Shoulder 90/90
Biomechanical analysis of shoulder 90/90 range of motion assessment for external and internal rotation with compensations.
Shoulder 90/90
Overview
The shoulder 90/90 assessment evaluates the range of motion and quality of movement in the shoulder during external and internal rotation with the arm in 90° abduction. This assessment measures the ability to achieve sufficient rotation while maintaining proper alignment and identifying any compensations.Events
| Event | Data Type | Description |
|---|---|---|
| MER | Int | Frame of maximum external rotation |
| MIR | Int | Frame of maximum internal rotation |
| Start | Int | Frame of movement start |
Discrete Metrics
| Metric | Data Type | Units | Description |
|---|---|---|---|
| MERAngle | Float | degrees | Maximum External Rotation angle |
| MIRAngle | Float | degrees | Maximum Internal Rotation angle |
| HorizontalAbductionCompMER | Int | - | Horizontal abduction compensation at MER (1 if > 30°, -1 if < -30°) |
| HorizontalAbductionCompMIR | Int | - | Horizontal abduction compensation at MIR (1 if > 30°, -1 if < -30°) |
| SideBendCompMER | Int | - | Side bend compensation at MER (1 if > 20°, -1 if < -20°) |
| SideBendCompMIR | Int | - | Side bend compensation at MIR (1 if > 20°, -1 if < -20°) |
| ElbowHikeCompMER | Int | - | Elbow hike compensation at MER (1 if > 0.05m, -1 if < -0.05m) |
| ElbowHikeCompMIR | Int | - | Elbow hike compensation at MIR (1 if > 0.05m, -1 if < -0.05m) |
| MERFunctional | Boolean | - | Whether MER is functional (> 90°) |
Notes
- All angular measurements follow ISB conventions
- MER is detected using peak detection with 30° prominence
- MIR is detected using peak detection with 30° prominence on inverted signal
- Start event is detected by finding a window of 30 frames where the shoulder rotation difference is less than 0.5 degrees
- Functional MER is defined as > 90°