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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

26/10/2021

Date data sharing statement initially provided

26/10/2021

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]

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

Condition category

Condition code

Physical Medicine / Rehabilitation

Other physical medicine / rehabilitation

Musculoskeletal

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]

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]

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]

Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.

Primary outcome [2]

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]

Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.

Primary outcome [3]

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]

Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.

Secondary outcome [1]

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]

Following prosthetic limb production and after a short (~15min) acclimatisation with each limb. Will be recorded for each socket type.

Secondary outcome [2]

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]

Immediately following gait testing (kinematic and kinetic testing)

Secondary outcome [3]

Socket geometry - 3D geometry of the positive casts will be measured using laser scanning for the three socket casting techniques.

Timepoint [3]

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

Sex

Both males and females

Can healthy volunteers participate?

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

Withdrawn

Reason for early stopping/withdrawal

Participant recruitment difficulties

Date of first participant enrolment

Anticipated

3/09/2018

Actual

Date of last participant enrolment

Anticipated

3/12/2018

Actual

Date of last data collection

Anticipated

25/02/2019

Actual

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

VIC

Recruitment hospital [1]

Caulfield Hospital - Caulfield

Recruitment postcode(s) [1]

3162 - Caulfield

Funding & Sponsors

Funding source category [1]

Charities/Societies/Foundations

Name [1]

The Promobilia Foundation

Address [1]

Nybrogatan 59, SE-114 40 Stockholm

Country [1]

Sweden

Primary sponsor type

University

Name

The University of Melbourne

Address

Grattan St, Parkville VIC 3010

Country

Australia

Secondary sponsor category [1]

University

Name [1]

RMIT

Address [1]

Plenty Rd, Bundoora VIC 3083

Country [1]

Australia

Other collaborator category [1]

Individual

Name [1]

Jim Lavranos

Address [1]

Caulfield Hospital - 260 Kooyong Rd, Caulfield VIC 3162

Country [1]

Australia

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

The University of Melbourne Human Research Ethics Committee

Ethics committee address [1]

Grattan St, Parkville, VIC, 3010

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

08/11/2016

Approval date [1]

12/12/2016

Ethics approval number [1]

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

Prof Peter Vee Sin Lee

Address

The University of Melbourne, Grattan St, Parkville, VIC, 3010

Country

Australia

Phone

+61 3 83444426

Fax

pvlee@unimelb.edu.au

Contact person for public queries

Name

Peter Vee Sin Lee

Address

The University of Melbourne, Grattan St, Parkville, VIC, 3010

Country

Australia

Phone

+61 3 83444426

Fax

pvlee@unimelb.edu.au

Contact person for scientific queries

Name

Peter Vee Sin Lee

Address

The University of Melbourne, Grattan St, Parkville, VIC, 3010

Country

Australia

Phone

+61 3 83444426

Fax

pvlee@unimelb.edu.au

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

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No documents have been uploaded by study researchers.

Documents added automatically

No additional documents have been identified.

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