single compartment, and a lack of significant degenerative changes in other compartments. In addition, both cruciate ligaments should be intact.
The need for further study
All of the presenters agreed that additional studies on treatments for knee arthritis in younger patients are needed.
“Patients younger than age 55 require close study to determine whether certain design features and materials provide more durable results than others,” said Dr. Callaghan.
“We definitely need further studies to decide what’s best for this group of patients,” agreed Dr. Amendola. “Most importantly, orthopaedists need to individualize treatment based on the patient and the amount of disease. The better the knee is when the orthopaedist first treats the patient, the better the outcome will be.”
Disclosure information on the panelists can be found at www.aaos.org/disclosure
Jennie McKee is a staff writer for AAOS Now. She can be reached at email@example.com
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