C. GERALD WARREN, M.P.A., and JUSTUS F. LEHMANN, M.D. Weight-bearing orthoses have been designed with the primary goal of reducing or eliminating weight bearing in skeletal structures. In evaluating various designs and adjustments of these orthoses, we found that the training of the subject in the use of his orthosis was one of the most significant factors in controlling weight bearing. Subjects fitted with instrumented ischial weight-bearing and patellar-tendon-bearing orthoses walked over a force plate which measured forces imparted to the floor. The force data from the orthoses and force plate were computer-processed with single frame, multiple exposure photographic data to provide plots of axial loading in the orthosis and total axial loading imparted to the floor during the duration of the stance phase. The difference between these two forces represents the load carried by the skeletal system. Measurements were made first with subjects who had no specific instructions about the use of their orthoses. The subjects were then instructed how to use their orthoses more efficiently. In all cases, the effect of training produced a 30 to 50 percent increase in loading borne through the orthosis.
The principles of weight-bearing ortho ses were reported as early as the mid-seven teenth century by Thomas who was the originator of what we have come to know as the Thomas Ring. 1 This orthosis was designed to carry the body weight from the ischium through double uprights to the floor. More recently, adaptations of the prosthetic socket design have been incorporated into a quadri lateral shell, which replaces the thigh lacer and ring in the ischial weight-bearing orthosis. The shell provides much more comfort to the wearer and is more effective in transmitting the body weight from the ischium and upper thigh to the floor, bypassing the lower thigh, knee, leg, and foot. 2
Mr. Warren is Assistant Professor and Coordinator of Research, Department of Rehabilitation Medicine, University of Washington School of Medicine, Seattle, WA 98105. Dr. Lehmann is Professor and Chairman, Depart ment of Rehabilitation Medicine, University of Wash ington School of Medicine. This article was adapted from an original investiga tive study presented at the annual conference of the American Physical Therapy Association in Houston in 1973. This project was supported in part by Social Rehabilitation Service Grant No. 16-P-56818/0-10.
Volume 55 /Number 5, May 1975
The development of the patellar-tendonbearing prosthesis led to the design of a patellar-tendon-bearing shell for use as a belowknee weight-bearing orthosis. 3 Body weight is transmitted from the patellar tendon and the medial flare of the tibia through the orthosis to the floor, bypassing the lower tibia, ankle, and foot. 4 Our study was undertaken to determine the effectiveness of weight bearing in these orthoses and the effects of training in their use on the load borne through the orthoses. METHOD To measure the effectiveness of weight bearing in these orthoses and the effects of training, each orthosis design was instrumented by installing strain gauge transducers in the uprights just above the ankle joints. The gauges measured axial forces in the orthoses, and a force plate in a walkway measured vertical and shear forces imparted to the floor. Single frame, multiple exposure photography was used to record the angular relationship of the orthosis to the force plate at each instant when force data were recorded. The angles were used with coincident vertical and fore-aft shear values to calculate the axial force transmitted to the
487
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
Effect of Training on the Use of Weight-Bearing Orthoses
FORCE PLATE
ISCHIAL WEIGHT-BEARING ORTHOSES
PERCENT OF STANCE
AXIAL FORCE
Fig. 1. Average axial force in force plate and in ischial weight-bearing orthosis with free ankle, fixed knee, and quadrilateral shell before training. floor. Thus, the total axial force transmitted to the floor and the axial force which was carried by the orthoses could be compared, the difference between the two being the force carried by the skeletal system. 2,3 The output from the strain gauge transducers and from the force plate were collected by signal conditioning equipment and were re corded by an on-line digital data collection system which includes a Honeywell DDP 516 computer. 2 For each evaluation, the subject walked over the force plate five times. Because the duration of each stance phase varied, the
METATARSAL HEADS
Fig. 2. Roentgenogram of foot in shoe with orthosis attached, showing metatarsal head contact and heel clearance. 488
A normal volunteer was fitted with an instrumented ischial weight-bearing orthosis with a plastic quadrilateral shell, double up rights, fixed knee joints, ankle joints which could be either fixed or free, struts on the stirrup, and a sole plate to the metatarsal heads. The subject was given time to familiarize himself with walking with the orthosis, but he was given no instruction in its use. He then walked over the force plate five times at a rate and length of stride which felt most comfort able to him. Figure 1 shows the average force curves of an untrained subject using a free ankle joint. The upper curve shows the total axial force transmitted to the floor, and the lower curve shows the axial force measured in the uprights. Loading in the orthosis reached a maximum at 30 percent of stance phase, but dropped off markedly after 60 percent of stance. The increase in skeletal weight bearing late in the stance phase resulted from active push-off and consequent loading of the meta tarsal heads. The point at which this force is transmitted through the sole to the floor is shown in the photograph of a roentgenogram (Fig. 2). Since it is difficult to learn to avoid active push-off, the subject was instructed to dorsiflex his foot during the latter part of stance. After he practiced until he was satisfied he was performing the instructed maneuver (3-5 steps), data were recorded. As shown in Figure 3, the instruction produced increased weight bearing in the orthosis, especially in the latter part of the stance; however, the lack of push-off produced considerable gait abnormality. Fixation of the ankle joint in dorsiflexion provided some compensation for the lack of push-off. The subject in this case was instructed to rock over the end of the sole plate and to avoid active push-off in the shoe. A practice period was allowed before data were recorded. These changes produced a more normal gait pattern without decreasing the load in the orthosis (Fig. 4). A rocker-bottom foot was then added to the PHYSICAL THERAPY
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
BRACE
data were made comparable by plotting them using percent of stance phase as the abscissa. The data could then be averaged for each evaluation.
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Fig. 3. Average axial force in force plate and in ischial weight-bearing orthosis with free ankle, fixed knee, and quadrilateral shell after training.
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Fig. 4. Average axial force in force plate and in ischial weight-bearing orthosis with fixed ankle, fixed knee, and quadrilateral shell after training. 1000
fixed ankle orthosis to eliminate push-off entirely, and the shoe on the opposite side was built up to compensate for the increase in height. These changes, however, produced some gait instability. The subject was then instructed to load the shell maximally by extending his hip early in the stance phase and to sit on the posterior rim of the shell. Manual application of pressure to the area contacted by the posterior rim of the shell facilitated the instruction. Again, after the subject practiced for a few steps, data from five passes over the force plate were recorded. These additional instructions, combined with the use of the rocker bottom, enabled the subject to place nearly all his weight on the orthosis uprights, as can be seen in Figure 5.
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PERCENT OF STANCE .
A X I A L FORCE
PATELLAR-TENDON-BEARING ORTHOSES
Fig. 5. Average axial force in force plate and in ischial weight-bearing orthosis with fixed ankle, fixed knee, rocker bottom, and quadrilateral shell after training.
The next series of measurements was made with instrumented patellar-tendon-bearing or thoses fitted to three normal subjects. The orthoses were fabricated as bivalved shells closed by metal ski boot buckles, and they had double-stopped ankle joints which could be set either fixed or free. Metal sole plates extended to the metatarsal heads. When fixed, the ankle joint was set in 7 degrees of dorsiflexion with the orthosis shell at a forward tilt of 10 degrees
from the vertical. This adjustment had been found to be optimal from the standpoint of comfort and function. 4 Heel clearance in the shoe was set at one centimeter. Figure 6 shows the average force curves for five steps for each of the three untrained subjects using a free ankle design. In this instance, the orthoses bore less than 20 percent of body weight; and, in all instances, a marked
Volume 55 / Number 5, May 1975
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Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
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Fig. 6. Average axial force in force plate and in patellar weight-bearing orthosis with free ankle and one-centimeter heel clearance before training.
FORCE PLATE BRACE
PERCENT OF STANCE
AXIAL FORCE
Fig. 7. Average axial force in force plate and in patellar weight-bearing orthosis with fixed ankle and one-centimeter heel clearance after training. drop-off occurred during the latter part of the stance phase. When the ankle joints were fixed and no instruction was given, a limited increase in loading of the orthoses was produced (Fig. 7). The subjects, however, could still plantar flex their feet and load the metatarsal heads. When the subjects were instructed to dorsiflex during the latter part of stance, an increase in load borne by the orthosis was seen, similar to 490
20
PERCENT OF STANCE
PERCENT OF STANCE
Fig. 8. Average axial force in force plate and in patellar weight-bearing orthosis with fixed ankle, one-centimeter heel clearance, and rocker bottom after training.
that shown in Figure 4 for the subject trained in the use of the ischial weight-bearing orthosis. In the next set of measurements, the subjects were instructed to kneel into the shell and attempt to increase the loads imparted to the patellar shelf. Manual application of pres sure to the patellar tendon facilitated the instruction. A practice period was again pro vided until the subject believed he was ex ecuting the instruction (3-6 steps). This instruc tion, combined with the use of the rockerbottom sole, produced increased loading in the orthosis during the early part of the stance phase (Fig. 8). The force in the orthosis was maintained throughout the latter part of the stance phase, since loading of the metatarsal heads was eliminated by the use of the rocker bottom. DISCUSSION
With both the ischial weight-bearing and the patellar-tendon-bearing orthoses in the free ankle configuration, the weight borne in the orthoses for untrained subjects dropped off significantly late in the stance phase. The drop-off was considered to result from loading of the metatarsal heads, which caused these orthoses to be relatively ineffective in reducing skeletal weight bearing. If a patient were fitted PHYSICAL THERAPY
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
1000
in kneeling into the patellar shelf of the shell produced an increase in weight borne by the patellar-bearing orthosis. The training in using the weight-bearing surfaces more efficiently, in conjunction with training to avoid loading the metatarsal heads, provided an increase in weight borne by both orthoses throughout the stance phase. When using the ischial weight-bearing design, the patient should be encouraged to extend his hip early in the stance phase and "sit" on the posterior rim of the shell. With a patellartendon-bearing orthosis, he should be en couraged to kneel into the patellar shelf. Manual application of pressure to these areas can be effective in providing tactile reinforce ment. Training a patient both to avoid loading the metatarsal heads and to use the weight-bearing surfaces of his orthosis effectively are, there fore, extremely important in transferring loads from his skeletal structure to his orthosis.
COMMENTS OF DISCUSSANT
questions is most timely: What loads pass through the brace? How can loads in the brace be regulated? Subtracting strain gauge data of the brace from force plate data is a logical way to answer the first question. In fact, the instrumentation described would yield much more information which might enrich the basic report. It would be enlightening, for example, to know the interaction between the phase of gait and the angle photographed between the brace and the
Joan E. Edelstein, M.A.
Weight-bearing braces are a particularly good example of the blend of prosthetic and orthotic techniques which the physical-therapist en counters. The pursuit of answers to two major Mrs. Edelstein is Research Scientist, New York University Post-graduate Medical School, New York, NY 10016.
Volume 55 / ISkimber 5, May 1975
REFERENCES 1. Thomas H: Diseases of the Hip, Knee, and Ankle Joints with Their Deformities Treated by a New and Efficient Method. Liverpool, T. Dobb, 1876 2. Lehmann JF, Warren CG, DeLateur BJ, et al: Biomechanical evaluation of axial loading in ischial weight-bearing braces of various designs. Arch Phys Med Rehabil 51:331-337, 1970 3. Mcllmurray WJ, Greenbaum W: Patellar Tendon Bearing Socket for Weight Bearing Braces. New York, Veterans Administration Prosthetics Center, 1961 4. Lehmann JF, Warren CG, Pemberton DR, et al: Load bearing function of patellar tendon bearing braces of various designs. Arch Phys Med Rehabil 52:366-370, 1971 5. Baxter ML, Allington RO, Koepke GH: Weight-dis tribution variables in the use of crutches and canes. Phys Ther 49:360-365, 1969
491
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
with one of these orthoses without receiving some gait training, he would likely walk with the degree of protection indicated in Figures 1, 6, or 7. He could achieve greater skeletal unloading if a single forearm crutch or cane were used on the contralateral side. 5 In the use of both orthosis designs, training subjects to avoid loading the metatarsal heads produced a significant increase in the weight borne in the orthosis. In both orthoses, the use of a fixed ankle design was considered to be more satisfactory because it allowed the meta tarsal heads to be unloaded without producing a gait abnormality. This unloading was possible since the sole plate provided some push-off function which, in normal gait, is actively transmitted through the metatarsal heads. Patients fitted with weight-bearing orthoses should be instructed to avoid loading the metatarsal heads, especially during the latter part of the stance phase. A fixed ankle with a sole plate should be used, and the patient should be encouraged to hold his toes up, or pull his foot up against the top of his shoe so that he can rock over the sole plate. In cases where he cannot be trained to raise his toes or foot, greater weight bearing in the orthosis can be achieved by eliminating the possibility of push-off through the use of a rocker-bottom design with fixed ankle joints. Training subjects in techniques for using the weight-bearing surfaces of their orthoses more efficiently was also found to be a factor in increasing the amount of weight borne in the orthosis. Instruction in sitting on the ischial seat, combined with the use of the rockerbottom design, allowed virtually all body weight to be borne by the orthosis. Instruction
The principles of weight-bearing ortho ses were reported as early as the mid-seven teenth century by Thomas who was the originator of what we have come to know as the Thomas Ring. 1 This orthosis was designed to carry the body weight from the ischium through double uprights to the floor. More recently, adaptations of the prosthetic socket design have been incorporated into a quadri lateral shell, which replaces the thigh lacer and ring in the ischial weight-bearing orthosis. The shell provides much more comfort to the wearer and is more effective in transmitting the body weight from the ischium and upper thigh to the floor, bypassing the lower thigh, knee, leg, and foot. 2
Mr. Warren is Assistant Professor and Coordinator of Research, Department of Rehabilitation Medicine, University of Washington School of Medicine, Seattle, WA 98105. Dr. Lehmann is Professor and Chairman, Depart ment of Rehabilitation Medicine, University of Wash ington School of Medicine. This article was adapted from an original investiga tive study presented at the annual conference of the American Physical Therapy Association in Houston in 1973. This project was supported in part by Social Rehabilitation Service Grant No. 16-P-56818/0-10.
Volume 55 /Number 5, May 1975
The development of the patellar-tendonbearing prosthesis led to the design of a patellar-tendon-bearing shell for use as a belowknee weight-bearing orthosis. 3 Body weight is transmitted from the patellar tendon and the medial flare of the tibia through the orthosis to the floor, bypassing the lower tibia, ankle, and foot. 4 Our study was undertaken to determine the effectiveness of weight bearing in these orthoses and the effects of training in their use on the load borne through the orthoses. METHOD To measure the effectiveness of weight bearing in these orthoses and the effects of training, each orthosis design was instrumented by installing strain gauge transducers in the uprights just above the ankle joints. The gauges measured axial forces in the orthoses, and a force plate in a walkway measured vertical and shear forces imparted to the floor. Single frame, multiple exposure photography was used to record the angular relationship of the orthosis to the force plate at each instant when force data were recorded. The angles were used with coincident vertical and fore-aft shear values to calculate the axial force transmitted to the
487
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
Effect of Training on the Use of Weight-Bearing Orthoses
FORCE PLATE
ISCHIAL WEIGHT-BEARING ORTHOSES
PERCENT OF STANCE
AXIAL FORCE
Fig. 1. Average axial force in force plate and in ischial weight-bearing orthosis with free ankle, fixed knee, and quadrilateral shell before training. floor. Thus, the total axial force transmitted to the floor and the axial force which was carried by the orthoses could be compared, the difference between the two being the force carried by the skeletal system. 2,3 The output from the strain gauge transducers and from the force plate were collected by signal conditioning equipment and were re corded by an on-line digital data collection system which includes a Honeywell DDP 516 computer. 2 For each evaluation, the subject walked over the force plate five times. Because the duration of each stance phase varied, the
METATARSAL HEADS
Fig. 2. Roentgenogram of foot in shoe with orthosis attached, showing metatarsal head contact and heel clearance. 488
A normal volunteer was fitted with an instrumented ischial weight-bearing orthosis with a plastic quadrilateral shell, double up rights, fixed knee joints, ankle joints which could be either fixed or free, struts on the stirrup, and a sole plate to the metatarsal heads. The subject was given time to familiarize himself with walking with the orthosis, but he was given no instruction in its use. He then walked over the force plate five times at a rate and length of stride which felt most comfort able to him. Figure 1 shows the average force curves of an untrained subject using a free ankle joint. The upper curve shows the total axial force transmitted to the floor, and the lower curve shows the axial force measured in the uprights. Loading in the orthosis reached a maximum at 30 percent of stance phase, but dropped off markedly after 60 percent of stance. The increase in skeletal weight bearing late in the stance phase resulted from active push-off and consequent loading of the meta tarsal heads. The point at which this force is transmitted through the sole to the floor is shown in the photograph of a roentgenogram (Fig. 2). Since it is difficult to learn to avoid active push-off, the subject was instructed to dorsiflex his foot during the latter part of stance. After he practiced until he was satisfied he was performing the instructed maneuver (3-5 steps), data were recorded. As shown in Figure 3, the instruction produced increased weight bearing in the orthosis, especially in the latter part of the stance; however, the lack of push-off produced considerable gait abnormality. Fixation of the ankle joint in dorsiflexion provided some compensation for the lack of push-off. The subject in this case was instructed to rock over the end of the sole plate and to avoid active push-off in the shoe. A practice period was allowed before data were recorded. These changes produced a more normal gait pattern without decreasing the load in the orthosis (Fig. 4). A rocker-bottom foot was then added to the PHYSICAL THERAPY
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
BRACE
data were made comparable by plotting them using percent of stance phase as the abscissa. The data could then be averaged for each evaluation.
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PERCENT OF STANCE
A X I A L FORCE
A X I A L FORCE
Fig. 3. Average axial force in force plate and in ischial weight-bearing orthosis with free ankle, fixed knee, and quadrilateral shell after training.
80
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100
Fig. 4. Average axial force in force plate and in ischial weight-bearing orthosis with fixed ankle, fixed knee, and quadrilateral shell after training. 1000
fixed ankle orthosis to eliminate push-off entirely, and the shoe on the opposite side was built up to compensate for the increase in height. These changes, however, produced some gait instability. The subject was then instructed to load the shell maximally by extending his hip early in the stance phase and to sit on the posterior rim of the shell. Manual application of pressure to the area contacted by the posterior rim of the shell facilitated the instruction. Again, after the subject practiced for a few steps, data from five passes over the force plate were recorded. These additional instructions, combined with the use of the rocker bottom, enabled the subject to place nearly all his weight on the orthosis uprights, as can be seen in Figure 5.
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PERCENT OF STANCE .
A X I A L FORCE
PATELLAR-TENDON-BEARING ORTHOSES
Fig. 5. Average axial force in force plate and in ischial weight-bearing orthosis with fixed ankle, fixed knee, rocker bottom, and quadrilateral shell after training.
The next series of measurements was made with instrumented patellar-tendon-bearing or thoses fitted to three normal subjects. The orthoses were fabricated as bivalved shells closed by metal ski boot buckles, and they had double-stopped ankle joints which could be set either fixed or free. Metal sole plates extended to the metatarsal heads. When fixed, the ankle joint was set in 7 degrees of dorsiflexion with the orthosis shell at a forward tilt of 10 degrees
from the vertical. This adjustment had been found to be optimal from the standpoint of comfort and function. 4 Heel clearance in the shoe was set at one centimeter. Figure 6 shows the average force curves for five steps for each of the three untrained subjects using a free ankle design. In this instance, the orthoses bore less than 20 percent of body weight; and, in all instances, a marked
Volume 55 / Number 5, May 1975
489
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
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Fig. 6. Average axial force in force plate and in patellar weight-bearing orthosis with free ankle and one-centimeter heel clearance before training.
FORCE PLATE BRACE
PERCENT OF STANCE
AXIAL FORCE
Fig. 7. Average axial force in force plate and in patellar weight-bearing orthosis with fixed ankle and one-centimeter heel clearance after training. drop-off occurred during the latter part of the stance phase. When the ankle joints were fixed and no instruction was given, a limited increase in loading of the orthoses was produced (Fig. 7). The subjects, however, could still plantar flex their feet and load the metatarsal heads. When the subjects were instructed to dorsiflex during the latter part of stance, an increase in load borne by the orthosis was seen, similar to 490
20
PERCENT OF STANCE
PERCENT OF STANCE
Fig. 8. Average axial force in force plate and in patellar weight-bearing orthosis with fixed ankle, one-centimeter heel clearance, and rocker bottom after training.
that shown in Figure 4 for the subject trained in the use of the ischial weight-bearing orthosis. In the next set of measurements, the subjects were instructed to kneel into the shell and attempt to increase the loads imparted to the patellar shelf. Manual application of pres sure to the patellar tendon facilitated the instruction. A practice period was again pro vided until the subject believed he was ex ecuting the instruction (3-6 steps). This instruc tion, combined with the use of the rockerbottom sole, produced increased loading in the orthosis during the early part of the stance phase (Fig. 8). The force in the orthosis was maintained throughout the latter part of the stance phase, since loading of the metatarsal heads was eliminated by the use of the rocker bottom. DISCUSSION
With both the ischial weight-bearing and the patellar-tendon-bearing orthoses in the free ankle configuration, the weight borne in the orthoses for untrained subjects dropped off significantly late in the stance phase. The drop-off was considered to result from loading of the metatarsal heads, which caused these orthoses to be relatively ineffective in reducing skeletal weight bearing. If a patient were fitted PHYSICAL THERAPY
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
1000
in kneeling into the patellar shelf of the shell produced an increase in weight borne by the patellar-bearing orthosis. The training in using the weight-bearing surfaces more efficiently, in conjunction with training to avoid loading the metatarsal heads, provided an increase in weight borne by both orthoses throughout the stance phase. When using the ischial weight-bearing design, the patient should be encouraged to extend his hip early in the stance phase and "sit" on the posterior rim of the shell. With a patellartendon-bearing orthosis, he should be en couraged to kneel into the patellar shelf. Manual application of pressure to these areas can be effective in providing tactile reinforce ment. Training a patient both to avoid loading the metatarsal heads and to use the weight-bearing surfaces of his orthosis effectively are, there fore, extremely important in transferring loads from his skeletal structure to his orthosis.
COMMENTS OF DISCUSSANT
questions is most timely: What loads pass through the brace? How can loads in the brace be regulated? Subtracting strain gauge data of the brace from force plate data is a logical way to answer the first question. In fact, the instrumentation described would yield much more information which might enrich the basic report. It would be enlightening, for example, to know the interaction between the phase of gait and the angle photographed between the brace and the
Joan E. Edelstein, M.A.
Weight-bearing braces are a particularly good example of the blend of prosthetic and orthotic techniques which the physical-therapist en counters. The pursuit of answers to two major Mrs. Edelstein is Research Scientist, New York University Post-graduate Medical School, New York, NY 10016.
Volume 55 / ISkimber 5, May 1975
REFERENCES 1. Thomas H: Diseases of the Hip, Knee, and Ankle Joints with Their Deformities Treated by a New and Efficient Method. Liverpool, T. Dobb, 1876 2. Lehmann JF, Warren CG, DeLateur BJ, et al: Biomechanical evaluation of axial loading in ischial weight-bearing braces of various designs. Arch Phys Med Rehabil 51:331-337, 1970 3. Mcllmurray WJ, Greenbaum W: Patellar Tendon Bearing Socket for Weight Bearing Braces. New York, Veterans Administration Prosthetics Center, 1961 4. Lehmann JF, Warren CG, Pemberton DR, et al: Load bearing function of patellar tendon bearing braces of various designs. Arch Phys Med Rehabil 52:366-370, 1971 5. Baxter ML, Allington RO, Koepke GH: Weight-dis tribution variables in the use of crutches and canes. Phys Ther 49:360-365, 1969
491
Downloaded from https://academic.oup.com/ptj/article-abstract/55/5/487/4567616 by Washington University School of Medicine Library user on 14 February 2019
with one of these orthoses without receiving some gait training, he would likely walk with the degree of protection indicated in Figures 1, 6, or 7. He could achieve greater skeletal unloading if a single forearm crutch or cane were used on the contralateral side. 5 In the use of both orthosis designs, training subjects to avoid loading the metatarsal heads produced a significant increase in the weight borne in the orthosis. In both orthoses, the use of a fixed ankle design was considered to be more satisfactory because it allowed the meta tarsal heads to be unloaded without producing a gait abnormality. This unloading was possible since the sole plate provided some push-off function which, in normal gait, is actively transmitted through the metatarsal heads. Patients fitted with weight-bearing orthoses should be instructed to avoid loading the metatarsal heads, especially during the latter part of the stance phase. A fixed ankle with a sole plate should be used, and the patient should be encouraged to hold his toes up, or pull his foot up against the top of his shoe so that he can rock over the sole plate. In cases where he cannot be trained to raise his toes or foot, greater weight bearing in the orthosis can be achieved by eliminating the possibility of push-off through the use of a rocker-bottom design with fixed ankle joints. Training subjects in techniques for using the weight-bearing surfaces of their orthoses more efficiently was also found to be a factor in increasing the amount of weight borne in the orthosis. Instruction in sitting on the ischial seat, combined with the use of the rockerbottom design, allowed virtually all body weight to be borne by the orthosis. Instruction
