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OUTLINE

 1.  Abstract
 2.  KEYWORDS
 3.  List of Abbreviations
 4.  Methods
 5.  Results
 6.  Discussion
 7.  Conclusions
 8.  Suppliers
 9.  Appendix. Supplementary materials
 10. References

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TABLES (3)

 1. Table 1
 2. Table 2
 3. Table




EXTRAS (1)

 1. Document




ARCHIVES OF REHABILITATION RESEARCH AND CLINICAL TRANSLATION

Volume 4, Issue 3, September 2022, 100200

ORIGINAL RESEARCH
A PROSPECTIVE ASSESSMENT OF AN ADJUSTABLE, IMMEDIATE FIT, SUBISCHIAL
TRANSFEMORAL PROSTHESIS

Author links open overlay panelTimothy R. Dillingham MD, MS a, Jessica L. Kenia
MS a, Frances S. Shofer PhD b, James S. Marschalek MS c
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ABSTRACT


OBJECTIVE

To assess the feasibility of an adjustable, subischial transfemoral prosthesis
by comparing self-reported outcome measures regarding socket comfort, fit and
utility relative to a persons’ conventionally made socket. Assessing limb
compressibility was another aim of this study.


DESIGN

A single-group pre-post intervention design.


SETTING

Physical medicine and rehabilitation biomechanics laboratory.


PARTICIPANTS

All 18 enrolled participants (N = 18) completed the feasibility trial. There
were 16 men and 2 women with an average age of 59.4 (±7) years. Most of the
participants (61.1%) had worn a socket for 1 to 10 years before the trial, 22.2%
of the participants had worn one for less than a year, and 16.7% of the
participants had worn a prosthesis for more than 10 years.


INTERVENTION

Participants were fit with the study prosthesis and used it for a 2-week home
trial.


MAIN OUTCOME MEASURES

A Prosthetic Comfort and Utility Questionnaire was completed on the
participant's conventional prosthetic device and the subischial socket system
after the trial.


RESULTS

The adjustable subischial prostheses were rated superior overall to the
participant's conventional sockets (40.9 ± 7.2 vs 32.8 ± 10.8; P=.004). Six of
the 10 parameters measured (adjustability, overall fit, prosthesis weight,
sitting comfort, standing comfort, and standing stability) were rated higher for
the adjustable prostheses compared to the conventional sockets. Compression of
the soft tissues of the thigh ranged from 5.6 ± 4.2 cm at the distal end to 7.3
± 3.6 cm at the proximal site. There were no falls, skin breakdown, or limb
ischemia. At the 2-month telephone follow-up, 61% of subjects had transitioned
to using the adjustable subischial socket most of the time.


CONCLUSIONS

The adjustable, immediate fit, subischial prosthesis provided safe, comfortable,
and functional ambulation for persons with transfemoral limb loss in this
short-term feasibility study. This study supports the consideration of a new
paradigm in transfemoral prosthetics—adjustable subischial sockets. These
devices should be tested in a larger multi-center study.

 * Previous article in issue
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KEYWORDS

Adjustable prosthesis
Amputation
Limb loss
Prosthetic
Transfemoral amputation
Transfemoral prosthesis


LIST OF ABBREVIATIONS

PCUQ
Prosthetic Comfort and Utility Questionnaire
PEQ
Prosthetic Evaluation Questionnaire

Traditional prosthesis fabrication often results in a hard socket that cannot
easily be adjusted to accommodate residual limb changes. The typical
transfemoral socket extends high up onto the leg— to the ischial tuberosity and
ischial ramus area and are called quadrilateral or ischial containment
sockets.1, 2, 3, 4, 5, 6, 7, 8 The residual limb changes significantly during
the first year after amputation in size and shape.9 Limb volume fluctuates daily
for many individuals, particularly those persons with renal and heart
disease.10,11 Conventional hard sockets accommodate volume changes by adding or
removing layers of socks to adjust socket volume—an often time-consuming process
requiring the patient to find a private location and disrobe.

Many persons with lower limb loss report substantial discomfort and pain with
their conventional sockets.12, 13, 14, 15 Data from a large, nationwide survey
of prosthesis users (n=934, of whom 38.5% had transfemoral limb loss) who were
members of the nonprofit advocacy group Amputee Coalition of America indicated
that one-third of adult respondents reported discomfort with their prosthesis.12
Another study involving persons with traumatic amputation found that only 43% of
the transfemoral participants reported satisfaction with prosthesis comfort.13 A
survey by the U.S. Department of Veterans Affairs indicated that an average of
45% of people with transfemoral limb loss wished to change to a different socket
type.14 Three out of 5 people reported seeking care from multiple prosthetists
because they were dissatisfied with the fit of their conventional devices or the
prosthetic services received.15

Comfort is, by far, the single most important characteristic correlated with
successful prosthetic ambulation yet is often lacking.12, 13, 14, 15, 16, 17
Residual limb pain and skin issues are prominent issues that lead to reduced
socket comfort among the adult population.12, 13, 14 Fully 63% of Operation
Enduring Freedom/Operation Iraqi Freedom respondents reported skin problems on
the residual limb and 54% of Vietnam War veteran respondents reported this
problem as well.14 Prosthesis satisfaction and increased use also have been
shown to significantly influence the likelihood of returning to work.18,19

The quadrilateral socket and the ischial containment (narrow mediolateral)
sockets have been commonly used since about the 1970s.1, 2, 3 The posterior wall
of the quadrilateral socket forms a flat area for weight bearing through the
ischial tuberosity and gluteal muscles.1,3,4 The lateral wall is contoured over
the greater trochanter and hip abductor muscle group.5 The ischial containment
socket was developed to provide a more stable purchase on the limb.5, 6, 7 This
design encloses the ischial tuberosity and ramus and places the femur in a more
adducted position than the quadrilateral design.6,7 Both types of sockets have
been found to restrict range of motion in the residual limb.8 A lower profile,
subischial socket design has been described that uses hard socket technology and
vacuum suspension.20, 21, 22, 23, 24

To enhance comfort and function an adjustable subischial transfemoral prosthesis
was developed by iFIT Prosthetics, LLC a (fig 1). This socket was designed from
experience gained through the development and commercialization of the
transtibial immediate fit adjustable socket.25, 26, 27

 1. Download : Download high-res image (468KB)
 2. Download : Download full-size image

Fig 1. The locking buckle system for closure of the subischial socket. The
buckles (situated on the lateral leg) and hooks (placed on the medial leg) close
the adjustable socket securely around the limb.

The adjustable subischial transfemoral socket uses a buckle and cable system
like the transtibial system to provide adjustability.25, 26, 27 The transfemoral
system, however, features 3 buckles at the proximal, mid, and distal areas to
accommodate volume changes and compressibility of the thigh soft tissues and
will accommodate longer limbs. A silicone liner with locking pin attaches the
socket to the patient's limb via shuttle lock.28 This is a common method for
suspension where the pin engages securely with a lock in the base of the socket
and is removed by pressing a release pin.

Like the transtibial adjustable socket, the transfemoral socket can be fitted
and aligned using a few hand tools in a single setting. The socket features a
low profile flexible inner liner with overlapping flaps that can be trimmed and
heat molded to accommodate the patient (fig 2). The proximal trim line is
subischial for enhanced sitting comfort and hip mobility. The subischial
adjustable socket assessed in this study was designed for someone with recent
amputation who will undergo changes in limb volume and for someone who wants
adjustability throughout the day. It can be used as a preparatory prosthesis or
a definitive device.

 1. Download : Download high-res image (647KB)
 2. Download : Download full-size image

Fig 2. The adjustable subischial transfemoral prosthesis. Components: (1)
locking buckle, (2) hook, (3) steel cable, (4) offset, (5) lateral rigid frame,
(6) flexible/inner liner, (7) outer flap, and (8) cup.

The purpose of this study was to examine the feasibility of a subischial
adjustable socket for people with transfemoral limb loss. The comfort, fit, and
utility with these adjustable sockets were examined in a cohort of people with
transfemoral limb loss. We hypothesized that the new adjustable sockets would
provide safe and comfortable ambulation. Safety, comfort, and function were our
primary outcomes. Another aim of this study was to assess the amount of
compression in the socket once the participant adjusted the device to the
preferred comfortable fit.


METHODS

People with transfemoral limb loss were recruited from the University of
Pennsylvania health system through referrals, mailings, and advertisements in
the local newspapers. Inclusion criteria consisted of unilateral transfemoral
amputation, a well-healed limb, ability to ambulate using a prosthesis, weight
under 260 pounds (estimated weight limit for socket componentry), and age 21
years and over. Exclusion criteria included open wounds or skin irritations,
excessive limb pain, previous stroke, and brain injury that interfered with
ambulation. This study was reviewed and approved by the University of
Pennsylvania institutional review board, and all subjects gave written informed
consent prior to participation. Subjects shown in this paper consented to have
their images used in this manner.

All participants were consented by the research coordinator and fit by the
principal investigator of the study in the Department of Physical Medicine and
Rehabilitation Gait and Biomechanics Laboratory. The subjects had
circumferential measurements taken of their limb at the distal third, midpoint,
and proximal third, as well as from groin to end of residual limb. The
measurements were taken on the skin directly and also while wearing a silicone
pin suspension sleeve. Participants were asked to complete a Prosthetic Comfort
and Utility Questionnaire (PCUQ) (see text box 1), which featured selected
questions from the Prosthetic Evaluation Questionnaire (PEQ).29 The
questionnaire was developed by selecting questions from the full PEQ to focus on
aspects that pertained specifically to the socket such as comfort, fit,
ambulation and utility. This strategy for assessing issues related to the
prosthesis itself has been used by us in evaluation of transtibial
prostheses.25,26 Another research team used a similar short questionnaire that
was adapted from the full PEQ for studying 5 different prosthetic feet.30 We
added specific questions regarding sitting comfort because this is an important
aspect for persons with transfemoral limb loss. For ease of scoring, this
questionnaire featured 10 questions each with a numeric rating scale from 1
(poor) to 5 (excellent), the same as was used by other investigators.30 The
total points on each question were added to derive an overall patient
satisfaction score (our primary outcome) with a possible range of scores from 10
to 50. Data were collected at the initial visit on the patient's conventional
device and at the 2-week follow-up on the test prosthesis. Data were collected
by the study coordinator without the principal investigator present in the room
to minimize any influence on the patient's perceptions of the devices.

Two adjustable socket sizes—standard and wide—were developed to encompass most
people with transfemoral limb loss. The subjects were all given a silicone
locking sleeve to wear. The prosthesis was suspended by a pin suspension system
using the silicone sleeve. Subjects were placed on an exam table while the
socket was placed on the residual limb to estimate how much to trim the proximal
brim (inner liner). Excess material was trimmed so that the socket fit such that
the proximal brim was below the ischial tuberosity and ramus. After trimming and
smoothing the edges of the socket, it was placed back on the residual limb and
tightened using the buckle system until a snug yet comfortable fit was achieved.
The trim line was again re-evaluated while standing to insure that it was fully
subischial. One of 2 different knees were used. An OFM2 Balance Knee from Ossurb
was used for persons with K1 and K2 ambulation levels,31 while the Ossur Mauch
knee was used for persons that were at K3 or K4 ambulation levels. This was
determined by the patient's description of their activity levels, as well as by
assessing the subject's current knee and whether they required assistive gait
devices such as a walker or cane. The participant's own prosthetic knee was left
on their conventional device as a safety precaution. In case any issue was
encountered with the adjustable subischial test device, they would always have
their conventional prosthesis available and in good working order for safe
ambulation. An Alpsc 3mm AKHD silicone locking liner and a College Parkd Breeze
foot were used for all subjects. Two rectangles measuring 6 by 4 inches of
anti-rotation material were placed within the socket on the inside of the
flexible liner to prevent rotation between the residual limb and the device when
ambulating.

At the end of the initial fitting, circumferences of internal socket diameter
were also measured. Measurements of the internal socket were taken using an
Ottobockd Inside Circumference Gauge (Salt Lake City, UT). The internal diameter
of the socket was marked in the position (buckle closure) that the patient found
most comfortable and functional. After removing the device, the circumferences
of the inner socket were measured at the distal third, midpoint, and proximal
third of the inner socket with the socket closed at the position of the marks
corresponding to a comfortable secure fit. These were then compared to the
residual limb circumferences with and without the silicone suspension sleeve on
the limb.

Commercially available offset adaptors were initially used to achieve an optimal
knee alignment. Later in the trial, an injection molded offset was designed and
manufactured by our team that matched the socket design to provide the necessary
socket flexion and knee offset for stable gait. The offset is attached to the
socket cup. This offset provides rotation at both the bottom of the cup and
through a rotatable pyramid adapter attached to the bottom for accepting the
knee unit. The prosthesis was assembled, fit, and aligned to provide a stable
base of support for comfortable and safe ambulation with the hip in
approximately 5° of flexion. Once subjects demonstrated they were able to
properly put on and take off the device, as well as walk proficiently, they were
cleared to take the prosthesis home for a 2-week trial.

At the initial visit, the subjects rated their conventional prostheses. At the
2-week follow up appointment after the subjects used the adjustable subischial
transfemoral prosthesis, they completed the PCUQ. This information was collected
by the study coordinator without the principal investigator present. Each
participant had their residual limb inspected for skin irritation or wounds. Any
report of a fall by the subject or breakage of the prosthetic socket or
prosthetic component was recorded. They were allowed to keep the adjustable
prosthesis (socket, knee unit, pylon, and foot) if they chose to do so after the
study. Participants who kept the prosthesis were followed up through telephone
call after 2 months to determine whether they were still wearing the adjustable
prosthesis.

A sample size of 12 to 14 was predicted to achieve >80% power, with an alpha of
0.05. using a clinically meaningful difference of 1 (effect size) on an
individual PCUQ question (range of score, 1-5) with SD of the mean difference as
large as 1.3. To describe the study population, frequencies and percentages were
calculated for categorical variables, and means and standard deviations were
calculated for continuous variables. To compare responses to the individual PCUQ
questions and the patient satisfaction score between the iFIT device and
patients’ conventional device, paired t-tests were used because the mean
differences were approximately normally distributed, with only mild left skew
and lightly tailed. Results are presented as mean difference ± 95% confidence
intervals between the adjustable socket and the conventional device. All
analyses were performed using SAS statistical software (version 9.4, SAS
Institute, Cary, NC). Data were collected by the study coordinator and
maintained by her independent of the principal investigator. All statistical
analyzes were performed by the biostatistician (F.S.) independent of the
principal investigator. Figure 3 was created using GraphPad Prism (version 9.2,
GraphPad Software, Inc, San Diego, CA).

 1. Download : Download high-res image (420KB)
 2. Download : Download full-size image

Fig 3. Results of the Socket Comfort and Utility Questionnaire comparing
conventional socket (own) and immediate fit socket (iFIT) after 2-week home
trial. CI, confidence interval.


RESULTS

Eighteen people with transfemoral limb loss volunteered to participate in the
study, and none dropped out of the study or were lost to follow-up. There were
16 men and 2 women who participated and completed the study with a mean age of
59.4 (±7.0) years (table 1). Fifty-six percent were white, 33% were African
American, and 11% were Hispanic. Most of the participants (5%) wore a suction
socket system with silicone suction liner and had limb loss resulting from
dysvascular disease (55.6%).

Table 1. Description of Participants: Variables for 18 Enrolled Participants

DemographicsEmpty
CellNPercentSexMen1689Women211.1Race/ethnicityWhite1055.6African
American633.3Hispanic211.1Etiology of limb
lossDysvascular1055.6Traumatic527.8Cancer316.7Type of conventional socket
suspension (all sockets were non-adjustable hard sockets)Suction (silicone
sleeve)950Suction (Skin suction)15.6Lanyard633.3Pin15.6Strap/waist belt15.6Type
of prosthetic knee on conventional socketMechanical knee739Computerized
knee1161Length of time wearing a prosthesisLess than 1 year422.21-10
years1161.1>10 years316.7Average time wearing the conventional prosthesis during
a typical day9 or more hours1161.17-9 hours004-6 hours211.11 to 3
hours527.8Average time wearing the adjustable prosthesis during a typical day9
or more hours9507-9 hours15.54-6 hours316.71-3 hours527.8

Participants rated the adjustable subischial transfemoral prosthesis
significantly better than the conventional prosthesis on the summary
satisfaction score PCUQ survey (40.9 vs 32.9; P=.004). For all 10 questions, the
adjustable prosthesis device was rated better than the conventional prosthesis
(mean difference for all 10 questions=0.81±0.39) and for 6 of the questions
(volume changes, adjustability, prosthesis weight, sitting comfort, standing
comfort, and standing stability), the adjustable subischial prosthesis was rated
significantly better (P<.05) (fig 3). The overall score was rated better for the
adjustable socket than for the conventional prosthesis in 16 of the 18
participants. Daily wear time was not significantly different between the
sockets despite differences in knee units between the test devices and what the
subjects normally wore.

The thigh tissue compressibility showed large differences between the residual
limb measurements and the adjustable socket internal circumferences (table 2).
These differences were 7.3 cm ±3.6 proximally, 7.2 cm ±3.9 at midpoint, and 5.6
cm ±4.2 at the distal end while wearing a liner (see table 2).

Table 2. Comparison of Residual Limb Circumference Measurements to Internal
Socket Diameter to Assess Compressibility of Residual Limb Tissue

Type of Residual LimbAverage Circumference Without Suspension Sleeve (cm)Average
Circumference Wearing Suspension Sleeve (cm)Average Internal Socket
Circumference (cm)Average Difference Between Limb (with Suspension Sleeve) and
Socket Circumference (cm)Proximal third residual limb51.7 (7.2)53.6 (SD 7.2)46.3
(SD 5.3)7.3 (SD 3.6)Midpoint residual limb47.2 (7.7)47.7 (SD 6.1)40.5 (SD
4.9)7.2 (SD 3.9)Distal third residual limb40.6 (7.0)41.3 (SD 5.9)35.7 (SD
5.6)5.6 (SD 4.2)



NOTE. A cohort of 18 people with unilateral transfemoral limb loss tested an
immediate fit, adjustable subischial prosthesis for a 2-week trial. The test
prosthesis was rated as superior to their conventional prostheses in
adjustability, overall fit, prosthesis weight, sitting comfort, standing comfort
and standing stability, as well as the overall satisfaction score. In this
cohort, 61% of the subjects transitioned to using the adjustable socket full
time. Thigh tissue demonstrated a high level of compressibility. This new
subischial socket is feasible and safe for use in persons with transfemoral limb
loss.



None of the participants reported a fall, skin breakdown, or other adverse
event. There were no component failures with the adjustable devices. One subject
started biking for exercise again because his sitting comfort was improved
(fig 4).

 1. Download : Download high-res image (266KB)
 2. Download : Download full-size image

Fig 4. The subischial socket with its low profile on the leg, allowed this
subject to comfortably ride a stationary bike.

All but 1 participant who completed the home trial elected to keep the
adjustable prosthesis. The participant who did not keep the prosthesis was
getting a revision surgery. At the 2-month follow up, 11 of the 18 participants
(61%) reported that they switched to wearing the adjustable socket for most of
the time. The other 6 participants reported that they wore the adjustable socket
interchangeably with their conventional device.


DISCUSSION

In this feasibility study, the adjustable, subischial transfemoral prosthesis
was shown to be safe, comfortable, and feasible as a potential alternative to
conventional sockets. Subjects rated the adjustable subischial socket as
significantly better than conventional prostheses on the primary outcome—the
overall PCUQ survey score. The results of this study are similar to those found
when comparing adjustable transtibial prostheses to conventional transtibial
prostheses.25,26 The adjustable subischial socket appeared to accommodate thigh
tissue compression that occurs within the socket.

For 6 of the 10 questions (see fig 3), the adjustable prosthesis was rated as
significantly better. The ability to accommodate volume changes had the highest
difference in favor of the adjustable subischial socket, which is not
surprising, because most of the participants used a rigid conventional socket,
which has limited ability to accommodate volume changes. All participants were
able to use the pin suspension system and locking buckle mechanisms to fit the
socket in a secure and comfortable manner. Sitting comfort was enhanced, with
significantly better scores noted for the subischial sockets. This can be
attributed to the lower profile brim that did not extend up into the pelvic
region (ischial ramus or ischial tuberosity).

Most of the conventional sockets (55.6%) worn by the participants had suction
suspension systems, followed by lanyard suspension (33.3%). Subjects found no
significant differences in taking the prosthesis off and putting it on with the
pin suspension system used in this trial.

At the end of the study, participants were asked if they wanted to keep their
adjustable prostheses. All of the subjects, except for 1 who reported getting
limb revision surgery, kept their prosthesis. In our follow-up of this cohort
after 2 months, 61% had switched to using the adjustable subischial prosthesis
for most of the time. Some had their computerized knees put onto the adjustable
socket. These results suggest that this subischial adjustable prosthesis may be
a feasible option for many transfemoral prosthetic users.

The adjustable subischial transfemoral prosthesis was rated as more comfortable
(sitting and standing), according to self-reported outcome scores. Comfort, an
important factor in prosthesis satisfaction and use, is an important
consideration when choosing the right system for each individual.12, 13, 14, 15,
16 The average person with limb loss visits the prosthetist 9 times per year and
requires a new socket every 1 to 2 years.12,13 With an adjustable socket, these
visits can likely be reduced, because the patient can themselves make size
adjustments to accommodate changes in limb size and shape. Considerable changes
in volume occur after the first year after amputation. Socket adjustability can
help accommodate these changes more readily. Persons with heart and renal
failure also tend to exhibit daily volume fluctuations and could find an
adjustable socket useful for maintaining a better fit throughout the day.

The componentry in the adjustable sockets provides strength and compliance for a
wide range of limb circumferences and lengths. They are mass produced using
injection molding technology, which provides consistent quality and strength.

With the adjustable socket, prosthesis fitting and gait training can begin when
surgical wounds are healed. Even with edema and bulbous residual limbs, patients
can begin rehabilitation and simply adjust the socket as the limb matures and
edema resolves. This prosthesis works with most commercially available feet and
knee units.

Early ambulation can be advantageous as it helps to minimize joint contractures
and deconditioning, and is associated with higher levels of prosthesis use.32,33
A recent study by Miller et al found that receiving a prosthesis earlier, within
the first 3 months’ post-amputation, reduced health care costs by $25,000 during
the following year.32 Past studies have found that only 26%34 to 57%35 of people
with a transfemoral amputation receive a prosthesis. A study in the U.S.
Department of Veterans Affairs found that patients who received a prosthesis
within a year from amputation had a 25% 3-year mortality rate versus 45% for
those who did not receive a prosthesis.36 Decreased wait time for getting a
comfortable and functional prosthesis is linked to increased satisfaction,
higher usage, and overall better long term outcomes.12,15,37

Another group that may benefit from an adjustable socket are children with limb
deficiencies who report frequent problems with conventional sockets as they
grow.38, 39, 40 Boonstra et al found that fully 74% of children and their
parents reported skin issues within the prosthesis as a problem and that 22% had
skin breakdown at the time of the study.40 The reason for these problems was
described by these researchers as “ill-fitting prostheses.”40 There is a high
care burden for families caring for pediatric patients with lower limb loss.
Total travel time, prosthetist visit time, and therapy time for pediatric
patients and their families averaged 42.7 hours a year, according to one
study.38 Adjustable sockets that accommodate growth could address these
problems.

The adjustable subischial prosthesis described in this feasibility study
represents a departure from conventional socket shapes and biomechanical
principles. In contrast to quadrilateral and ischial containment sockets, which
extend far up the residual limb into the groin and perineum, the adjustable
sockets are lower in profile, extending up the leg to a point well below the
ischium. The soft tissues are firmly yet comfortably grasped with the adjustable
socket, and, according to the subject's self-reported outcome measures, provide
a stable base of support for safe stable ambulation.

Even though the sockets are flexible and adjustable, they provide sufficient
strength and durability for the user. These injection-molded sockets underwent
cyclic testing using the International Standardization Organization
specifications. They exceeded these standards for strength and durability.41
Experience in Jamaica demonstrated that similar adjustable prostheses
(transtibial) are durable even in demanding environments with daily use.27

The level of thigh soft tissue compressibility discovered in this study suggests
that conventional sockets using limb casts or digital limb scans with
3-dimensional printing to create the hard socket, are unlikely to accurately
predict the proper accommodation of soft tissue limb compression. Previous
researchers designed subischial sockets made from limb casts that were made
smaller than the limb.20, 21, 22, 23, 24 They then used suction suspension to
pull the soft tissues into the socket. These investigators demonstrated modest
utility with this approach.22, 23, 24

Many conventional transfemoral prostheses are unaffordable to the large segment
of the population who are under- or uninsured and lack the financial resources
to cover the devices’ out-of-pocket costs. A study by Mackenzie et al found the
average cost of an above the knee prosthesis is $18,744, with patients needing a
new prosthesis every 2.3 years.38 Insurance companies are often reluctant to
reimburse for multiple socket revisions for a person with a changing residual
limb. The adjustable subischial transfemoral socket is less expensive than
conventional sockets, providing a more accessible option for many patients as
either a preparatory device to accommodate loss of limb volume after surgery or
as a definitive device.

There were notable strengths of this feasibility study. The outcome measures
assessed important aspects of socket comfort and utility. Significant findings
across multiple questions and the overall significant score with a sample of 18
subjects is compelling. We had a racially diverse sample, although most were
men. Subjects rated the adjustable subischial transfemoral socket as better than
conventional sockets in our main outcome measure and subcategories of comfort
and function. These represent meaningful aspects of prosthesis use and patient
satisfaction. None of the subjects had difficulty buckling or removing the
socket. At the 2-month follow-up, 61% of subjects altered their prosthesis use
in favor of wearing the adjustable socket the majority of time. This is further
endorsement of the usefulness and acceptance of this new socket technology.


STUDY LIMITATIONS

There are several limitations in the present study. This is a study from a
single institution. Given the nature of the study, subjects were not blinded as
to the prosthesis they were using. The study used a sample of convenience, and
participants who entered the study might have been less satisfied with their
devices than a general population of prosthesis users. Subjects were able to
keep the prosthesis after the study, and this might have introduced some bias.
We were not able to completely match the knee units for participants who wore
computerized knees on their conventional devices. However, this did not seem to
affect the scoring of the socket system, the daily ambulation with the devices,
or the patients’ willingness to continue using these study prostheses after the
trial. Our subjects used the knees we provided them in a safe manner and
demonstrated safe and functional ambulation. The questionnaire used in the study
was adapted from the Prosthetic Evaluation Questionnaire, and therefore has not
been fully validated. We addressed to the extent possible, issues of potential
influence by the principal investigator. The principal investigator was not
present when collecting data. All statistical analyses were conducted by an
independent statistician (F.S.) on the team who resides in a separate
department.


CONCLUSIONS

The adjustable subischial transfemoral prostheses in this study demonstrated
feasibility and safety for use by persons with transfemoral limb loss. Residual
limbs demonstrated a high degree of tissue compressibility. This study provides
evidence to support the consideration of these devices for persons with
transfemoral limb loss. They should be evaluated in a larger multi-center study.

Text Box 1. Prosthetic Comfort and Utility QuestionnaireCharacteristics of the
prototype prosthesis. Rated on a scale of 1 through 5: 1, Poor; 2, Below
Average; 3, Average; 4, Above Average; 5, Excellent.
 * 1.
   
   Comfort while standing

 * 2.
   
   Comfort while walking short distances

 * 3.
   
   Comfort while walking long distances

 * 4.
   
   Comfort while sitting

 * 5.
   
   Weight of the prosthesis

 * 6.
   
   Stability while standing

 * 7.
   
   Stability while walking

 * 8.
   
   Taking the prosthesis off and putting it on

 * 9.
   
   The ability of your device to accommodate volume changes

 * 10.
   
   How satisfied are you with the overall fit and alignment of this prosthesis?


SUPPLIERS

a. iFIT Prosthetics LLC- iFIT TF Prosthesis. b. Ossur Americas- OFM2 Knee,
Mauch. c. Alps- AKHD gel locking liner. d. College Park Industries- Breeze foot.
e. Ottobock- Inside circumference gauge.


APPENDIX. SUPPLEMENTARY MATERIALS

Download : Download Word document (29KB)

Recommended articles



REFERENCES

 1.  1
     CW. Radcliffe
     Functional considerations in the fitting of above-knee prostheses
     Artif Limbs, 2 (1955), pp. 35-60
     
     View in ScopusGoogle Scholar
 2.  2
     V. Rothschild
     A casting and modification method for the narrow ML socket
     J Prosthet Orthot, 1 (1989), pp. 199-201
     
     CrossRefView in ScopusGoogle Scholar
 3.  3
     J. Foort
     Socket design for the above-knee amputee
     Prosthet Orthot Int, 3 (1979), pp. 73-81
     
     CrossRefView in ScopusGoogle Scholar
 4.  4
     S Kapp, JA Miller, PF Pasquina, RA. Cooper
     Lower limb prosthetics
     PF Pasquina, RA Cooper (Eds.), Care of the combat amputee, Borden
     Institute, Washington, DC (2009), pp. 553-580
     Google Scholar
 5.  5
     CM Schuch, CH. Pritham
     Transfemoral amputation: prosthetic management
     Atlas of limb prosthetics: surgical, prosthetic and rehabilitation
     principles (2nd ed.), Mosby, St. Louis (1992), pp. 509-532
     Google Scholar
 6.  6
     K Hachisuka, Y Umezu, H Ogata, S Ohmine, K Shinkoda, H. Arizono
     Subjective evaluations and objective measurements of the ischial-ramal
     containment prosthesis
     J UOEH, 21 (1999), pp. 107-118
     
     CrossRefView in ScopusGoogle Scholar
 7.  7
     CH. Pritham
     Biomechanics and shape of the above-knee socket considered in light of the
     ischial containment concept
     Prosthet Orthot Int, 14 (1990), pp. 9-21
     
     CrossRefView in ScopusGoogle Scholar
 8.  8
     R Klotz, B Colobert, M Botino, I. Permentiers
     Influence of different types of sockets on the range of motion of the hip
     joint by the transfemoral amputee
     Ann Phys Rehabil Med, 54 (2011), pp. 399-410
     View PDFView articleView in ScopusGoogle Scholar
 9.  9
     G Berke
     Post-operative management of the lower extremity amputee: standards of
     care. Official findings of the state of-the-science conferences #2
     J Prosthet Orthot, 16 (2004), pp. 6-12
     Google Scholar
 10. 10
     SG Zachariah, R Saxena, JR Fergason, JE. Sanders
     Shape and volume change in the transtibial residuum over the short term:
     preliminary investigation of six subjects
     J Rehabil Res Dev, 41 (2004), pp. 683-694
     
     CrossRefView in ScopusGoogle Scholar
 11. 11
     JE Sanders, DS Harrison, KJ Allyn, TR. Myers
     Clinical utility of in-socket residual limb volume change measurement: case
     study results
     Prosthet Orthot Int, 33 (2009), pp. 378-390
     
     CrossRefView in ScopusGoogle Scholar
 12. 12
     LE Pezzin, TR Dillingham, EJ MacKenzie, P Ephraim, P. Rossbach
     Use and satisfaction with prosthetic limb devices and related services
     Arch Phys Med Rehabil, 85 (2004), pp. 723-729
     View PDFView articleView in ScopusGoogle Scholar
 13. 13
     TR Dillingham, LE Pezzin, EJ MacKenzie, AR. Burgess
     Use and satisfaction with prosthetic devices among persons with
     trauma-related amputations: a long-term outcome study
     Am J Phys Med Rehabil, 80 (2001), pp. 563-571
     
     View in ScopusGoogle Scholar
 14. 14
     GM Berke, J Fergason, JR Milani, et al.
     Comparison of satisfaction with current prosthetic care in veterans and
     service members from Vietnam and OIF/OEF conflicts with major traumatic
     limb loss
     J Rehabil Res Dev, 47 (2010), pp. 361-371
     
     CrossRefGoogle Scholar
 15. 15
     JP. Seaman
     Survey of individuals wearing lower limb prostheses
     J Prosthet Orthot, 22 (2010), pp. 257-265
     
     View in ScopusGoogle Scholar
 16. 16
     Evelyth, R. When state-of-the-art is second best. Available
     at:http://www.pbs.org/wgbh/nova/next/tech/durable-prostheses. Accessed
     March 10, 2021.
     Google Scholar
 17. 17
     FT Hoaglund, HE Jergesen, L Wilson, LW Lamoreux, R. Roberts
     Evaluation of problems and needs of veteran lower-limb amputees in the San
     Francisco Bay Area during the period 1977-1980
     J Rehabil R D, 20 (1983), pp. 57-71
     
     View in ScopusGoogle Scholar
 18. 18
     S Millstein, D Bain, GA. Hunter
     A review of employment patterns of industrial amputees: factors influencing
     rehabilitation
     Prosthet Orthot Int, 9 (1985), pp. 69-78
     
     CrossRefView in ScopusGoogle Scholar
 19. 19
     K. Sheikh
     Return to work following limb injuries
     J Soc Occup Med, 35 (1985), pp. 114-117
     
     CrossRefView in ScopusGoogle Scholar
 20. 20
     S Fatone, R. Caldwell
     Northwestern University Flexible Subischial Vacuum Socket for persons with
     transfemoral amputation-Part 1: description of technique
     Prosthet Orthot Int, 41 (2017), pp. 237-245
     
     CrossRefView in ScopusGoogle Scholar
 21. 21
     S Fatone, R. Caldwell
     Northwestern University Flexible Subischial Vacuum Socket for persons with
     transfemoral amputation: Part 2 Description and preliminary evaluation
     Prosthet Orthot Int, 41 (2017), pp. 246-250
     
     CrossRefView in ScopusGoogle Scholar
 22. 22
     S Fatone, R Caldwell, J Angelico, et al.
     Comparison of ischial containment and subischial sockets on comfort,
     function, quality of life, and satisfaction with device in persons with
     unilateral transfemoral amputation: a randomized crossover trial
     Arch Phys Med Rehabil, 102 (2021), pp. 2063-2073
     e2
     
     View in ScopusGoogle Scholar
 23. 23
     S Fatone, J Yohay, R. Caldwell
     Change in residual limb size over time in the NU-FlexSIV socket: a case
     study
     Prosthet Orthot Int, 42 (2018), pp. 620-625
     
     CrossRefView in ScopusGoogle Scholar
 24. 24
     SE Brown, E Russell Esposito, AJ Ikeda, JM Wilken, S Fatone
     Evaluation of NU-FlexSIV socket performance for military service members
     with transfemoral amputation
     US Army Med Dep J (2-18) (2018), pp. 38-47
     
     View in ScopusGoogle Scholar
 25. 25
     T Dillingham, J Kenia, F Shofer, J. Marschalek
     A prospective assessment of an adjustable, immediate fit, transtibial
     prosthesis
     PM R, 111 (2019), pp. 1210-1217
     
     CrossRefView in ScopusGoogle Scholar
 26. 26
     C McCloskey, J Kenia, F Shofer, J Marschalek, T. Dillingham
     Improved self-reported comfort, stability, and limb temperature regulation
     with an immediate fit, adjustable transtibial prosthesis
     Arch Rehabil Res Clin Transl, 2 (2020), Article 100090
     View PDFView articleGoogle Scholar
 27. 27
     J Kenia, B Wolf, J Marschalek, T. Dillingham
     An immediate fit, adjustable, modular prosthetic system for addressing
     world-wide limb loss disability
     Arch Rehabil Res Clin Transl, 3 (2021), Article 100120
     View PDFView articleGoogle Scholar
 28. 28
     R. Krosin
     The pin lock reference manual for prosthetists
     Hanger Prosthetics & Orthotics (2005), pp. 2-6
     Google Scholar
 29. 29
     MW Legro, GD Reiber, DG Smith, M del Aguila, J Larsen, D. Boone
     Prosthesis evaluation questionnaire for persons with lower limb
     amputations: assessing prosthesis-related quality of life
     Arch Phys Med Rehabil, 79 (1998), pp. 931-938
     View PDFView articleView in ScopusGoogle Scholar
 30. 30
     SU Raschke, MS Orendurff, JL Mattie, et al.
     Biomechanical characteristics, patient preference and activity level with
     different prosthetic feet: a randomized double blind trial with laboratory
     and community testing
     J Biomech, 48 (2015), pp. 146-152
     
     View in ScopusGoogle Scholar
 31. 31
     EM Balk, A Gazula, G Markozannes, et al.
     Lower limb prostheses: measurement instruments, comparison of component
     effects by subgroups, and long-term outcomes
     Agency for Healthcare Research and Quality (US), Rockville (MD) (2018 Sep)
     (Comparative Effectiveness Review, No. 213.) Table 1, Lower limb extremity
     prosthesis Medicare Functional Classification Levels (K levels) Available
     at: https://www.ncbi.nlm.nih.gov/books/NBK531517/table/ch2.tab1//. Accessed
     May 11, 2021
     Google Scholar
 32. 32
     TA Miller, R Paul, M Forthofer, SR. Wurdeman
     Impact of time to receipt of prosthesis on total healthcare costs 12 months
     postamputation
     Am J Phys Med Rehabil, 99 (2020), pp. 1026-1031
     
     CrossRefView in ScopusGoogle Scholar
 33. 33
     TA Miller, R Paul, M Forthofer, SR Wurdeman
     The role of earlier receipt of a lower limb prosthesis on emergency
     department utilization
     PM R, 13 (2021), pp. 819-826
     
     CrossRefView in ScopusGoogle Scholar
 34. 34
     BF Mundell, HM Kremers, S Visscher, KM Hoppe, KR. Kaufman
     Predictors of receiving a prosthesis for adults with above-knee amputations
     in a well-defined population
     PM R, 8 (2016), pp. 730-737
     View PDFView articleCrossRefView in ScopusGoogle Scholar
 35. 35
     L Resnik, M. Borgia
     Predicting prosthetic prescription after major lower-limb amputation
     J Rehabil Res Dev, 52 (2015), pp. 641-652
     
     View in ScopusGoogle Scholar
 36. 36
     JE Kurichi, P Kwong, WB Vogel, D Xie, D Cowper Ripley, BE Bates
     Effects of prosthetic limb prescription on 3-year mortality among Veterans
     with lower-limb amputation
     J Rehabil Res Dev, 52 (2015), pp. 385-396
     
     View in ScopusGoogle Scholar
 37. 37
     JB Webster, KN Hakimi, RM Williams, AP Turner, DC Norvell, JM. Czerniecki
     Prosthetic fitting, use, and satisfaction following lower-limb amputation:
     a prospective study
     J Rehabil Res Dev, 49 (2012), pp. 1493-1504
     
     View in ScopusGoogle Scholar
 38. 38
     EJ MacKenzie, RC Castillo, AS Jones, et al.
     Health-care costs associated with amputation or reconstruction of a
     limb-threatening injury
     JBJS, 89 (2007), pp. 1685-1692
     
     View in ScopusGoogle Scholar
 39. 39
     WM Vannah, JR Davids, DM Drvaric, Y Setoguchi, BJ. Oxley
     A survey of function in children with lower limb deficiencies
     Prosthet Orthot Int, 23 (1999), pp. 239-244
     
     CrossRefView in ScopusGoogle Scholar
 40. 40
     AM Boonstra, LJ Rijnders, JW Groothoff, WH. Eisma
     Children with congenital deficiencies or acquired amputations of the lower
     limbs: functional aspects
     Prosthet Orthot Int, 24 (2000), pp. 19-27
     
     CrossRefView in ScopusGoogle Scholar
 41. 41
     International Organization for Standardization. Prosthetics—Structural
     testing of lower-limb prostheses-requirements and test methods. ISO
     10328:2006. Available at:
     https://www.iso.org/obp/ui/#iso:std:iso:10328:ed-2:v1:en. Accessed June 2,
     2021.
     Google Scholar


CITED BY (0)



This study was funded by the National Institutes of Health, National Institute
on Aging (Grants: SB1AG050430 and R42AG050430) and by the National Institute of
Child Health and Human Development and National Center for Medical
Rehabilitation Research (Grant R42 HD069067).

Disclosures: Timothy R. Dillingham is the founder, major owner, and director of
iFIT Prosthetics, LLC, and has financial interest in the prosthetic system
presented in this article. He signed a National Institutes of Health compliant
conflict of interest management agreement with the University of Pennsylvania
Provost for Research. The other authors have nothing to disclose.

Clinical Trial Registration Number: NCT02886936

© 2022 The Authors. Published by Elsevier Inc. on behalf of American Congress of
Rehabilitation Medicine.


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