Knee Adduction / Abduction

Why this matters

Frontal-plane knee mechanics are where the chain goes wrong fastest. The knee is a hinge; it's meant to flex and extend in the sagittal plane, not collapse sideways. When the knee collapses inward (adduction / valgus), the patellofemoral joint loads asymmetrically — the lateral edge of the patella grinds against the femur — and the medial collateral ligament takes tensile load it wasn't designed for. Outward collapse (abduction / varus) is rarer but loads the lateral compartment of the knee similarly.

Knee adduction is almost never a "knee problem" — it's a downstream sign of a hip stabiliser deficit (gluteus medius), or a foot stability deficit (over-pronation), or both. Coaching the knee directly rarely works. Strengthening the upstream / downstream stabilisers does.

What good looks like

At midstance the knee tracks straight over the foot. From the front, the thigh, knee, and ankle align in a roughly vertical line. The patella points forward, not inward.

Common faults

• Valgus collapse (>10° adduction) — knee falls inward under load. The hallmark of patellofemoral pain risk. Pair with pelvic drop = "dynamic valgus" — high-risk pattern.
• Varus / bow-leg (<−10°) — knee splays outward. Less common; loads the lateral meniscus and IT band.

Coaching cues

• "Knees over toes." Visual cue during single-leg drills.
• Strength: lateral band walks, single-leg squats with mirror feedback, hip-airplane drills.

Related measurements

• Pelvic Drop — the upstream driver. Treat them as one observation: "dynamic valgus."
• Pronation — the downstream driver. Over-pronation pulls the tibia into internal rotation, which rotates the knee into valgus.