COVID-19 studies are our top priority. For all other trials, there is a 4-week delay in processing a trial submitted/resubmitted to the ANZCTR and additional delays for updates of registered trials. We appreciate your patience.

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
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
Retrospectively registered

Titles & IDs
Public title
Intra-operatively Measurements with a Computer Navigation Software System Before and After Posterior Cruciate Release in Patients Undergoing Primary Total Knee Arthroplasty
Scientific title
Intra-operative Assessment of Posterior Cruciate Ligament Release on Extension and Flexion Gap Balance in Primary Total Knee Arthroplasty
Secondary ID [1] 301199 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Effect of posterior cruciate release during primary total knee arthroplasties 317346 0
Condition category
Condition code
Musculoskeletal 315453 315453 0 0
Surgery 315634 315634 0 0
Other surgery

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
The goal of this study is not to change the patients' outcome. It is just to perform a measurement during the surgical procedure that implies adding a step to the procedure.

When performing a total knee arthroplasty (TKA) the surgeon decides if he wants to preserve the posterior cruciate ligament (PCL) or if he wants to resect it. Both procedures can be done and papers with evidence supporting both procedures have been published over the last decades. Nevertheless, few studies have quantified the changes in the gap (between femur and tibia) balancing when the posterior cruciate ligament is resected.

Participants in this study will be submitted to a total knee arthroplasty assisted by a navigation software system and robot. We will not submit patients to a new treatment or implants. These are patients that would be submitted to this type of total knee arthroplasty regardless they participate in this study or not. The objective is to quantify, with the use of this software, how much does the gap balance changes when we perform a primary total knee replacement sacrificing the posterior cruciate ligament, just by adding a step to the normal procedure. To do that, we will analyse data captured intra-operatively by optical motion capture technology from Smith & Nephew NAVIO™ Surgical System (robot and computer navigation software) during the surgical steps:
-After medial and lateral meniscus anterior horns resection, osteophyte resection and other soft-tissue release except for PCL resection: as we always do in a standard procedure
-After bone cuts but before PCL resection, measuring with trial implants in place: extra measurement specific to this study
-After bone cuts and PCL resection, measuring with trial implants in place: as we always do in a standard procedure. Normal surgical time of approximately 70 minutes may be extended by 3 to 5 minutes while additional data is captured.
This way, only one extra measurement that doesn’t involve a major alteration of the procedure is done, and there is a very low risk/negligible risk for the patient and surgical outcome. The goal of this study is not to change the patients' outcome.

The surgeon who is chief investigator of this study will be the only one performing surgery. He is a fellowship arthroplasty trained orthopaedic surgeon (since 2004) with years of experience on total knee replacements (over 120 procedures a year) and robotic surgery (more than 60 procedures a year).

All the data collected in the operating theatre during a single surgery will be store in a digital database password protected. Only researchers involved will have access to it and they are aware of privacy laws and have signed a confidentiality form.
No information is collected and stored without prior informed and signed consent from patients and patients are aware that this data may be subject of analysis for future and ongoing studies that may be conducted and published.
Under no circumstance will we use patients’ identifiable information on published studies, and patients are free to refuse to allow their data storage in the database without prejudice to their healthcare.
Intervention code [1] 317634 0
Not applicable
Comparator / control treatment
No control group
Control group

Primary outcome [1] 323700 0
To quantify the difference in flexion gap after intra-operative PCL release. Changes will be measured by comparing pre-release and post-release gap graphs generated using the NAVIo robot and navigation software.
Timepoint [1] 323700 0
At conclusion of making bone cuts during surgery prior to definitive implant insertion. Approximately 45 minutes into surgery
Secondary outcome [1] 382650 0
To verify or refute if there is a disproportionate increase in flexion gap after PCL resection. This will be measured intraoperatively using Smith and Nephew NAVIO Robotic surgical system device to quantify medial and lateral joint gaps
Timepoint [1] 382650 0
Approximately 45 minutes into surgery

Key inclusion criteria
Adults from all genders selected for robotic computer navigated primary posterior-stabilised total knee arthroplasty due to knee osteoarthritis
Minimum age
40 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
-Patient who need revision knee arthroplasty
-Patients who need primary TKA for other reason than osteoarthritis
-Pregnant women
-Patients under 18 years-old
-Aboriginal and Torres Strait Islander people
-Patients with a medical, social condition, language barrier (not speaking and understanding English) that restrains them to make a conscious and well informed decision to participate in the study.
-Patients without complete information that allows proper analysis
-Patients who refuse to be a part of the study

Study design
Statistical methods / analysis
Statistical analysis will be performed by outsourced specialists in the field yet to define. They will not have access to participants personal identifiable data.

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)

Funding & Sponsors
Funding source category [1] 305649 0
Self funded/Unfunded
Name [1] 305649 0
Dr Andrew Comley
Address [1] 305649 0
Level 2, Wakefield Orthopaedic Clinic, 120 Angas Street, Adelaide, 5000 South Australia
Country [1] 305649 0
Primary sponsor type
Dr Andrew Comley
Level 2, Wakefield Orthopaedic Clinic, 120 Angas Street, Adelaide, 5000 South Australia
Secondary sponsor category [1] 306056 0
Name [1] 306056 0
Address [1] 306056 0
Country [1] 306056 0

Ethics approval
Ethics application status
Ethics committee name [1] 305933 0
Calvary Heath Care Adelaide; Calvary Health Care Adelaide Human Research Ethics Committee
Ethics committee address [1] 305933 0
Calvary Adelaide Hospital, 120 Angas Street, Adelaide, 5000 South Australia
Ethics committee country [1] 305933 0
Date submitted for ethics approval [1] 305933 0
Approval date [1] 305933 0
Ethics approval number [1] 305933 0

Brief summary
Intervention and Objectives:
-Intra-operatively measure the effect that posterior cruciate ligament (PCL) resection has on gap balancing by doing sequential flexion gap measurements before and after PCL resection using NAVIO robotic for primary posterior-stabilised total knee arthroplasties (PS TKA).
-Determine if PCL resection induces a constant gap difference on the medial and lateral compartment in extension and at different flexion angles

Early complete release of the PCL during the exposure will change the flexion gap which will have clinical significant implication in the flexion gap balancing at the time of surgery

Study Purpose;
Midflexion instability has been flagged by the Australian Joint Replacement registry as an increasing cause of revision of Total Knee replacements. The aim of this study is to quantify flexion gap changes during surgery caused by releasing the PCL. It is hoped that quantifying this will allow more consistent results and improved survivorship after total knee replacement.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 102118 0
Dr Andrew Comley
Address 102118 0
Level 2, Wakefield Orthopaedic Clinic, 120 Angas Street, Adelaide 5000 South Australia
Country 102118 0
Phone 102118 0
+61 0400107870
Fax 102118 0
Email 102118 0
Contact person for public queries
Name 102119 0
Dr Andrew Comley
Address 102119 0
Level 2, Wakefield Orthopaedic Clinic, 120 Angas Street, Adelaide 5000 South Australia
Country 102119 0
Phone 102119 0
+61 0400107870
Fax 102119 0
Email 102119 0
Contact person for scientific queries
Name 102120 0
Dr Andrew Comley
Address 102120 0
Level 2, Wakefield Orthopaedic Clinic, 120 Angas Street, Adelaide 5000 South Australia
Country 102120 0
Phone 102120 0
+61 0400107870
Fax 102120 0
Email 102120 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Data will be available to research team only
What supporting documents are/will be available?
No other documents available
Summary results
No Results