Loss of the lower limb results in decreased muscle power, loss of joint motion and sensation, and the necessity to adapt to various prostheses.1 The loss of function of the lower limbs produces changes in gait that contribute to increased energy expenditure during ambulation.2,3 Macfarlane et al.4 have shown that energy cost is directly related to the mechanics of gait, so that alteration in gait characteristics results in increased energy cost and adaptations in many activities of daily living.5
Ambulation requires forward movement and body stability.6 To remediate any loss in normal gait or stability, the prosthesis must provide duplication of lower limb joint motion and substitute for muscle control around the joints. In addition, the individual must compensate for the loss of sensation and provide balance over the prosthetic limb.7,8 Even with high quality, technologically advanced prostheses, individuals with lower limb loss expend greater amounts of energy during gait.2,3,9,10
Individuals with lower limb loss walk slower, have less efficient gait patterns (asymmetry), decreased shock absorption, and increased energy expenditure.3,5,11–14 The higher the level of amputation, the greater the alterations in gait.11 The loss of the knee joint in an individual with a transfemoral (TF), as opposed to a transtibial (TT) level amputation, results in a greater loss of function,2,10 because the knee joint is the most energy efficient lower limb joint in gait.15 The contraction of the muscles around the knee is primarily eccentric, which is a more efficient form of contraction, and contributes to shock absorption at heelstrike. In addition, loss of the foot-ankle joint, which affects both levels of amputations, decreases balance and force attenuation at heelstrike and dynamic propulsion at push-off.12,15–17 Regardless of the level of amputation, deviation from normal gait characteristics results in variations in the center of gravity and causes alteration in joint excursion and muscle recruitment leading to an increased energy cost of ambulation.2,3,9
SPINAL STABILIZATION EXERCISES
As an active component of locomotion, contracting muscles support bones, ligaments, and joints.18 Coordination of muscle contraction around the spinal column helps to support and stabilize the trunk during unexpected or sudden loading and during gait.19–21 Hodges et al.22 suggest that, in anticipation of the reactive forces produced during gait, the spine is stabilized by a centrally mediated co-contraction of the anterior and posterior trunk muscles, namely the transverse abdominis (TrA) and multifidus (Mfs).18,23–25
Rehabilitation programs for individuals with limb loss typically focus on improving balance, lower limb strength, and gait, rather than incorporating functional movement patterns that coordinate lower limb movement with core strengthening.10,26,27 Spinal stabilization training is a program of exercises that focuses on recruiting stabilizing muscles of the spine (TrA and Mfs), while superimposing upper and lower limb exercises on co-contraction of these muscles.18,28,29 The exercises begin by first training the spinal stabilizers using isometric holding of the TrA. After this is accomplished, upper- and lower limb exercises are added while holding the isometric contraction to increase muscular endurance.18
To date, there have been no reported studies that have examined the efficacy of spinal stabilization exercises for individuals with lower limb loss. Typically, spinal stabilization training programs are designed to treat patients with low back pain and focus primarily on reducing pain and increasing function in this population. The purpose of this study was to determine whether a spinal stabilization exercise-training program would improve the spatial and temporal parameters of gait in individuals with lower limb loss.
A convenience sample of 34 participants, 19 with TT and 15 with TF amputations, were recruited from three prosthetic centers located in Long Island, NY. The subjects were men and women between the ages of 18 and 70 years and had been wearing their present prosthesis for at least 1 year. Most of the subjects were younger, more active, and physically fit than typical individuals with lower limb loss. Several subjects participated in sports on a competitive level, and almost half participated in recreational sports on a regular basis. The Touro College Institutional Review Board for the Protection of Human Subjects approved this study, and informed consent was obtained from the participants.
STUDY DESIGN AND INTERVENTION
This study used a repeated measures pretest-posttest design to examine the effects of spinal stabilization training on the spatial and temporal parameters of gait, including base of support (BOS), step length, stride length, velocity, and cadence in individuals with limb loss. Individuals with lower limb pain that limited ambulation or ability to exercise, those with a back condition for which spinal stabilization training was contraindicated, and individuals who had previously participated in spinal stabilization training were excluded from this study.
Six exercises, including abdominal bracing, were selected for the 8-week spinal stabilization-training program. Each exercise, as described in Table 1, included sequences for progressing from easier to more difficult levels during the training period. Progression of exercise difficulty was accomplished by increasing both the excursion and the number of limb movements. The rate of progression was modified on an individual basis, and the number of exercises was minimized to encourage compliance. The selection criteria were based on the muscles recruited by the exercises, the ease of progression from one exercise level to the next, and consideration for the time required to complete an exercise session. According to Liebenson,18 utilization of these exercises would be an effective method for facilitating and strengthening the TrA and Mfs musculature.
All subjects were brought into their respective prosthetic centers for three sessions within a 9-week period. At the first session, subjects signed the informed consent document, completed an information form, participated in baseline data collection in their present prosthesis, and were instructed in the spinal stabilization exercises. Baseline gait characteristics were measured using the GAITRite System, manufactured by CIR Systems Inc. (Clifton, NY), which consists of a 3 ft by 15 ft electronic walkway embedded with an active sensing area 2 ft by 12 ft, that uses a Windows-based computer software program for gait analysis. Gait analysis in this study included measurement of BOS, step length, stride length, gait velocity, and cadence.
The GAITRite System has demonstrated high reliability for measurement of gait in normal subjects30,31,32 but has not been established for individuals with lower limb loss. Therefore, in this study, the reliability of the GAITRite System for measurement of gait characteristics in individuals with lower limb loss was determined with a test-retest procedure. Subjects completed three passes or trials on the GAITRite walkway to assess initial gait characteristics. Although the first pass served to familiarize subjects with the walkway and test procedures, the next two trials were recorded as baseline data. For each trial, subjects began walking 10 ft before and continued walking 10 ft past the GAITRite walkway, so that steps measured on the walkway were more representative of a normal gait pattern for these subjects.
In addition, all subjects were instructed in the spinal stabilization program, viewed a video of the exercises, and were given a copy to take home. The video included instruction of proper exercise techniques and description of exercise progressions. All subjects were provided with a journal to record their exercise and training progress throughout the 8-week study. Subjects were told to check off exercises on completion, comment on their exercise progress, and report any difficulty they had with the training program. Included with the journal were written instructions for each of the six exercises. During the second meeting, 1 week later, the investigators reassessed each subject's ability to perform the exercises correctly. Any modification of exercise technique was discussed with the subject and initiated at that time. Questions concerning exercise progression were answered during weekly contacts with the subjects. Investigators maintained a log of all communication with subjects. Previous studies33 have demonstrated that communication, video instructions, and diaries have helped to improve compliance with exercise programs. At the end of 8 weeks of training, each participant was retested on the GAITRite System using the same protocol used at baseline to assess any changes in gait parameters. During this meeting, subjects also submitted their exercise journals.
Anthropometric data, including age, height, and weight for men and women are reported as means and standard deviations. In addition, cause of amputation, time since amputation, and frequency of weekly exercise for men and women are described in Table 2. Reliability of measurement for all gait parameters with the GAITRite System was determined with a test-retest procedure and analyzed with Pearson Product-Moment Correlation Coefficients. Two-tailed paired t-tests were used for pretraining and posttraining comparisons of all gait parameters including BOS, step length, stride length, gait velocity, and cadence. In addition, independent t-tests were used to compare differences in all gait parameters between individuals with TF and TT amputations on both pretest and posttest measurements. Statistical significance for all test comparisons was set at 5% (p ≤ 0.05). All statistical analyses were performed with IBM SPSS Software for predictive analytics version 17.
Subjects for this study consisted of 34 participants, 22 men, and 12 women, at a mean age of 44.2 ± 11.5 and 50.1 ± 14.5 years, respectively, with approximately 80% of the subjects younger than 60 years. The average heights and weights of men (176.5 ± 10.4 cm and 82.9 ± 12.1 kg) and women (163.8 ± 7.1 cm and 68.6 ± 10.8 kg) were similar to normal individuals. Nineteen subjects were amputated at the TT level, whereas 15 subjects had TF amputations. Thirty subjects listed “trauma” as the cause of amputation, whereas only four subjects cited vascular complications. At the time of the study, all subjects had had their amputations for at least 4 years. Ten of the 34 subjects had their amputations for 4 to 6 years, whereas 24 had had their amputations for more than 7 years. Approximately two thirds of the subjects (16 men and 5 women) reported exercising from one to three to four to seven times per week (Table 2). All participants had “state of the art” prostheses, with various types of energy storing feet, and either hydraulic or computerized microprocessor prosthetic knee joints in the TF prostheses.
The measurement of spatial and temporal characteristics of gait with the GAITRite System in individuals with lower limb loss proved to be highly reliable on consecutive testing as indicated by test-retest correlation coefficients as follows: amputated (r = 0.898) and sound side (r = 0.884) BOS, amputated (r = 0.976) and sound side (r = 0.949) step length, amputated (r = 0.981) and sound side (r = 0.977) stride length, gait velocity (r = 0.964), and cadence (r = 0.919).
The results of the paired t-test analysis comparing pretraining and posttraining gait measurements demonstrated significant increases in step length on the amputated side, stride length on both the amputated and sound sides, and gait velocity (Table 3). However, step length on the sound side, cadence, and BOS on the amputated and sound sides did not show significant pretraining to posttraining changes. The results of the independent t-test analysis for comparing spatial and temporal characteristics of gait between individuals with TF and TT amputations showed no significant differences in amputated and sound side step length and stride length, velocity, and cadence either for pretest or posttest comparisons. However, BOS measures were significantly different between individuals with TF and TT amputation on the amputated side for pretest and on the amputated and sound sides for posttest comparisons.
JOURNALS AND PERSONAL COMMUNICATIONS
Weekly exercise journals were returned by 22 of 34 subjects. Positive comments were noted in the journals or recorded by the investigators during weekly contacts. Several subjects reported that they “felt stronger,” whereas others stated that the exercises had improved their balance. One subject felt that the exercises had improved his skiing techniques, and another stated that they improved his running endurance.
Although previous studies have shown that the measurement of gait characteristics with the GAITRite System is highly reliable in normal individuals,30,31,32 there have been no reported studies on the reliability of the measurement of gait characteristics in individuals with lower limb loss. In this study, the measurement of gait characteristics with the GAITRite System has been shown to be highly reliable in all measures of gait in individuals with lower limb loss.
The results of the pretest to posttest comparisons showed significant increases in step length on the amputated side, stride length on both sound and amputated sides, and gait velocity, thus supporting the research hypothesis that an 8-week training program of spinal stabilization exercises would significantly increase selected gait parameters.
Step length is reflective of the time spent in stance15 and is indicative of the ability to bear weight on the stance limb. According to Tokuno et al.,6 stability and weightbearing on the stance limb are valid predictors of step length. In addition, the control and forward momentum of the swing limb also influence distance covered during a step. Therefore, an increased prosthetic step length represents stability on the prosthetic side and control on the sound side, and it may indicate improved reaching ability of the intact limb and increased stance tolerance on the prosthetic limb.
Increases in limb stability and control produced by proximal stability are further supported by the significant increases in stride length that were found on both the sound and amputated sides. The distance measured in stride is dependent on the function of both limbs. Therefore, significant increases in the stride length represent improvements in both stance and swing. In amputated side stride length, the stance component is directly related to weightbearing and stability on the prosthesis. Swing phase improvements indicate increased prosthetic control, with an increased ability to reach forward with that limb.
Although changes in sound side step length were not found to be significant in this study, stride length that considers stance and swing together showed a significant increase on both amputated and sound sides. Because the right and left legs are interdependent during gait, the significant increases in stride length on both sides were perhaps a more important finding than the step length increases on the prosthetic side.6,34 This may indicate an improved core stability that would increase weightbearing on both limbs and increase control of the lower limbs.
The significant increases found for gait velocity in this study demonstrated an increase in self-selected walking speed. Waters and Mulroy3 have observed that individuals with lower limb loss intuitively choose a walking speed that requires the lowest energy expenditure. Therefore, increases in velocity may suggest that the subjects attained a more efficient gait at higher self-selected walking speeds.35
Although increases in gait velocity proved to be significant, changes in cadence were not significantly different after spinal stabilization training. Several investigators15,36 have shown that increases in gait velocity were related to increases in both step length and cadence. However, Norkin and Levange37 have reported significant variability in the way individuals increase walking speed. Some individuals increase step length, whereas others increase cadence. Therefore, an increase in gait velocity may be due to increases in step length or cadence.
Although the investigators would have normally expected to see differences in several of the gait characteristics between individuals with TT and TF amputations, this findings only demonstrated significant differences in BOS, with wider BOS values in individuals with TF amputations. Individuals with TF amputations seem to ambulate with a wider than normal BOS than individuals with TT amputations. As in able-bodied individuals, individuals with lower limb loss must shift their pelvis toward the weightbearing side to maintain stability at mid-stance, and this pelvic shift may be greater for individuals with TF amputations, because they are missing the joint proprioception that a normal knee usually provides. They also lack muscle afferents and have less musculature in the lower limb and a shorter lever arm to act on their prosthesis. Although other measures of gait including step length, stride length, gait velocity, and cadence showed reasonably large differences between individuals with TT and TF amputations, the lack of significance may be partially explained by the unusually large variability in these measures on both pretests and posttests.
LIMITATIONS OF THE STUDY
The results of this study should be interpreted in light of several limitations. In addition to the lack of a control group, the subjects in this study were younger, more active, and more physically fit than typical individuals with lower limb loss.3 Therefore, researchers should be cautioned about generalizing the results of this study to the typically older, more debilitated population of individuals with lower limb loss.
Exercises performed in the quadruped position were found to be problematic for some individuals. Balancing and stabilizing the body on hands and knees were challenging for subjects with TF amputations. In subjects with TT amputations, increased pressure on the anterior portion of the tibia at the top of the socket resulted in pain in the residual limb. Perhaps, core-strengthening performed prone would have been a more appropriate choice, because prone position exercise facilitates contraction of the same muscles activated in quadruped position exercise.18,38
One inclusion criterion stated that changes or alignment adjustments to the subjects' prostheses would not be allowed during the 8-week training period. Although the majority of the subjects did not have adjustments, and none replaced their prosthesis, some subjects required alignment or socket adjustments to prevent injury to the residual limb. Therefore, it may be important to allow prosthetic adjustments when necessary to prevent injury to the residual limb.
SUGGESTIONS FOR FURTHER RESEARCH
This study indicated the potential clinical benefits of including spinal stabilization exercises in a rehabilitation program for individuals with lower limb loss. Further studies with larger sample size and the inclusion of a control group would increase the strength of these results. In addition, studies using subjects who are more representative of the older, more debilitated population of individuals with lower limb loss would be clinically useful. Other studies could examine the effects of spinal stabilization exercises on gait parameters not assessed in this study such as gait symmetry in terms of differences in step length, stance time and weightbearing on the sound and amputated sides, and self-selected walking speed over longer distances.
This study evaluated the effects of an 8-week spinal stabilization training program on the spatial and temporal parameters of gait in individuals with lower limb loss. Amputated side step length, sound and amputated side stride length, and gait velocity were significantly higher after exercise intervention, suggesting that spinal stabilization exercise training may be an effective method of improving gait in this population. The results of this study further suggest that individuals with lower limb loss may benefit from redirecting exercise programs to focus more on core strengthening to improve stability and control of the prosthesis and promote more balanced weight acceptance on the sound and prosthetic limbs.
The authors would like to acknowledge Advanced Prosthetics & Orthotic, Inc., A Step Ahead Prosthetics & Orthotics and Progressive Orthotics & Prosthetics for their kind assistance and professional cooperation in providing access to their patient populations as well as the use of their facilities.
1.Underwood HA, Tokuno CD, Eng JJ. A comparison of two prosthetic feet on the multi-joint and multi-plane kinetic gait compensations in individuals with a unilateral trans-tibial amputation. Clin Biomech (Bristol Avon)
2.Czerniecki J. Rehabilitation
in limb deficiency. 1. Gait and motion analysis. Arch Phys Med Rehabil
3.Waters RL, Mulroy SJ. Energy expenditure of walking in individuals with lower limb amputation. In: Atlas of Amputations and Limb Deficiencies: Surgical and Prosthetics.
Rosemont, IL: American Academy of Orthopaedic Surgeons; 2004:395–407.
4.Macfarlane P, Nielsen D, Shurr D. Mechanical gait analysis of transfemoral amputees: SACH foot versus the Flex-Foot. J Prosthet Orthot
5.Yack HJ, Nielsen DH, Shurr D. Kinetic patterns during stair ascent in patients with transtibial amputations using three different prosthesis. J Prosthet Orthot
6.Tokuno C, Sanderson D, Inglis T, Chua R. Postural and movement adaptations by individuals with a unilateral below-knee amputation during gait initiation. Gait Posture
7.Miller W, Speechley M, Deathe AB. Balance confidence among people with lower-limb amputations. Phys Ther
8.Zuniga EN, Leavitt LA, Calvert JC, et al. Gait patterns in above-knee amputees. Arch Phys Med Rehabil
9.Bateni H, Olney S. Kinematics and kinetic variations of below-knee amputee gait. J Prosthet Orthot
10.Seymour R. Prosthetics and Orthotics.
Philadelphia, PA: Lippincott Williams & Wilkins; 2002.
11.Gard SA, Konz RJ. Effect of a shock-absorbing pylon on the gait of persons with unilateral transtibial amputation. J Rehabil Res Dev
12.Engsberg JR, Herbert LM, Grimston SK, et al. Relation among indices of effort and oxygen uptake in below-knee amputee and able-bodied children. Arc Phys Med Rehabil
13.Isakov E, Keren O, Benjuya N. Trans-tibial amputee gait: time-distance parameters and EMG activity. Prosthet Orthot Int
14.Nolan L, Wit A, Dudziñski K, et al. Adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. Gait Posture
15.Perry J. Gait Analysis: Normal and Pathological Function.
NJ: Slack; 1992.
16.Hafner BJ, Sanders JE, Czerniecki JM, Fergason J. Transtibial energy-storage-and-return prosthetic devices: a review of energy concepts and a proposed nomenclature. J Rehabil Res Dev
17.Trantowski-Farrell R, Pinzur M. A preliminary comparison of function and outcome in patients with diabetic dysvascular disease. J Prosthet Orthot
18.Liebenson C. Spinal stabilization training: the transverse abdominus. J Bodyw Mov Ther
19.Bullock-Saxton J, Janda V, Bullock M. Reflex activation of gluteal muscles in walking. Spine
20.Hodges PW, Holm AK, Holm S, et al. Intervertebral stiffness of the spine is increased by evoked contraction of transversus abdominis and the diaphragm: in vivo porcine studies. Spine
21.Lee D. The Pelvic Girdle: An Approach to the Examination and Treatment of the Lumbo-Pelvic-Hip Region
. Edinburgh, UK: Churchill Livingstone; 1999:35.
22.Hodges PW, Richardson C, Hasan Z. Contraction of the abdominal muscles associated with movement of the lower limb. Phys Ther
23.Cholewicki J, VanVliet JJ IV. Relative contribution of trunk muscles to the stability of the lumbar spine during isometric exertions. Clin Biomech (Bristol, Avon)
24.Panjabi MM. The stabilizing system of the spine. Part I. Function, dysfunction, adaptation and enhancement. J Spinal Disord
25.Panjabi MM. The stabilizing system of the spine. Part II. Neutral some and instability hypothesis. J Spinal Disord
26.Eisert O, Tester OW. Dynamic exercises of lower extremity amputees. Arch Phys Med Rehabil
27.Gailey RS, Gailey AM. Prosthetic Gait Training Program For Lower Extremity Amputees.
Miami: Advanced Rehabilitation
Therapy Inc.; 1989.
29.Jemmett R. Spinal Stabilization—The New Science of Back Pain
. 2nd ed. Halifax: Novont Health Publishing; 2003.
30.Dutton M. Orthopaedic Examination, Evaluation and Intervention.
NY: McGraw Hill; 2004.
31.GAITRite User's Guide.
Clifton, NY: CIR Systems Inc.; 2004.
32.Bilney B, Morris M, Webster K. Concurrent related validity of the GAITRite walkway system for quantification of the spatial and temporal parameters of gait. Gait Posture
33.Alexandre NM, Nordin M, Hiebert R, Campello M. Predictors of compliance with short-term treatment among patients with back pain. Rev Panam Salud Publica.
34.Sadeghi H, Prince F, Zabjek KF, Labelle H. Simultaneous, bilateral, and three-dimensional gait analysis of elderly people without impairments. Am J Phys Med Rehabil
35.Sjödahl C, Jarnlo GG, Söderberg B, Persson BM. Pelvic motion in trans-femoral amputees in the frontal and transverse plane before and after special gait re-education. Prosthet Orthot Int
36.Smith L, Weiss E, Lehmkuhl L. Brunnstrom's Clinical Kinesiology
. 5th ed. Philadelphia, PA: F.A. Davis Company; 1996.
37.Norkin C, Levangie P. Joint Structure and Function: A Comprehensive Analysis
. 2nd ed. Philadelphia, PA: F.A. Davis Company; 1992.
38.Lehman GJ, Lennon D, Tresidder B, et al. Muscle recruitment patterns during the prone leg extension. BMC Musculoskelet Disord