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Test protocol · Injury-risk screening

CMAS Cut Test45° · 60° cuts 90° coming soon

1Record2Upload3See the CMAS score
The problem: many non-contact ACL injuries happen while cutting. The postures that load the knee most (wide foot plant, knee valgus, trunk lean over the plant leg) can be seen on video. Until now, scoring them meant slow frame-by-frame review.

VueMotion automates the Cutting Movement Assessment Score (CMAS) from three synchronised iPhones. One person controls the capture from an iPad or iPhone, and the score arrives after upload.

ρ 0.80
CMAS vs peak knee abduction moment
0–11
score range, 9 items
3
synced camera views
01 · Setup

Camera and cone placement

Pick a cut angle to see the layout, which follows the CMAS paper. All three cameras and the 5 m approach stay in the same place for every angle. Only the exit cone moves. 45° and 60° are supported now; 90° is coming soon.

PhaseApproach
StepPenultimate contact (PFC)Plant (final contact)
C1

Sagittal

Side-on at the plant point, about 5 m away, on the side opposite the exit. Scores PFC braking, trunk and knee flexion.

C2

Frontal

On the approach line, about 3 m beyond the plant point, facing the athlete. Scores plant width, knee valgus, foot and trunk position.

C3

Oblique (20°)

Level with C2 (about 3 m out), 20° off the approach line on the exit side, facing the plant. The paper recommends 20° over 45° because it gives less parallax error.

90° is coming soon. The layout is shown so you can plan ahead; automated CMAS scoring currently covers 45° and 60° cuts.

All cameras: tripod, lens at athlete hip height (≈ 1 m), landscape, 1× lens, 1080p at 120 fps or higher (the CMAS authors recommend ≥ 100 Hz). Start 0.5 m behind the timing gate if you use one. To test the other leg, mirror the exit cone and move C1 and C3 to their mirror positions. C2 does not move.

02 · Capture

Three cameras, one operator

The VueMotion Controller capture module runs all three iPhones from one iPad or iPhone. Recording starts together on every camera and the three views upload as one trial.

Controller (iPad / iPhone) C2 Frontal C1 Sagittal C3 Oblique
1

Connect

Open the Controller and connect the three iPhones, each labelled C2, C1 or C3.

2

Frame check

Live previews: the plant marker is centred and the full path is in shot on every camera.

3

Tag

Choose the athlete and the test tag, e.g. CMAS-60-R (angle and plant leg).

4

Record

One tap starts all three cameras. Stop once the athlete passes the exit cone.

5

Upload

The three views upload as one trial and AI analysis starts automatically.

Equipment

  • 3 × iPhone 11 or newer + 3 tripods
  • 1 × iPad or iPhone (controller)
  • Start and exit cones + a flat plant marker
  • Measuring tape (10 m or longer)

Athlete protocol

  • Full warm-up, including progressive cuts
  • Maximal or sport-specific intensity
  • 3 good trials per leg for each angle
  • Discard trials with early slowing or a missed marker

Camera settings

  • 1080p at 120 fps (240 fps outdoors)
  • Auto-FPS off, focus and exposure locked
  • Do Not Disturb on, Auto-Lock never
  • Only the tested athlete in frame
03 · What is scored

What the cameras look for at the plant

Frontal view (C2) · athlete plants with the right leg and cuts to their left

    A wide plant, knee valgus and trunk lean over the plant leg all lengthen the lever arm between the ground reaction force and the knee. That raises the knee abduction moment, a key surrogate of ACL injury risk.

    #CMAS itemMain viewPoints
    1No clear braking strategy on the penultimate foot contact (PFC)C10 or 1
    2Wide lateral leg plant (more than ~0.35 m)C20 / 1 / 2
    3Hip in an initially internally rotated positionC2 · C30 or 1
    4Initial knee valgus positionC20 or 1
    5Foot not in a neutral positionAll0 or 1
    6Trunk position vs the intended direction (medial / upright / lateral or rotated)C2 · C30 / 1 / 2
    7Trunk upright or leaning back throughout contactC1 · C30 or 1
    8Limited knee flexion during final contact (≤ 30°)C1 · C30 or 1
    9Excessive knee valgus motion during contactC2 · C30 or 1

    Total CMAS = sum of item scores, 0–11. Higher scores mean more "high-risk" postures.

    04 · Results

    What you get after upload

    Pose estimation, event detection (PFC, plant, peak knee flexion, toe-off) and item scoring all run automatically. There is no manual frame-by-frame review.

    Total CMAS · example
    0 / 11
    ≤ 34–6≥ 7

    Bands are the lower, middle and upper thirds of scores in the validation study, not clinical cut-offs.

    Item-by-item scores

    All nine items, with the measured angle or distance behind each score.

    Key-event kinograms

    PFC, plant touchdown, peak knee flexion and toe-off, from all three views.

    Left vs right

    Mean CMAS per plant leg across trials, with asymmetries flagged.

    Trends and reports

    Track change over time. PDF report, plus CSV / API for Enterprise and Academy accounts.

    CMAS screens movement quality linked to knee load. It does not diagnose, and it does not predict an individual's injury.

    With thanks to the CMAS authors

    The Cutting Movement Assessment Score was developed and validated by Thomas Dos'Santos, Christopher Thomas, Alistair McBurnie, Thomas Donelon, Lee Herrington and Paul A. Jones (Manchester Metropolitan University, University of Salford, Manchester United FC and Canterbury Christ Church University). VueMotion automates their published criteria; the scoring framework is theirs.

    1. Dos'Santos T, Thomas C, McBurnie A, Donelon T, Herrington L, Jones PA. The Cutting Movement Assessment Score (CMAS) qualitative screening tool: application to mitigate anterior cruciate ligament injury risk during cutting. Biomechanics. 2021;1(1):83–101. doi:10.3390/biomechanics1010007
    2. Dos'Santos T, McBurnie A, Donelon T, Thomas C, Comfort P, Jones PA. A qualitative screening tool to identify athletes with 'high-risk' movement mechanics during cutting: the Cutting Movement Assessment Score (CMAS). Physical Therapy in Sport. 2019;38:152–161.
    3. Jones PA, Rai A, Dos'Santos T, Herrington LC. Inter-professional and methodological agreement in using the Cutting Movement Assessment Score (CMAS). Biomechanics. 2023;3(2):181–192.