Lateral extra-articular tenodesis linked to fewer ACL revisions in young patients

Design

Multicentre retrospective cohort with multivariable analysis

Population

780 patients aged 25 or under having primary ACL reconstruction

Primary outcome

Revision ACL reconstruction

Effect

LET OR 0.37 (0.22-0.62); slope 12 degrees or more: 21.0% vs 9.2%, NNT 9

This cohort study included 780 patients aged 25 or under having primary ACL reconstruction at three high-volume Dutch centres, with at least two years of follow-up. Posterior tibial slope was measured on lateral radiographs, and the analysis adjusted for graft type and other factors.

Overall, 10.8% needed revision. A slope of 12 degrees or more was present in 28% and was more common among those revised; each extra degree of lateral slope was associated with about 9% higher odds of revision. Adding lateral extra-articular tenodesis was associated with lower odds of revision (OR 0.37, 95% CI 0.22 to 0.62). In steep-slope knees, revision fell from 21.0% to 9.2% (absolute reduction 11.8%, number needed to treat 9); in flatter knees from 13.2% to 5.4% (number needed to treat 13).

The association held regardless of slope, which suggests LET is worth considering in young, high-risk patients whether or not the slope is steep. The decision to add LET was not randomised, so surgeon choice and patient selection may contribute. The finding is consistent with earlier randomised evidence supporting LET in young patients, and slope-reducing osteotomy remains a separate question for revision cases.

• Measure posterior tibial slope on the lateral radiograph before every primary ACL reconstruction in patients under 25.
• Consider adding lateral extra-articular tenodesis in young patients returning to pivoting sport.
• Discuss a higher revision risk with patients whose slope is 12 degrees or more.
• Record slope and LET use prospectively to audit your own revision rates.

Why it matters

Tibial slope is often unmeasured at the primary operation, yet it identifies the knees most likely to fail.

Don't overread it

This is a non-randomised cohort; the lower revision rate with LET may partly reflect who was chosen for it.

The statistics, in plain English

A number needed to treat of 9 means adding LET to about nine young steep-slope knees would be associated with one fewer revision. The interval around the absolute reduction (2.3% to 21.3%) is wide, so the true benefit could be much smaller or larger.

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