The desire to replace failing body parts with synthetic ones is part of what makes us human. Teeth were an easy first choice, and dentures made from animal teeth date back to the 7th century BC. It took thousands of years to get to prosthetic limbs and thousands more to get to prosthetic limbs with joints. The first joint replacement surgery was performed around 1900. The first attempt to replace a hip was with carved ivory, then later glass (unfortunately, it broke in the patient), and then, about 100 years ago, steel.
By the 1960s, hip replacement prostheses had developed to the model used today. During the past 20 years, the number of hip replacements performed per year has more than doubled and the average age of the patient undergoing hip replacement continues to decline. There are more than 400,000 hip replacements per year, and the average patient age is 65 years old.
Most hip replacements are needed due to wear and tear, causing arthritis. Women tend to get arthritis more than men and, as a result, they have a higher rate for replacements. The two suspected reasons for the increasing demand for replacements is joint wear down from overuse, or obesity. Our joints just aren’t built to handle extra weight. More than half of the people getting hip replacements are obese.
Joint wear down is also increasing because people remain athletic as adults. This is a healthy pursuit, and one that adults in the past didn’t pursue after their teenage years. The desire for athletes to continue with strenuous activity into their fifties and sixties means that when the hip starts to fail, they’d rather replace it early to get back to exercising, rather than taking it easy until they’re too old to exercise with the same fervor.
At the same time, the recovery has grown easier. People used to spend an average of five days in the hospital after hip replacement. This number has been trickling downward as well thanks to ERAS (Enhanced Recovery After Surgery). The recovery now is more focused on early rehabilitation and less opioid pain medicine. Turns out it’s easier to get patients out of bed when they aren’t sedated.
There’s an option to a total hip replacement—hip resurfacing. This involves putting a metal cap over the head of the femur and a matching metal cup into the socket of the hip where the “thigh bone connects to the hip bone,” which creates a new, smoother surface on both sides of the joint.
Hip resurfacing surgery preserves more bone than a hip replacement, reduces the chance of future dislocation and has a higher chance of preserving femur length. Total hip replacement involves removing the head of the femur, which creates a potential opportunity to replace it with an implant a little too tall or short, thereby changing the length of the patient’s leg. In addition, resurfacing has a faster recovery time than total hip replacement. Ed Jovanovski, an NHL player, and Major League pitcher, Colby Lewis, both returned to playing their sports within a year of having hip resurfacing. (That’s amazing.)
Resurfacing isn’t for everyone. It’s used more often on younger patients and men. The failure rate is higher in women due to anatomical differences in the hip. Also, the outcomes aren’t as good in obese patients, or patients with osteoporosis. During the past decade, there have been serious concerns about the use of metal-on-metal resurfacing implants, their long-term success, and whether the metal ions that get into the surrounding tissue cause any problems. The Food and Drug Administration have removed a number of implant options off their approval list, and resurfacing procedures have waned in recent years.
Medical device companies aren’t deterred and are on the hunt for stable, long lasting alternatives such as ceramics. Currently, there are studies in Europe looking at the success rate of ceramic implants and initial results are good. But until there’s a long lasting, stable and safe implant, it’s hard to recommend resurfacing rather than replacement.
Health economists are concerned about the costs associated with the increase in surgeries since hip replacement is one of the more costly, elective surgeries. But studies don’t always take into account the money saved by keeping someone active, both in terms of overall health and ability to work. And what’s the value of being able to walk, swim, or cycle without pain? Priceless. But like all medical procedures, it’s best to prevent needing them. You can prevent hip problems by maintaining proper weight, stretching and building muscle around the joint. Every 10 pounds of weight above the waist adds about 80 pounds of weight across the hip and knee joints; studies show that people who lose weight reduce their need for hip replacements. Lastly, doing a variety of exercises builds muscle around the joint and the varying motions prevent the wear of repetitive wear. Bike, swim, run—just not on the same day.
Salvatore Iaquinta, M.D., is a head-and-neck surgeon at Kaiser Permanente. He is also the author of The Year They Tried to Kill Me.
