Review on LARS - An alternative for ligament reconstruction

I was asked about the efficacy of LARS as an alternative surgical option for ACL reconstruction. 

In recent years, the use of LARS ligaments have been increasing with promising clinical results. In fact, these ligaments have been in clinical use for over 15 years. LARS stands for Ligament Augmentation & Reconstruction System, and these artificial ligaments are intended for the intra or extra-articular reconstruction of ruptured ligaments.

Background

LARS can be used in conjunction with suturing to the remnant of the ruptured ligament, or as an autogenous reconstruction. In both cases LARS allows the original ligament tissues to heal in the absence of traction and provides an earlier return to normal function. LARS can also be used for extra-articular reconstructions in tendon repairs.

LARS have been used in reconstructions of:

• Rotator Cuff
• Acromio-Clavicular Dislocation
• Bicep Tendon
• Hip Abudctor Mechanism
• Anterior and Posterior Cruciate Ligaments (ACL, PCL)
• Medial and Lateral Collateral Ligaments (MCL, LCL)
• Patellar Tendon
• Achilles Tendon
• Lateral Ankle Instability

Biological and mechanical testing on resistance, fatigue and creep have shown that LARS ligaments are highly effective ligament reconstruction and augmentation devices, and long-term clinical results are excellent. The use of the LARS artificial ligament requires a specific surgical technique, with dedicated LARS instruments. 

LARS for ACL?

 

The LARS ACL has the intra-articular bundles in clockwise or anticlockwise orientation; this is to mimic the natural ligaments in the right or left knee. It can be used in acute injuries or where there is a good ACL stump that is well vascularised. In chronic cases, if the rupture is on the femoral part or the ACL has attached to the PCL, this can be dissected off the PCL and can then be reconstructed like an acute case. In chronic cases where there are no usable ACL remnants, an autogenous reconstruction reinforced by LARS is recommended.

LARS ACL ligaments come in many different sizes so that selection according to weight and activity can be precise. The ACL synthetic ligaments have been used extensively with excellent clinical results.

Research Findings on LARS for ACL 

1. Patient satisfaction needs as related to knee stability and objective findings after ACL reconstruction using the LARS (Lavoie et al, 2000; The Knee, p.157-163)

Aim: The purposes of this study are to compare patient satisfaction with the objective measurement of knee stability and assess early complications following ACL reconstruction using a LARS. 

Method: 47 patients were reviewed 8–45 months after surgery. 

Conclusion: The LARS may be a safe device to reconstruct an ACL tear.

2. A new generation of artificial ligaments in reconstruction of the ACL. A Two year follow up of a randomised trial bone patella bone in 27 patients vs LARS in 26 patients. Assessment before and at 2, 6, 12, 24 months after surgery (Nav et al, 2002; Journal of Bone & Joint Surgery, p.356-360) 

Results: There were no cases of synovitus or of infection of the knee. There was no difference regarding the failure rate of the groups. 

- The IKDC (International Knee Documentation Committee) Subjective Knee Form showed no significant differences between the two groups at any stage of the follow up. 

- The KOOS (Knee injury Osteoarthritis Outcome Score) evaluation showed consistently higher results in all subscales for the LARS group during the first year of follow up.

- After 24 months these differences were no longer evident. 

Conclusion: Our findings suggest that at follow up at 24 months the LARS seems to be a satisfactory treatment option, especially when an early return to high levels of activity is demanded.

  

3. The use of the Free Fibres in Acute ACL Repairs (Laboureau, 1997; Biomaterial Advances)

Background: LARS allows a purely arthroscopic technique which respects proprioception. It is a conservative approach since the tunnels drilled are small. The results are at least comparable to other techniques but simpler and faster for the patient.

Sample: 219 patients, follow-up 1-5 years

Results: Post operative arthroscopic and histological controls showed that the LARS were well tolerated and invaded by fibrous tissue while the torn ACL was perfectly healed when the injury was located at the upper or lower extremity but not so well for mid substance injuries.

4. ACL reconstruction, using artificial Ligament, 5 years follow up (Cerulli et al, 2007; International Society of Orthopaedic Surgery and Traumatology, 33 (Supp1): S238-242)

Method: 5-year follow-up

Conclusion: The researchers did not experience any bad complications as of the 80s; none of the patients had significant swelling of the knee as signs of chronic post-op synovitis, and the objective and subjective results were positive in over 95%. From the 25 cases tested, only one had bad results, based on the clinical and instrumental evaluation, which showed residual knee instability.

Summary

In conclusion, I would say that there has been some good clinical results shown with the use of LARS as an alternative option for ligament and tendon reconstructions. However there has not been enough strong research evidence as yet to support the clinical reports. Therefore, more research is needed to investigate the long-term efficacy of LARS and its rehabilitation outcomes.