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Trial registered on ANZCTR

Registration number
Ethics application status
Submitted, not yet approved
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
A trial to compare two different surgical techniques used to prevent the unstable knee cap from further episodes of dislocation in patients at significant risk or recurrence.
Scientific title
Medial patello-femoral ligament reconstruction using hamstring autograft versus use of the ligament augmentation reconstruction system (LARS): a prospective randomised controlled trial comparing clinical outcomes, and recurrence rates, in physically active patients.
Secondary ID [1] 298152 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Patellar instability
312703 0
Condition category
Condition code
Musculoskeletal 311204 311204 0 0
Other muscular and skeletal disorders
Injuries and Accidents 311385 311385 0 0
Other injuries and accidents
Surgery 311386 311386 0 0
Surgical techniques

Study type
Description of intervention(s) / exposure
All patients will be undergoing a surgical reconstruction of the medial patellofemoral ligament, performed by an orthopaedic surgeon. The operation takes 60-90 minutes to perform. The first part of the operation is an arthroscopy and then the reconstruction is performed if appropriate. Patients are randomised using a computer program, at this stage.
Arm 1 of the study, will undergo a reconstruction of the medial patellofemoral ligament using one of their own hamstrings. Arm 2 will have a similar procedure performed, except a ligament made of polyethylene terephthalate is used instead of the autograft. The two procedures differ only in the nature of the graft use.
The operation is performed with the patient under a general anaesthetic. All patient have a standard arthroscopy performed, via two portals in the knee (one anteromedial and one anterolateral). A complete arthroscopic assessment of the knee is performed and any cartilage lesions noted and / or treated. Following this a small incision is made along the medial border of the patella and a second on over the medial epicondyle (ME) of the distal femur. The graft (LARS or hamstring) is attached to the medial border of the patella using 2 x bioabsorable suture anchors and then passed along the course of the native MPFL, immediately superficial and apposed to it, to its attachment at the medial epicondyle, where it is attached to the ME using a third anchor. The anchors used are bioabsorbable.
For patients in Arm 1, the hamstring graft is harvested via a small incision placed over the attachment of the gracilis tendon to the proximal medial tibial, and a tendon harvested used to separated the tendon from its muscle, resulting in a tendon graft approximately 20cm long and 3mm in diameter. For patients in Arm 2, the artificial ligament is used instead of the hamstring graft. The results of the randomisation and the operation performed by the operation performed, are recorded and any discrepancy will be noted during the follow-up.
All patients are placed in a range of motion brace for 2 months post surgery, in which they are allowed to bear full weight. They both follow the same physiotherapy-supervised rehabilitation program which commences around 2 weeks post surgery. The latter requires 1 x 1 hour physiotherapy weekly for a total of 8 weeks. These are 1 on 1 physiotherapy sessions. The physiotherapist instructs the patient in quadriceps recruitment and control exercise, as well as co-contractions in the range 0-45dg for 3 weeks, and then 0-90dg for the following 3 weeks. They come out of the brace at 2 months post surgery, and progress their strength and balance. Running in straight lines is possible around 3 months post surgery and return to full sport can vary from 4-6 months post surgery.
Intervention code [1] 314376 0
Treatment: Surgery
Comparator / control treatment
Arm 1 is the control group. These patients undergoing the MPFL reconstruction using the hamstring graft to perform the operation as described above.
Control group

Primary outcome [1] 319962 0
Kujala scores (a validated patient-scored outcome for patellar instability)
Timepoint [1] 319962 0
Baseline (prior to surgery, and the 1, 2 and five years post surgery. The primary end point will be 2 years post surgery
Secondary outcome [1] 369993 0
Tegner activity scores, a validated patient-scored outcome for patellar instability
Timepoint [1] 369993 0
1,2 and 5 years post surgery
Secondary outcome [2] 369994 0
Recurrent patellar instability/ surgery.. All further episodes of instability will be noted during the follow-up period and / or further surgery required.
Patients will be reviewed at these time points and the results are recorded in the surgeons computerised notes. There is only one surgeon involved in the study and all details are recorded in the surgeon's database.
Timepoint [2] 369994 0
1,2 and 5 years post surgery

Key inclusion criteria
History of patellar dislocation with examination findings consistent with this diagnosis (positive patellar apprehension test, MRI findings consistent with this diagnosis - bone bruising pattern and MPFL disruption or attenuation)
Physically active - involved in physical activity at least 3 times per week
Skeletally mature - closed epiphyses about the knee on imaging (MRI, CT, or x-rays)
No previous surgery on the knee
Failed 6 weeks course of physiotherapy
Intact collateral and cruciate ligaments
No meniscal injury
Minimum age
12 Years
Maximum age
50 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Rheumatological or connective tissue disease
Generalized ligamentous laxity
Unfit for a general anesthetic
Previous knee surgery

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Sealed opaque envelop
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
computer generated sequence
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
Descriptive analysis of the patient population means and ranges will be performed for continuous variables. Discrete variables will be reported as percentages and frequencies. Generalised linear models will be use to evaluate patient reported outcomes. 2 sided hypothesis testing will be used, and statistical significance will be set at P<0.05. A post-hoc power analysis will be performed and the patients will be recruited until the power of the study is 80%

Recruitment status
Not yet recruiting
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] 13687 0
Calvary Private Hospital ACT - Bruce
Recruitment postcode(s) [1] 26377 0
2600 - Canberra
Recruitment postcode(s) [2] 26378 0
2617 - Bruce

Funding & Sponsors
Funding source category [1] 302681 0
Self funded/Unfunded
Name [1] 302681 0
Address [1] 302681 0
Country [1] 302681 0
Primary sponsor type
Mark D Porter
Canberra Orthopaedics and Sports Medicine, Suite 21 Calvary Clinic, Bruce, ACT 2617, Australia
Secondary sponsor category [1] 302611 0
Name [1] 302611 0
Address [1] 302611 0
Country [1] 302611 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 303299 0
Barton Private Hospital Medical Advisory and Ethics Committee
Ethics committee address [1] 303299 0
Barton Private Hospital
3 Sydney Avenue
Barton, ACT 2600
Ethics committee country [1] 303299 0
Date submitted for ethics approval [1] 303299 0
Approval date [1] 303299 0
Ethics approval number [1] 303299 0

Brief summary
Instability of the knee cap is a common problem and has a high recurrence rate, even with appropriate physiotherapy. When it has recurred, surgery becomes the necessary treatment. The surgical technique most commonly used involves the use of one of the patient's hamstrings to make a new ligament, the medial patello-femoral ligament. This technique uses one of the patient's own hamstrings and there is increased pain and an increased risk of complications associated with taking the hamstring graft. An artificial ligament, referred to as the ligament augmentation reconstruction system (LARS), is an alternative ligament that has been used for this operation, instead of the hamstring graft. This has the potential benefit of less pain, and a lower risk of complications. However there is no research to compare the outcomes of the two techniques used to reconstruct the ligament. The goal of the study was to compare the patient outcomes in patients undergoing the operation with the use of a hamstring graft versus the use of the LARS graft. Patients who are appropriate candidates and who agree to take part in the study, are randomly allocated to group 1 who have a hamstring graft, or group 2 who have a LARS ligament. Both groups will follow the same rehabilitation protocol to be supervised by a physiotherapist. Patients are allowed to weight bear as tolerable with a brace on, and the range of motion permitted in the brace is gradually increased over a period of 8 weeks. After this the patient can wean from the use of the brace. Patients can expect to make a complete recovery within 4 months of the surgery. The outcomes of interest are a questionnaire referred to as the Kajula score and Tegner activity score. These are completed before surgery and again at 1, 2, and 5 years post surgery. The results will be compared using statistical analysis.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 93186 0
Dr Mark Porter
Address 93186 0
Canberra Orthopaedics and Sports Medicine, Suite 21 Calvary Clinic, Mary Potter Circuit, Bruce, ACT 2617
Country 93186 0
Phone 93186 0
+61 02 62535404
Fax 93186 0
Email 93186 0
Contact person for public queries
Name 93187 0
Dr Mark Porter
Address 93187 0
Canberra Orthopaedics and Sports Medicine, Suite 21 Calvary Clinic, Mary Potter Circuit, Bruce, ACT 2617
Country 93187 0
Phone 93187 0
+61 02 62535404
Fax 93187 0
Email 93187 0
Contact person for scientific queries
Name 93188 0
Dr Mark Porter
Address 93188 0
Canberra Orthopaedics and Sports Medicine, Suite 21 Calvary Clinic, Mary Potter Circuit, Bruce, ACT 2617
Country 93188 0
Phone 93188 0
+61 02 62535404
Fax 93188 0
Email 93188 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?
Ethical approval
Summary results
No Results