Advice
Evidence review
Evidence review
Clinical and technical evidence
Regulatory bodies
A search of the Medicines and Healthcare Products Regulatory Agency website revealed no manufacturer Field Safety Notices or Medical Device Alerts for this device.
The LARS is not licensed for use in the US, so no search of Food and Drug Administration (FDA) database: Manufacturer and User Device Facility Experience (MAUDE) was undertaken.
Clinical evidence
A literature search revealed 659 studies on the LARS: 649 of these studies were excluded for failing to meet the inclusion and exclusion criteria, mainly because the studies did not use the LARS device. The remaining 10 papers were assessed for quality. The 5 comparative papers, of which 1 is a randomised trial and 4 are cohort studies, represent the best‑quality evidence and are described in this briefing and summarised in tables 2–7.
The safety profile of the LARS was most comprehensively addressed in the systematic review conducted by Batty et al. (2015). This review included 20 studies of knee surgery using the LARS, 3 of which were comparative studies that are also discussed individually in this briefing (Nau et al. 2002; Liu et al. 2010, Pan et al. 2013). The other 17 studies were non‑comparative case series. A total of 1102 knee surgeries were reported in the Batty et al. (2015) review: 13 anterior cruciate ligament (ACL) patient cohorts (843 knees, of which 50 were revisions); 4 posterior cruciate ligament (PCL) cohorts (120 knees, 0 revisions); and 5 combined ACL and PCL cohorts (139 knees, 0 revisions).
In this study the authors reported that the incidence of complications in each category (failure, revision and non‑infective effusion and synovitis) ranged from 0% to 3% for ACL and PCL surgeries.
In addition to the LARS, theBatty et al. study also reported on other synthetic ligaments, namely Kennedy LAD, Leeds‑Kieo I, Leeds‑Kieo II, Dacron, Gore‑Tex and Trevira‑Hochfest. The LARS had the lowest overall failure rate at 2.4% (20/862) with other synthetic ligaments having failure rates that ranged from 7.7% (Leeds‑Kieo, 1/13) to 33.6% (Dracon, 168/499). LARS had the lowest overall revision rate, at 2.2% (21/945) with the Kennedy LAD having the second lowest, 3.5% (13/368), and the Dacron the highest at 11.7% (48/409). There were no observed incidences of non‑infective effusion and synovitis for the Leeds‑Keio II (0/13). A rate of 0.4% (2/562) was reported for the LARS, with the highest reported rate being 26.6% (103/387) for the Gore‑Tex. A summary is provided in table 1.
Table 1 Summary of the Batty et al. (2015) study
|
Study component |
Description |
|
Objectives/hypotheses |
To assess safety and efficacy of LARS and other synthetic devices for cruciate ligament surgery. |
|
Study design |
Systematic review. |
|
Inclusion/exclusion criteria |
Included studies: Controlled and uncontrolled trials, n>10, that assessed safety and efficacy of synthetic devices used for ACL and PCL. Excluded studies: in vivo, animal studies, not reported in English, non‑peer reviewed, abstract only, cruciate reconstruction in conjunction with high tibial or distal femoral osteotomy. |
|
Primary outcomes |
Rates of failure, revision, and non‑infective effusion and synovitis. |
|
Statistical methods |
Summative data were used for categorical variables, with means and standard deviations for continuous variables. Meta‑analysis was not possible because of heterogeneity and inconsistent outcome reporting. |
|
Studies |
20 studies on LARS involving ACL, PCL and combined. Total of 1102 knees included (ACL, 843; PCL, 120; and combined, 139). Mean follow‑up ranged from 22–95 months for ACL cohorts; 26–44 months for PCL and 27–44 months for combined cohorts. |
|
Results: Failure |
LARS: ACL: 2.6% (19/736) PCL: 1.0% (1/99) A combined ACL and PCL procedure: 0.0% (0/27) Kennedy LAD: ACL: 13.9% (180/1,364) Leeds‑Keio I: ACL: 16.8% (60/365) Leeds‑Keio II: ACL: 7.7% (1/13) Dacron: ACL: 33.6%(168/499) Gore‑Tex: ACL:12.9%(59/475) Trevira‑Hochfest: ACL: 9.8% (26/265) PCL: 16.7% (2/12) |
|
Results: Revision |
ACL: 2.6% (19/728) PCL: 0.0% (0/120) Combined ACL and PCL: 2.2% (2/89) Range for all devices: 2.2% LARS to 11.7% (Dacron, 48/409) |
|
Results: Non‑infective effusion/synovitis |
ACL: 0.2% (1/438) PCL: 1.2% (1/79) Combined ACL and PCL: NR Range for all devices: 0% (Leeds‑Keio II, 0/13) to 26.6% (Gore‑Tex, 103/387) The authors noted that half of the LARS studies did not report synovitis and effusion and so the reported low incidence should be interpreted with caution. |
|
Conclusions |
Authors concluded that the LARS studies reported acceptably low rates of failure and complications for ACL and PCL, including revision surgery. |
|
Abbreviations: ACL, anterior cruciate ligament; n, number of patients; NR, not reported; PCL, posterior cruciate ligament. |
|
The clinical evidence on the use of the LARS in knee reconstruction has been divided into 2 groups relating to either ACL or PCL reconstruction. The studies used a variety of measures of knee stability and function as outcome measures.
Measures of knee stability:
-
KT‑1000 evaluation is a clinical test of anterior tibial motion relative to the femur. The test measures the extent of this motion in millimetres compared with the uninjured knee. Higher scores represent greater knee laxity (Arneja and Leith 2009).
-
The posterior drawer test measures the integrity and laxity of the PCL. The clinician stabilises the patient's foot using 1 of a variety of positions then pushes the proximal tibia posteriorly. The translation or movement is estimated in millimetres, relative to the opposite, uninjured knee (Feltham and Albright 2001). Objective and subjective knee functioning is independent of the degree of PCL laxity (Shelbourne et al. 1999), but this laxity does lead to a change in knee mechanics (Logan et al. 2004).
Patient‑reported measures of knee function:
-
The Lysholm score is a questionnaire measuring knee function within 8 domains: limp, locking, pain, stair climbing, support, instability, swelling and squatting. The overall score ranges from 0‑100, with a score of 95–100 considered excellent, 84–94 good, 65–83 fair and 65 or lower, poor (Briggs et al. 2009).
-
The Tegner score is a self‑assigned score. Patients assign themselves a score from 0–10, with 0 representing 'sick leave or disability pension because of knee problems' and 10 representing 'competitive sports — soccer, football, rugby (national elite)' (Briggs et al. 2009).
-
The International Knee Documentation Committee (IKDC) score is a questionnaire assessing 4 areas: subjective assessment, symptoms, range of motion and ligament examination. People are categorised within each domain and overall as normal, nearly normal, abnormal and severely abnormal (Hefti et al. 1993).
-
The Knee Injury and Osteoarthritis Outcome Score (KOOS) allows knee function to be assessed across 5 domains: pain, symptoms, daily living, sports and recreation, and knee‑related quality of life. A score is decided by the patient for each of the 5 domains, ranging from 0 (extreme symptoms) to 100 (no symptoms; KOOS website).
Anterior cruciate ligament
The use of the LARS for ACL reconstruction was investigated in 3 studies that are summarised in this briefing. Of these, 1 reported a randomised controlled trial conducted in Canada (Nau et al. 2002) and 2 were retrospective cohort studies conducted in China (Liu et al. 2010; Pan et al. 2013).
All 3 studies report clinical measures of knee stability as well as patient‑reported measures of knee function. Statistically significant differences between autograft and the LARS were rarely observed, and were fewest at later assessment time points. Only the study by Liu et al. (2010) reported a statistically significant difference at the final time point, where the LARS patients had statistically greater stability at 49 months than autograft, as measured by KT‑1000.
Rates of complications were reported in less than 10% of autograft patients and less than 5% of the LARS patients within each of these ACL studies. No reports of infection or synovitis were observed in Nau et al. (2002) or Liu et al. (2010) or reported to have been observed in Pan et al. (2013). The 3 studies involved a total of 83 people having the LARS, 2 of whom reported complications. There was 1 case of excess laxity in the study by Nau et al. (1/83, 1.2%), which required surgical intervention to retighten the graft and the other was a report of pain caused by a tibial screw in the trial by Liu et al. (1/83, 1.2%). No statistical analysis was reported to have been conducted on rates of complications in these studies.
These studies are summarised within tables 2, 3, 4 and 5.
Table 2 Summary of the Nau et al. (2002) study
|
Study component |
Description |
|
Objectives/hypotheses |
To compare clinical outcomes and patient satisfaction between BPTB autografts and LARS. |
|
Study design |
Prospective randomised controlled trial. |
|
Setting |
Patients recruited December 1996–August 1998. Follow‑up at 2, 6, 12 and 24 months. |
|
Inclusion/exclusion criteria |
Inclusion criteria were adults with closed growth plates and chronic symptomatic rupture of ACL. People with a history of previous surgery on the ACL, infection or septic arthritis in either knee, or additional ligamentous instability in the affected knee were excluded. |
|
Primary outcomes |
Tegner score, IKDC evaluation, Instrumented laxity testinga, KOOS evaluation. |
|
Statistical methods |
Pre‑operative treatment group characteristics and post‑operative outcomes were compared. Student's unpaired t‑test was used for parametric data, chi‑square test for categorical data and Mann–Whitney U test for non‑parametric data. Statistically significant differences at p<0.05. |
|
Participants |
n=27 in BPTB group; n=26 in the LARS group. 1 patient from each group was lost to follow‑up. |
|
Results |
No significant differences between the groups in Tegner score and IKDC evaluation. The LARS patients reported statistically significant higher laxity than BPTB, at 6 months; thereafter differences were not significant. No significant difference between KOOS subscales pre‑operatively and at 24 months. The LARS group recorded significantly higher scores in some subdomains at intermediate time points. Excess laxity was shown by one BPTB and 1 LARS patient, the latter requiring further surgery. The 2 people who were lost to follow‑up were assumed to have experienced failure. |
|
Conclusions |
Authors concluded that the use of the LARS in ACL reconstruction provided high patient satisfaction in first 24 months but longer‑term results were required. |
|
Abbreviations: ACL, anterior cruciate ligament; BPTB, bone‑patellar tendon‑bone; IKDC, International Knee Documentation Committee; KOOS, Knee Injury and Osteoarthritis Outcome Score; n, number of patients. aInstrumented laxity testing — This test may refer to the KT‑1000 measure, although the specific details of the test were not provided. |
|
Table 3 Results from Nau et al. (2002) study
|
BPTB |
LARS |
Analysis |
||
|
Randomised |
n=27 |
n=26 |
||
|
Efficacy |
n=26 |
n=25 |
2 lost to follow‑up. |
|
|
Primary outcome: IKDC scorea |
||||
|
Subjective domain: (median) |
Pre‑op: C 2 months: C 6 months: B 12 months: B 24 months: A |
Pre‑op: C 2 months: B 6 months: B 12 months: B 24 months: A |
No statistically significant differences across the groups (p>0.05) at all time points. |
|
|
Stability domain: (median) |
Pre‑op: C 2 months: A 6 months: B 12 months: B 24 months: B |
Pre‑op: C 2 months: B 6 months: B 12 months: B 24 months: B |
No statistically significant differences across the groups (p>0.05) at all time points. |
|
|
Range of movement domain: (median) |
Pre‑op: A 2 months: B 6 months: A 12 months: A 24 months: A |
Pre‑op: A 2 months: B 6 months: A 12 months: A 24 months: A |
No statistically significant differences across the groups (p>0.05) at all time points. |
|
|
Symptoms domain: (median) |
Pre‑op: D 2 months: D 6 months: C 12 months: C 24 months: A |
Pre‑op: D 2 months: D 6 months: C 12 months: C 24 months: B |
No statistically significant differences across the groups (p>0.05) at all time points. |
|
|
Selected secondary outcomes: |
||||
|
Instrumented laxity testingb (mm) (mean±SD) |
24 months: 2.38±1.8 |
24 months: 4.86±3.8 |
6 months: p=0.01 (BPTB<LARS) Results not reported at other time points but p>0.05. |
|
|
KOOS evaluation |
NR |
NR |
No statistically significant differences (p>0.05) between groups pre‑operatively and at 24 months. The LARS group recorded statistically significant higher scores in some subdomains at intermediate time points. |
|
|
Tegner score |
NR |
NR |
No statistically significant differences (p>0.05) between the groups at all‑time points. |
|
|
Safety |
n=26 |
n=25 |
2 lost to follow‑up. |
|
|
Excessive laxity |
3.8% (1/26) |
4.0% (1/25) |
The LARS patient needed surgery. |
|
|
Abbreviations: BPTB, bone‑patellar tendon‑bone graft; IKDC, International Knee Documentation Committee; KOOS, Knee Injury and Osteoarthritis Outcome Score; n, number of patients. aIKDC score key: A = Normal, B = Nearly normal, C = Abnormal, D = Severely abnormal. bInstrumented laxity testing — This test may refer to the KT‑1000 measure, although the specific details of the test were not provided. |
||||
Table 4 Summary of the Liu et al. (2010) study
|
Study component |
Description |
|
Objectives/hypotheses |
To compare the outcomes after ACL reconstruction using either a 4SHG or a LARS and assess the effectiveness of the 2 grafts. |
|
Study design |
Retrospective cohort study. |
|
Setting |
Patients having ACL reconstruction surgery January 2003–July 2004. All procedures were performed by the same surgeon. Mean follow‑up 49 months. |
|
Inclusion/exclusion criteria |
All patients who had surgery for an ACL rupture during the recruitment period were considered for inclusion. Exclusion criteria were a combined ligament injury, radiographically visible degenerative changes, previous knee surgery history, contralateral knee ligament injury and less than 4 years' follow‑up. |
|
Primary outcomes |
Lysholm score, Tegner score, IKDC score and KT‑1000 evaluation. |
|
Statistical methods |
Pre‑operative treatment group characteristics and post‑operative outcomes compared statistically. Continuous variables analysed by the unpaired Student's t‑test, nominal data analysed by chi‑square test and categorical variables analysed by Wilcoxon test. Statistically significant differences at p<0.05. |
|
Participants |
n=32 in 4SHG group and n=28 in the LARS group, with no statistical differences across gender, age, cause of injury, mean time to surgery, Lysholm score and Tegner score. |
|
Results: Lysholm score, (mean±SD) |
4SHG group:
LARS group:
This difference was not statistically significant across the 2 groups (p>0.05). |
|
Results: Tegner score, (mean±SD) |
4SHG group:
LARS group:
This difference was not statistically significant across the 2 groups (p>0.05). |
|
Results: IKDC scorea (post‑operative only) |
4SHG group: A=22, B=6, C=4, D=0 LARS group: A=21, B=5, C=2, D=0 This difference was not statistically significant across the 2 groups (p>0.05). |
|
Results: KT‑1000, (mean mm±SD) |
4SHG group: 2.4±0.5 mm LARS group: 1.2±0.3 mm LARS group had statistically significantly less anterior displacement than 4SHG group (p=0.013). |
|
Results: Adverse events |
2 patients (6.2%) in the 4SHG group lost 5° of full flexion and a third (3.1%) developed arthrofibrosis; 1 patient (3.6%) in the LARS group needed removal of a tibial screw because of pain. |
|
Conclusions |
Authors concluded functional outcomes were improved with both LARS and 4SHG. Patients in the LARS group displayed higher knee stability than those in the 4SHG group. |
|
Abbreviations: 4SHG, 4‑strand hamstring tendon graft; ACL, anterior cruciate ligament; IKDC, International Knee Documentation Committee; n, number of patients; SD, standard deviation. aIKDC score key: A = Normal, B = Nearly normal, C = Abnormal, D = Severely abnormal. |
|
Table 5 Summary of the Pan et al. (2013) study
|
Study componen |
Description |
|
Objectives/hypotheses |
To compare 4‑year outcomes of ACL reconstruction using arthroscopic surgery and BPTB autografts or LARS. |
|
Study design |
Retrospective cohort study. |
|
Setting |
Patients treated for a ruptured ACL July 2004–March 2006. All procedures were performed by the same surgeon. Mean follow‑up was 50 months. |
|
Inclusion/exclusion criteria |
Included patients had an ACL rupture, possibly with meniscal and/or cartilaginous injury. Patients with previous knee surgery, contralateral knee ligament injury, osteoarthritis or infection were excluded. 62 patients met the inclusion criteria and were allocated to groups based on patient preference. |
|
Primary outcomes |
Lysholm knee scoring scale, Tegner score, IKDC score and KT‑1000 evaluation. |
|
Statistical methods |
Continuous variables were analysed by the unpaired Student's t‑test, nominal data were analysed by the chi‑square test and categorical variables were analysed by the Wilcoxon‑signed rank test. Statistically significant differences at p<0.05. |
|
Participants |
n=30 in the BPTB group and n=30 in the LARS group, with no statistical differences across gender, age, time to operation, Lysholm score, Tegner score and IKDC score. |
|
Results: Lysholm score, (mean±SD) |
BPTB group:
LARS group:
This difference was not statistically significant across the 2 groups (p>0.05). |
|
Results: Tegner score, (mean±SD) |
BPTB group:
LARS group:
This difference was not statistically significant across the 2 groups (p>0.05). |
|
Results: IKDC scorea |
BPTB group:
LARS group:
This difference was not statistically significant across the 2 groups (p>0.05). |
|
Results: KT‑1000, (mean mm±SD) |
BPTB group: 2.62±2.12 mm LARS group: 2.29±2.03 mm Results not statistically significant across the 2 groups (p>0.05). |
|
Results: Adverse events |
There were no reported cases of synovitis or infection in either group. Anterior knee pain occurred in 2 patients (6.7%) from the BPTB group which lasted for around 18 months after surgery. |
|
Conclusions |
Authors concluded BPTP and the LARS had similar clinical outcomes at 4 years follow‑up and were satisfactory treatment options for ACL rupture. |
|
Abbreviations: ACL, anterior cruciate ligament; BPTB, bone‑patellar tendon‑bone; IKDC, International Knee Documentation Committee; n, number of patients; SD, standard deviation. aIKDC score key: A = Normal, B = Nearly normal, C = Abnormal, D = Severely abnormal. |
|
Posterior cruciate ligament
Two retrospective cohort studies, both conducted in China, assessed the use of the LARS in posterior cruciate ligament (PCL) reconstruction (Li et al. 2009; Xu 2014). These papers are summarised in tables 5 and 6.
The study by Li et al. (2009) reported that 2‑years post‑operatively, the Lysholm score, KT‑1000 test and posterior drawer test results for the LARS patients were statistically significantly better than those for autograft patients. The study by Xu et al. (2014), found no statistically significant differences in any of the outcomes measured 51 months post‑operatively.
One LARS patient (n=19; 5.3%) in the study by Xu et al. (2014) experienced synovitis and recovered after having an arthroscopic synovectomy. No other complications with the LARS were reported.
Table 6 Summary of the Li et al. (2009) study
|
Study component |
Description |
|
Objectives/hypotheses |
To compare the outcomes of PCL reconstruction using either 4SHG or LARS. |
|
Study design |
Retrospective cohort study. |
|
Setting |
Patients presented August 2002–March 2006 with chronic PCL rupture. All procedures were performed by the same surgeon. Mean length of follow‑up was slightly longer for 4SHG than the LARS at 2.4 and 2.2 years respectively. |
|
Inclusion/exclusion criteria |
All consecutive chronic PCL rupture patients were assessed against inclusion and exclusion criteria. Inclusion required patients to have a symptomatic isolated PCL rupture. Exclusion criteria were combined ligament injury, radiographically visible degenerative changes, contralateral knee ligament injury and follow‑up of less than 2 years. 36 of 54 identified patients were included. |
|
Primary outcomes |
Lysholm score, Tegner score, IKDC rating, KT‑1000 evaluation and posterior drawer test. |
|
Statistical methods |
Results from the primary outcomes were tested across the 2 groups using the Wilcoxon signed rank test. Statistical significance was set at p<0.05. |
|
Participants |
n=15 in 4SHG group; n=21 in the LARS group. |
|
Results: Lysholm score, median (range) |
4SHG group:
LARS group:
This difference was statistically significant across the 2 groups (p<0.05). |
|
Results: Tegner score, median (range) |
4SHG group:
LARS group:
This difference was statistically significant across the 2 groups (p<0.05). |
|
Results: IKDC scorea |
4SHG group:
LARS group:
This difference was not statistically significant across the 2 groups (p=0.285). |
|
Results: KT‑1000 |
4SHG group:
LARS group:
This difference was statistically significant across the 2 groups (p<0.05). |
|
Results: Posterior drawer test |
4SHG group:
LARS group:
This difference was statistically significant across the 2 groups (p<0.05). |
|
Results: Adverse events |
No patient had immediate post‑operative complications. 1 member of each group (6.7% and 4.8%) experienced anterior knee pain. 2 patients (13.3%) in the 4SHG group felt paraesthesia on the medial side of the knee, but recovered within 6 months. 1 knee (6.7%) in the 4SHG group developed arthrofibrosis requiring arthroscopic lysis and manipulation with satisfactory results. |
|
Conclusions |
Authors concluded that the LARS was clinically more useful than 4SHG in treating PCL, restoring better knee stability and knee function, with no complications at 2 years. However, longer term follow‑up is needed as problems with the LARS graft may occur later. |
|
Abbreviations: 4SHG, 4‑strand hamstring graft; IKDC, International Knee Documentation Committee; n, number of patients; PCL, posterior cruciate ligament. aIKDC score key: A = Normal, B = Nearly normal, C = Abnormal, D = Severely abnormal. |
|
Table 7 Summary of the Xu et al. (2014) study
|
Study component |
Description |
|
Objectives/hypotheses |
To follow patients receiving PCL reconstruction using 4SHG or LARS and compare their clinical results in a long‑term follow‑up. |
|
Study design |
Retrospective cohort study. |
|
Setting |
Patients undergoing surgery December 2006–September 2008 by a single surgeon. Mean follow‑up of 51 months. |
|
Inclusion/exclusion criteria |
56 patients with PCL reconstruction were eligible for inclusion, of which 21 patients were excluded because of posteromedial or posterolateral corner injuries (11), multi‑ligament injuries (8) and bilateral PCL rupture (2). Patients self‑selected into treatment groups. |
|
Primary outcomes |
Lysholm score, Tegner score, IKDC rating, KT‑1000 score and reported complications. |
|
Statistical methods |
Treatment groups and outcomes tested for statistical differences. Unpaired Student's t–test was used to analyse continuous variables, chi square test to analyse nominal data and Wilcoxon signed rank test to analyse categorical variables. Statistical significance was set at p<0.05. |
|
Participants |
n=16 in 4SHG group and n=19 in the LARS group, with no statistically significant differences across age, gender, side of injury and time from injury to surgery. |
|
Results: Lysholm score (mean±SD) |
4SHG group:
LARS group:
The estimated treatment effect was not statistically significant across the 2 groups (p>0.05). |
|
Results: Tegner score (mean±SD) |
4SHG group:
The estimated treatment effect was not statistically significant across the 2 groups (p>0.05). |
|
Results: IKDC scorea |
4SHG group:
LARS group:
The estimated treatment effect was not statistically significant across the 2 groups (p>0.05). |
|
Results: KT‑1000 (mean mm±SD) |
4SHG group:
LARS group:
The estimated treatment effect was not statistically significant across the 2 groups (p>0.05). |
|
Results: Adverse events |
2 patients (12.5%) reported anteromedial knee pain after hamstring autografts, but recovered in a few months. 1 LARS patient (5.3%) developed synovitis post‑operatively and received an arthroscopic synovectomy. |
|
Conclusions |
Authors concluded that there was no statistically significant difference in clinical endpoints between use of 4SHG or LARS in PCL reconstruction. |
|
Abbreviations: 4SHG, 4‑strand hamstring tendon autograft; IKDC, International Knee Document Committee; n, number of patients; PCL, posterior cruciate ligament; SD, standard deviation. aIKDC score key: A = Normal, B = Nearly normal, C = Abnormal, D = Severely abnormal. |
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Recent and ongoing studies
A search of clinicaltrials.gov and the Australian New Zealand Clinical Trial Registry (ANZCTR) identified no ongoing LARS studies.
The distributor provided details of 2 Australian trials using the LARS for ACL reconstruction:
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An evaluation of outcome measures across rehabilitation of 2 different ACL reconstruction techniques. Aim: to quantitatively measure recovery of function following ACL reconstruction using hamstring reconstruction or the LARS. Patient numbers: hamstring reconstruction, 32; LARS, 32; healthy control, 50. Outcome measures: isokinetic testing, quadriceps strength, hamstring strength, step‑down test, physical activity (measured by global positioning system with accelerometer). Status: Recruitment started in February 2012. Data collection is complete with the final report expected in 2015.
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Comparison of hamstring and the LARS hamstring augmentation double‑bundle ACL reconstruction: 2, 5 and 10‑year follow‑up. Aim: to provide mid‑ to long‑term results for patients following ACL repair using double‑bundle hamstring reconstruction or double‑bundle hamstring reconstruction augmented by the LARS. Patient numbers: double‑bundle hamstring reconstruction, 56; double‑bundle hamstring reconstruction augmented by the LARS, 56. Outcome measures: International Knee Documentation Committee score; Tegner score; Cincinnati rating system; Lysholm score; Lachman's test; ACL quality‑of‑life score; ACL recovery score; VAS pain rating; and KT‑1000 score. Status: Recruitment started April 2012. Data collection is ongoing, with publication of results expected from 2, 5 and 10‑year follow‑up points.
Costs and resource consequences
No published evidence on resource consequences was identified.
The distributor, Corin Group, states that the LARS is used widely across NHS trusts, with a total of 1142 LARS synthetic ligaments sold in the UK in 2014. The distributor also estimated that 25% of these ligaments were used in cruciate ligament procedures. Of these, approximately 3% were ACL and 97% were PCL.
One factor that could affect resource use is recovery time following surgery. It has been suggested that people having ligament replacement procedures with the LARS have a shorter rehabilitation and a faster return to pre‑injury function (Li et al. 2009; Gao et al. 2010). According to Li et al. (2009) this is because autografts and allografts must go through a process of remodelling, called ligamentisation (Scheffler et al. 2008). The LARS does not undergo this process (Liu et al. 2010) so people who have LARS surgery require less conservative treatment post‑operatively. However, current evidence to support this theory is based on small patient numbers in non‑comparative studies (Machotka 2010). It is not clear from the available evidence how the claimed faster rehabilitation would impact on resource use.
Using the LARS in ligament replacement may reduce resource use if it lowers the number of revision procedures needed as a result of graft failure. The Batty et al. (2015) study suggested that revision rates are lower for LARS surgery compared with other synthetic ligaments, although it is not clear if the difference was statistically significant (Batty et al. 2015). There is no clear evidence that revision rates are better for LARS surgeries compared to autografts and allografts. Smith et al. (2014) noted a failure rate of 0.78% for the LARS, which was lower than the rates recorded for autologous hamstring graft reconstruction (1.8–10.1%). However, the follow‑up length for the hamstring graft procedures was significantly longer, preventing a direct comparison of these figures.
Strengths and limitations of the evidence
The review by Batty et al. (2015) was a well‑conducted systematic review that synthesised the safety and efficacy data for synthetic ligament procedures on more than 1100 knees, reported in published, peer‑reviewed studies that were comparative, cohort, and case series of more than 10 patients. The scope was limited to synthetic devices in surgery of ACL or PCL, excluding studies of autograft or allograft procedures. This meant that complication figures were not compiled for autograft and allograft procedures, which are routinely used in current NHS practice, making it difficult to compare between the LARS and standard care. Limitations of the evidence included a paucity of well‑conducted, long‑term clinical trials and variability and heterogeneity in outcome reporting.
The quality of the efficacy evidence was evaluated using appropriate checklists. Potential sources of bias are summarised in table 8.
Table 8 Assessed sources of potential bias within included studies
|
Study |
Selection bias |
Performance bias |
Attrition bias |
Detection bias |
|
Nau et al. (2002) |
Yes |
No |
No |
Yes |
|
Liu et al. (2010) |
No |
Yes |
N/A |
Yes |
|
Pan et al. (2013) |
Yes |
Yes |
N/A |
Yes |
|
Li et al. (2009) |
Yes |
Yes |
N/A |
Yes |
|
Xu et al. (2014) |
Yes |
Yes |
N/A |
Yes |
The study by Nau et al. (2002), the only randomised trial summarised in this briefing, used a weak randomisation process (sealed envelopes) that could have resulted in selection bias. The distribution of sexes in the groups was also unbalanced; 19% women in the LARS group compared with 44% women in the autograft group. However, this was the only study with the same post‑operative rehabilitation protocol for both treatment groups and the same surgeon conducted all the procedures. Together, these factors eliminated major sources of performance bias.
As with all the studies, failure to blind participants may have resulted in detection bias. This is of particular concern for patient‑reported measures, such as IKDC and Tegner scores. The correlation between patient‑reported satisfaction and clinical measures of knee laxity can be poor (Lavoie et al. 2000; Hyder et al. 1997). This suggests patient‑reported measures may be prone to influence, although measures of laxity may also be poor surrogate outcomes. The methods used to collect patient‑reported measures in any of the studies were insufficiently detailed in any of the studies included to establish whether there was a risk of detection bias. The small sample size of the Nau et al. (2002) study (n=53) limited the likelihood of detecting statistically significant differences across the groups and pre‑ and post‑operatively.
The study by Liu et al. (2010) was at lower risk of selection bias because it used a temporal cut‑off to separate patients. However, this may have introduced procedural confounders, such as change in ward or physiotherapy practice over time. The study was retrospective and patients with incomplete follow‑up were excluded prior to analysis, which could have resulted in bias and limited external validity. Performance bias was possible because different post‑operative rehabilitation protocols were adopted for the 2 groups, although the same surgeon conducted all procedures. Li et al. (2009) noted that differences arising from alternative rehabilitation programmes should diminish over time, although at what point the effect would be negligible is unknown. Detection bias was also a risk because patients and clinicians were unblinded to the intervention being used. The small sample size in this study made detection of statistically significant differences difficult. Only univariate analysis was used, which did not control for confounding influences.
In the study by Pan et al. (2013) patients chose their preferred treatment regimen, which may have introduced selection bias. The study had a similar potential for performance and detection bias to Liu et al. (2010). No confounding factors were controlled for in the statistical analysis. This was the largest study (n=62) but no power calculations were provided to inform effect size. Incomplete follow‑up data was an exclusion criterion, which limited the generalisability of results.
Li et al. (2009) did not report the allocation method or test for statistically significant differences in the characteristics of treatment groups pre‑operatively, introducing a risk of selection bias. The study may also have performance bias, as a result of differing post‑operative rehabilitation regimes, and detection bias, because the patients and clinicians were not blinded to the intervention being used. The sample size in this study was small, the follow‑up was the shortest of the 5 studies, and only univariate analysis was conducted.
The study by Xu et al. (2014) used a similar methodology to that of Pan et al. (2013), creating risks of selection, performance and detection bias by the same mechanisms. Again, the sample size was small, confounders were not controlled and the external validity may have been limited by the patient recruitment method.
None of the included studies followed patients beyond 5 years. Longer‑term outcomes and rates of complications cannot be evaluated on the basis of these included studies.