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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
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
The Arthroplasty and Bariatric Surgery study in obese patients with osteoarthritis
Scientific title
The Arthroplasty and Bariatric Surgery (ABS) study: a randomised controlled trial to determine the efficacy of laparoscopic adjustable gastric banding prior to total knee arthroplasty in obese patients with osteoarthritis
Secondary ID [1] 273372 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Osteoarthritis 279142 0
Obesity 279143 0
Condition category
Condition code
Musculoskeletal 279331 279331 0 0
Diet and Nutrition 279332 279332 0 0

Study type
Description of intervention(s) / exposure
The intervention group will undergo Laparoscopic adjustable gastric banding (LAGB) followed by total knee arthroplasty (TKA) 12 months later or after 20% loss of baseline body weight if this occurs earlier.
LAGB is a single procedure that involves placing a silicone band around the top of the stomach. The band has a balloon on its inner surface. The balloon is connected by tubing to an access port placed under the skin. Saline can be injected into the port to make the band tighter or removed to make it less tight. Doing this assists with control of appetite. If the band is adjusted optimally, there should be very little hunger, there is loss of interest in food and a tendency to eat less amounts, less often. The procedure is performed laparoscopically, sometimes known as “keyhole” surgery. It is performed under a general anaesthetic and takes about 30 minutes.
TKA is also a single surgical procedure whereby the diseased knee joint is replaced with artificial one. The knee is a hinge joint which provides motion at the point where the thigh meets the lower leg. During a total knee replacement, the end of the thigh (femur) bone is removed and replaced with a metal shell. The end of the lower leg bone (tibia) is also removed and replaced with a channelled plastic piece with a metal stem. Depending on the condition of the kneecap portion of the knee joint, a plastic "button" may also be added under the kneecap surface. The procedure is performed under either a general or spinal anaesthetic and takes about 1 hour
Intervention code [1] 283707 0
Treatment: Surgery
Comparator / control treatment
The control group will undergo TKA alone.
Control group

Primary outcome [1] 279937 0
The primary outcome will be a composite of (i) death from any cause; (ii) peri-operative complications (medical or surgical); (iii) post-operative complications (medical or surgical) that result in a delay in discharge, eg: fracture, neuropraxia, sepsis, nosocomial infection, myocardial infarction, bowel obstruction, venous thrombo-embolic event (VTE), cerebrovascular accident (CVA), renal failure; (iv) wound complications (breakdown, infections, haematomas, dehiscence); (v) joint infections (Centres for Disease Control definitions applied); and (vi) unplanned procedures and/or readmissions in the first 12 months following TKA.
The processes for identifying outcomes will be conducted by a Project Research Officer who will be blinded to the intervention allocation. Active surveillance for outcomes will comprise the following:
-Recording of data regarding patient demographics (sex, age and country of birth), co-morbidities, and anaesthetic and surgery details on the day of surgery.
-Attendance at all unit ward rounds to capture complications and readmissions
-Attendance at X-ray meetings to capture technical complications of surgery
-Review of all medical records on patient discharge and follow-up at each outpatients review
-Recording of alignment of all post-operative full-leg standing radiographs
-Phone calls to participants at 3-monthly intervals
-Retrieval and review of records from other healthcare institutions as required
The Project Officer will collate information on all possible primary outcomes of interest for review by an outcomes verification panel comprising at least 4 independent clinicians blinded to the patient's intervention allocation. The panel will include at least 2 peri-operative physicians and 2 orthopaedic surgeons. Ascertainment of outcomes will be undertaken according to review against strict criteria (to be determined and endorsed by the panel).
Timepoint [1] 279937 0
Within 12 months of TKA
Secondary outcome [1] 294807 0
Bed Day Utlization
Assessment via medical record review
Timepoint [1] 294807 0
Within 12 months of TKA
Secondary outcome [2] 294808 0
Weight loss
As per individuals being weighed on scales
Timepoint [2] 294808 0
Within 12 months of TKA
Secondary outcome [3] 294809 0
Function and Quality of Life as measured using the WOMAC and Short Form 12
Timepoint [3] 294809 0
Pre and 12 months post TKA
Secondary outcome [4] 294810 0
Cost Effectiveness of LAGB + TKA compared to TKA alone
Information regarding utilisation of health services, including medications and in- and outpatient services, will be captured by linkage of our database to administrative and clinical databases maintained by the study institution.
Timepoint [4] 294810 0
At 12 months post TKA

Key inclusion criteria
Age less than 65 years at time of LAGB; (ii) BMI equal to or greater than 35 kg/m2; (iii) End-stage osteoarthritis, on the surgical waiting list for primary TKA at the study institution; (iv) Willing and able to cooperate in a long-term weight management programme.
Minimum age
20 Years
Maximum age
65 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
(i) Revision surgery or surgery for neoplastic disease; (ii) Inability to provide informed consent; (iii) A medical condition which in the opinion of the investigators makes the patient unsuitable for participation in the trial (iv) Previous oesophagogastric surgery such as fundoplication; (v) Lack of acceptance of the randomisation process.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
When a subject has fulfilled all study criteria allocation take place. The patient’s assignment will be performed by the data manager who will have no direct contact with the subject either before or after assignment. The clinicians involved in the assessment or treatment of patients will have no role in the assignment process. Opaque envelopes containing patient assignment will be prepared.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Random assignment will be computer generated by a researcher not directly involved in the study. Randomisation will be clustered into groups of random size of between 8 and 12 to ensure even distribution without bias
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Stopped early
Data analysis
Data collected is being analysed
Reason for early stopping/withdrawal
Participant recruitment difficulties
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] 284187 0
Government body
Name [1] 284187 0
National Health and Medical Research Council
Address [1] 284187 0
GPO Box 1421
Canberra ACT 2601
Country [1] 284187 0
Primary sponsor type
Professor Peter Choong
Department of Orthopaedics
St. Vincent's Hospital (Melbourne)
Level 3 Daly wing
35 Victoria parade
Fitzroy 3065
Secondary sponsor category [1] 269143 0
Name [1] 269143 0
Associate Professor Wendy Brown
Address [1] 269143 0
Centre for Obesity Research and Education
Monash Medical School
Level 6, The Alfred Centre
99 Commercial road
Melbourne 3004
Country [1] 269143 0
Secondary sponsor category [2] 269145 0
Name [2] 269145 0
Professor Danny Liew
Address [2] 269145 0
Centre for Clinical Epidemiology, Biostatistics and Health Services Research
Royal Melbourne Hospital
7 East, Main Building
Grattan street
Parkville 3050
Country [2] 269145 0
Secondary sponsor category [3] 269146 0
Name [3] 269146 0
Dr Michelle Dowsey
Address [3] 269146 0
Department of Orthopaedics
St. Vincent's Hospital (Melbourne)
Level 3 Daly wing
35 Victoria parade
Fitzroy 3065
Country [3] 269146 0

Ethics approval
Ethics application status
Ethics committee name [1] 286152 0
The St. Vincent's Hospital (Melbourne) Human Research Committee - A
Ethics committee address [1] 286152 0
35 Victoria Parade,
Fitzroy. 3065.
Ethics committee country [1] 286152 0
Date submitted for ethics approval [1] 286152 0
Approval date [1] 286152 0
Ethics approval number [1] 286152 0
HREC-A 142/11

Brief summary
The Arthroplasty and Bariatric Surgery (ABS) study intends to examine the clinical outcomes and cost effectiveness of preceding total knee replacement (TJR) with laparoscopic adjustable gastric banding (LAGB) in a randomised controlled trial (RCT).
This will be a 4 year multi-institutional randomized controlled trial in severely obese patients with end stage osteoarthritis. The study will recruit 120 severely obese people with osteoarthritis who are on the waiting list for TKR and randomly allocate them to receive the current standard of care for TKR or a combination of LAGB followed by TKR. We plan to measure weight loss, pain and function, quality of life and complications, as well as the cost effectiveness of a strategy that combines LAGB +TKR, compared to TKR alone. Participants will all be followed for one year at which time the benefits in terms of, weight loss, clinical and health improvements, adverse events and costs would be measured.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 33378 0
Prof Peter Choong
Address 33378 0
University of Melbourne
Department of Surgery
L2 Clinical Sciences Building
St. Vincent's Public Hospital
29 Regant St,
Fitzroy. 3065
Country 33378 0
Phone 33378 0
+61 39231 2365
Fax 33378 0
Email 33378 0
Contact person for public queries
Name 16625 0
Mrs Angela Cochrane
Address 16625 0
St. Vincent's Hospital (Melbourne)
Department of Orthopaedics
Level 3 Daly wing
35 Victoria parade
Fitzroy 3065
Country 16625 0
Phone 16625 0
+61 39231 2364
Fax 16625 0
+61 3 9416 3610
Email 16625 0
Contact person for scientific queries
Name 7553 0
A/Prof Michelle Dowsey
Address 7553 0
ST. Vincent's Hospital (Melbourne)
Department of Orthopaedics
Level 3 Daly wing
35 Victoria parade
Fitzroy 3065
Country 7553 0
Phone 7553 0
+61 3 9288 3955
Fax 7553 0
+61 3 9416 3610
Email 7553 0

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 other documents available
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary