Lateral Extra-Articular Tenodesis (LET)

Patient information — Dr Christopher Spelman, Orthopaedic Surgeon

Overview

Lateral extra-articular tenodesis (LET) is a procedure performed on the outer side of the knee, usually at the same time as an anterior cruciate ligament (ACL) reconstruction. It reinforces the structures on the outside of the joint to control rotational stability. A strip of the iliotibial band (a strong band of tissue on the outer thigh) is left attached below the knee, passed beneath the lateral ligament and fixed to the thigh bone, creating an additional restraint against the pivoting movement that a torn ACL allows.

Why it is performed

Even after a well-performed ACL reconstruction, some patients continue to have subtle rotational looseness (a “pivot shift”), which is associated with poorer outcomes and a higher chance of graft failure. Adding an LET reduces this rotational laxity and protects the ACL graft. It is not required for everyone – it is targeted at patients at higher risk of graft failure.

Who may benefit

Dr Spelman may recommend adding an LET to your ACL reconstruction if you have one or more of the following higher-risk features:

●      Young age (particularly under 25 years)

●      Return to high-risk pivoting or contact sports

●      High-grade rotational laxity (a marked pivot shift)

●      Generalised ligamentous laxity (naturally loose joints)

●      Revision ACL surgery (a previously failed reconstruction)

Outcomes and what the evidence shows

The STABILITY randomised controlled trial studied young, active patients undergoing hamstring ACL reconstruction with or without an LET. Adding an LET significantly reduced clinical failure (25% versus 40%) and graft rupture (4% versus 11%) at two years. The number of patients who needed to have an LET added to prevent one graft rupture was approximately 14. Later analysis confirmed that the LET was protective against graft rupture and persistent rotational laxity.

Importantly, although there has been a theoretical concern that reinforcing the outer side of the knee could “over-tighten” it and lead to arthritis, the best available evidence indicates that adding an LET to ACL reconstruction does not increase the rate of osteoarthritis; associated meniscal injury at the time of the original injury is a stronger predictor of later arthritis.

Complications

Adding an LET involves a small additional incision on the outer thigh and generally adds little to the overall risk of ACL surgery. Specific considerations include:

●      Lateral knee pain or tenderness – some patients notice discomfort over the outer side of the knee with movement in the early months; this usually settles.

●      Hardware irritation – if a staple or screw is used to fix the tissue, it can occasionally be prominent or irritating and rarely needs removal.

●      Theoretical over-constraint – excessive tightening of the outer side; careful surgical technique (correct tension and knee position during fixation) minimises this, and it does not appear to translate into increased arthritis in the medium term.

●      Wound issues and numbness – a small area of altered sensation near the incision can occur.

●      The general risks of any knee surgery – infection and blood clots – remain uncommon.

Summary

For selected high-risk patients, adding an LET to ACL reconstruction meaningfully reduces the chance of the graft failing, with only a small increase in surgical risk. Dr Spelman will advise whether it is appropriate for your knee.