JPO Journal of Prosthetics & Orthotics:
A Method for Training Step-Over-Step Stair Descent Gait With Stance Yielding Prosthetic Knees: A Technical Note
Highsmith, M. Jason DPT, CP, FAAOP; Kahle, Jason T. CPO, FAAOP; Lewandowski, Amanda L. DPT; Kim, Seok Hun PT, PhD; Mengelkoch, Larry J. PT, PhD
M. JASON HIGHSMITH, DPT, CP, FAAOP, JASON T. KAHLE, CPO, FAAOP, AMANDA L. LEWANDOWSKI, DPT, SEOK HUN KIM, PT, PhD, and LARRY J. MENGELKOCH, PT, PhD, are affiliated with the School of Physical Therapy and Rehabilitation Sciences, University of South Florida, Tampa, Florida.
Disclosure: The authors declare no conflict of interest.
Correspondence to: M. Jason Highsmith, DPT, CP, FAAOP, College of Medicine, School of Physical Therapy & Rehabilitation Sciences, University of South Florida, 12901 Bruce B. Downs Blvd. MDC 077, Tampa, FL 33612-4799; e-mail: email@example.com
ABSTRACT: Limited information is available concerning stair descent training for transfemoral amputees using prosthetic knees. Literature describing stair descent training techniques are predominantly available for the step-to-step stair descent method. A thoroughly descriptive technique for training prosthetic knee users to reciprocally descend stairs, using a step-over-step pattern is not available. The purpose of this technical note is to describe a procedure for training stance-yielding prosthetic knee users how to descend stairs using a reciprocal, step-over-step pattern. The technique describes stair setup, safety considerations including hand railing, use of a gait belt, guarding techniques and a one versus two therapist technique. Nineteen subjects were initially trained in this technique, and all subjects demonstrated the ability to reciprocally descend stairs after training. Reciprocal step-over-step stair descent is not appropriate for all transfemoral amputees; however, we recommend considering the supervised, therapeutic application of this technique for all transfemoral amputees using stance yielding prosthetic knees. We suggest that practicing this technique might improve a prosthetic knee user's overall functional performance such as their ability to utilize stumble recovery during a missed step, to transition more symmetrically from stand to sit and to utilize knee flexion during the loading response of gait.
Information regarding stair descent performance using prosthetic knees is available in terms of outcome data and biomechanical comparisons.1,2 Literature describing training techniques for stair descent is also available in pathologic populations; however, only the nonreciprocal, step-to-step method is described.3 Another common name for the nonreciprocal, step-to-step pattern is the tap-step pattern,4 and clinicians commonly relate this to patients with the command “down with the bad” when referring to leading stair descent by stepping down with the involved leg.5 Literature detailing a technique for training a prosthetic knee user to perform the reciprocal step-over-step stair descent technique is very limited. The step-over-step method of stair descent has been a viable option for transfemoral amputees since the introduction of the Mauch Swing and Stance (SNS) knee unit in 1968.6,7 A Mauch knee patient instructional manual8 pictorially demonstrates two methods of step-over-step stair descent and recommends decreasing stance resistance if the user feels they are “waiting for the prosthetic knee to bend.” Because a thorough technical description is lacking, the purpose of this technical note is to describe a procedure for training a stance yielding prosthetic knee user how to descend stairs using a reciprocal, step-over-step method.
The first safety consideration is the stair design. Initial training with an inexperienced amputee may best be conducted on a smaller therapy stair set. Such training stairs are ideal as they incorporate bilateral handrails, are routinely finished with high-friction grip tape on the stair tread, and are commonly only three to five steps in height, which can minimize anxiety regarding ultimate height (Figure 1).
Standard practice is that the primary therapist guards from a position between the ground and the patient.3 In addition, although the technique can be administered with one therapist, the authors' experience is that having an additional person guarding from above/behind assures the patient is closely watched and protected while standing in this precarious position. In addition, it is recommended that the person guarding from above/behind the patient hold onto a standard gait belt appropriately applied to the patient's waist.3 (Figure 2)
Handrails, although not necessary for all persons, can be beneficial in terms of security.9–11 Therapy stair cases are routinely equipped with bilateral handrails that bolster patient confidence. If structurally permanent building staircases are utilized, bilateral railing may not be within reach. In such cases, it is recommended that the patient initially utilize the handrail opposite the prosthesis to mirror assistive device training, but eventually practice using either side.3 Still in other situations (i.e., outdoor stairs, stadium bleachers, grandstands, movie theatres), no railing may be available, and in these cases, lower skilled ambulators may be able to practice with their assistive device or by holding onto the shoulder of a person walking in front of them. Advanced users may be able to achieve stair descent without the use of a railing; however, both of the latter subjects are beyond the scope of this technical note.
Handrails can be a hindrance in some cases.9–11 For instance, the patient may apply excess load through the upper limbs, thereby decreasing lower limb load. This can potentially create reliance on upper limb support that can be difficult to minimize long-term or create additional friction at the hand/rail interface that must be overcome before advancing forward.11
The primary therapist guards with an open palm just distal to the knee axis. The fingers are extended as opposed to flexed, preventing their placement on the posterior aspect of the knee (Figure 3) in the event of knee collapse, which could potentially injure the fingers. This position enables the therapist to guard against rapid prosthetic knee collapse into flexion by simply pushing the prosthetic shank posteriorly, extending the knee. This position is only an option when two persons are available to train the patient. If only one person is able to train the patient, the therapist will guard and simultaneously train from the front, and the prosthetic shank will be blocked by the therapist's opposing leg (Figure 4).
INITIAL PATIENT POSITION
Using the tap-step pattern (“up with the good,” also known as the step-to-step pattern), the patient climbs two or three steps then turns around to prepare for descent training. With the primary therapist guarding from below and assisting practitioner positioned above/behind, the patient steps forward into the initial position. The initial position places the midfoot of the prosthetic foot at the step's leading edge (Figure 5). This minimizes the risk of toe loading, which is necessary to trigger the prosthetic knee's swing phase release. This foot placement permits the prosthetic knee's stance control to manage knee stability, minimizing the risk of knee collapse during step descent.
Once initially positioned, the primary therapist provides a visual cue (hand target) for the patient to contact with the toes (or limb end point)12 of the sound limb (Figure 6). The hand target must be positioned far enough in front of the patient to permit the sound side heel to adequately clear the step. Similarly, the hand target must be in the correct vertical position, such that the toe can contact it without the patient having to flex a joint to reach it comfortably. Contacting the sound-side toe to the therapist's hand target is important to establish kinesthetic memory of all joints12,13 relative to the body's orientation when performing stair-descent. In addition, reaching out the sound foot to touch the hand target while standing on the prosthetic limb at the step's edge promotes increased weightbearing in the socket and balance on the prosthetic side in preparation for descent. It should be noted that this position is considered precarious by many patients and may require multiple repetitions or multiple practice sessions to accomplish because of the need for coaching, practice, and reassurance. When the patient is confidently able to step out and reach the hand target with precision, they are ready to proceed to step descent practice.
STEPPING DOWN LEADING WITH SOUND LIMB
Using the instructions above in “Initial Practice,” the patient places his sound foot out in preparation for stepping (or step descent practice). Once the sound foot contacts the hand target, the therapist lightly grips the lateral aspects of the sound forefoot and shows the patient visually that the heel need only descend approximately 6 to 8 inches (15.2–20.3 cm). The therapist informs the patient that to place the sound heel on the lower step, the prosthetic knee must be slowly flexed. Allow the patient to return the sound foot to the step while the therapist explains that the patient is quite likely contracting the hip extensors of the residual limb to maintain prosthetic knee extension as he stands on the stairs at rest. In other words, the patient is pulling his residual limb into hip extension against the posterior wall of the prosthetic socket. The therapist can tap on the anterior socket wall and explain that either 1) force must be applied to the anterior socket wall or 2) the force being applied on the posterior socket wall must be decreased to flex the prosthetic knee for stair descent.
With this explanation completed, provide the hand target once again, for the sound side foot. Once the foot contacts the target, instruct the patient to push on the anterior socket wall (or release force on the posterior wall) to step down. Once this has been accomplished successfully and if repetition is desired, have the patient reset his sound foot on the step and repeat as necessary until mastered.
STEPPING DOWN LEADING WITH PROSTHETIC LIMB
Once the patient is able to descend leading with the sound limb and the sound limb is bearing the patient's weight, the next component is to descend leading with the prosthetic limb. This is the most common stair descent technique for patients and fits with the very typical “down with the bad” instruction. Although not likely needed, the same hand target practice can be used for this portion as well.
RECIPROCAL, STEP-OVER-STEP DESCENT—PUTTING IT ALL TOGETHER
At this point, the patient has mastered descent with both limbs individually and is ready to practice the reciprocating, step-over-step pattern descent. Start the patient three to five steps up from the floor in the initial position. The first time the patient attempts this whole skill pattern, it is recommended that the two therapist method of guarding be utilized. With the guarding and safety considerations in place, begin with the hand target for the sound side, so the patient descends leading with the sound limb first. Once the patient steps down leading with the sound limb, he should immediately be instructed to step down over the step the sound limb is on with the prosthetic limb and repeat this reciprocal, step-over-step pattern. Practice and cue as necessary.
Once reciprocal stair descent is mastered on a smaller therapy set of stairs, other factors should be considered and introduced given each patient's unique functional needs. A metronome14 can be utilized, for example, to alter or solidify the stepping rate. Depending on the patient's stability needs, guarding can potentially be progressively decreased from two to one therapist and eventually to decreasing levels of assistance. The staircases practiced on should be altered to introduce variance in terms of step size, environmental distraction, hand railing availability, lighting, and climate conditions.
The purpose of this technical note is to introduce a technique to train stance yielding prosthetic knee users how to walk reciprocally down stairs. As a part of a clinical trial, utilizing this technique, we trained 19 transfemoral amputees to descend stairs reciprocally. We measured their stair descent ability and confirmed that after training, all were able to demonstrate reciprocal stair descent.2 We also indicated that this may not be appropriate for everyone to practice on a daily basis as a part of their routine ambulatory activities.
The knee moment reported (normalized to height and weight: N/kg) for reciprocal stair descent in transfemoral amputees using stance yielding knees is higher than that reported for stumble recovery, sitting down from standing, and knee flexion in the loading response of gait.1,15–17 (Table 1) We suggest that it is important to consider training all transfemoral amputees using stance yielding knees in reciprocal stair descent as it potentially has functional carry over and motor learning in other functional activities. Other such activities that rely on stance control include stumble recovery, sitting down from standing, and knee flexion in the loading response of gait. In addition, these tasks are included in the initial set up and adjustment of a C-Leg.18,19 For instance, at the initial C-Leg fitting and setup, one of the first tasks is to have a patient sit in a chair repeatedly until patient and prosthetist are satisfied with sitting resistance. The user should be satisfied and confident with the resistance, such that they are willing and able to apply as much load into the prosthesis as possible, thereby unloading the uninvolved side and maximizing kinetic symmetry while transitioning from stand to sit.16
With emphases on patient outcomes becoming the norm and the functional capabilities of prosthetic componentry expanding, the role of physical rehabilitation to assure mastery of device function is increasing. The presence of detailed rehabilitation techniques in the literature is limited. This technical note presents a strategy for training the transfemoral amputee how to utilize the reciprocal stair descent capability of stance yielding knees and offers considerations to expand for individualized functional needs. The technique is associated with positive clinical outcomes data, but the task of reciprocal stair descent is probably not appropriate for all transfemoral amputees utilizing stance yielding prosthetic knee mechanisms. Whether or not a patient ever utilizes the technique in daily life, training such patients with a comparable technique, at least therapeutically, may have functional significance in other daily activities such as stumble recovery during a missed step, in moving from stand to sit, and during the loading response of gait.
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KEY INDEXING TERMS: C-Leg; Mauch SNS; microprocessor knee; physical therapy; reciprocal gait; rehabilitation; transfemoral amputee
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