Patients with a lower limb amputation are at an increased risk for secondary physical complications, such as osteoarthritis, osteoporosis and low back pain. Without proper care, these secondary physical conditions can cause long term problems, including bone fractures and hip and knee replacements.
“I think an amputation is a new beginning for some people and every effort should be maintained to make it a new beginning,” Joseph Lane, MD, attending orthopedic surgeon at the Hospital for Special Surgery, New York, N.Y., told O&P Business News. “There is a window of time and surgeons and physicians need to work with that. They have to make a good prosthesis and a good fit and if the stump is not correct they have to fix the stump because everything else will disintegrate if the patient will not use a prosthesis or they get disuse osteoporosis. If the patient is having problems, then the problems have to be addressed as best as possible.”
Low back pain
While low back pain is common among able-bodied patients, studies have shown low back pain is more persistent and bothersome among lower limb amputees, which can affect performance of everyday activities.
“Low back pain becomes an even greater concern for amputees because, unlike arthritis and osteoporosis which are slow and take a couple of decades to occur in many cases, this rears its ugly head within a couple of years and makes it difficult to work or to participate in everyday activities,” Robert Gailey, PhD, PT, of the Department of Physical Therapy at the University of Miami Miller School of Medicine and the Functional Outcomes Research and Evaluation Center at the Miami Department of Veterans Affairs Healthcare System, told O&P Business News.
Proper prosthetic alignment and fit play a role in the severity of an amputee’s back pain, so patients should make regular visits to their prosthetist to help maintain their device.
“From a prosthetics standpoint, it is important that amputees visit their prosthetist on a regular basis to make sure the prosthesis is fitting properly and is properly aligned. Often, patients treat their prosthesis like their car, they only go in when it is broken and doesn’t get them where they want to go. Often, when a prosthetist chooses the appropriate components with a well-fitting socket and alignment back pain due to prosthetic fit or posture may be reduced or eliminated,” Gailey said. “Often patients think back pain is something they have to live with, but if they maintain regular appointments with their prosthetist or physical therapist, any changes that occur in their body weight, posture or gait deviations could be identified with the proper treatment prescribed to alleviate some of those back pain problems.”
Even with a properly aligned prosthesis, it is important for amputees to keep stress off the spine by staying active and maintaining a healthy body weight. Proper posture is also essential to reduce stress. Usually, amputees will put more weight on their sound limb to avoid weight-bearing within the prosthesis, the pelvis must compensate putting additional stresses on the spine and increasing lordosis.
“Because people with limb loss are have a higher risk of back pain, staying fit, maintaining body weight and being aware their posture can help reduce the onset of back pain, which is almost inevitable,” Gailey said.
When patients underuse their leg after amputation they can develop regional osteoporosis, which will cause the bone to fracture in the event of a fall. Among long-term prosthetic users, 80% to 90% have a 30% reduction in bone density in the amputated side hip.
“Bone maintains density by having forces or stresses placed upon it,” Gailey said. “Prosthetic socket designs today place most of the weight bearing capacity on the soft tissue and there is no axial loading. Therefore with the absence of axial loading, the bone begins to lose density over time.”
Although all lower limb amputees are at an increased risk for osteoporosis in general, gender can also play a role in whether a patient develops osteoporosis or not.
“There is published evidence to suggest that while male amputees generally have healthy bone mineral density values in their spine and a sound side limb, women present with osteopenic bone mineral density values in their spine and sound side limb,” Philip M. Stevens, MEd, CPO, FAAOP, Hanger Prosthetics and Orthotics Inc., Salt Lake City, Utah, said. “Given their generally lowered bone mineral density values, it is not too surprising to note that the density values on the amputated extremities are lower among women than that observed among men. For men, the numbers are generally at osteopenic levels. For women, they are at osteoporotic values.”
Osteoporosis can be prevented and treated, but may be missed in the amputated leg during diagnosis because, according to Lane, while bone mineral density may be measured in the hip and spine, it is often not measured in the amputated leg. Although exercise may cause a fracture in patients who already have osteoporosis, it also can help strengthen the bone and prevent osteoporosis from being a problem in the first place.
“Some literature suggests more active patients who wear their prostheses and exercise tend to have relatively higher bone mineral density values,” Stevens said. “By contrast, decreased activity levels or prolonged disuse atrophy post amputation have both been tied to lowered bone mineral density.”
Besides exercise, patients can treat osteoporosis through osteoporotic agents, such as pro-calcium D, bisphosphonates or bone building agents.
Although there is no clear study that can identify the exact cause of osteoarthritis in amputees, it is generally understood that it is caused by increased wear and stress applied to the contralateral limb, whether when walking, standing or rising from a chair.
“Patients don’t rise up out of the chair with symmetry using their prosthetic leg equally to their sound limb, so as they rise out of the chair they shift more weight to the sound limb,” Gailey said. “If somebody breaks a leg and they do it for a couple of months while they are healing, it is probably not going to have a long-term effect. However, if a patient loses their limb in their early 20s or 30s and they do it over a lifetime it is going to have an impact.”
Amputees will shift the majority of their body weight over to their sound limb when standing, adding more stress of abnormal posture to the limb. Most amputees also put more weight onto the sound limb during walking.
“In terms of arthritis, it is maintaining good alignment of the joint. If a patient is wearing a poorly designed prosthesis that is unbalanced and not lined up, then they will wear out the joint. So it is important to get the alignment of the prosthesis in a weight bearing mode and make it correct,” Lane said. “However, no matter how good a prosthesis is, many amputees clearly favor the contralateral leg. Arthritis in the contralateral leg can occur, the amputee can wear out the leg and I have seen amputees end up with knee replacement or hip replacements in the contralateral leg because, as their good leg, they overuse it.”
Total joint replacement
Many individuals with arthritis in a lower limb joint undergo total joint replacement to help relieve the pain.
“Joint replacement surgery is still the gold standard for relieving pain in arthritic joints,” Geoffrey H. Westrich, MD, associate attending orthopedic surgeon at the Hospital for Special Surgery, said. “It works exceedingly well in patients with and without amputation by relieving their pain and restoring their function and quality of life.”
Total joint replacement of the hip or knee is rarely performed on amputees, but the complicated process can be done.
“Surgeons are used to doing joint replacements on patients with a leg without an amputation and from a technical perspective it can be a much harder operation. If a patient does not have the lower part of their limb and you are trying to do a joint replacement, there are all sorts of different issues,” Westrich said. “For example, for hip replacement, we need to dislocate the hip and the way we do that is we release the external rotator tendons, we release the capsule, and then we twist the leg. But if the patient has an amputation, it is hard to do that. There is nothing to grab onto or hold onto.” “Sometimes we need to insert a traction pin in the bone to assist with dislocating the hip.” “Similarly, with total knee replacement in patients with a previous amputation, the lack of bone below the knee makes the surgery challenging. Again, sometimes a traction pin needs to be inserted in the bone to assist with separating the bones and maneuvering the knee properly.”
Before surgery it is important to get a sense of how the patient is doing physically and help them set reasonable expectations post-surgery. Coordinating with a physical therapist that specializes in dealing with amputees after the surgery is also important because amputees need to be well versed on donning and doffing the prosthesis, as well as precautions they should take to protect the hip from fracture or dislocation.
Despite the complexities of performing total joint replacement on amputees, if the procedure is done properly the patient can expect a full recovery.
“As long as [the total joint replacement] is done properly, amputees can do really well,” Westrich said. “[The procedure] is best done in a major joint replacement center by a fellowship trained joint replacement surgeon and most preferably by surgeons who have operated on patients who have had amputations before. The last thing you want when you are in that situation and already potentially compromised because of the amputation, is to have someone who tries to do a joint replacement and runs into trouble because they have not been down that road before.”
Reducing the risk of injury
Besides exercising, maintaining a healthy body weight and keeping the prostheses properly aligned, amputees can take additional steps to help reduce the risk of secondary physical complications.
Microprocessor prosthetic devices, or motorized knees, can assist the amputee in standing, sitting and walking. They help decrease the reliance on the limb when patients stand up from a chair or walk up and down stairs, which lessens stress on the joints and may reduce the risk of injury.
“We hope that patients who need help will use more sophisticated prosthetic devices that will assist them to get out of a chair by reducing the amount of effort on the contralateral limb,” Gailey said. “What we are looking at currently is methods to increase lower limb symmetry of work during daily activities, whether it is rising up from a chair, level walking or using the stairs, so people will reduce the reliance on the sound limb and utilize the prosthesis which could in return reduce or delay arthritic changes to the knee.”
Gailey outlined several ways a person using a prosthesis could avoid complications and reduce the risk of injury. First, amputees should make sure their prosthesis fits at all times. The prosthesis and sound limb should also be equal in height, and they should avoid having their prosthesis shortened.
People with limb loss should walk with an equal width of walking base, stand with equal weight distributed between the limbs and maintain good posture whether sitting or standing. It is important for amputees to avoid favoring their sound leg. People with limb loss should also avoid hopping excessively on their sound limb when not wearing a prosthesis. Crutches should be used around the house when they are not wearing their prosthesis. If pain is present, use of a cane during walking can help reduce excessive stress to the knee or back.
Most importantly, amputees should keep a regular schedule with their physician, prosthetist and physical therapist who will be able to detect and treat any minor problems early before they become severe or complex secondary physical conditions that require more aggressive treatments.
“The key element is raising expectations for patients. If you give them a poor fitting prosthesis and it doesn’t fit well, they have low expectations. But if they have high expectations, patients will walk much better,” Lane said. “They also need to have a role model at the rehabilitation center they go to. The center should have good walkers who can work with these patients and help them with this process.” — by Casey Tingle
Disclosures: Gailey, Lane, Stevens and Westrich have no relevant financial disclosures.