Helping amputee patients return to optimal gait patterns.

How many times have we heard it? We ask a recent amputee what his goals are, and he responds, "I just hope I can walk." In times past, it may have been a lofty goal to train a geriatric amputee with diabetes and heart disease to walk around the house on a solid ankle, cushioned heel (SACH) foot with a safety knee. However, with advances in prosthetic technology and aggressive rehabilitation protocols developed to return service members with complex battle-related amputations to duty, today’s PTs are challenged to aim higher.

"Civilians get crappy legs, but ours [are] going to be top of the line." — A wounded soldier with a transfemoral amputation.

While high-tech prosthetic components—computerized knees, energy-return feet, and shock-absorbing pylons—are readily available for our service men and women returning from combat, procuring such equipment for the typical amputee in the civilian world can be a big hurdle. Medicare guidelines¹, followed by many private payors, require that each patient be categorized according to his potential functional level (see K-Levels sidebar on page 20). The componentry allowed is directly related to the "K Level."² For example, a person categorized as K2 is authorized to get a multi-axis foot and polycentric knee, while a K3 can get equipment equivalent to that used by a soldier. The objective is not to get every patient the fanciest equipment on the market, but rather to give each patient as many options as possible to meet his or her personal goals.

Goal-setting is a learning process for the patient, who may not know what expectations are realistic. Exposing new amputees to amputees farther along in the rehabilitation process—through peer support, amputee support groups, prosthetic clinics, or simply by scheduling them to attend therapy at the same time—can help new amputees envision the possibilities.

For several reasons, many amputees are undertrained to use today’s prosthetics. Many of those reasons have to do with the level of training the therapist has in working with prosthetics. College coursework is geared toward the immediate, postoperative period and early prosthetic training with limited prosthetic-specific material.

For therapists who attended school when there were three prosthetic feet on the market, our training is outdated. There is a paucity of high-quality continuing-education programming at the intermediate and advanced level to bring us up to speed. Also, many clinicians work in settings with too few amputee patients to allow them to develop expertise. Both limited training and limited experience will lead therapists to set low expectations and undertrain the client.

"Before everything else, getting ready is the secret of success." — Henry Ford

Flexibility, strength, and aerobic conditioning remain the core of a preprosthetic program. Even small range-of-motion limitations can have a large impact on the gait pattern, or the ability to use a prosthesis at all. At our facility, we teach patients that it is easier to keep the flexibility than it is to get it back.

Controlling a prosthesis also requires a great deal of strength in the legs and the trunk. We see many amputees who are weeks to months postoperative still doing the basic mat exercises they learned in the first few days after surgery. The exercise program must be advanced beyond straight leg raises and glute sets if the patient is to achieve success with the prosthesis.

Core strengthening and stabilization is the foundation for all other strength training. In addition to traditional abdominal crunches, our clients are instructed in ball exercises (such as prone push-ups, reverse flyes, supermans, alternating hip extensions, and supine bridges with alternating leg lifts) and stabilization exercises. Early emphasis in this area may help prevent episodes of low back pain that plague many amputees.³

Aerobic conditioning should begin soon after surgery to prepare the patient for the increased energy demands associated with using a prosthesis.⁴ It is also helpful for preventing the weight gain that frequently follows amputation and may affect prosthetic fit. We teach patients who take blood pressure medications that may dampen heart-rate response to exercise and monitor their exercise intensity using the Rate of Perceived Exertion scale.⁵ Combined upper- and lower-extremity ergometry has been shown to be effective in the amputee population.⁶ We also use the recumbent stepper (modified with the seat adjustment unlocked), upper-body ergometer, and stationary and recumbent cycles.

Once the client has received the prosthesis, gait training can also provide an effective aerobic workout. The entire exercise session may take 1 1/2 hours. In our experience, adherence to the exercise program can be a good indicator of which patients will do the hard work necessary to become proficient with a prosthesis. Those who cannot, or will not, do a challenging exercise program will not likely be assigned a K rating above 2, as their potential to walk at the community level is questionable.

Another area that strongly impacts walking potential is poor balance, or fear of falling.⁷ Even if a patient has the skills to maintain his balance, fear of falling can lead to inactivity and limited use of the prosthesis. A comprehensive fall-prevention program can begin soon after surgery and progress through functional balance training with the prosthesis. Activities to enhance muscle recruitment within the prosthetic socket, such as multi-angle isometrics, improve both prosthetic control and balance. The Amputee Mobility Predictor⁸ is an easily administered test that can identify functional balance deficits that negatively impact prosthetic success.

Lack of sensation, especially vibration, plays a role in balance problems.⁹ Prosthetic legs capable of transmitting sensation are in the developmental stages and are not readily available, even to military personnel. In the clinic, an amputee can be trained to "feel" his prosthetic foot. With practice, an amputee can tell the difference between vibration on the outer border versus the inner border of the foot, or between the heel and the big toe. This sensation can be expanded to include differentiation of pressure on varied aspects of the prosthetic foot. Not only does this type of training help with balance and gait training, but it also helps some amputees make a mental transition from "the prosthesis is a tool" to "the prosthesis is part of my body."

"I figure the faster I pedal, the faster I can retire." — Lance Armstrong

Exercises for flexibility, strengthening, aerobic conditioning, and balance are all done in preparation for gait training. For most unilateral vascular amputees, the long-term goals will be geared toward community ambulation with a unilateral assistive device, and they may take up to 6 months to achieve. Gait analysis and treatment strategies are in many ways similar to training patients with hemiplegia, the distal leg being desensate with impaired motor control. Where the hemiplegic patient is taught weight-bearing on the involved leg, the amputee is taught prosthetic trust. Both patients must be trained to step past the involved leg—for the hemiplegic patient, this is to initiate smooth, effortless swing, and for the amputee patient, this is to activate the prosthetic knee and/or flex the energy-storage foot. For this reason, a standard walker is not generally appropriate for an amputee, as it interferes with the forward progression necessary to take advantage of many prosthetic components.

As is the case with many hemiplegics, the amputee’s self-selected walking speed is generally slower than the most efficient walking speed.^4,10 Walking harnessed on a treadmill, with or without unweighting, provides a safe and secure venue for increasing both speed and endurance, and allows for the repetition required to turn good practice into good walking habits.¹¹ Gait training for both populations will include walking on varied surfaces, changing directions, and traversing architectural barriers.

The major difference in the gait-training process is the necessity for the therapist to be familiar with prosthetic issues. The therapist must be able to teach the patient how to correctly wear and use the prosthesis and to troubleshoot fitting issues. Until the patient is proficient with donning the prosthesis, the therapist should check the socket fit at the beginning of each session. If the socket is not correctly fitted, the patient will lack the stability needed to walk correctly and gait deviations will ensue.

Additionally, the therapist must recognize both internal (patient-centered) and external (prosthetic) causes of gait deviations. For example, if an amputee has an uncompensated Trendelenburg deviation, it could be due to weak abductors. It might also be caused by the patient not being down in the socket, by a loose suspension strap (both of which lead to decreased medial-lateral support), or by excessive femoral abduction ("bell-clapping") within the socket as the distal residual leg shrinks. Close collaboration with the prosthetist will help sort out the root causes and may prevent countless sessions spent trying to strengthen the abductors.

"Today is your day. Your mountain is waiting, so get on your way." — Dr Seuss

Therapist-prosthetist communication throughout the process is essential for optimal rehabilitation of the amputee. Each profession owns a body of knowledge that must be brought together if the amputee is to achieve his goals.¹² Future advances in medical management and prosthetic componentry will continue to demand teamwork. Power-driven knees to assist in sit-to-stand and reciprocal stair-climbing are already being developed. Improved limb-salvage procedures will require innovations in skin-socket interface. Osteointegrated prosthetics continue to be improved upon and may one day make today’s suspension systems obsolete. Therapists should arm ourselves to meet the challenge.

Stephanie Smith, MPT, has been working at Walton Rehabilitation Outpatient Center, Augusta, Ga, since 2001, specializing in orthopedics, pain management, and cancer exercise programming. She can be reached at ssmith@wrh.org. Diane Wilson, PT, relishes her job as an outpatient orthopedic physical therapist at Walton Rehabilitation Health System. She can be reached at www.dwilson@wrh.org.

References
1. Centers for Medicare and Medicaid Services. Available at: www.cms.hhs.gov . Accessed June 16, 2006.

2. Gailey R, Roach K. The functional value of prosthetic foot/ankle systems to the transtibial amputee. Abstract available at: www.ptjournal.org/abstracts/pt2003/abstractsPt2003.cfm?pubNo=PL-RR-173-F . Accessed July 19, 2006.

3. Ephraim PL, Wegener ST, MacKenzie EJ, Dillingham TR, Pezzin LE. Phantom pain, residual limb pain, and back pain in amputees: results of a national survey. Arch Phys Med Rehabil. 2005;86:1910–1919.

4. Hsu MJ, Nielsen DH, Lin-Chan SJ, Shurr D. The effects of prosthetic foot design on physiologic measurements, self-selected walking velocity, and physical activity in people with transtibial amputation. Arch Phys Med Rehabil. 2006;87:123–129.

5. Wonisch M, Hofmann P, Fruhwald FM, et al. Influence of beta-blocker use on percentage of target heart rate exercise prescription. Eur J Cardiovasc Prev Rehabil. 2003;10:296–301.

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8. Gailey RS, Roach KE, Applegate EB, et al. The amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee’s ability to ambulate. Arch Phys Med Rehabil. 2002;83: 613–627.

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11. Pohl M, Mehrolz J, Ritschel C, Ruckriem S. Speed-dependent treadmill training in ambulatory hemiparetic stroke patients: a randomized controlled trial. Stroke. 2002;33:553–558.

12. Bedotto RA. Biomechanical assessment and treatment in lower extremity prosthetics and orthotics. Phys Med Rehabil Clin N Am. 2006;17:203–243.