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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Does Soft Tissue Balancing Using Intra-Operative Pressure Sensors Improve Clinical Outcomes in Total Knee Arthroplasty? A Multi-Centre Randomised Controlled Trial
Scientific title
Does Soft Tissue Balancing Using Intra-Operative Pressure Sensors Improve Clinical Outcomes in Total Knee Arthroplasty? A Multi-Centre Randomised Controlled Trial
Secondary ID [1] 293489 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Osteoarthritis 305682 0
Rheumatoid arthritis 307797 0
Condition category
Condition code
Musculoskeletal 304903 304903 0 0
Musculoskeletal 304904 304904 0 0
Other muscular and skeletal disorders
Surgery 306856 306856 0 0
Surgical techniques

Study type
Description of intervention(s) / exposure
During routine TKA surgery, readings from a Verasense pressure sensor will be recorded, and then used to guide soft-tissue balancing of the knee. The Verasense device is a sterile, single-use sensor that is temporarily inserted in the compartment between the femoral and tibial implant components during surgery. It will be in situ for 5-10 minutes, depending on the adjustments required to achieve a balanced knee state. Micro-electronic elements calculate the compartment pressure loads as the knee is bent and straightened out. The orthopaedic surgeon will be administering the intervention.
A non-surgical team member present at all cases will record intra-operative data and will sign the surgical data form to verify fidelity to the study. In addition, random surgical visitations to research sites by the Principal Investigator and Study Coordinator will be undertaken to monitor and document strict adherence to study protocol.
Intervention code [1] 299734 0
Treatment: Surgery
Intervention code [2] 301161 0
Treatment: Devices
Comparator / control treatment
During routine TKA surgery, readings from a Verasense pressure sensor will be recorded, but the surgeon will be blinded to those data, and will manually balance the soft tissues of the knee. All intra-operative Verasense data will be recorded on the surgical data form by the company prosthetic representative who normally operates the Verasense monitor during surgical procedures. Each representative will undergo specific training on data collection, blinding and recording requirements.
Control group

Primary outcome [1] 304097 0
Change in the average score of the four subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS) that are most specific to recovery after total knee arthroplasty: pain, symptoms, function in daily living and knee-related quality of life.
Timepoint [1] 304097 0
1 year-2 weeks pre-operatively and 1-year post-operatively
Secondary outcome [1] 340943 0
Mean change in composite patient-reported levels of pain, symptoms, activities of daily living, sport/recreation and knee-related quality of life as measured by all five subscales on the Knee Osteoarthritis Outcome Score (KOOS)
Timepoint [1] 340943 0
1 year-2 weeks pre-operatively, 6 months post-operatively, 2 years post-operatively
Secondary outcome [2] 340950 0
Change in composite patient-reported outcomes on the Knee Society Score (2011) - symptoms, satisfactions, expectations and function
Timepoint [2] 340950 0
1 year-2 weeks pre-operatively, 1 year post-operatively, 2 years post-operatively
Secondary outcome [3] 340952 0
Change in patient-reported overall awareness of knee joint as measured by the Forgotten Joint Score (FJS-12)
Timepoint [3] 340952 0
1 year-2 weeks pre-operatively, 1 year post-operatively, 2 years post-operatively
Secondary outcome [4] 340956 0
Patient-reported overall health status as measured by the EQ5D-5L score
Timepoint [4] 340956 0
1 year-2 weeks pre-operatively, 1 year post-operatively, 2 years post-operatively
Secondary outcome [5] 340959 0
Tibiofemoral compartmental pressure loads as measured by Verasense pressure monitor (initial and final medial and lateral readings at 10 degrees, 45 degrees and 90 degrees of flexion)
Timepoint [5] 340959 0
Secondary outcome [6] 340960 0
Tibiofemoral match as measured by rotation of tibia at 10 degrees, 45 degrees and 90 degrees of flexion
Timepoint [6] 340960 0
Secondary outcome [7] 340962 0
Functional outcome: Timed Up and Go Test (TUG)
Timepoint [7] 340962 0
6 months post-operatively
Secondary outcome [8] 340963 0
Functional outcome: Six-Minute Walk Test (6MWT)
Timepoint [8] 340963 0
6 months post-operatively
Secondary outcome [9] 346436 0
Surgeon determination of knee balance with pressure sensor in situ. Prior to performing knee balancing (for both the intervention and control groups), the screen with pressure values will be turned away from the surgeon. The surgeon will be asked if the knee is balanced or unbalanced at 10, 45 and 90 degrees of flexion: Balanced? Yes or No. Agreement is defined as two out of three flexion positions.
Timepoint [9] 346436 0
Secondary outcome [10] 346437 0
Functional outcome: Knee range of motion (maximal passive extension and maximal passive flexion) using a goniometer
Timepoint [10] 346437 0
6-10 weeks post-operatively and 6 months post-operatively
Secondary outcome [11] 346438 0
Perth CT Protocol - objective assessment of the alignment of components in TKA (mechanical angle, AP femorotibial axis, femoral coronal angle, tibial coronal angle, femoral flexion, tibial slope, femoral rotation, femorotibial match, tuberosity lateralisation, Berger tibial rotation)
Timepoint [11] 346438 0
Assessed at a single time point prior to discharge from hospital after index surgery
Secondary outcome [12] 346439 0
Assessment of native lower limb anatomy for pre-operative templating and overall surgical planning using routine radiographs (AP erect, 30-degree lateral and patellar skyline views and four-foot films)
Timepoint [12] 346439 0
Within one year pre-operatively
Secondary outcome [13] 346723 0
Implant positioning as assessed by routine radiographs (AP erect, 30-degree lateral and patellar skyline views)
Timepoint [13] 346723 0
Immediately post-operatively, 1 year post-operatively, 2 years post-operatively
Secondary outcome [14] 346724 0
In-hospital data:
Readiness for discharge as determined by treating physiotherapist (measured by the following criteria: pain controlled with oral medication; able to get in and out of bed and to toilet without assistance; able to mobilise safely and independently; able to mobilise safely on steps); and as determined medically fit for discharge by hospital medical staff
Timepoint [14] 346724 0
Prior to participant discharge
Secondary outcome [15] 346725 0
In-hospital data:
Total length of stay, as determined by hospital medical records (day of discharge minus day of admission)
Timepoint [15] 346725 0
Within one month post-discharge
Secondary outcome [16] 346726 0
In-hospital data:
Discharge destination, as determined by hospital medical records and as defined by one of the following options: home; in-patient rehabilitation unit; nursing home facility
Timepoint [16] 346726 0
Within one month post-discharge

Key inclusion criteria
1. All patients suitable for TKA aged 20-85 years
2. Patients who meet the indications for a primary unilateral or bilateral total knee arthroplasty using the Smith & Nephew Legion or Genesis II cruciate-retaining or posterior-stabilised total knee arthroplasty system
3. Subjects diagnosed with one or more of the following conditions: osteoarthritis; rheumatoid or other inflammatory arthritis; post-traumatic osteoarthritis
Minimum age
20 Years
Maximum age
85 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Any surgery where increased prosthetic constraint will be required due to significant ligament deficiencies (such as constrained condylar or rotating hinge prostheses)
2. Any surgery performed for acute fracture or tumour involvement
3. Participants unable to provide consent or complete questionnaires due to cognitive incapacity or English language deficit
4. Participants unable to commit to full follow-up schedule over two years (due to geographic distance or physical challenges)
5. Pregnant female, or planning on becoming pregnant during study period

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Centralised computer-based randomisation service by phone. Allocation will take place immediately prior to commencement of surgery.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants will be randomised using minimisation by the randomisation service. Patient age, surgeon and gender will be included in the minimisation. For those patients undergoing simultaneous bilateral TKA or sequential unilateral TKA at different time points during the trial, both knees will be allocated to the same arm: randomisation is done at the level of the patient, not the knee.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
The primary outcome for this study will be the average of the four subscales of the KOOS at 12 months. Normality of data distribution will be assessed, and Student's T test will be used to compare differences in means with continuous variables. The chi-squared test and Fisher's exact test will be used for categorical data analysis as appropriate. Intention-to-treat analysis will be performed in the primary analysis. In addition, an as-treated analysis including participants according to treatment received will also be added as a secondary analysis. If greater than 20% of data are missing from the randomised sample, the missing data will be imputed. However, attempts will be made to minimise missing data by contacting patients directly by phone or via mail follow-up.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 9472 0
St George Private Hospital - Kogarah
Recruitment hospital [2] 10844 0
Canterbury Hospital - Campsie
Recruitment hospital [3] 10862 0
Wollongong Hospital - Wollongong
Recruitment hospital [4] 10864 0
Kareena Private Hospital - Caringbah
Recruitment hospital [5] 10865 0
The Sutherland Hospital - Caringbah
Recruitment hospital [6] 10866 0
Sydney Southwest Private Hospital - Liverpool
Recruitment hospital [7] 10867 0
Fairfield Hospital - Prairiewood
Recruitment hospital [8] 10869 0
Calvary Public Hospital ACT - Bruce
Recruitment hospital [9] 10873 0
Calvary John James Hospital - Deakin
Recruitment hospital [10] 10874 0
Calvary Health Care Tasmania - Launceston campus - Launceston
Recruitment hospital [11] 13096 0
Canberra Private Hospital - Deakin
Recruitment postcode(s) [1] 18199 0
2217 - Kogarah
Recruitment postcode(s) [2] 22588 0
2194 - Campsie
Recruitment postcode(s) [3] 22608 0
2500 - Wollongong
Recruitment postcode(s) [4] 22610 0
2229 - Caringbah
Recruitment postcode(s) [5] 22611 0
2170 - Liverpool
Recruitment postcode(s) [6] 22612 0
2176 - Prairiewood
Recruitment postcode(s) [7] 22614 0
2617 - Bruce
Recruitment postcode(s) [8] 22618 0
2600 - Deakin
Recruitment postcode(s) [9] 22619 0
7250 - Launceston

Funding & Sponsors
Funding source category [1] 298107 0
Commercial sector/Industry
Name [1] 298107 0
Address [1] 298107 0
1855 Griffin Road, Suite A-310
Dania Beach, FL 33004
Country [1] 298107 0
United States of America
Funding source category [2] 298116 0
Commercial sector/Industry
Name [2] 298116 0
Smith & Nephew, Pty Ltd.
Address [2] 298116 0
1450 Brooks Road
Memphis, TN 38116
Country [2] 298116 0
United States of America
Primary sponsor type
Dr Samuel Macdessi
Sydney Knee Specialists
Suite 8, Level 3
19 Kensington Street
Kogarah, NSW 2217
Secondary sponsor category [1] 297198 0
Name [1] 297198 0
Address [1] 297198 0
Country [1] 297198 0

Ethics approval
Ethics application status
Ethics committee name [1] 299126 0
South Eastern Sydney Local Health District HREC
Ethics committee address [1] 299126 0
Room G71 East Wing
Edmund Blacket Building
Prince of Wales Hospital
Randwick, NSW 2031
Ethics committee country [1] 299126 0
Date submitted for ethics approval [1] 299126 0
Approval date [1] 299126 0
Ethics approval number [1] 299126 0
18/135 (HREC/18/POWH/320)

Brief summary
Total knee arthroplasty (TKA), or total knee replacement surgery, is a successful operation in alleviating pain and improving function for the majority of people with end-stage knee osteoarthritis. However, up to 20% of patients undergoing TKA report some dissatisfaction following their surgery. Dissatisfaction after TKA is multi-factorial, but the surgical causes are commonly related to imbalance of the ligaments (soft tissues) that surround the knee at the time of surgery or slight malalignment of the upper and lower leg bones.
Current thinking in the field of total knee replacement centres around optimising the balance of the ligaments as the prostheses are implanted, because it is generally agreed that this equilibrium is associated with the best outcomes for patients. Traditionally, surgeons have decided whether a knee is balanced during surgery by using their experience to manually assess the feel of the joint. Other methods used to balance the knee have involved measuring the space between the femur (thigh bone) and tibia (shin bone) based on ligament tensioning and using computer navigation to assess the stresses across the joint.
Since the introduction of wireless sensor technology, surgeons have another tool to measure soft tissue balance and the ways in which the bones move against each other. Intra-operative pressure sensors use micro-electronics to calculate pressure loads in the compartment between the femur and tibia as the knee is bent and straightened out. Surgeons can use this information to appropriately align the implants for optimum balance.
The intra-operative device used in this study is called the Verasense pressure monitor, and it is used by some surgeons in knee replacements operations outside this study.
It is important to state that there has been no rigorous research to date that shows an association between using the Verasense device and better outcomes such as less pain, more function and overall satisfaction. The aim of this study is to investigate whether there are such benefits to using intra-operative sensors to achieve balance.
Participants will be randomly assigned to either a manual balancing (MB) group or a sensor-guided balancing (SGB) group. For patients in the MB group, surgeons will use standard methods to achieve soft tissue balance. For patients in the SGB group, surgeons will use readings from the Verasense device to achieve soft tissue balance.
Participants will be followed closely over the course of two years to monitor the progress in each group. The results of this trial will aim to inform future clinical practice with regard to soft-tissue balance and alignment in total knee arthroplasty
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 79386 0
Dr Samuel Macdessi
Address 79386 0
Sydney Knee Specialists
Suite 8, Level 3
19 Kensington Street
Kogarah, NSW 2217
Country 79386 0
Phone 79386 0
+61 2 8307 0333
Fax 79386 0
+61 2 8307 0334
Email 79386 0
Contact person for public queries
Name 79387 0
Ms Jil Wood, Clinical Research Manager
Address 79387 0
Sydney Knee Specialists
Suite 8, Level 3
19 Kensington Street
Kogarah, NSW 2217
Country 79387 0
Phone 79387 0
+61 2 8307 0333
Fax 79387 0
+61 2 8307 0334
Email 79387 0
Contact person for scientific queries
Name 79388 0
Dr Samuel Macdessi
Address 79388 0
Sydney Knee Specialists
Suite 8, Level 3
19 Kensington Street
Kogarah, NSW 2217
Country 79388 0
Phone 79388 0
+61 2 8307 0333
Fax 79388 0
+61 2 8307 0334
Email 79388 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
What data in particular will be shared?
Individual participant data underlying published results, after de-identification
When will data be available (start and end dates)?
Beginning 6 months after publication and no end date determined
Available to whom?
Case-by-case basis at the discretion of Principal Investigator
Available for what types of analyses?
Systematic review, including IPD meta-analyses
By what mechanism will data be made available?
Access subject to approval by Principal Investigator with requirement to sign data access agreement
What supporting documents are/will be available?
Study protocol
Type [1] 1324 0
Study protocol
URL/details/comments [1] 1324 0
Summary results
Not applicable