On each of these mini episodes, Catherine and I chat about a new article or new surgical technique in the field of sports medicine. We’ll give you our quick take on the most recent data and how this data will impact our practice.

Today, we’re discussing a brand-new paper hot off the press titled: “Predictors of Tunnel Widening After Anterior Cruciate Ligament Reconstruction” published in the November 2025 issue of AJSM. This study digs into why femoral and tibial tunnels enlarge after ACL reconstruction with hamstring grafts – and what anatomic and surgical factors might be driving it.

Tunnel widening matters: it impacts revision surgery, graft stability, and in some cases early failures. So, this is a clinically meaningful topic.

We will start with some background. Tunnel widening after ACL reconstruction is not new…but why it happens is debated. There are a few proposed mechanisms:

· Biologic factors: synovial fluid ingress, cytokines, graft necrosis, remodeling.

· Mechanical factors: graft motion (“windshield wiper” / “bungee effect”), repetitive shear.

· Anatomic factors: posterior tibial slope increasing anterior tibial translation forces.

· Surgical factors: fixation method, tunnel position, graft choice (hamstring vs BTB or Quad). This study asked three key questions:

1. Does posterior tibial slope (PTS) predict tunnel widening?

2. Do meniscus root tears contribute?

3. Does adding a lateral extra-articular tenodesis (LET) influence tunnel change?

· This is the first large cohort looking at all these together over 2 years, with both tibial and femoral tunnel measurements.

· The study included 307 patients who underwent primary ACL reconstruction using hamstring autograft. The femoral and tibial tunnels were measured immediately postop and again at 2 years. Medial and lateral posterior tibial slope was measured on long-leg lateral radiographs. The authors also looked at the incidence of additional LET, meniscus root injury and BMI.

· They used univariate and multivariate regression to determine independent predictors.

So, what did they find? Tune in and enjoy the episode!