PHYS THER
Vol. 88, No. 12, December 2008, pp. 1568-1577
DOI: 10.2522/ptj.20070337
Gait Characteristics of a Soldier With a Traumatic Hip Disarticulation
Barri L Schnall,
Brian S Baum and
Anne M Andrews
BL Schnall, MPT, is Biomechanics Lab Physical Therapist, Center for Performance and Clinical Research, Military Advanced Training Center, Walter Reed Army Medical Center, Bldg 2A, Room 146, 6900 Georgia Ave NW, Washington, DC 20307 (USA)
BS Baum, MS, is Biomechanics Lab Engineer, Center for Performance and Clinical Research, Military Advanced Training Center, Walter Reed Army Medical Center
AM Andrews, PhD, RD, CSSD, is Chief, Education and Research Division, Nutrition Care Directorate, Walter Reed Army Medical Center
Address all correspondence to Ms Schnall at: barri.schnall{at}na.amedd.army.mil
Submitted November 9, 2007;
Accepted July 30, 2008
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Abstract
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Background and Purpose: No reports have analyzed the temporal-spatial, kinematic, or kinetic components of gait coupled with a metabolic analysis of patients with hip disarticulations. Most of the research on this population is based on older adults. As a result, guidelines for reasonable functional outcomes for patients with hip disarticulations who are young, premorbidly fit, and goal oriented are lacking. This report describes quantitative measures of energy cost and gait characteristics of a young soldier with a unilateral traumatic hip disarticulation.
Case Description: One patient, a soldier with a unilateral hip disarticulation, was evaluated in the Gait and Motion Analysis Laboratory at 3 months and 38 months postinjury.
Outcomes: The patient progressed from use of crutches at 3 months postinjury to independent ambulation at the follow-up visit at 38 months postinjury. At 38 months postinjury, he wore his prosthesis 12 hours per day and achieved step-length symmetry, and his oxygen consumption was 14.49 mL/kg/min at self-selected walking speed. Self-selected walking speed increased from 0.57 m/s at 3 months to 0.86 m/s at 38 months postinjury. During both visits, support time remained greater on the intact limb (72%) than the involved limb (57%), compensatory trunk and pelvic motions were used to advance the prosthetic limb, and the vertical ground reaction force profile was within 2 standard deviations of the data for an uninjured comparison group on the prosthetic side and plateaued on the sound limb.
Discussion: Young individuals with traumatic hip disarticulations can achieve and maintain functional independent ambulation with gait deviations. However, metabolic demands may not be as great as previously expected.
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Introduction
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As a result of the recent conflicts in Afghanistan and Iraq, US soldiers have incurred complex injuries. Between 2002 and June 2007, 14 soldiers had sustained a hip disarticulation (HD), with 8 having unilateral amputations and 6 having multiple limb involvement.1 Military personnel who are young, premorbidly fit, and goal oriented pose new challenges for rehabilitation professionals, as there is little to no research on this population to guide prognosis of function and gait training or to understand their prosthetic demands. The incidence of HD surgeries among patients with amputations has been reported as 0.5% to 3.0%.2–4 Most of these surgeries are due to vascular impairment or malignancy and tend to have poor outcomes.4,5 Of those patients who have the ability to walk, many opt for prosthesis-free crutch walking.6 As a result of the small number of prosthetic users with this diagnosis, limited research is available to guide clinicians in their care and rehabilitation. Gait outcome measures, such as kinetic, kinematic, and metabolic measures, would provide clinicians with valuable information that they could use to assist them with their goal setting and associated treatment choices.
Unfortunately, no documentation of kinetic data has been reported in the literature, and few studies have reported kinematic and metabolic data. One case study reporting kinematic data involved a 73-year-old man with cardiopulmonary disease,7 so the results may not generalize to a younger population. Specific kinematic parameters noted in that study included increased pelvic tilt and rotation range of motion (ROM) for prosthetic advancement and hip hiking (increased hip abduction on the unaffected limb during stance, with simultaneous elevation of the affected side of the pelvis during swing) for clearance in mid-swing, with concurrent vaulting on the sound side. The patient's gait speed was only 0.20 m/s using a walker. Another study compared metabolic data of 8 middle-aged patients with HD with that of 10 patients with transpelvic amputations (TPs) (previously known as "hemipelvectomies") and 11 control subjects without HD or TP. The average self-selected walking speeds were reported as 0.79, 0.66, and 1.25 m/s, respectively.8 Subjects decreased their walking speed (to 50%–60% of the control group's walking speed) in order to maintain an energy cost similar to that of the control group. However, when the data were expressed in energy cost per unit of distance, patients with HD spent 82% greater energy and patients with TP spent 125% greater energy compared with the control group.
Some studies7–9 confirm that people with amputation have a higher energy cost and higher heart rates than people who are able bodied during similar activities. It also is widely acknowledged that the higher the level of amputation, the greater the energy requirement.9,10 When compared with people who were uninjured, people with a transtibial (TT) amputation were reported to have 12% to 34% greater oxygen consumption (
O2),11 those at a transfemoral level were reported to have 25% to 35% greater energy cost,10 and those with HD were reported to have 80% greater energy cost.8 Indeed, even people with shorter limb lengths within similar amputation levels have been reported to have greater energy cost compared with people with longer limbs. For example, patients with a TT amputation who had a longer residual limb had a 12.5% energy increase and those with shorter tibial lengths had an energy cost that was 33.5% greater compared with controls.11
The purpose of this case report is to improve the rehabilitation process for young soldiers with traumatic HD by providing data on gait characteristics and metabolic costs. By documenting the capabilities, in terms of level of function, achieved and maintained by a person with HD, the current perception that patients with such a high level of lower-extremity amputation typically abandon their prosthesis for assistive devices or wheelchairs can be revised.4–6
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Patient History and Review of Systems
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The presentation of this retrospective data analysis was approved by Walter Reed Army Medical Center's Department of Clinical Investigation and the Public Affairs Office. The patient provided consent for evaluation and treatment.
A 27-year-old man sustained a right traumatic HD and left thigh shrapnel injury during military service. The soldier underwent a comprehensive rehabilitation program. Care included the patient and caregivers working with members of the orthopedics department, including physical medicine and rehabilitation, physical therapy, occupational therapy, psychology, nursing, social work, and prosthetics, and the gait laboratory to assist the patient in achieving his goals. His rehabilitation course was complicated by development and subsequent excision of heterotopic ossification (HO) at 8 months postamputation.
The initial 3-dimensional (3D) gait evaluation took place at 3 months postinjury. The patient was 1.82 m tall and weighed 74.8 kg. At that time, he wore a right total-contact check socket with bilateral iliac crest suspension, an Otto Bock spring-assisted hip unit,* a C-leg knee unit,* an endoskeletal shank, and a Luxon Max multi-axial foot* and used axillary crutches. A wheelchair was used for community mobility. The patient's stated goal was to walk independently. He required assistance for activities of daily living (ADLs). Wound healing was good; although some shrapnel fragments were embedded, they were not problematic. The primary problems at that time were socket fit and tolerance, which were appropriate at that stage of rehabilitation.
A follow-up gait evaluation was conducted when the patient was 30 years of age (38 months postinjury). At that time, he was 1.83 m tall and weighed 82.1 kg. During the follow-up evaluation, the following prosthetic components were used: a total-surface-bearing definitive carbon fiber socket with silicone liner, suction and belt suspension, an Otto Bock spring-assisted hip unit, a C-Leg knee unit, an endoskeletal shank, and a dynamic response foot. He wore the prosthesis 12 hours per day, ambulated independently on level surfaces, and reported no pain that might interfere with walking. He continued to be independent in ADLs, and he was driving and working full time. Primary goals were consistent, safe, independent negotiation of uneven surfaces and stairs.
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Examination
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The initial gait evaluation did not include a physical therapy evaluation; however, this was incorporated later into the gait laboratory standard operating procedure. During the 38-month postinjury gait assessment, the physical therapy evaluation included lower-extremity joint ROM, strength (force-generating capacity), and sensation/pain assessments. Although functional independence had been achieved on all surfaces, the patient's stated goals at the time of this gait evaluation were to walk without assistive devices on all surfaces and levels and to run.
Gait Analysis
A 3D gait analysis is part of our facility's standard operating procedure for clinical care for people with amputations and includes video capture as well (video clips).
In preparation for gait analysis, passive retroreflective markers were placed on the patient's body according to the Cleveland Clinic marker set. The spherical markers (0.5- to 2-cm-diameter balls affixed to a flat disc) were placed on specific bilateral anatomic and bony landmarks to identify planes of motion and joint axes as follows: acromium-clavicular joints, lateral epicondyle of the humerus, dorsal wrist, anterior-superior iliac spine (ASIS), posterior-superior iliac spine (PSIS), lateral thigh triads, medial and lateral epicondyles of the knees, lateral shank triads, medial and lateral malleoli, heel, toe, and one offset on the right scapula. The pelvic marker placement was obscured by the suspension belt and socket and, therefore, were approximated and placed on the socket over the desired landmark. Eight Eagle cameras
collected temporal-spatial and kinematic data at 120 Hz as the patient walked across an 8-m walkway at his self-selected walking speed. Two forceplates (model OR6–7
) embedded into the walkway and internally synchronized with the camera system measured ground reaction force data at a frequency of 1,200 Hz. At least 6 "good" trials were collected for averaging purposes. A "good" trial was defined as having at least one foot cleanly strike a forceplate completely within the boundary of the plate. Positional data of the markers were smoothed with a low-pass Butterworth filter at 6 Hz, and temporal-spatial parameters, sagittal joint kinematics, and vertical ground reaction forces were calculated using the OrthoTrak program. Joint kinematic and ground reaction force data using optical motion capture systems and forceplates have been deemed reliable and valid during gait analyses.12,13
The patient's data were compared with data collected from a control group for clinical comparisons. The control group consisted of 60 military personnel with no orthopedic, neurologic, or other conditions that would affect gait.
Metabolic Analysis
A metabolic analysis was conducted after a 30-minute rest following the 38-month postinjury gait assessment. Oxygen uptake (in milliliters per kilogram of body weight per minute) and heart rate (in beats per minute) were measured via a K4b2 breath-by-breath metabolic analysis unit
and a heart rate monitor,|| respectively. The K4b2 unit is commonly used for metabolic analyses, and its accuracy and reliability have been reported.14 Data from the K4b2 unit were collected continuously and divided into the following 3 stages for analysis: (1) rest: 10 minutes in a reclined position, (2) work: 10 minutes of walking on a level surface of a 226.6-m-long track at the patient's self-selected walking speed, (3) recovery: reclining for 10 minutes after the bout of walking or until the heart rate was within 10 beats of the baseline measurement, whichever occurred later. Average walking speed was calculated from the distance traveled during the 10-minute walking test. Results were compared with those from the literature because metabolic data were not collected on the control subjects in this case study.
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Outcomes
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Physical Therapy Evaluation
Relevant findings from the physical therapy evaluation at the time of the follow-up gait assessment are summarized. Range of motion was 0 degrees for left hip extension and for knee extension and 50 degrees for straight leg raise. Strength of the left lower extremity was 5/5, as measured by manual muscle testing. Sensation was intact. The patient reported phantom sensation and phantom pain, the incidence of which had decreased since removal of HO. He stated that the occurrence of daily phantom pain had spontaneous onset and resolution and that it lasted only 10 seconds and did not interfere with walking. Pain was reported as 4/10 at the sacrum/low back region. Left hip and knee pain occurred at the end of the day after activity that was greater than usual and was 8/10 at worst. This pain was relieved with rest.
Gait Analysis
Temporal-spatial and kinematic data are reported for the initial (3-month postinjury) and follow-up (38-month postinjury) evaluations. Kinetic data were collected only at the follow-up evaluation, as the patient used axillary crutches during the initial evaluation.
The temporal-spatial findings (Tab. 1) revealed decreased and asymmetric step length (longer on the prosthetic side) at the initial evaluation and "normal" length and symmetric steps at the follow-up session. For the purpose of this report, the term "normal" will be used to describe gait of individuals who are healthy and uninjured, as defined by 2 standard deviations of the control group data for each parameter. Cadence was decreased from the control group at both the initial and follow-up evaluations but improved by 10 steps per minute at the follow-up evaluation. Stance time was close to control values on the prosthetic side for both evaluations. Stance time for the intact limb was increased from control values, to 72% of the gait cycle during both evaluations; stance time for the control group was 60% bilaterally. Step width was within normal limits initially, when the patient was using axillary crutches. Step width was double the normal width at the follow-up evaluation, when he was ambulating without an assistive device. Self-selected walking speed increased by 0.29 m/s to 0.86 m/s but was still 0.43 m/s below the control group value of 1.29 m/s.
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Table 1. Temporal-Spatial Data for the Patient With Hip Disarticulation at 3 and 38 Months Postinjury Compared With a Control Group Without Injuries
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Kinematic profiles changed considerably between the initial and follow-up evaluations (Tab. 2). Trunk lean (Fig. 1A) exhibited a range that was greater than normal at both evaluations, with a distinct oscillating pattern at 38 months postinjury. Trunk lateral flexion (Fig. 1B) exhibited a reversed pattern, with a bias toward leaning to the prosthetic limb during the initial evaluation. At the follow-up evaluation, the lateral flexion excursion (
=10.5°, SD=1.8°) had increased and the bias shifted toward leaning to the intact limb. Pelvic tilt (Fig. 2A) showed a posterior tilt with excessive motion compared with controls at the initial evaluation. At the follow-up evaluation, a marked 15-degree anterior then posterior thrust was evident prior to and through toe-off when advancing the prosthetic limb. Excursion increased from the initial evaluation. Pelvic obliquity (Fig. 2B) demonstrated minimal motion near neutral throughout the entire gait cycle at the initial gait evaluation. At 38 months postinjury, the obliquity pattern resembled that of the control group; however, it was elevated on the prosthetic (right) side throughout gait, and the elevation during swing was consistent with hip hiking. Hip flexion excursion changed between the initial and follow-up evaluations, from 21 to 33 degrees for the prosthetic limb and from 28 to 58 degrees for the sound limb, respectively (Fig. 3). At the initial evaluation, the prosthetic knee flexion range was –3 to 6 degrees (foot-strike to pre-swing [contact of opposite foot], respectively). At the follow-up evaluation, this range was –9 to –2 degrees. Peak stance extension of the sound knee after loading response was –13 degrees initially and –12 degrees at follow-up. At 38 months, peak dorsiflexion of the sound ankle was 26 degrees compared with 12 degrees in the control group. During the follow-up visit, the vertical ground reaction force profile of the prosthetic limb showed a double-bump pattern similar to that of the control group, although timing of the initial peak was delayed; the intact limb demonstrated an elongated and altered pattern (Fig. 4).
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Table 2. Kinematic Parameters (Average±SD) for the Patient With Hip Disarticulation at 3 and 38 Months Postinjury Compared With the Control Groupa
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Figure 1. Trunk anterior-posterior lean (A) and lateral flexion (B) of the patient with hip disarticulation at 3 and 38 months postinjury compared with controls (±2 SD). The gait cycles are normalized to consecutive footstrikes of the right limb (the patient's prosthetic limb).
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Figure 2. Pelvic tilt (A) and obliquity (B) of the patient with hip disarticulation at 3 and 38 months postinjury compared with controls (±2 SD). The gait cycles are normalized to consecutive footstrikes of the right limb (the patient's prosthetic limb).
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Figure 3. Hip flexion-extension of the patient with hip disarticulation at (A) 3 months and (B) 38 months postinjury compared with controls (±2 SD). The gait cycles are normalized to consecutive footstrikes of the right limb (the patient's prosthetic limb).
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Figure 4. Vertical ground reaction force of the prosthetic and intact limbs compared with controls (±2 SD). The gait cycles are normalized to consecutive footstrikes of each limb.
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Metabolic Analysis
Metabolic analysis was not a standard procedure at the time of the initial evaluation but is reported for the follow-up visit. Metabolic results at 38 months postinjury showed average resting O2 was 3.55 mL/kg/min and heart rate was 64 bpm. During the steady state work stage at an average walking speed of 0.85 m/s, O2 increased to 14.49 mL/kg/min and heart rate increased to 131 bpm. Oxygen consumption decreased to 4.51 mL/kg/min during recovery but did not reach baseline levels. Similarly, heart rate decreased to 86 bpm by the 10-minute mark of the recovery phase but remained elevated from resting measurements. The patient required 17 minutes to get within 10 beats of the initial resting heart rate, which was the criterion for termination of testing. Heart rate and energy expenditure data from this case study and selected published studies within the literature are displayed in Table 3.
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Discussion
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Some of the preliminary findings recorded in the early rehabilitation phase changed as the patient became a more experienced prosthetic user. Initially, step length of both limbs was reduced compared with control group data, with the prosthetic limb step length longer than the intact limb step length. The patient spent much more time (72% of gait) on the intact limb, and walking speed and cadence were both less than in the control group. The reduced walking speed and cadence values were expected because the patient was only 3 months postinjury and using axillary crutches for support during ambulation. The step length and support time data indicate an overreliance on the intact limb and potentially a lack of confidence and stability in the prosthesis at that time. At 38 months postinjury, the step lengths had become symmetric and were within normal limits; however, support time remained similar to the 3-month postinjury values. Walking speed and cadence improved from the initial evaluation to the follow-up evaluation but were slower than the control group data at both time periods. These measurements were comparable to some previously reported values for patients with HD8 and transfemoral amputations.10 The increase in step width at the follow-up evaluation was anticipated due to the abandonment of axillary crutches and need for stability during free gait. Overall, the patient's function had greatly improved as related to temporal-spatial parameters, but he still relied heavily on his intact limb for support.
The patient's gait kinematic data varied from our lab control data most markedly at the trunk and pelvis to assist with prosthetic advancement and clearance, as previously reported.15 As reported earlier, the patient had surgical excision of HO at 8 months postinjury. Indications for the surgery included difficulty with socket fit or pain, either of which would contribute to an avoidance (involved lower extremity) gait pattern. Decreased stance time on the prosthetic limb, for example, is characteristic of an avoidance pattern. The removal of the HO eliminated noxious stimuli, allowed for intimate socket fit (essential for all individuals with amputations), and enabled the patient to resume an aggressive course of rehabilitation. However, it is not possible to apportion what functional gains were directly linked to the removal of HO and what functional gains were due to the natural progression of this athletic patient. The altered pattern of the intact limb hip flexion indicates effort to stabilize while the prosthetic limb is in the swing phase of gait. The prosthetic knee was biased toward extension in stance for stability, while the intact knee maintained increased flexion throughout stance at 3 months postinjury. At 38 months postinjury, a loading response was achieved on the intact side, but the stance flexion bias remained, probably for proprioceptive feedback. Because the proprioceptive chain is nonexistent on the involved lower extremity, the sound side may develop compensatory strategies. One such strategy may be maintaining knee stance flexion in order to provide prolonged stimulation to the mechanoreceptors in that joint. Stimulation of these mechanoreceptors may contribute to a greater sense of control and stability during stance.16,17 The intact ankle reacted to the proximal deviations with an increased and prolonged dorsiflexion excursion through late stance, which may have contributed to the achievement of a more symmetric step length.
Interestingly, the prosthetic side demonstrated a normal vertical ground reaction force; despite the temporal-spatial deviations, it appears that the patient was able to load the prosthesis. Conversely, the vertical ground reaction force profile on the intact limb demonstrated an elongated and altered pattern. The elongated pattern was due to a longer stance time on the intact limb; we speculate that the altered pattern was caused by a reliance on the intact limb to support the body weight for an extended period of time, thus requiring additional stabilization. The body attempting to stabilize itself while "balancing" on one limb during gait was exhibited in the vertical ground reaction force profile. These findings indicate that the patient may have had an initial reluctance to load the prosthetic limb, but once loaded, he quickly stepped through the stance phase to shift his body weight back onto the intact limb. Because the patient progressed to independent ambulation without an assistive device and gait speed increased, different kinematic strategies were used to enable this to occur. In an uninjured population, kinematics are not drastically altered by change in speed; however, speed has a direct impact on kinetic calculations.18
Metabolic data were collected at 38 months postinjury. Previous research has established that a person ambulating with a prosthesis experiences a greater increase in O2 compared with a person with intact limbs.9,19 In addition, it is recognized that the higher the level of amputation, the greater the oxygen cost.9
At rest, our patient's O2 was 3.5 mL/kg/min. However, during walking at self-selected speed, his O2 was 14.49 mL/kg/min, an increase of 10.99 mL/kg/min. Waters et al9 reported O2 measurements of 2.8 mL/kg/min at rest, 3.5 mL/kg/min during quiet standing, and 13.0 mL/kg/min during walking at self-selected speed on a level 60.5-m track in people who were uninjured and healthy. There were no participants with HD in that study for comparison. Nevertheless, during quiet standing, our patient had resting O2 levels similar to those of the participants in the study by Waters and colleagues. Although our patient had higher resting O2 levels compared with the participants in the study by Waters and colleagues, the increase in O2 from rest to self-selected walking was of a similar magnitude in both our case study and the study by Waters and colleagues (10.99 mL/kg/min versus 10.2 mL/kg/min, respectively). Jaegers et al20 found that people with transfemoral amputations had slower comfortable walking speeds compared with a control group and had similar energy expenditure at their self-selected walking speed. When they walked at the same speed as the control group, their energy expenditure was 25% to 35% higher.20 Similar results were found for people with HD and people with TP in the study by Nowroozi et al.8 At self-selected walking speeds, the participants with HD and those with TP they had 80% to 125% higher energy costs compared with a control group.8
Published guidelines indicate that energy expenditure may increase by 100% or more during ambulation in individuals with HD.21 Our data are consistent with previous findings with regard to kinematic strategies and energy expenditure requirements being greater with higher levels of amputation. However, some of the data collected from our patient are inconsistent with published findings. Compared with literature reporting metabolic demands of patients with HD, our patient's metabolic demand was greater; however, his walking speed also was increased relative to cited references. This may be due, in part, to the fact that our patient was young, premorbidly fit, and healthy. Most of the reported data on patients with HD include data from older subjects or those using assistive devices. Future studies need to focus on identifying reasonable outcomes for younger patients who have sustained HDs.
Within 3 months following traumatic HD, independent ambulation with crutches was achieved by a young, athletic soldier. After discharge from the rehabilitation center, he was ambulating independently without an assistive device and had maintained that level of independence at the 38 months postinjury.
Certain limitations of this case study must be considered during interpretation. Because this was a case study of a young, premorbidly fit soldier, the results may not be generalizeable to other populations, nor may they be representative of a larger similar population. However, because of the patient's premorbid physical status and age, we can anticipate that he had an advantage in healing over an older population, and the results of this patient demonstrate what can be achieved functionally after HD.
A limitation also existed with marker setup during the 3D motion analysis. Typically, pelvic markers are placed on the ASIS and PSIS; however, due to the presence of the socket, these markers had to be placed on the socket rather than on the skin over the landmarks. Because the socket is designed to fit snugly over the pelvis with minimal relative motion, it is reasonable to assume that markers on the socket track the general motion of the pelvis. Minor errors may exist in the hip joint center estimation due to the added thickness of the socket material; it was not possible to confirm that the markers were placed exactly over the ASIS and PSIS. As the socket conformed to these processes, associated landmarks on the socket improved confidence in the marker placement. We, therefore, determined that obtaining pelvic and hip joint center estimations with this approach was reasonable. One other limitation is that the available literature for metabolic data in this population reports the use of a variety of metabolic equipment and protocols. As a result, it is difficult to make direct comparisons between our data and previously published results and our control subjects did not undergo metabolic testing, so a direct comparison was not possible.
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Conclusions
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Data from this case study suggest that patients with HD, regardless of age or comorbidities, demonstrate similar gait characteristics. Due to this high level of amputation, variations of movement strategies are limited and energy cost is greater. Based on this patient's data, the metabolic demands for a young, otherwise healthy, adult with traumatic amputation may not be as great as previously reported. Current technology continues to strive to meet the needs of this new generation of patients. This case study shows that with the appropriate prosthetic prescription, alignment, and rehabilitation, a young, otherwise healthy, person with a unilateral HD is able to achieve and maintain independent community ambulation status on all levels and surfaces at a greater metabolic cost compared with adults without disabilities. These results raise the bar and challenge conventional ideas on functional capabilities of patients with HD.
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Footnotes
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Ms Schnall, Mr Baum, and Dr Andrews participated, in varying degrees, in the conception and design, acquisition of data, data analysis and interpretation, and drafting and revision of the article, and all authors have seen and agree with the contents of the manuscript.
The authors thank the Military Amputee Research Program for support of this project.
* Otto Bock HealthCare GmbH, Max-Näder-Straβe 15, D-37115 Duderstadt, Germany. 
Motion Analysis Corporation, 3617 Westwind Blvd, Santa Rosa, CA 95403
AMTI, 176 Waltham St, Watertown, MA 02472.
COSMED, Via dei Piani di Mt Savello 37, Pavona di Albano, Rome I-00040, Italy.
|| Polar Electro Inc, 1111 Marcus Ave, Suite M15, Lake Success, NY 11042.
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References
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- Walter Reed Army Medical Center. 2006. Available at: https://amputee.wramc.amedd.army.mil/.
- Dillingham TR, Pezzin LE, MacKenzie EJ. Limb amputation and limb deficiency: epidemiology and recent trends in the United States. South Med J. 2002;95:875–883.[Web of Science][Medline]
- Wakelin SJ, Oliver CW, Kaufman MH. Hip disarticulation: the evolution of a surgical technique. Injury. 2004;35:299–308.[CrossRef][Medline]
- Denes Z, Till A. Rehabilitation of patients after hip disarticulation. Arch Orthop Trauma Surg. 1997;116:498–499.[Medline]
- Unruh T, Fisher DF Jr, Unruh TA, et al. Hip disarticulation: an 11-year experience. Arch Surg. 1990;125:791–793.[Abstract/Free Full Text]
- Zaffer SM, Braddom RL, Conti A, et al. Total hip disarticulation prosthesis with suction socket: report of two cases. Am J Phys Med Rehabil. 1999;78:160–162.[Medline]
- McAnelly RD, Refaeian M, O'Connell DG, et al. Successful prosthetic fitting of a 73-year-old hip disarticulation amputee patient with cardiopulmonary disease. Arch Phys Med Rehabil. 1998;79:585–588.[Medline]
- Nowroozi F, Salvanelli ML, Gerber LH. Energy expenditure in hip disarticulation and hemipelvectomy amputees. Arch Phys Med Rehabil. 1983;64:300–303.[Web of Science][Medline]
- Waters RL, Perry J, Antonelli D, Hislop H. Energy cost of walking of amputees: the influence of level of amputation. J Bone Joint Surg Am. 1976;58:42–46.[Abstract/Free Full Text]
- Waters RL, Mulroy S. The energy expenditure of normal and pathologic gait. Gait Posture. 1999;9:207–231.[CrossRef][Web of Science][Medline]
- Gonzalez EG, Corcoran PJ, Reyes RL. Energy expenditure in below-knee amputees: correlation with stump length. Arch Phys Med Rehabil. 1974;55:111–119.[Web of Science][Medline]
- Frigo C, Rabuffetti M, Kerrigan DC, et al. Functionally oriented and clinically feasible quantitative gait analysis method. Med Biol Eng Comput. 1998;36:179–185.[CrossRef][Web of Science][Medline]
- Richards JG. The measurement of human motion: a comparison of commercially available systems. Hum Mov Sci. 1999;18:589–602.[CrossRef]
- Duffield R, Dawson B, Pinnington HC, Wong P. Accuracy and reliability of a Cosmed K4b2 portable gas analysis system. J Sci Med Sport. 2004;7:11–22.[Web of Science][Medline]
- Chin T, Sawamura S, Shiba R, et al. Energy expenditure during walking in amputees after disarticulation of the hip: a microprocessor-controlled swing-phase control knee versus a mechanical-controlled stance-phase control knee. J Bone Joint Surg Br. 2005;87:117–119.
- Solomonow M, Krogsgaard M. Sensorimotor control of knee stability: a review. Scand J Med Sci Sports. 2001;11:64–80.[CrossRef][Web of Science][Medline]
- Williams GN, Chmielewski T, Rudolph K, et al. Dynamic knee stability: current theory and implications for clinicians and scientists. J Orthop Sports Phys Ther. 2001;31:546–566.[Web of Science][Medline]
- Lelas JL, Merriman GJ, Riley PO, Kerrigan DC. Predicting peak kinematic and kinetic parameters from gait speed. Gait Posture. 2003;17:106–112.[CrossRef][Web of Science][Medline]
- Gailey R, Wenger M, Raya M, et al. Energy expenditure of trans-tibial amputees during ambulation at self-selected pace. Prosthet Orthot Int. 1994;18:84–91.[Web of Science][Medline]
- Jaegers S, Vos L, Rispens P, Hof A. The relationship between comfortable and most metabolically efficient walking speed in persons with unilateral above-knee amputation. Arch Phys Med Rehabil. 1993;74:521–525.[CrossRef][Web of Science][Medline]
- Zajtchuk R. Textbook of Military Medicine, Part IV: Rehabilitation of the Injured Combatant. Vol. 1. Washington, DC: Department of the Army, Office of the Surgeon General; 1998.
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Introduction
Patient History and Review...
