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Trial registered on ANZCTR


Registration number
ACTRN12618001399280
Ethics application status
Approved
Date submitted
16/08/2018
Date registered
20/08/2018
Date last updated
23/08/2018
Type of registration
Prospectively registered

Titles & IDs
Public title
Understanding the biomechanics of below the knee prosthetic socket fit: comparing pressure cast and traditional patella tendon bearing techniques
Scientific title
Understanding the biomechanics of transtibial socket fit: comparing pressure cast and traditional patella tendon bearing techniques
Secondary ID [1] 295798 0
Nil known
Universal Trial Number (UTN)
U1111-1218-9416
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Transtibial amputation 309230 0
Condition category
Condition code
Physical Medicine / Rehabilitation 308103 308103 0 0
Other physical medicine / rehabilitation
Musculoskeletal 308176 308176 0 0
Other muscular and skeletal disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Intervention Name: Pressure cast (PCAST) Prosthetic Socket
A Caulfield hospital staff member with International Society for Prosthetics and Orthotics (ISPO) category I qualifications will cast, fabricate and fit the PCAST sockets. Briefly, the PCAST technique involves wrapping participants’ residual limb, wearing a cotton sock, in plaster wrap uniformly; followed by placement of the limb into the PCAST tank (made of polyvinyl chloride) filled with water, separated from the limb by a polyethelene diaphragm. The water pressure is increased until the participants can stand with a portion of their weight supported by the pressurised water. Once the plaster wrap hardens, the tank is depressurised and the plaster removed. No rectifications to the positive socket mould based on the plaster wrap are performed with the exception of the smoothing of obvious rough edges. Participants will be fit with two versions of the PCAST socket: one with 50% of their weight supported by the residual limb during casting, and one with ~85% of their weight supported by the residual limb during casting. Participants will also be cast with a traditional Patella tendon bearing (PTB) socket using standard techniques, described elsewhere. The casting and initial fitting of the prosthetic socket will take approximately 2 hours. The study will take place at the Royal Melbourne Hospital and the University of Melbourne. The hard sockets will be manufactured using standard techniques and the prosthetic limbs comprised standard modular components and a multi-articulating foot.

The sockets will only be worn during the data collection periods, hence no adherence to socket wearing is required. At the beginning of each data collection session, the participants will undergo 15 minutes acclimatisation walking with the socket and test prostheses prior to data collection. Following data collection with one socket type, the participants will be given a rest period of approximately 10 minutes during which they will sit with their own prostheses donned, prior to data collection with the next socket type.
Intervention code [1] 312161 0
Treatment: Devices
Comparator / control treatment
Three sockets will be cast for each participants. The outcomes will be compared for these three socket types. The PCAST socket with 50% load bearing will be the reference 'comparator' socket with which the PCAST 85% load bearing and the PTB sockets will be compared.
Control group
Active

Outcomes
Primary outcome [1] 307119 0
Gait kinematic data; composite measure comprising trunk, pelvic, knee and ankle angle data. Data will be collected using motion capture techniques in the Computer Assisted Rehabilitation Environment (CAREN). The CAREN features a dual belt instrumented treadmill on a moveable platform, surrounded by a virtual reality screen which provides appropriate optic flow during walking.
Timepoint [1] 307119 0
Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.
Primary outcome [2] 307120 0
Gait kinetic data; composite measure comprising trunk, pelvic, knee and ankle moment and power data and ground reaction force data. Data will be collected using motion capture techniques in the Computer Assisted Rehabilitation Environment (CAREN). The CAREN features a dual belt instrumented treadmill on a moveable platform, surrounded by a virtual reality screen which provides appropriate optic flow during walking.
Timepoint [2] 307120 0
Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.
Primary outcome [3] 307140 0
Spatio-temporal gait data: composite outcome measure comprising stance, swing and stride times, step width and step and stride length data. Spatio-temporal measures are will also be used to calculate measures stability including step width variability and the margin of stability. Data will be collected using the instrumented treadmill of the Computer Assisted Rehabilitation Environment (CAREN). The CAREN features a dual belt treadmill on a moveable platform, surrounded by a virtual reality screen which provides appropriate optic flow during walking.
Timepoint [3] 307140 0
Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.
Secondary outcome [1] 350760 0
Pressure profile at the interface of the socket and participants residual limb. The pressure data will be collected using the F-socket residual limb/socket interface pressure measurement system (Tekscan Inc., USA).
Timepoint [1] 350760 0
Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.
Secondary outcome [2] 350761 0
Socket Comfort Score (SCS). Validated survey instrument to determine the users perceived socket comfort. Participants rated the comfort of their socket on a 0–10 scale where 0 represented the most uncomfortable and 10 the most comfortable sockets imaginable
Timepoint [2] 350761 0
Immediately following gait testing (kinematic and kinetic testing)
Secondary outcome [3] 350819 0
Socket geometry - 3D geometry of the positive casts will be measured using laser scanning for the three socket casting techniques.
Timepoint [3] 350819 0
Following socket casting, prior to gait testing.

Eligibility
Key inclusion criteria
Eligibility requirements dictate that participants
o had unilateral transtibial amputations, caused by trauma, osteosarcoma or congenital defects
o were adults, between the ages of 18 and 40 with no compounding co-morbidities which negatively affect their stability or mobility.
o require no aids additional to their prosthetic limb for mobility
o were established and frequent users of their prosthetics
o were community ambulators, with Medicare functional levels K3 or K4
Minimum age
18 Years
Maximum age
40 Years
Gender
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
o compounding co-morbidities which negatively affect their stability or mobility.
o required aids additional to their prosthetic limb for mobility

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
It is anticipated that ten participants with amputations will be recruited for enrollment in the study. No similar studies exist of with amputee populations and non-level walking with different component with which to assess power. However, a study by Sin et al. (2001) assessed prosthetic alignment during non-level walking for six transtibial amputees with significant power. In addition, due to the complicated nature of the experimental procedure and the large amount of resulting motion capture data, we do not have the resources, both experimental and computational, for a larger sample size. Participants will be made aware of the small sample size and must consent to understanding the implications this may have about protecting their identities.

Data will be assessed for normality and, if appropriate, standard parametric tests (ANOVA, t-tests etc) used to compare the socket types against the collected measures.

Sin S, Chow DH, Cheng C. Significance of non-level walking on transtibial prosthesis fitting with particular reference to the effects of anterior-posterior alignment. Journal of rehabilitation research and development. 2001;38(1):1-6.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 11679 0
Caulfield Hospital - Caulfield
Recruitment postcode(s) [1] 23725 0
3162 - Caulfield

Funding & Sponsors
Funding source category [1] 300389 0
Charities/Societies/Foundations
Name [1] 300389 0
The Promobilia Foundation
Address [1] 300389 0
Nybrogatan 59, SE-114 40 Stockholm
Country [1] 300389 0
Sweden
Primary sponsor type
University
Name
The University of Melbourne
Address
Grattan St, Parkville VIC 3010
Country
Australia
Secondary sponsor category [1] 299843 0
University
Name [1] 299843 0
RMIT
Address [1] 299843 0
Plenty Rd, Bundoora VIC 3083
Country [1] 299843 0
Australia
Other collaborator category [1] 280301 0
Individual
Name [1] 280301 0
Jim Lavranos
Address [1] 280301 0
Caulfield Hospital - 260 Kooyong Rd, Caulfield VIC 3162
Country [1] 280301 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 301198 0
The University of Melbourne Human Research Ethics Committee
Ethics committee address [1] 301198 0
Grattan St, Parkville, VIC, 3010
Ethics committee country [1] 301198 0
Australia
Date submitted for ethics approval [1] 301198 0
08/11/2016
Approval date [1] 301198 0
12/12/2016
Ethics approval number [1] 301198 0
1647884

Summary
Brief summary
Conventional PTB transtibial prosthetic sockets are widely-used throughout the developing world, however, the manufacture of PTB sockets is still highly dependent on the skill and experience of the attending prosthetist. A PCAST technique for the manufacture of transtibial sockets has been shown to be a potential alternative to PTB sockets, with similar initial patient outcomes recorded for the two sockets.
The PTB socket is formed by deliberately creating regions of loading corresponding with the perceived pressure tolerant and intolerant areas of the residual limb. Although, pressure cast sockets aim to load the residual limb more uniformly, eliminating regions of high pressure; previous studies have shown this does not occur. In the PTB socket, the anterior aspect of the socket is shaped closely around either side of the tibial ridge providing rotational stability of the limb. Given the PCAST does not feature this shaping, it is hypothesised that the wearer makes a number of musculo-skeletal adaptations in order to walk stably.
Previous comparisons of the PCAST and PTB sockets have explored the space and time characteristics of gait and subjective comfort levels of the wearers. All previously performed tests have involved level walking at self-selected comfortable or fast pace. No studies to date have examined the musculoskeletal gait adaptations of wearers of pressure-cast sockets, or the relationships between the gait biomechanics and the resultant loading patterns in the socket. Thus, further research is required to investigate through what mechanisms or biomechanical adaptations these fundamentally different sockets achieve similar patient outcomes, and how these adaptations change when walking on a non-level surface.
Historically, load bearing hydrocasting techniques have been performed with the patient standing with either with 50% of their body weight supported by the pressurised liquid, or during full weight bearing. Intuitively, the rationale for each of these loading conditions is that the loading condition during casting reflects the limb loading during stance and the single support phase of gait respectively. However, there is no empirical data to suggest the either method leads to superior fit, gait biomechanics or comfort. Nor is there any data to quantify the volume, geometry or alignment requirements of the sockets manufactured using the differing hydrocast loading conditions. An understanding of the aforementioned will allow the refinement and potentially improved consistency of hydrocasting techniques among researchers.
Trial website
Trial related presentations / publications
Public notes
Previous publications associated with this trial:
Lee PV, Lythgo N, Laing S, Lavranos J, Thanh NH. Pressure casting technique for transtibial prosthetic socket fit in developing countries. J Rehabil Res Dev. 2014;51(1):101-10. 10.1682/JRRD.2012.10.0191

Laing S, Lythgo N, Lavranos J, Lee PV. Transtibial Prosthetic Socket Shape in a Developing Country: A study to compare initial outcomes in Pressure Cast hydrostatic and Patella Tendon Bearing designs. Gait & Posture, 2017. 58: p. 363-368. 10.1016/j.gaitpost.2017.08.017

Contacts
Principal investigator
Name 86194 0
Prof Peter Vee Sin Lee
Address 86194 0
The University of Melbourne, Grattan St, Parkville, VIC, 3010
Country 86194 0
Australia
Phone 86194 0
+61 3 83444426
Fax 86194 0
Email 86194 0
pvlee@unimelb.edu.au
Contact person for public queries
Name 86195 0
Prof Peter Vee Sin Lee
Address 86195 0
The University of Melbourne, Grattan St, Parkville, VIC, 3010
Country 86195 0
Australia
Phone 86195 0
+61 3 83444426
Fax 86195 0
Email 86195 0
pvlee@unimelb.edu.au
Contact person for scientific queries
Name 86196 0
Prof Peter Vee Sin Lee
Address 86196 0
The University of Melbourne, Grattan St, Parkville, VIC, 3010
Country 86196 0
Australia
Phone 86196 0
+61 3 83444426
Fax 86196 0
Email 86196 0
pvlee@unimelb.edu.au

No information has been provided regarding IPD availability
Summary results
No Results