BY LINDA HARDER | PHOTOGRAPHY BY TRACEY BROWN
Living longer has its advantages. But our lower extremity joints weren’t necessarily built to withstand all of the stresses placed on them. Our orthopedic experts discuss the latest in repairing these critical joints when they suffer lifelong damage.
With baby boomers increasingly seeking hip and knee replacements at a younger age, and with longer-lasting component materials, getting a good ‘fit’ is increasingly critical. Hip replacements are now expected to last for 20 years or more, both fueling and responding to this trend. Robot-assisted total hip arthroplasty (THA) is a newer option to increase the precision in component orientation, now available in Maryland.
William Cook, MD, chair of orthopedics at The University of Maryland Upper Chesapeake Health System, is among the first to employ MAKOplasty® for THA in Maryland. “MAKOplasty is a CT-guided navigation system that gives us a new level of accuracy,” he states. “It uses a software program based on a 3D model of the area that enables us to plan our surgery based on the patient’s unique anatomy. We optimally position our implants ahead of time based on the computer model. Then, when we’re performing the procedure, the robot prevents changes and minimizes bone resection.”
Since the hospital system purchased the MAKOplasty component for hips in the fall of 2013, Dr. Cook and his colleagues have performed approximately 20 procedures with robotic assistance. “The exciting thing about MAKOplasty for hips is that it can precisely align the acetabular cup in the correct inclination and the correct version, to create the most stable hip possible. We can precisely duplicate the anatomy, leading to a lower risk of dislocation and reduced leg length discrepancy. One of the main reasons for patient dissatisfaction following hip replacement is leg length discrepancy.”
He adds, “We can duplicate a patient’s hip offset, which is the distance between the socket and the leg. If the soft tissue is aligned properly, it restores the muscle tension and decreases pain and recovery time.“
A good candidate for MAKOplasty is someone who is not overly obese or muscular and has bone that is not excessively osteoporotic. Dr. Cook explains, “I currently reserve this procedure for very active patients, such as someone who is jogging or playing tennis. The difference is less critical for older, less active patients.”
After the patient decides to have MAKOplasty, he or she typically undergoes a 3D CT scan one to two weeks in advance of the procedure. The data from the scan is fed into the computer program, then the surgeon selects the appropriate sized implant and the amount of bone to be removed. Patients typically have a one-night stay in the hospital, and then are discharged to home with full weight bearing.
Depending on the patient, they may receive home or outpatient physical therapy. “Pain scores are consistently lower,” says Dr. Cook. “Most patients can recover in four to six weeks instead of three months with the robotic approach.”
Dr. Cook performs the majority of THAs using an anterior approach, which he has employed on appropriate candidates for the past 10 years (see Maryland Physician July/August 2012, “Joint Tune Ups” for more on anterior hip replacements). “An anterior approach prevents having to detach and reattach muscles, which can lead to atrophy and/or a limp,” he notes. “A posterior approach has a higher dislocation rate, and a lateral approach requires muscle detachment. However, due to the positioning of the leg in the anterior approach, it’s not appropriate for everyone, such as those with significant osteoporotic bone, which can fracture, or obese patients.”
Rethink Pain Management
Dr. Cook has seen a growing trend among referring physicians to send patients who fail physical therapy and anti-inflammatories for pain management. “There is a tendency to send patients for narcotics rather than referring them to an orthopedic surgeon. In my opinion, that’s not the ideal management of these patients. While you don’t want a patient to undergo surgery unnecessarily, physicians may not be recognizing that many of these patients have issues that won’t be satisfactorily addressed by narcotics. The infection risk in THA is less than 1% nationally, and the satisfaction rate is greater than 95%.”
Dr. Cook comments, “In the 70s and 80s, the mindset was to have patients wait until they were in their 60s or 70s to get a THA. That started to change in the early 2000s. My philosophy is that we can offer these procedures to younger patients now because we can expect one implant to last up to 30 years. The more precisely it mimics the patient’s anatomy, the better the outcome and longevity. One of the reasons I love being a joint surgeon is that you give people back their lives.”
Is Cementless Knee Arthroplasty Superior?
The increase over the years in the number of hip replacements is linear, but knee replacements are increasing exponentially, according to Antoni Goral, MD, medical director of the Joint Center at Holy Cross Hospital. “We’re doing about 800,000 knee replacements today, but by 2030, we expect that to grow to 3.5 million. Why? In part because we’ve been doing knee arthroscopy since the 1980s for meniscal tears and other problems, and people go back to high levels of activities. We relieved people’s symptoms, but were we setting many of them up for developing arthritis over time? For young and active patients, wear and loosening contribute to the need for revision surgery of a prior knee replacement.”
If knees were simple hinge joints, it might be easier to repair or replace them. But because they involve both rollback and pivoting, they are complex to treat. As with hips, more people are choosing to have a knee replacement while younger and more active. That also makes it crucial for knee surgeons to carefully assess and recommend the optimal approach.
Dr. Goral explains, “Most of the load on a hip joint is compressive, but with knees, many of the loads are shear. The goal of knee arthroplasty is to restore the normal kinematics of the knee.”
Evaluation and Non-Surgical Approaches
“Some physicians still focus on using anti-inflammatories even when there’s no inflammation,” complains Dr. Goral. “Analgesics, such as acetaminophen around the clock, are better in these cases. Some studies suggest that chondroitin and glucosamine supplements are protective of cartilage, but the American Academy of Orthopaedic Surgeons has graded this approach a “C,” meaning that the evidence can’t presently support that claim.”
He adds, “If there are flare-ups, injecting cortisone or a biological lubricant such as hyaluronics into the joint may help. Injectable medications, unlike pills, have to get into the joint. I tell people that you can’t put oil on the hood of a car, you have to put it in the engine.”
History of Cementless
Cementless knee arthroplasty has been available since the 1980s, when loosening of a knee replacement over time was believed to be due to ‘cement disease’ – a reaction to the cement used to adhere the replacement. During surgery, the bone is slightly compacted, contributing to the problem.
“Today, we believe that a combination of motion and minute particles that wear away lead to inflammation and enzymes that trigger osteoclasts. The osteoclasts then gradually eat away the bone,” says Dr. Goral. “There are sharp changes in loading going from bone to implant, so manufacturers have tried to design an ‘ingrowth’ approach using more porous implant surfaces into which bone could grow. In the 1980s, the implants would have layers of tiny beads or a mesh to address this, but we found that they separated and left too much space over time.
“While the vast majority of knee replacements today are still cemented, we’ve tried various cementless approaches over the years. Today, one approach uses a powdery plasma spray that increases osteo integration. However, with a cementless approach, you need to provide additional stabilization of the implant during early recovery.”
To provide the necessary stabilization after a cementless approach, there are three options for fixing the tibial side – pegs, screws or stems. Dr. Goral comments, “There are advocates for each approach, though I personally prefer stems. All three hold the implant firmly for the three to four months that the bone is potentially growing up to, and into the surface.”
According to Dr. Goral, cementless and cemented knee arthroplasties have roughly the same results. “Most studies of implant longevity and patient satisfaction have found that the restoration of a neutral knee alignment is most important, not the implant technology,” he notes. “Better, more customized instrumentation and robotic guidance improve outcomes. The ideal outcome is a ‘forgotten’ joint, one that has no clicks or pain and that feels stable enough that the patient forgets it is there.”
On the Horizon
In the future, Dr. Goral believes that platelet-rich plasma, which contains growth factors, may be used to promote healing. “It’s safe, but we’re not sure yet if it’s effective. Autologous, adipose-derived stem cells may also hold promise, though there’s insufficient evidence as of now, so it’s not reimbursed by insurers.”
Healing Complex Ankle Fractures
Knees and hips get much of the attention in orthopaedics, but a strong, properly fixated ankle is critical to staying mobile. According to Stuart Miller, MD, MedStar Orthopaedics foot and ankle surgeon, “When you go up a set of stairs, you’re putting five times your body weight on your ankle. And ankle fractures, surprisingly, are one of the most common fractures, occurring across all age groups.”
Fortunately, a growth in dedicated foot and ankle specialists, better technology, and more flexible stabilization devices are revolutionizing care of this key joint.
Growth in Foot and Ankle Specialists
“There’s been an explosion in foot and ankle specialists recently,” Dr. Miller claims. “Some 10 years ago, there were six in the greater Baltimore area; today, there are 12 specialists, and two more are coming soon. When a fellowship-trained specialist performs a foot or ankle procedure, it may be more precise because it’s all we do.”
Dr. Miller says, “I perform many total ankle joint replacements today. More than 80% of these patients have trauma-caused arthritis. One journal recently reported that it can take 21 years from an ankle fracture to the development of arthritis. It’s why we’re seeing so much of it now. Over the years, we’ve learned that even a small amount of displacement creates a big problem over time.”
Anatomic Locking Fibular Plates
A substantial improvement in ankle fracture stabilization is the number of new anatomically locking fibular plates that are available. Designed to fit on the lateral aspect of the distal fibula, these devices maximize bone fracture stabilization and minimize soft tissue irritation.
“They are pre-contoured to fit the patient’s anatomy, and use locking screws that function somewhat like a molly bolt, to work far better in comminuted osteoporotic fractures,” explains Dr. Miller.
Fixation of Syndesmosis & Fracture Suture “Buttons” Offer Advantages Over Screws
Newer approaches to stabilizing the ligaments and bones following a complex ankle fracture have eliminated the need to use screws, which are removed in a follow-up procedure. These approaches instead use a tiny incision to insert a suture between two ‘buttons.’
“We drill across the tibia and fibula, insert a tiny oblong rod or ‘button’ that’s analogous to a rice kernel in shape,” Dr. Miller states. “We pull/twist it so that it can’t go back through the hole. Today, we’re also using this method to fix ankle syndesmotic injury and gain stability. Biomet Sports Medicine offers a ZipTight™ Fixation System and Arthrex offers a Knotless TightRope® System for syndesmosis repair. They are low-profile and knotless, to prevent soft-tissue irritation and allow more precise duplication of joint mechanics during movement.”
From Casts to ROM Splints
Newer approaches to immobilizing ankles after a fracture are putting cast technicians out of business. “We got rid of our cast tech at Union Memorial Hospital years ago,” Dr. Miller notes. “Our patients go into a splint after surgery and then to a Range of Motion (ROM) ‘boot’ at one week. We use it like a cast for the first four to six weeks post-op, then start gradually introducing weight bearing. This approach promotes faster and better rehabilitation, the skin is healthier, and patients can take the boot off to do gentle ROM and to bathe. If the fracture is stable, patients may even be able to take the boot off at night.”
The ROM boots can be non-inflated (appropriate for minor injuries), pre-inflated, or have an adjustable bladder that allows the ankle to be fixed at a given point or permits range of movement within a set angle. Dr. Miller concludes, “With the elimination of casting, patients no longer have to spend months getting back range of motion, and they are much happier.”
William Cook, MD, chair of orthopaedics at The University of Maryland Upper Chesapeake Health System
Antoni Goral, MD, medical director of the Joint Center at Holy Cross Hospital
Stuart Miller, MD, MedStar Orthopaedics foot and ankle surgeon